mirror of https://github.com/asterisk/asterisk
You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
10867 lines
364 KiB
10867 lines
364 KiB
|
|
|
|
|
|
|
|
|
|
|
|
Network Working Group S. Andersen
|
|
Request for Comments: 3951 Aalborg University
|
|
Category: Experimental A. Duric
|
|
Telio
|
|
H. Astrom
|
|
R. Hagen
|
|
W. Kleijn
|
|
J. Linden
|
|
Global IP Sound
|
|
December 2004
|
|
|
|
|
|
Internet Low Bit Rate Codec (iLBC)
|
|
|
|
Status of this Memo
|
|
|
|
This memo defines an Experimental Protocol for the Internet
|
|
community. It does not specify an Internet standard of any kind.
|
|
Discussion and suggestions for improvement are requested.
|
|
Distribution of this memo is unlimited.
|
|
|
|
Copyright Notice
|
|
|
|
Copyright (C) The Internet Society (2004).
|
|
|
|
Abstract
|
|
|
|
This document specifies a speech codec suitable for robust voice
|
|
communication over IP. The codec is developed by Global IP Sound
|
|
(GIPS). It is designed for narrow band speech and results in a
|
|
payload bit rate of 13.33 kbit/s for 30 ms frames and 15.20 kbit/s
|
|
for 20 ms frames. The codec enables graceful speech quality
|
|
degradation in the case of lost frames, which occurs in connection
|
|
with lost or delayed IP packets.
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
Andersen, et al. Experimental [Page 1]
|
|
|
|
RFC 3951 Internet Low Bit Rate Codec December 2004
|
|
|
|
|
|
Table of Contents
|
|
|
|
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4
|
|
2. Outline of the Codec . . . . . . . . . . . . . . . . . . . . . 5
|
|
2.1. Encoder. . . . . . . . . . . . . . . . . . . . . . . . . 5
|
|
2.2. Decoder. . . . . . . . . . . . . . . . . . . . . . . . . 7
|
|
3. Encoder Principles . . . . . . . . . . . . . . . . . . . . . . 7
|
|
3.1. Pre-processing . . . . . . . . . . . . . . . . . . . . . 9
|
|
3.2. LPC Analysis and Quantization. . . . . . . . . . . . . . 9
|
|
3.2.1. Computation of Autocorrelation Coefficients. . . 10
|
|
3.2.2. Computation of LPC Coefficients. . . . . . . . . 11
|
|
3.2.3. Computation of LSF Coefficients from LPC
|
|
Coefficients . . . . . . . . . . . . . . . . . . 11
|
|
3.2.4. Quantization of LSF Coefficients . . . . . . . . 12
|
|
3.2.5. Stability Check of LSF Coefficients. . . . . . . 13
|
|
3.2.6. Interpolation of LSF Coefficients. . . . . . . . 13
|
|
3.2.7. LPC Analysis and Quantization for 20 ms Frames . 14
|
|
3.3. Calculation of the Residual. . . . . . . . . . . . . . . 15
|
|
3.4. Perceptual Weighting Filter. . . . . . . . . . . . . . . 15
|
|
3.5. Start State Encoder. . . . . . . . . . . . . . . . . . . 15
|
|
3.5.1. Start State Estimation . . . . . . . . . . . . . 16
|
|
3.5.2. All-Pass Filtering and Scale Quantization. . . . 17
|
|
3.5.3. Scalar Quantization. . . . . . . . . . . . . . . 18
|
|
3.6. Encoding the Remaining Samples . . . . . . . . . . . . . 19
|
|
3.6.1. Codebook Memory. . . . . . . . . . . . . . . . . 20
|
|
3.6.2. Perceptual Weighting of Codebook Memory
|
|
and Target . . . . . . . . . . . . . . . . . . . 22
|
|
3.6.3. Codebook Creation. . . . . . . . . . . . . . . . 23
|
|
3.6.3.1. Creation of a Base Codebook . . . . . . 23
|
|
3.6.3.2. Codebook Expansion. . . . . . . . . . . 24
|
|
3.6.3.3. Codebook Augmentation . . . . . . . . . 24
|
|
3.6.4. Codebook Search. . . . . . . . . . . . . . . . . 26
|
|
3.6.4.1. Codebook Search at Each Stage . . . . . 26
|
|
3.6.4.2. Gain Quantization at Each Stage . . . . 27
|
|
3.6.4.3. Preparation of Target for Next Stage. . 28
|
|
3.7. Gain Correction Encoding . . . . . . . . . . . . . . . . 28
|
|
3.8. Bitstream Definition . . . . . . . . . . . . . . . . . . 29
|
|
4. Decoder Principles . . . . . . . . . . . . . . . . . . . . . . 32
|
|
4.1. LPC Filter Reconstruction. . . . . . . . . . . . . . . . 33
|
|
4.2. Start State Reconstruction . . . . . . . . . . . . . . . 33
|
|
4.3. Excitation Decoding Loop . . . . . . . . . . . . . . . . 34
|
|
4.4. Multistage Adaptive Codebook Decoding. . . . . . . . . . 35
|
|
4.4.1. Construction of the Decoded Excitation Signal. . 35
|
|
4.5. Packet Loss Concealment. . . . . . . . . . . . . . . . . 35
|
|
4.5.1. Block Received Correctly and Previous Block
|
|
Also Received. . . . . . . . . . . . . . . . . . 35
|
|
4.5.2. Block Not Received . . . . . . . . . . . . . . . 36
|
|
|
|
|
|
|
|
|
|
Andersen, et al. Experimental [Page 2]
|
|
|
|
RFC 3951 Internet Low Bit Rate Codec December 2004
|
|
|
|
|
|
4.5.3. Block Received Correctly When Previous Block
|
|
Not Received . . . . . . . . . . . . . . . . . . 36
|
|
4.6. Enhancement. . . . . . . . . . . . . . . . . . . . . . . 37
|
|
4.6.1. Estimating the Pitch . . . . . . . . . . . . . . 39
|
|
4.6.2. Determination of the Pitch-Synchronous
|
|
Sequences. . . . . . . . . . . . . . . . . . . . 39
|
|
4.6.3. Calculation of the Smoothed Excitation . . . . . 41
|
|
4.6.4. Enhancer Criterion . . . . . . . . . . . . . . . 41
|
|
4.6.5. Enhancing the Excitation . . . . . . . . . . . . 42
|
|
4.7. Synthesis Filtering. . . . . . . . . . . . . . . . . . . 43
|
|
4.8. Post Filtering . . . . . . . . . . . . . . . . . . . . . 43
|
|
5. Security Considerations. . . . . . . . . . . . . . . . . . . . 43
|
|
6. Evaluation of the iLBC Implementations . . . . . . . . . . . . 43
|
|
7. References . . . . . . . . . . . . . . . . . . . . . . . . . . 43
|
|
7.1. Normative References . . . . . . . . . . . . . . . . . . 43
|
|
7.2. Informative References . . . . . . . . . . . . . . . . . 44
|
|
8. ACKNOWLEDGEMENTS . . . . . . . . . . . . . . . . . . . . . . . 44
|
|
APPENDIX A: Reference Implementation . . . . . . . . . . . . . . . 45
|
|
A.1. iLBC_test.c. . . . . . . . . . . . . . . . . . . . . . . 46
|
|
A.2 iLBC_encode.h. . . . . . . . . . . . . . . . . . . . . . 52
|
|
A.3. iLBC_encode.c. . . . . . . . . . . . . . . . . . . . . . 53
|
|
A.4. iLBC_decode.h. . . . . . . . . . . . . . . . . . . . . . 63
|
|
A.5. iLBC_decode.c. . . . . . . . . . . . . . . . . . . . . . 64
|
|
A.6. iLBC_define.h. . . . . . . . . . . . . . . . . . . . . . 76
|
|
A.7. constants.h. . . . . . . . . . . . . . . . . . . . . . . 80
|
|
A.8. constants.c. . . . . . . . . . . . . . . . . . . . . . . 82
|
|
A.9. anaFilter.h. . . . . . . . . . . . . . . . . . . . . . . 96
|
|
A.10. anaFilter.c. . . . . . . . . . . . . . . . . . . . . . . 97
|
|
A.11. createCB.h . . . . . . . . . . . . . . . . . . . . . . . 98
|
|
A.12. createCB.c . . . . . . . . . . . . . . . . . . . . . . . 99
|
|
A.13. doCPLC.h . . . . . . . . . . . . . . . . . . . . . . . .104
|
|
A.14. doCPLC.c . . . . . . . . . . . . . . . . . . . . . . . .104
|
|
A.15. enhancer.h . . . . . . . . . . . . . . . . . . . . . . .109
|
|
A.16. enhancer.c . . . . . . . . . . . . . . . . . . . . . . .110
|
|
A.17. filter.h . . . . . . . . . . . . . . . . . . . . . . . .123
|
|
A.18. filter.c . . . . . . . . . . . . . . . . . . . . . . . .125
|
|
A.19. FrameClassify.h. . . . . . . . . . . . . . . . . . . . .128
|
|
A.20. FrameClassify.c. . . . . . . . . . . . . . . . . . . . .129
|
|
A.21. gainquant.h. . . . . . . . . . . . . . . . . . . . . . .131
|
|
A.22. gainquant.c. . . . . . . . . . . . . . . . . . . . . . .131
|
|
A.23. getCBvec.h . . . . . . . . . . . . . . . . . . . . . . .134
|
|
A.24. getCBvec.c . . . . . . . . . . . . . . . . . . . . . . .134
|
|
A.25. helpfun.h. . . . . . . . . . . . . . . . . . . . . . . .138
|
|
A.26. helpfun.c. . . . . . . . . . . . . . . . . . . . . . . .140
|
|
A.27. hpInput.h. . . . . . . . . . . . . . . . . . . . . . . .146
|
|
A.28. hpInput.c. . . . . . . . . . . . . . . . . . . . . . . .146
|
|
A.29. hpOutput.h . . . . . . . . . . . . . . . . . . . . . . .148
|
|
A.30. hpOutput.c . . . . . . . . . . . . . . . . . . . . . . .148
|
|
|
|
|
|
|
|
Andersen, et al. Experimental [Page 3]
|
|
|
|
RFC 3951 Internet Low Bit Rate Codec December 2004
|
|
|
|
|
|
A.31. iCBConstruct.h . . . . . . . . . . . . . . . . . . . . .149
|
|
A.32. iCBConstruct.c . . . . . . . . . . . . . . . . . . . . .150
|
|
A.33. iCBSearch.h. . . . . . . . . . . . . . . . . . . . . . .152
|
|
A.34. iCBSearch.c. . . . . . . . . . . . . . . . . . . . . . .153
|
|
A.35. LPCdecode.h. . . . . . . . . . . . . . . . . . . . . . .163
|
|
A.36. LPCdecode.c. . . . . . . . . . . . . . . . . . . . . . .164
|
|
A.37. LPCencode.h. . . . . . . . . . . . . . . . . . . . . . .167
|
|
A.38. LPCencode.c. . . . . . . . . . . . . . . . . . . . . . .167
|
|
A.39. lsf.h. . . . . . . . . . . . . . . . . . . . . . . . . .172
|
|
A.40. lsf.c. . . . . . . . . . . . . . . . . . . . . . . . . .172
|
|
A.41. packing.h. . . . . . . . . . . . . . . . . . . . . . . .178
|
|
A.42. packing.c. . . . . . . . . . . . . . . . . . . . . . . .179
|
|
A.43. StateConstructW.h. . . . . . . . . . . . . . . . . . . .182
|
|
A.44. StateConstructW.c. . . . . . . . . . . . . . . . . . . .183
|
|
A.45. StateSearchW.h . . . . . . . . . . . . . . . . . . . . .185
|
|
A.46. StateSearchW.c . . . . . . . . . . . . . . . . . . . . .186
|
|
A.47. syntFilter.h . . . . . . . . . . . . . . . . . . . . . .190
|
|
A.48. syntFilter.c . . . . . . . . . . . . . . . . . . . . . .190
|
|
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . .192
|
|
Full Copyright Statement . . . . . . . . . . . . . . . . . . . . .194
|
|
|
|
1. Introduction
|
|
|
|
This document contains the description of an algorithm for the coding
|
|
of speech signals sampled at 8 kHz. The algorithm, called iLBC, uses
|
|
a block-independent linear-predictive coding (LPC) algorithm and has
|
|
support for two basic frame lengths: 20 ms at 15.2 kbit/s and 30 ms
|
|
at 13.33 kbit/s. When the codec operates at block lengths of 20 ms,
|
|
it produces 304 bits per block, which SHOULD be packetized as in [1].
|
|
Similarly, for block lengths of 30 ms it produces 400 bits per block,
|
|
which SHOULD be packetized as in [1]. The two modes for the
|
|
different frame sizes operate in a very similar way. When they
|
|
differ it is explicitly stated in the text, usually with the notation
|
|
x/y, where x refers to the 20 ms mode and y refers to the 30 ms mode.
|
|
|
|
The described algorithm results in a speech coding system with a
|
|
controlled response to packet losses similar to what is known from
|
|
pulse code modulation (PCM) with packet loss concealment (PLC), such
|
|
as the ITU-T G.711 standard [4], which operates at a fixed bit rate
|
|
of 64 kbit/s. At the same time, the described algorithm enables
|
|
fixed bit rate coding with a quality-versus-bit rate tradeoff close
|
|
to state-of-the-art. A suitable RTP payload format for the iLBC
|
|
codec is specified in [1].
|
|
|
|
Some of the applications for which this coder is suitable are real
|
|
time communications such as telephony and videoconferencing,
|
|
streaming audio, archival, and messaging.
|
|
|
|
|
|
|
|
|
|
Andersen, et al. Experimental [Page 4]
|
|
|
|
RFC 3951 Internet Low Bit Rate Codec December 2004
|
|
|
|
|
|
Cable Television Laboratories (CableLabs(R)) has adopted iLBC as a
|
|
mandatory PacketCable(TM) audio codec standard for VoIP over Cable
|
|
applications [3].
|
|
|
|
This document is organized as follows. Section 2 gives a brief
|
|
outline of the codec. The specific encoder and decoder algorithms
|
|
are explained in sections 3 and 4, respectively. Appendix A provides
|
|
a c-code reference implementation.
|
|
|
|
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
|
|
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
|
|
document are to be interpreted as described in BCP 14, RFC 2119 [2].
|
|
|
|
2. Outline of the Codec
|
|
|
|
The codec consists of an encoder and a decoder as described in
|
|
sections 2.1 and 2.2, respectively.
|
|
|
|
The essence of the codec is LPC and block-based coding of the LPC
|
|
residual signal. For each 160/240 (20 ms/30 ms) sample block, the
|
|
following major steps are performed: A set of LPC filters are
|
|
computed, and the speech signal is filtered through them to produce
|
|
the residual signal. The codec uses scalar quantization of the
|
|
dominant part, in terms of energy, of the residual signal for the
|
|
block. The dominant state is of length 57/58 (20 ms/30 ms) samples
|
|
and forms a start state for dynamic codebooks constructed from the
|
|
already coded parts of the residual signal. These dynamic codebooks
|
|
are used to code the remaining parts of the residual signal. By this
|
|
method, coding independence between blocks is achieved, resulting in
|
|
elimination of propagation of perceptual degradations due to packet
|
|
loss. The method facilitates high-quality packet loss concealment
|
|
(PLC).
|
|
|
|
2.1. Encoder
|
|
|
|
The input to the encoder SHOULD be 16 bit uniform PCM sampled at 8
|
|
kHz. It SHOULD be partitioned into blocks of BLOCKL=160/240 samples
|
|
for the 20/30 ms frame size. Each block is divided into NSUB=4/6
|
|
consecutive sub-blocks of SUBL=40 samples each. For 30 ms frame
|
|
size, the encoder performs two LPC_FILTERORDER=10 linear-predictive
|
|
coding (LPC) analyses. The first analysis applies a smooth window
|
|
centered over the second sub-block and extending to the middle of the
|
|
fifth sub-block. The second LPC analysis applies a smooth asymmetric
|
|
window centered over the fifth sub-block and extending to the end of
|
|
the sixth sub-block. For 20 ms frame size, one LPC_FILTERORDER=10
|
|
linear-predictive coding (LPC) analysis is performed with a smooth
|
|
window centered over the third sub-frame.
|
|
|
|
|
|
|
|
|
|
Andersen, et al. Experimental [Page 5]
|
|
|
|
RFC 3951 Internet Low Bit Rate Codec December 2004
|
|
|
|
|
|
For each of the LPC analyses, a set of line-spectral frequencies
|
|
(LSFs) are obtained, quantized, and interpolated to obtain LSF
|
|
coefficients for each sub-block. Subsequently, the LPC residual is
|
|
computed by using the quantized and interpolated LPC analysis
|
|
filters.
|
|
|
|
The two consecutive sub-blocks of the residual exhibiting the maximal
|
|
weighted energy are identified. Within these two sub-blocks, the
|
|
start state (segment) is selected from two choices: the first 57/58
|
|
samples or the last 57/58 samples of the two consecutive sub-blocks.
|
|
The selected segment is the one of higher energy. The start state is
|
|
encoded with scalar quantization.
|
|
|
|
A dynamic codebook encoding procedure is used to encode 1) the 23/22
|
|
(20 ms/30 ms) remaining samples in the two sub-blocks containing the
|
|
start state; 2) the sub-blocks after the start state in time; and 3)
|
|
the sub-blocks before the start state in time. Thus, the encoding
|
|
target can be either the 23/22 samples remaining of the two sub-
|
|
blocks containing the start state or a 40-sample sub-block. This
|
|
target can consist of samples indexed forward in time or backward in
|
|
time, depending on the location of the start state.
|
|
|
|
The codebook coding is based on an adaptive codebook built from a
|
|
codebook memory that contains decoded LPC excitation samples from the
|
|
already encoded part of the block. These samples are indexed in the
|
|
same time direction as the target vector, ending at the sample
|
|
instant prior to the first sample instant represented in the target
|
|
vector. The codebook is used in CB_NSTAGES=3 stages in a successive
|
|
refinement approach, and the resulting three code vector gains are
|
|
encoded with 5-, 4-, and 3-bit scalar quantization, respectively.
|
|
|
|
The codebook search method employs noise shaping derived from the LPC
|
|
filters, and the main decision criterion is to minimize the squared
|
|
error between the target vector and the code vectors. Each code
|
|
vector in this codebook comes from one of CB_EXPAND=2 codebook
|
|
sections. The first section is filled with delayed, already encoded
|
|
residual vectors. The code vectors of the second codebook section
|
|
are constructed by predefined linear combinations of vectors in the
|
|
first section of the codebook.
|
|
|
|
As codebook encoding with squared-error matching is known to produce
|
|
a coded signal of less power than does the scalar quantized start
|
|
state signal, a gain re-scaling method is implemented by a refined
|
|
search for a better set of codebook gains in terms of power matching
|
|
after encoding. This is done by searching for a higher value of the
|
|
gain factor for the first stage codebook, as the subsequent stage
|
|
codebook gains are scaled by the first stage gain.
|
|
|
|
|
|
|
|
|
|
Andersen, et al. Experimental [Page 6]
|
|
|
|
RFC 3951 Internet Low Bit Rate Codec December 2004
|
|
|
|
|
|
2.2. Decoder
|
|
|
|
Typically for packet communications, a jitter buffer placed at the
|
|
receiving end decides whether the packet containing an encoded signal
|
|
block has been received or lost. This logic is not part of the codec
|
|
described here. For each encoded signal block received the decoder
|
|
performs a decoding. For each lost signal block, the decoder
|
|
performs a PLC operation.
|
|
|
|
The decoding for each block starts by decoding and interpolating the
|
|
LPC coefficients. Subsequently the start state is decoded.
|
|
|
|
For codebook-encoded segments, each segment is decoded by
|
|
constructing the three code vectors given by the received codebook
|
|
indices in the same way that the code vectors were constructed in the
|
|
encoder. The three gain factors are also decoded and the resulting
|
|
decoded signal is given by the sum of the three codebook vectors
|
|
scaled with respective gain.
|
|
|
|
An enhancement algorithm is applied to the reconstructed excitation
|
|
signal. This enhancement augments the periodicity of voiced speech
|
|
regions. The enhancement is optimized under the constraint that the
|
|
modification signal (defined as the difference between the enhanced
|
|
excitation and the excitation signal prior to enhancement) has a
|
|
short-time energy that does not exceed a preset fraction of the
|
|
short-time energy of the excitation signal prior to enhancement.
|
|
|
|
A packet loss concealment (PLC) operation is easily embedded in the
|
|
decoder. The PLC operation can, e.g., be based on repeating LPC
|
|
filters and obtaining the LPC residual signal by using a long-term
|
|
prediction estimate from previous residual blocks.
|
|
|
|
3. Encoder Principles
|
|
|
|
The following block diagram is an overview of all the components of
|
|
the iLBC encoding procedure. The description of the blocks contains
|
|
references to the section where that particular procedure is further
|
|
described.
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
Andersen, et al. Experimental [Page 7]
|
|
|
|
RFC 3951 Internet Low Bit Rate Codec December 2004
|
|
|
|
|
|
+-----------+ +---------+ +---------+
|
|
speech -> | 1. Pre P | -> | 2. LPC | -> | 3. Ana | ->
|
|
+-----------+ +---------+ +---------+
|
|
|
|
+---------------+ +--------------+
|
|
-> | 4. Start Sel | ->| 5. Scalar Qu | ->
|
|
+---------------+ +--------------+
|
|
|
|
+--------------+ +---------------+
|
|
-> |6. CB Search | -> | 7. Packetize | -> payload
|
|
| +--------------+ | +---------------+
|
|
----<---------<------
|
|
sub-frame 0..2/4 (20 ms/30 ms)
|
|
|
|
Figure 3.1. Flow chart of the iLBC encoder
|
|
|
|
1. Pre-process speech with a HP filter, if needed (section 3.1).
|
|
|
|
2. Compute LPC parameters, quantize, and interpolate (section 3.2).
|
|
|
|
3. Use analysis filters on speech to compute residual (section 3.3).
|
|
|
|
4. Select position of 57/58-sample start state (section 3.5).
|
|
|
|
5. Quantize the 57/58-sample start state with scalar quantization
|
|
(section 3.5).
|
|
|
|
6. Search the codebook for each sub-frame. Start with 23/22 sample
|
|
block, then encode sub-blocks forward in time, and then encode
|
|
sub-blocks backward in time. For each block, the steps in Figure
|
|
3.4 are performed (section 3.6).
|
|
|
|
7. Packetize the bits into the payload specified in Table 3.2.
|
|
|
|
The input to the encoder SHOULD be 16-bit uniform PCM sampled at 8
|
|
kHz. Also it SHOULD be partitioned into blocks of BLOCKL=160/240
|
|
samples. Each block input to the encoder is divided into NSUB=4/6
|
|
consecutive sub-blocks of SUBL=40 samples each.
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
Andersen, et al. Experimental [Page 8]
|
|
|
|
RFC 3951 Internet Low Bit Rate Codec December 2004
|
|
|
|
|
|
0 39 79 119 159
|
|
+---------------------------------------+
|
|
| 1 | 2 | 3 | 4 |
|
|
+---------------------------------------+
|
|
20 ms frame
|
|
|
|
0 39 79 119 159 199 239
|
|
+-----------------------------------------------------------+
|
|
| 1 | 2 | 3 | 4 | 5 | 6 |
|
|
+-----------------------------------------------------------+
|
|
30 ms frame
|
|
Figure 3.2. One input block to the encoder for 20 ms (with four sub-
|
|
frames) and 30 ms (with six sub-frames).
|
|
|
|
3.1. Pre-processing
|
|
|
|
In some applications, the recorded speech signal contains DC level
|
|
and/or 50/60 Hz noise. If these components have not been removed
|
|
prior to the encoder call, they should be removed by a high-pass
|
|
filter. A reference implementation of this, using a filter with a
|
|
cutoff frequency of 90 Hz, can be found in Appendix A.28.
|
|
|
|
3.2. LPC Analysis and Quantization
|
|
|
|
The input to the LPC analysis module is a possibly high-pass filtered
|
|
speech buffer, speech_hp, that contains 240/300 (LPC_LOOKBACK +
|
|
BLOCKL = 80/60 + 160/240 = 240/300) speech samples, where samples 0
|
|
through 79/59 are from the previous block and samples 80/60 through
|
|
239/299 are from the current block. No look-ahead into the next
|
|
block is used. For the very first block processed, the look-back
|
|
samples are assumed to be zeros.
|
|
|
|
For each input block, the LPC analysis calculates one/two set(s) of
|
|
LPC_FILTERORDER=10 LPC filter coefficients using the autocorrelation
|
|
method and the Levinson-Durbin recursion. These coefficients are
|
|
converted to the Line Spectrum Frequency representation. In the 20
|
|
ms case, the single lsf set represents the spectral characteristics
|
|
as measured at the center of the third sub-block. For 30 ms frames,
|
|
the first set, lsf1, represents the spectral properties of the input
|
|
signal at the center of the second sub-block, and the other set,
|
|
lsf2, represents the spectral characteristics as measured at the
|
|
center of the fifth sub-block. The details of the computation for 30
|
|
ms frames are described in sections 3.2.1 through 3.2.6. Section
|
|
3.2.7 explains how the LPC Analysis and Quantization differs for 20
|
|
ms frames.
|
|
|
|
|
|
|
|
|
|
|
|
|
|
Andersen, et al. Experimental [Page 9]
|
|
|
|
RFC 3951 Internet Low Bit Rate Codec December 2004
|
|
|
|
|
|
3.2.1. Computation of Autocorrelation Coefficients
|
|
|
|
The first step in the LPC analysis procedure is to calculate
|
|
autocorrelation coefficients by using windowed speech samples. This
|
|
windowing is the only difference in the LPC analysis procedure for
|
|
the two sets of coefficients. For the first set, a 240-sample-long
|
|
standard symmetric Hanning window is applied to samples 0 through 239
|
|
of the input data. The first window, lpc_winTbl, is defined as
|
|
|
|
lpc_winTbl[i]= 0.5 * (1.0 - cos((2*PI*(i+1))/(BLOCKL+1)));
|
|
i=0,...,119
|
|
lpc_winTbl[i] = winTbl[BLOCKL - i - 1]; i=120,...,239
|
|
|
|
The windowed speech speech_hp_win1 is then obtained by multiplying
|
|
the first 240 samples of the input speech buffer with the window
|
|
coefficients:
|
|
|
|
speech_hp_win1[i] = speech_hp[i] * lpc_winTbl[i];
|
|
i=0,...,BLOCKL-1
|
|
|
|
From these 240 windowed speech samples, 11 (LPC_FILTERORDER + 1)
|
|
autocorrelation coefficients, acf1, are calculated:
|
|
|
|
acf1[lag] += speech_hp_win1[n] * speech_hp_win1[n + lag];
|
|
lag=0,...,LPC_FILTERORDER; n=0,...,BLOCKL-lag-1
|
|
|
|
In order to make the analysis more robust against numerical precision
|
|
problems, a spectral smoothing procedure is applied by windowing the
|
|
autocorrelation coefficients before the LPC coefficients are
|
|
computed. Also, a white noise floor is added to the autocorrelation
|
|
function by multiplying coefficient zero by 1.0001 (40dB below the
|
|
energy of the windowed speech signal). These two steps are
|
|
implemented by multiplying the autocorrelation coefficients with the
|
|
following window:
|
|
|
|
lpc_lagwinTbl[0] = 1.0001;
|
|
lpc_lagwinTbl[i] = exp(-0.5 * ((2 * PI * 60.0 * i) /FS)^2);
|
|
i=1,...,LPC_FILTERORDER
|
|
where FS=8000 is the sampling frequency
|
|
|
|
Then, the windowed acf function acf1_win is obtained by
|
|
|
|
acf1_win[i] = acf1[i] * lpc_lagwinTbl[i];
|
|
i=0,...,LPC_FILTERORDER
|
|
|
|
The second set of autocorrelation coefficients, acf2_win, are
|
|
obtained in a similar manner. The window, lpc_asymwinTbl, is applied
|
|
to samples 60 through 299, i.e., the entire current block. The
|
|
|
|
|
|
|
|
Andersen, et al. Experimental [Page 10]
|
|
|
|
RFC 3951 Internet Low Bit Rate Codec December 2004
|
|
|
|
|
|
window consists of two segments, the first (samples 0 to 219) being
|
|
half a Hanning window with length 440 and the second a quarter of a
|
|
cycle of a cosine wave. By using this asymmetric window, an LPC
|
|
analysis centered in the fifth sub-block is obtained without the need
|
|
for any look-ahead, which would add delay. The asymmetric window is
|
|
defined as
|
|
|
|
lpc_asymwinTbl[i] = (sin(PI * (i + 1) / 441))^2; i=0,...,219
|
|
|
|
lpc_asymwinTbl[i] = cos((i - 220) * PI / 40); i=220,...,239
|
|
|
|
and the windowed speech is computed by
|
|
|
|
speech_hp_win2[i] = speech_hp[i + LPC_LOOKBACK] *
|
|
lpc_asymwinTbl[i]; i=0,....BLOCKL-1
|
|
|
|
The windowed autocorrelation coefficients are then obtained in
|
|
exactly the same way as for the first analysis instance.
|
|
|
|
The generation of the windows lpc_winTbl, lpc_asymwinTbl, and
|
|
lpc_lagwinTbl are typically done in advance, and the arrays are
|
|
stored in ROM rather than repeating the calculation for every block.
|
|
|
|
3.2.2. Computation of LPC Coefficients
|
|
|
|
From the 2 x 11 smoothed autocorrelation coefficients, acf1_win and
|
|
acf2_win, the 2 x 11 LPC coefficients, lp1 and lp2, are calculated
|
|
in the same way for both analysis locations by using the well known
|
|
Levinson-Durbin recursion. The first LPC coefficient is always 1.0,
|
|
resulting in ten unique coefficients.
|
|
|
|
After determining the LPC coefficients, a bandwidth expansion
|
|
procedure is applied to smooth the spectral peaks in the
|
|
short-term spectrum. The bandwidth addition is obtained by the
|
|
following modification of the LPC coefficients:
|
|
|
|
lp1_bw[i] = lp1[i] * chirp^i; i=0,...,LPC_FILTERORDER
|
|
lp2_bw[i] = lp2[i] * chirp^i; i=0,...,LPC_FILTERORDER
|
|
|
|
where "chirp" is a real number between 0 and 1. It is RECOMMENDED to
|
|
use a value of 0.9.
|
|
|
|
3.2.3. Computation of LSF Coefficients from LPC Coefficients
|
|
|
|
Thus far, two sets of LPC coefficients that represent the short-term
|
|
spectral characteristics of the speech signal for two different time
|
|
locations within the current block have been determined. These
|
|
coefficients SHOULD be quantized and interpolated. Before this is
|
|
|
|
|
|
|
|
Andersen, et al. Experimental [Page 11]
|
|
|
|
RFC 3951 Internet Low Bit Rate Codec December 2004
|
|
|
|
|
|
done, it is advantageous to convert the LPC parameters into another
|
|
type of representation called Line Spectral Frequencies (LSF). The
|
|
LSF parameters are used because they are better suited for
|
|
quantization and interpolation than the regular LPC coefficients.
|
|
Many computationally efficient methods for calculating the LSFs from
|
|
the LPC coefficients have been proposed in the literature. The
|
|
detailed implementation of one applicable method can be found in
|
|
Appendix A.26. The two arrays of LSF coefficients obtained, lsf1 and
|
|
lsf2, are of dimension 10 (LPC_FILTERORDER).
|
|
|
|
3.2.4. Quantization of LSF Coefficients
|
|
|
|
Because the LPC filters defined by the two sets of LSFs are also
|
|
needed in the decoder, the LSF parameters need to be quantized and
|
|
transmitted as side information. The total number of bits required
|
|
to represent the quantization of the two LSF representations for one
|
|
block of speech is 40, with 20 bits used for each of lsf1 and lsf2.
|
|
|
|
For computational and storage reasons, the LSF vectors are quantized
|
|
using three-split vector quantization (VQ). That is, the LSF vectors
|
|
are split into three sub-vectors that are each quantized with a
|
|
regular VQ. The quantized versions of lsf1 and lsf2, qlsf1 and
|
|
qlsf2, are obtained by using the same memoryless split VQ. The
|
|
length of each of these two LSF vectors is 10, and they are split
|
|
into three sub-vectors containing 3, 3, and 4 values, respectively.
|
|
|
|
For each of the sub-vectors, a separate codebook of quantized values
|
|
has been designed with a standard VQ training method for a large
|
|
database containing speech from a large number of speakers recorded
|
|
under various conditions. The size of each of the three codebooks
|
|
associated with the split definitions above is
|
|
|
|
int size_lsfCbTbl[LSF_NSPLIT] = {64,128,128};
|
|
|
|
The actual values of the vector quantization codebook that must be
|
|
used can be found in the reference code of Appendix A. Both sets of
|
|
LSF coefficients, lsf1 and lsf2, are quantized with a standard
|
|
memoryless split vector quantization (VQ) structure using the squared
|
|
error criterion in the LSF domain. The split VQ quantization
|
|
consists of the following steps:
|
|
|
|
1) Quantize the first three LSF coefficients (1 - 3) with a VQ
|
|
codebook of size 64.
|
|
2) Quantize the next three LSF coefficients 4 - 6 with VQ a codebook
|
|
of size 128.
|
|
3) Quantize the last four LSF coefficients (7 - 10) with a VQ
|
|
codebook of size 128.
|
|
|
|
|
|
|
|
|
|
Andersen, et al. Experimental [Page 12]
|
|
|
|
RFC 3951 Internet Low Bit Rate Codec December 2004
|
|
|
|
|
|
This procedure, repeated for lsf1 and lsf2, gives six quantization
|
|
indices and the quantized sets of LSF coefficients qlsf1 and qlsf2.
|
|
Each set of three indices is encoded with 6 + 7 + 7 = 20 bits. The
|
|
total number of bits used for LSF quantization in a block is thus 40
|
|
bits.
|
|
|
|
3.2.5. Stability Check of LSF Coefficients
|
|
|
|
The LSF representation of the LPC filter has the convenient property
|
|
that the coefficients are ordered by increasing value, i.e., lsf(n-1)
|
|
< lsf(n), 0 < n < 10, if the corresponding synthesis filter is
|
|
stable. As we are employing a split VQ scheme, it is possible that
|
|
at the split boundaries the LSF coefficients are not ordered
|
|
correctly and hence that the corresponding LP filter is unstable. To
|
|
ensure that the filter used is stable, a stability check is performed
|
|
for the quantized LSF vectors. If it turns out that the coefficients
|
|
are not ordered appropriately (with a safety margin of 50 Hz to
|
|
ensure that formant peaks are not too narrow), they will be moved
|
|
apart. The detailed method for this can be found in Appendix A.40.
|
|
The same procedure is performed in the decoder. This ensures that
|
|
exactly the same LSF representations are used in both encoder and
|
|
decoder.
|
|
|
|
3.2.6. Interpolation of LSF Coefficients
|
|
|
|
From the two sets of LSF coefficients that are computed for each
|
|
block of speech, different LSFs are obtained for each sub-block by
|
|
means of interpolation. This procedure is performed for the original
|
|
LSFs (lsf1 and lsf2), as well as the quantized versions qlsf1 and
|
|
qlsf2, as both versions are used in the encoder. Here follows a
|
|
brief summary of the interpolation scheme; the details are found in
|
|
the c-code of Appendix A. In the first sub-block, the average of the
|
|
second LSF vector from the previous block and the first LSF vector in
|
|
the current block is used. For sub-blocks two through five, the LSFs
|
|
used are obtained by linear interpolation from lsf1 (and qlsf1) to
|
|
lsf2 (and qlsf2), with lsf1 used in sub-block two and lsf2 in sub-
|
|
block five. In the last sub-block, lsf2 is used. For the very first
|
|
block it is assumed that the last LSF vector of the previous block is
|
|
equal to a predefined vector, lsfmeanTbl, obtained by calculating the
|
|
mean LSF vector of the LSF design database.
|
|
|
|
lsfmeanTbl[LPC_FILTERORDER] = {0.281738, 0.445801, 0.663330,
|
|
0.962524, 1.251831, 1.533081, 1.850586, 2.137817,
|
|
2.481445, 2.777344}
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
Andersen, et al. Experimental [Page 13]
|
|
|
|
RFC 3951 Internet Low Bit Rate Codec December 2004
|
|
|
|
|
|
The interpolation method is standard linear interpolation in the LSF
|
|
domain. The interpolated LSF values are converted to LPC
|
|
coefficients for each sub-block. The unquantized and quantized LPC
|
|
coefficients form two sets of filters respectively. The unquantized
|
|
analysis filter for sub-block k is defined as follows
|
|
|
|
___
|
|
\
|
|
Ak(z)= 1 + > ak(i)*z^(-i)
|
|
/__
|
|
i=1...LPC_FILTERORDER
|
|
|
|
The quantized analysis filter for sub-block k is defined as follows
|
|
___
|
|
\
|
|
A~k(z)= 1 + > a~k(i)*z^(-i)
|
|
/__
|
|
i=1...LPC_FILTERORDER
|
|
|
|
A reference implementation of the lsf encoding is given in Appendix
|
|
A.38. A reference implementation of the corresponding decoding can
|
|
be found in Appendix A.36.
|
|
|
|
3.2.7. LPC Analysis and Quantization for 20 ms Frames
|
|
|
|
As previously stated, the codec only calculates one set of LPC
|
|
parameters for the 20 ms frame size as opposed to two sets for 30 ms
|
|
frames. A single set of autocorrelation coefficients is calculated
|
|
on the LPC_LOOKBACK + BLOCKL = 80 + 160 = 240 samples. These samples
|
|
are windowed with the asymmetric window lpc_asymwinTbl, centered over
|
|
the third sub-frame, to form speech_hp_win. Autocorrelation
|
|
coefficients, acf, are calculated on the 240 samples in speech_hp_win
|
|
and then windowed exactly as in section 3.2.1 (resulting in
|
|
acf_win).
|
|
|
|
This single set of windowed autocorrelation coefficients is used to
|
|
calculate LPC coefficients, LSF coefficients, and quantized LSF
|
|
coefficients in exactly the same manner as in sections 3.2.3 through
|
|
3.2.4. As for the 30 ms frame size, the ten LSF coefficients are
|
|
divided into three sub-vectors of size 3, 3, and 4 and quantized by
|
|
using the same scheme and codebook as in section 3.2.4 to finally get
|
|
3 quantization indices. The quantized LSF coefficients are
|
|
stabilized with the algorithm described in section 3.2.5.
|
|
|
|
From the set of LSF coefficients computed for this block and those
|
|
from the previous block, different LSFs are obtained for each sub-
|
|
block by means of interpolation. The interpolation is done linearly
|
|
in the LSF domain over the four sub-blocks, so that the n-th sub-
|
|
|
|
|
|
|
|
Andersen, et al. Experimental [Page 14]
|
|
|
|
RFC 3951 Internet Low Bit Rate Codec December 2004
|
|
|
|
|
|
frame uses the weight (4-n)/4 for the LSF from old frame and the
|
|
weight n/4 of the LSF from the current frame. For the very first
|
|
block the mean LSF, lsfmeanTbl, is used as the LSF from the previous
|
|
block. Similarly as seen in section 3.2.6, both unquantized, A(z),
|
|
and quantized, A~(z), analysis filters are calculated for each of the
|
|
four sub-blocks.
|
|
|
|
3.3. Calculation of the Residual
|
|
|
|
The block of speech samples is filtered by the quantized and
|
|
interpolated LPC analysis filters to yield the residual signal. In
|
|
particular, the corresponding LPC analysis filter for each 40 sample
|
|
sub-block is used to filter the speech samples for the same sub-
|
|
block. The filter memory at the end of each sub-block is carried
|
|
over to the LPC filter of the next sub-block. The signal at the
|
|
output of each LP analysis filter constitutes the residual signal for
|
|
the corresponding sub-block.
|
|
|
|
A reference implementation of the LPC analysis filters is given in
|
|
Appendix A.10.
|
|
|
|
3.4. Perceptual Weighting Filter
|
|
|
|
In principle any good design of a perceptual weighting filter can be
|
|
applied in the encoder without compromising this codec definition.
|
|
However, it is RECOMMENDED to use the perceptual weighting filter Wk
|
|
for sub-block k specified below:
|
|
|
|
Wk(z)=1/Ak(z/LPC_CHIRP_WEIGHTDENUM), where
|
|
LPC_CHIRP_WEIGHTDENUM = 0.4222
|
|
|
|
This is a simple design with low complexity that is applied in the
|
|
LPC residual domain. Here Ak(z) is the filter obtained for sub-block
|
|
k from unquantized but interpolated LSF coefficients.
|
|
|
|
3.5. Start State Encoder
|
|
|
|
The start state is quantized by using a common 6-bit scalar quantizer
|
|
for the block and a 3-bit scalar quantizer operating on scaled
|
|
samples in the weighted speech domain. In the following we describe
|
|
the state encoding in greater detail.
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
Andersen, et al. Experimental [Page 15]
|
|
|
|
RFC 3951 Internet Low Bit Rate Codec December 2004
|
|
|
|
|
|
3.5.1. Start State Estimation
|
|
|
|
The two sub-blocks containing the start state are determined by
|
|
finding the two consecutive sub-blocks in the block having the
|
|
highest power. Advantageously, down-weighting is used in the
|
|
beginning and end of the sub-frames, i.e., the following measure is
|
|
computed (NSUB=4/6 for 20/30 ms frame size):
|
|
|
|
nsub=1,...,NSUB-1
|
|
ssqn[nsub] = 0.0;
|
|
for (i=(nsub-1)*SUBL; i<(nsub-1)*SUBL+5; i++)
|
|
ssqn[nsub] += sampEn_win[i-(nsub-1)*SUBL]*
|
|
residual[i]*residual[i];
|
|
for (i=(nsub-1)*SUBL+5; i<(nsub+1)*SUBL-5; i++)
|
|
ssqn[nsub] += residual[i]*residual[i];
|
|
for (i=(nsub+1)*SUBL-5; i<(nsub+1)*SUBL; i++)
|
|
ssqn[nsub] += sampEn_win[(nsub+1)*SUBL-i-1]*
|
|
residual[i]*residual[i];
|
|
|
|
where sampEn_win[5]={1/6, 2/6, 3/6, 4/6, 5/6}; MAY be used. The
|
|
sub-frame number corresponding to the maximum value of
|
|
ssqEn_win[nsub-1]*ssqn[nsub] is selected as the start state
|
|
indicator. A weighting of ssqEn_win[]={0.8,0.9,1.0,0.9,0.8} for 30
|
|
ms frames and ssqEn_win[]={0.9,1.0,0.9} for 20 ms frames; MAY
|
|
advantageously be used to bias the start state towards the middle of
|
|
the frame.
|
|
|
|
For 20 ms frames there are three possible positions for the two-sub-
|
|
block length maximum power segment; the start state position is
|
|
encoded with 2 bits. The start state position, start, MUST be
|
|
encoded as
|
|
|
|
start=1: start state in sub-frame 0 and 1
|
|
start=2: start state in sub-frame 1 and 2
|
|
start=3: start state in sub-frame 2 and 3
|
|
|
|
For 30 ms frames there are five possible positions of the two-sub-
|
|
block length maximum power segment, the start state position is
|
|
encoded with 3 bits. The start state position, start, MUST be
|
|
encoded as
|
|
|
|
start=1: start state in sub-frame 0 and 1
|
|
start=2: start state in sub-frame 1 and 2
|
|
start=3: start state in sub-frame 2 and 3
|
|
start=4: start state in sub-frame 3 and 4
|
|
start=5: start state in sub-frame 4 and 5
|
|
|
|
|
|
|
|
|
|
|
|
Andersen, et al. Experimental [Page 16]
|
|
|
|
RFC 3951 Internet Low Bit Rate Codec December 2004
|
|
|
|
|
|
Hence, in both cases, index 0 is not used. In order to shorten the
|
|
start state for bit rate efficiency, the start state is brought down
|
|
to STATE_SHORT_LEN=57 samples for 20 ms frames and STATE_SHORT_LEN=58
|
|
samples for 30 ms frames. The power of the first 23/22 and last
|
|
23/22 samples of the two sub-frame blocks identified above is
|
|
computed as the sum of the squared signal sample values, and the
|
|
23/22-sample segment with the lowest power is excluded from the start
|
|
state. One bit is transmitted to indicate which of the two possible
|
|
57/58 sample segments is used. The start state position within the
|
|
two sub-frames determined above, state_first, MUST be encoded as
|
|
|
|
state_first=1: start state is first STATE_SHORT_LEN samples
|
|
state_first=0: start state is last STATE_SHORT_LEN samples
|
|
|
|
3.5.2. All-Pass Filtering and Scale Quantization
|
|
|
|
The block of residual samples in the start state is first filtered by
|
|
an all-pass filter with the quantized LPC coefficients as denominator
|
|
and reversed quantized LPC coefficients as numerator. The purpose of
|
|
this phase-dispersion filter is to get a more even distribution of
|
|
the sample values in the residual signal. The filtering is performed
|
|
by circular convolution, where the initial filter memory is set to
|
|
zero.
|
|
|
|
res(0..(STATE_SHORT_LEN-1)) = uncoded start state residual
|
|
res((STATE_SHORT_LEN)..(2*STATE_SHORT_LEN-1)) = 0
|
|
|
|
Pk(z) = A~rk(z)/A~k(z), where
|
|
___
|
|
\
|
|
A~rk(z)= z^(-LPC_FILTERORDER)+>a~k(i+1)*z^(i-(LPC_FILTERORDER-1))
|
|
/__
|
|
i=0...(LPC_FILTERORDER-1)
|
|
|
|
and A~k(z) is taken from the block where the start state begins
|
|
|
|
res -> Pk(z) -> filtered
|
|
|
|
ccres(k) = filtered(k) + filtered(k+STATE_SHORT_LEN),
|
|
k=0..(STATE_SHORT_LEN-1)
|
|
|
|
The all-pass filtered block is searched for its largest magnitude
|
|
sample. The 10-logarithm of this magnitude is quantized with a 6-bit
|
|
quantizer, state_frgqTbl, by finding the nearest representation.
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
Andersen, et al. Experimental [Page 17]
|
|
|
|
RFC 3951 Internet Low Bit Rate Codec December 2004
|
|
|
|
|
|
This results in an index, idxForMax, corresponding to a quantized
|
|
value, qmax. The all-pass filtered residual samples in the block are
|
|
then multiplied with a scaling factor scal=4.5/(10^qmax) to yield
|
|
normalized samples.
|
|
|
|
state_frgqTbl[64] = {1.000085, 1.071695, 1.140395, 1.206868,
|
|
1.277188, 1.351503, 1.429380, 1.500727, 1.569049,
|
|
1.639599, 1.707071, 1.781531, 1.840799, 1.901550,
|
|
1.956695, 2.006750, 2.055474, 2.102787, 2.142819,
|
|
2.183592, 2.217962, 2.257177, 2.295739, 2.332967,
|
|
2.369248, 2.402792, 2.435080, 2.468598, 2.503394,
|
|
2.539284, 2.572944, 2.605036, 2.636331, 2.668939,
|
|
2.698780, 2.729101, 2.759786, 2.789834, 2.818679,
|
|
2.848074, 2.877470, 2.906899, 2.936655, 2.967804,
|
|
3.000115, 3.033367, 3.066355, 3.104231, 3.141499,
|
|
3.183012, 3.222952, 3.265433, 3.308441, 3.350823,
|
|
3.395275, 3.442793, 3.490801, 3.542514, 3.604064,
|
|
3.666050, 3.740994, 3.830749, 3.938770, 4.101764}
|
|
|
|
3.5.3. Scalar Quantization
|
|
|
|
The normalized samples are quantized in the perceptually weighted
|
|
speech domain by a sample-by-sample scalar DPCM quantization as
|
|
depicted in Figure 3.3. Each sample in the block is filtered by a
|
|
weighting filter Wk(z), specified in section 3.4, to form a weighted
|
|
speech sample x[n]. The target sample d[n] is formed by subtracting
|
|
a predicted sample y[n], where the prediction filter is given by
|
|
|
|
Pk(z) = 1 - 1 / Wk(z).
|
|
|
|
+-------+ x[n] + d[n] +-----------+ u[n]
|
|
residual -->| Wk(z) |-------->(+)---->| Quantizer |------> quantized
|
|
+-------+ - /|\ +-----------+ | residual
|
|
| \|/
|
|
y[n] +--------------------->(+)
|
|
| |
|
|
| +------+ |
|
|
+--------| Pk(z)|<------+
|
|
+------+
|
|
|
|
Figure 3.3. Quantization of start state samples by DPCM in weighted
|
|
speech domain.
|
|
|
|
The coded state sample u[n] is obtained by quantizing d[n] with a 3-
|
|
bit quantizer with quantization table state_sq3Tbl.
|
|
|
|
state_sq3Tbl[8] = {-3.719849, -2.177490, -1.130005, -0.309692,
|
|
0.444214, 1.329712, 2.436279, 3.983887}
|
|
|
|
|
|
|
|
Andersen, et al. Experimental [Page 18]
|
|
|
|
RFC 3951 Internet Low Bit Rate Codec December 2004
|
|
|
|
|
|
The quantized samples are transformed back to the residual domain by
|
|
1) scaling with 1/scal; 2) time-reversing the scaled samples; 3)
|
|
filtering the time-reversed samples by the same all-pass filter, as
|
|
in section 3.5.2, by using circular convolution; and 4) time-
|
|
reversing the filtered samples. (More detail is in section 4.2.)
|
|
|
|
A reference implementation of the start-state encoding can be found
|
|
in Appendix A.46.
|
|
|
|
3.6. Encoding the Remaining Samples
|
|
|
|
A dynamic codebook is used to encode 1) the 23/22 remaining samples
|
|
in the two sub-blocks containing the start state; 2) the sub-blocks
|
|
after the start state in time; and 3) the sub-blocks before the start
|
|
state in time. Thus, the encoding target can be either the 23/22
|
|
samples remaining of the 2 sub-blocks containing the start state, or
|
|
a 40-sample sub-block. This target can consist of samples that are
|
|
indexed forward in time or backward in time, depending on the
|
|
location of the start state. The length of the target is denoted by
|
|
lTarget.
|
|
|
|
The coding is based on an adaptive codebook that is built from a
|
|
codebook memory that contains decoded LPC excitation samples from the
|
|
already encoded part of the block. These samples are indexed in the
|
|
same time direction as is the target vector and end at the sample
|
|
instant prior to the first sample instant represented in the target
|
|
vector. The codebook memory has length lMem, which is equal to
|
|
CB_MEML=147 for the two/four 40-sample sub-blocks and 85 for the
|
|
23/22-sample sub-block.
|
|
|
|
The following figure shows an overview of the encoding procedure.
|
|
|
|
+------------+ +---------------+ +-------------+
|
|
-> | 1. Decode | -> | 2. Mem setup | -> | 3. Perc. W. | ->
|
|
+------------+ +---------------+ +-------------+
|
|
|
|
+------------+ +-----------------+
|
|
-> | 4. Search | -> | 5. Upd. Target | ------------------>
|
|
| +------------+ +------------------ |
|
|
----<-------------<-----------<----------
|
|
stage=0..2
|
|
|
|
+----------------+
|
|
-> | 6. Recalc G[0] | ---------------> gains and CB indices
|
|
+----------------+
|
|
|
|
Figure 3.4. Flow chart of the codebook search in the iLBC encoder.
|
|
|
|
|
|
|
|
|
|
Andersen, et al. Experimental [Page 19]
|
|
|
|
RFC 3951 Internet Low Bit Rate Codec December 2004
|
|
|
|
|
|
1. Decode the part of the residual that has been encoded so far,
|
|
using the codebook without perceptual weighting.
|
|
|
|
2. Set up the memory by taking data from the decoded residual. This
|
|
memory is used to construct codebooks. For blocks preceding the
|
|
start state, both the decoded residual and the target are time
|
|
reversed (section 3.6.1).
|
|
3. Filter the memory + target with the perceptual weighting filter
|
|
(section 3.6.2).
|
|
|
|
4. Search for the best match between the target and the codebook
|
|
vector. Compute the optimal gain for this match and quantize that
|
|
gain (section 3.6.4).
|
|
|
|
5. Update the perceptually weighted target by subtracting the
|
|
contribution from the selected codebook vector from the
|
|
perceptually weighted memory (quantized gain times selected
|
|
vector). Repeat 4 and 5 for the two additional stages.
|
|
|
|
6. Calculate the energy loss due to encoding of the residual. If
|
|
needed, compensate for this loss by an upscaling and
|
|
requantization of the gain for the first stage (section 3.7).
|
|
|
|
The following sections provide an in-depth description of the
|
|
different blocks of Figure 3.4.
|
|
|
|
3.6.1. Codebook Memory
|
|
|
|
The codebook memory is based on the already encoded sub-blocks, so
|
|
the available data for encoding increases for each new sub-block that
|
|
has been encoded. Until enough sub-blocks have been encoded to fill
|
|
the codebook memory with data, it is padded with zeros. The
|
|
following figure shows an example of the order in which the sub-
|
|
blocks are encoded for the 30 ms frame size if the start state is
|
|
located in the last 58 samples of sub-block 2 and 3.
|
|
|
|
+-----------------------------------------------------+
|
|
| 5 | 1 |///|////////| 2 | 3 | 4 |
|
|
+-----------------------------------------------------+
|
|
|
|
Figure 3.5. The order from 1 to 5 in which the sub-blocks are
|
|
encoded. The slashed area is the start state.
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
Andersen, et al. Experimental [Page 20]
|
|
|
|
RFC 3951 Internet Low Bit Rate Codec December 2004
|
|
|
|
|
|
The first target sub-block to be encoded is number 1, and the
|
|
corresponding codebook memory is shown in the following figure. As
|
|
the target vector comes before the start state in time, the codebook
|
|
memory and target vector are time reversed; thus, after the block has
|
|
been time reversed the search algorithm can be reused. As only the
|
|
start state has been encoded so far, the last samples of the codebook
|
|
memory are padded with zeros.
|
|
|
|
+-------------------------
|
|
|zeros|\\\\\\\\|\\\\| 1 |
|
|
+-------------------------
|
|
|
|
Figure 3.6. The codebook memory, length lMem=85 samples, and the
|
|
target vector 1, length 22 samples.
|
|
|
|
The next step is to encode sub-block 2 by using the memory that now
|
|
has increased since sub-block 1 has been encoded. The following
|
|
figure shows the codebook memory for encoding of sub-block 2.
|
|
|
|
+-----------------------------------
|
|
| zeros | 1 |///|////////| 2 |
|
|
+-----------------------------------
|
|
|
|
Figure 3.7. The codebook memory, length lMem=147 samples, and the
|
|
target vector 2, length 40 samples.
|
|
|
|
The next step is to encode sub-block 3 by using the memory which has
|
|
been increased yet again since sub-blocks 1 and 2 have been encoded,
|
|
but the sub-block still has to be padded with a few zeros. The
|
|
following figure shows the codebook memory for encoding of sub-block
|
|
3.
|
|
|
|
+------------------------------------------
|
|
|zeros| 1 |///|////////| 2 | 3 |
|
|
+------------------------------------------
|
|
|
|
Figure 3.8. The codebook memory, length lMem=147 samples, and the
|
|
target vector 3, length 40 samples.
|
|
|
|
The next step is to encode sub-block 4 by using the memory which now
|
|
has increased yet again since sub-blocks 1, 2, and 3 have been
|
|
encoded. This time, the memory does not have to be padded with
|
|
zeros. The following figure shows the codebook memory for encoding
|
|
of sub-block 4.
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
Andersen, et al. Experimental [Page 21]
|
|
|
|
RFC 3951 Internet Low Bit Rate Codec December 2004
|
|
|
|
|
|
+------------------------------------------
|
|
|1|///|////////| 2 | 3 | 4 |
|
|
+------------------------------------------
|
|
|
|
Figure 3.9. The codebook memory, length lMem=147 samples, and the
|
|
target vector 4, length 40 samples.
|
|
|
|
The final target sub-block to be encoded is number 5, and the
|
|
following figure shows the corresponding codebook memory. As the
|
|
target vector comes before the start state in time, the codebook
|
|
memory and target vector are time reversed.
|
|
|
|
+-------------------------------------------
|
|
| 3 | 2 |\\\\\\\\|\\\\| 1 | 5 |
|
|
+-------------------------------------------
|
|
|
|
Figure 3.10. The codebook memory, length lMem=147 samples, and the
|
|
target vector 5, length 40 samples.
|
|
|
|
For the case of 20 ms frames, the encoding procedure looks almost
|
|
exactly the same. The only difference is that the size of the start
|
|
state is 57 samples and that there are only three sub-blocks to be
|
|
encoded. The encoding order is the same as above, starting with the
|
|
23-sample target and then encoding the two remaining 40-sample sub-
|
|
blocks, first going forward in time and then going backward in time
|
|
relative to the start state.
|
|
|
|
3.6.2. Perceptual Weighting of Codebook Memory and Target
|
|
|
|
To provide a perceptual weighting of the coding error, a
|
|
concatenation of the codebook memory and the target to be coded is
|
|
all-pole filtered with the perceptual weighting filter specified in
|
|
section 3.4. The filter state of the weighting filter is set to
|
|
zero.
|
|
|
|
in(0..(lMem-1)) = unweighted codebook memory
|
|
in(lMem..(lMem+lTarget-1)) = unweighted target signal
|
|
|
|
|
|
in -> Wk(z) -> filtered,
|
|
where Wk(z) is taken from the sub-block of the target
|
|
|
|
weighted codebook memory = filtered(0..(lMem-1))
|
|
weighted target signal = filtered(lMem..(lMem+lTarget-1))
|
|
|
|
The codebook search is done with the weighted codebook memory and the
|
|
weighted target, whereas the decoding and the codebook memory update
|
|
uses the unweighted codebook memory.
|
|
|
|
|
|
|
|
Andersen, et al. Experimental [Page 22]
|
|
|
|
RFC 3951 Internet Low Bit Rate Codec December 2004
|
|
|
|
|
|
3.6.3. Codebook Creation
|
|
|
|
The codebook for the search is created from the perceptually weighted
|
|
codebook memory. It consists of two sections, where the first is
|
|
referred to as the base codebook and the second as the expanded
|
|
codebook, as it is created by linear combinations of the first. Each
|
|
of these two sections also has a subsection referred to as the
|
|
augmented codebook. The augmented codebook is only created and used
|
|
for the coding of the 40-sample sub-blocks and not for the 23/22-
|
|
sample sub-block case. The codebook size used for the different
|
|
sub-blocks and different stages are summarized in the table below.
|
|
|
|
Stage
|
|
1 2 & 3
|
|
--------------------------------------------
|
|
22 128 (64+0)*2 128 (64+0)*2
|
|
Sub- 1:st 40 256 (108+20)*2 128 (44+20)*2
|
|
Blocks 2:nd 40 256 (108+20)*2 256 (108+20)*2
|
|
3:rd 40 256 (108+20)*2 256 (108+20)*2
|
|
4:th 40 256 (108+20)*2 256 (108+20)*2
|
|
|
|
Table 3.1. Codebook sizes for the 30 ms mode.
|
|
|
|
Table 3.1 shows the codebook size for the different sub-blocks and
|
|
stages for 30 ms frames. Inside the parentheses it shows how the
|
|
number of codebook vectors is distributed, within the two sections,
|
|
between the base/expanded codebook and the augmented base/expanded
|
|
codebook. It should be interpreted in the following way:
|
|
(base/expanded cb + augmented base/expanded cb). The total number of
|
|
codebook vectors for a specific sub-block and stage is given by the
|
|
following formula:
|
|
|
|
Tot. cb vectors = base cb + aug. base cb + exp. cb + aug. exp. cb
|
|
|
|
The corresponding values to Figure 3.1 for 20 ms frames are only
|
|
slightly modified. The short sub-block is 23 instead of 22 samples,
|
|
and the 3:rd and 4:th sub-frame are not present.
|
|
|
|
3.6.3.1. Creation of a Base Codebook
|
|
|
|
The base codebook is given by the perceptually weighted codebook
|
|
memory that is mentioned in section 3.5.3. The different codebook
|
|
vectors are given by sliding a window of length 23/22 or 40, given by
|
|
variable lTarget, over the lMem-long perceptually weighted codebook
|
|
memory. The indices are ordered so that the codebook vector
|
|
containing sample (lMem-lTarget-n) to (lMem-n-1) of the codebook
|
|
|
|
|
|
|
|
|
|
|
|
Andersen, et al. Experimental [Page 23]
|
|
|
|
RFC 3951 Internet Low Bit Rate Codec December 2004
|
|
|
|
|
|
memory vector has index n, where n=0..lMem-lTarget. Thus the total
|
|
number of base codebook vectors is lMem-lTarget+1, and the indices
|
|
are ordered from sample delay lTarget (23/22 or 40) to lMem+1 (86 or
|
|
148).
|
|
|
|
3.6.3.2. Codebook Expansion
|
|
|
|
The base codebook is expanded by a factor of 2, creating an
|
|
additional section in the codebook. This new section is obtained by
|
|
filtering the base codebook, base_cb, with a FIR filter with filter
|
|
length CB_FILTERLEN=8. The construction of the expanded codebook
|
|
compensates for the delay of four samples introduced by the FIR
|
|
filter.
|
|
|
|
cbfiltersTbl[CB_FILTERLEN]={-0.033691, 0.083740, -0.144043,
|
|
0.713379, 0.806152, -0.184326,
|
|
0.108887, -0.034180};
|
|
|
|
___
|
|
\
|
|
exp_cb(k)= + > cbfiltersTbl(i)*x(k-i+4)
|
|
/__
|
|
i=0...(LPC_FILTERORDER-1)
|
|
|
|
where x(j) = base_cb(j) for j=0..lMem-1 and 0 otherwise
|
|
|
|
The individual codebook vectors of the new filtered codebook, exp_cb,
|
|
and their indices are obtained in the same fashion as described above
|
|
for the base codebook.
|
|
|
|
3.6.3.3. Codebook Augmentation
|
|
|
|
For cases where encoding entire sub-blocks, i.e., cbveclen=40, the
|
|
base and expanded codebooks are augmented to increase codebook
|
|
richness. The codebooks are augmented by vectors produced by
|
|
interpolation of segments. The base and expanded codebook,
|
|
constructed above, consists of vectors corresponding to sample delays
|
|
in the range from cbveclen to lMem. The codebook augmentation
|
|
attempts to augment these codebooks with vectors corresponding to
|
|
sample delays from 20 to 39. However, not all of these samples are
|
|
present in the base codebook and expanded codebook, respectively.
|
|
Therefore, the augmentation vectors are constructed as linear
|
|
combinations between samples corresponding to sample delays in the
|
|
range 20 to 39. The general idea of this procedure is presented in
|
|
the following figures and text. The procedure is performed for both
|
|
the base codebook and the expanded codebook.
|
|
|
|
|
|
|
|
|
|
|
|
Andersen, et al. Experimental [Page 24]
|
|
|
|
RFC 3951 Internet Low Bit Rate Codec December 2004
|
|
|
|
|
|
- - ------------------------|
|
|
codebook memory |
|
|
- - ------------------------|
|
|
|-5-|---15---|-5-|
|
|
pi pp po
|
|
|
|
| | Codebook vector
|
|
|---15---|-5-|-----20-----| <- corresponding to
|
|
i ii iii sample delay 20
|
|
|
|
Figure 3.11. Generation of the first augmented codebook.
|
|
|
|
Figure 3.11 shows the codebook memory with pointers pi, pp, and po,
|
|
where pi points to sample 25, pp to sample 20, and po to sample 5.
|
|
Below the codebook memory, the augmented codebook vector
|
|
corresponding to sample delay 20 is drawn. Segment i consists of
|
|
fifteen samples from pointer pp and forward in time. Segment ii
|
|
consists of five interpolated samples from pi and forward and from po
|
|
and forward. The samples are linearly interpolated with weights
|
|
[0.0, 0.2, 0.4, 0.6, 0.8] for pi and weights [1.0, 0.8, 0.6, 0.4,
|
|
0.2] for po. Segment iii consists of twenty samples from pp and
|
|
forward. The augmented codebook vector corresponding to sample delay
|
|
21 is produced by moving pointers pp and pi one sample backward in
|
|
time. This gives us the following figure.
|
|
|
|
- - ------------------------|
|
|
codebook memory |
|
|
- - ------------------------|
|
|
|-5-|---16---|-5-|
|
|
pi pp po
|
|
|
|
| | Codebook vector
|
|
|---16---|-5-|-----19-----| <- corresponding to
|
|
i ii iii sample delay 21
|
|
|
|
Figure 3.12. Generation of the second augmented codebook.
|
|
|
|
Figure 3.12 shows the codebook memory with pointers pi, pp and po
|
|
where pi points to sample 26, pp to sample 21, and po to sample 5.
|
|
Below the codebook memory, the augmented codebook vector
|
|
corresponding to sample delay 21 is drawn. Segment i now consists of
|
|
sixteen samples from pp and forward. Segment ii consists of five
|
|
interpolated samples from pi and forward and from po and forward, and
|
|
the interpolation weights are the same throughout the procedure.
|
|
Segment iii consists of nineteen samples from pp and forward. The
|
|
same procedure of moving the two pointers is continued until the last
|
|
augmented vector corresponding to sample delay 39 has been created.
|
|
This gives a total of twenty new codebook vectors to each of the two
|
|
|
|
|
|
|
|
Andersen, et al. Experimental [Page 25]
|
|
|
|
RFC 3951 Internet Low Bit Rate Codec December 2004
|
|
|
|
|
|
sections. Thus the total number of codebook vectors for each of the
|
|
two sections, when including the augmented codebook, becomes lMem-
|
|
SUBL+1+SUBL/2. This is provided that augmentation is evoked, i.e.,
|
|
that lTarget=SUBL.
|
|
|
|
3.6.4. Codebook Search
|
|
|
|
The codebook search uses the codebooks described in the sections
|
|
above to find the best match of the perceptually weighted target, see
|
|
section 3.6.2. The search method is a multi-stage gain-shape
|
|
matching performed as follows. At each stage the best shape vector
|
|
is identified, then the gain is calculated and quantized, and finally
|
|
the target is updated in preparation for the next codebook search
|
|
stage. The number of stages is CB_NSTAGES=3.
|
|
|
|
If the target is the 23/22-sample vector the codebooks are indexed so
|
|
that the base codebook is followed by the expanded codebook. If the
|
|
target is 40 samples the order is as follows: base codebook,
|
|
augmented base codebook, expanded codebook, and augmented expanded
|
|
codebook. The size of each codebook section and its corresponding
|
|
augmented section is given by Table 3.1 in section 3.6.3.
|
|
|
|
For example, when the second 40-sample sub-block is coded, indices 0
|
|
- 107 correspond to the base codebook, 108 - 127 correspond to the
|
|
augmented base codebook, 128 - 235 correspond to the expanded
|
|
codebook, and indices 236 - 255 correspond to the augmented expanded
|
|
codebook. The indices are divided in the same fashion for all stages
|
|
in the example. Only in the case of coding the first 40-sample sub-
|
|
block is there a difference between stages (see Table 3.1).
|
|
|
|
3.6.4.1. Codebook Search at Each Stage
|
|
|
|
The codebooks are searched to find the best match to the target at
|
|
each stage. When the best match is found, the target is updated and
|
|
the next-stage search is started. The three chosen codebook vectors
|
|
and their corresponding gains constitute the encoded sub-block. The
|
|
best match is decided by the following three criteria:
|
|
|
|
1. Compute the measure
|
|
|
|
(target*cbvec)^2 / ||cbvec||^2
|
|
|
|
for all codebook vectors, cbvec, and choose the codebook vector
|
|
maximizing the measure. The expression (target*cbvec) is the dot
|
|
product between the target vector to be coded and the codebook vector
|
|
for which we compute the measure. The norm, ||x||, is defined as the
|
|
square root of (x*x).
|
|
|
|
|
|
|
|
|
|
Andersen, et al. Experimental [Page 26]
|
|
|
|
RFC 3951 Internet Low Bit Rate Codec December 2004
|
|
|
|
|
|
2. The absolute value of the gain, corresponding to the chosen
|
|
codebook vector, cbvec, must be smaller than a fixed limit,
|
|
CB_MAXGAIN=1.3:
|
|
|
|
|gain| < CB_MAXGAIN
|
|
|
|
where the gain is computed in the following way:
|
|
|
|
gain = (target*cbvec) / ||cbvec||^2
|
|
|
|
3. For the first stage, the dot product of the chosen codebook vector
|
|
and target must be positive:
|
|
|
|
target*cbvec > 0
|
|
|
|
In practice the above criteria are used in a sequential search
|
|
through all codebook vectors. The best match is found by registering
|
|
a new max measure and index whenever the previously registered max
|
|
measure is surpassed and all other criteria are fulfilled. If none
|
|
of the codebook vectors fulfill (2) and (3), the first codebook
|
|
vector is selected.
|
|
|
|
3.6.4.2. Gain Quantization at Each Stage
|
|
|
|
The gain follows as a result of the computation
|
|
|
|
gain = (target*cbvec) / ||cbvec||^2
|
|
|
|
for the optimal codebook vector found by the procedure in section
|
|
3.6.4.1.
|
|
|
|
The three stages quantize the gain, using 5, 4, and 3 bits,
|
|
respectively. In the first stage, the gain is limited to positive
|
|
values. This gain is quantized by finding the nearest value in the
|
|
quantization table gain_sq5Tbl.
|
|
|
|
gain_sq5Tbl[32]={0.037476, 0.075012, 0.112488, 0.150024, 0.187500,
|
|
0.224976, 0.262512, 0.299988, 0.337524, 0.375000,
|
|
0.412476, 0.450012, 0.487488, 0.525024, 0.562500,
|
|
0.599976, 0.637512, 0.674988, 0.712524, 0.750000,
|
|
0.787476, 0.825012, 0.862488, 0.900024, 0.937500,
|
|
0.974976, 1.012512, 1.049988, 1.087524, 1.125000,
|
|
1.162476, 1.200012}
|
|
|
|
The gains of the subsequent two stages can be either positive or
|
|
negative. The gains are quantized by using a quantization table
|
|
times a scale factor. The second stage uses the table gain_sq4Tbl,
|
|
and the third stage uses gain_sq3Tbl. The scale factor equates 0.1
|
|
|
|
|
|
|
|
Andersen, et al. Experimental [Page 27]
|
|
|
|
RFC 3951 Internet Low Bit Rate Codec December 2004
|
|
|
|
|
|
or the absolute value of the quantized gain representation value
|
|
obtained in the previous stage, whichever is larger. Again, the
|
|
resulting gain index is the index to the nearest value of the
|
|
quantization table times the scale factor.
|
|
|
|
gainQ = scaleFact * gain_sqXTbl[index]
|
|
|
|
gain_sq4Tbl[16]={-1.049988, -0.900024, -0.750000, -0.599976,
|
|
-0.450012, -0.299988, -0.150024, 0.000000, 0.150024,
|
|
0.299988, 0.450012, 0.599976, 0.750000, 0.900024,
|
|
1.049988, 1.200012}
|
|
|
|
gain_sq3Tbl[8]={-1.000000, -0.659973, -0.330017,0.000000,
|
|
0.250000, 0.500000, 0.750000, 1.00000}
|
|
|
|
3.6.4.3. Preparation of Target for Next Stage
|
|
|
|
Before performing the search for the next stage, the perceptually
|
|
weighted target vector is updated by subtracting from it the selected
|
|
codebook vector (from the perceptually weighted codebook) times the
|
|
corresponding quantized gain.
|
|
|
|
target[i] = target[i] - gainQ * selected_vec[i];
|
|
|
|
A reference implementation of the codebook encoding is found in
|
|
Appendix A.34.
|
|
|
|
3.7. Gain Correction Encoding
|
|
|
|
The start state is quantized in a relatively model independent manner
|
|
using 3 bits per sample. In contrast, the remaining parts of the
|
|
block are encoded by using an adaptive codebook. This codebook will
|
|
produce high matching accuracy whenever there is a high correlation
|
|
between the target and the best codebook vector. For unvoiced speech
|
|
segments and background noises, this is not necessarily so, which,
|
|
due to the nature of the squared error criterion, results in a coded
|
|
signal with less power than the target signal. As the coded start
|
|
state has good power matching to the target, the result is a power
|
|
fluctuation within the encoded frame. Perceptually, the main problem
|
|
with this is that the time envelope of the signal energy becomes
|
|
unsteady. To overcome this problem, the gains for the codebooks are
|
|
re-scaled after the codebook encoding by searching for a new gain
|
|
factor for the first stage codebook that provides better power
|
|
matching.
|
|
|
|
First, the energy for the target signal, tene, is computed along with
|
|
the energy for the coded signal, cene, given by the addition of the
|
|
three gain scaled codebook vectors. Because the gains of the second
|
|
|
|
|
|
|
|
Andersen, et al. Experimental [Page 28]
|
|
|
|
RFC 3951 Internet Low Bit Rate Codec December 2004
|
|
|
|
|
|
and third stage scale with the gain of the first stage, when the
|
|
first stage gain is changed from gain[0] to gain_sq5Tbl[i] the energy
|
|
of the coded signal changes from cene to
|
|
|
|
cene*(gain_sq5Tbl[i]*gain_sq5Tbl[i])/(gain[0]*gain[0])
|
|
|
|
where gain[0] is the gain for the first stage found in the original
|
|
codebook search. A refined search is performed by testing the gain
|
|
indices i=0 to 31, and as long as the new codebook energy as given
|
|
above is less than tene, the gain index for stage 1 is increased. A
|
|
restriction is applied so that the new gain value for stage 1 cannot
|
|
be more than two times higher than the original value found in the
|
|
codebook search. Note that by using this method we do not change the
|
|
shape of the encoded vector, only the gain or amplitude.
|
|
|
|
3.8. Bitstream Definition
|
|
|
|
The total number of bits used to describe one frame of 20 ms speech
|
|
is 304, which fits in 38 bytes and results in a bit rate of 15.20
|
|
kbit/s. For the case of a frame length of 30 ms speech, the total
|
|
number of bits used is 400, which fits in 50 bytes and results in a
|
|
bit rate of 13.33 kbit/s. In the bitstream definition, the bits are
|
|
distributed into three classes according to their bit error or loss
|
|
sensitivity. The most sensitive bits (class 1) are placed first in
|
|
the bitstream for each frame. The less sensitive bits (class 2) are
|
|
placed after the class 1 bits. The least sensitive bits (class 3)
|
|
are placed at the end of the bitstream for each frame.
|
|
|
|
In the 20/30 ms frame length cases for each class, the following hold
|
|
true: The class 1 bits occupy a total of 6/8 bytes (48/64 bits), the
|
|
class 2 bits occupy 8/12 bytes (64/96 bits), and the class 3 bits
|
|
occupy 24/30 bytes (191/239 bits). This distribution of the bits
|
|
enables the use of uneven level protection (ULP) as is exploited in
|
|
the payload format definition for iLBC [1]. The detailed bit
|
|
allocation is shown in the table below. When a quantization index is
|
|
distributed between more classes, the more significant bits belong to
|
|
the lowest class.
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
Andersen, et al. Experimental [Page 29]
|
|
|
|
RFC 3951 Internet Low Bit Rate Codec December 2004
|
|
|
|
|
|
Bitstream structure:
|
|
|
|
------------------------------------------------------------------+
|
|
Parameter | Bits Class <1,2,3> |
|
|
| 20 ms frame | 30 ms frame |
|
|
----------------------------------+---------------+---------------+
|
|
Split 1 | 6 <6,0,0> | 6 <6,0,0> |
|
|
LSF 1 Split 2 | 7 <7,0,0> | 7 <7,0,0> |
|
|
LSF Split 3 | 7 <7,0,0> | 7 <7,0,0> |
|
|
------------------+---------------+---------------+
|
|
Split 1 | NA (Not Appl.)| 6 <6,0,0> |
|
|
LSF 2 Split 2 | NA | 7 <7,0,0> |
|
|
Split 3 | NA | 7 <7,0,0> |
|
|
------------------+---------------+---------------+
|
|
Sum | 20 <20,0,0> | 40 <40,0,0> |
|
|
----------------------------------+---------------+---------------+
|
|
Block Class | 2 <2,0,0> | 3 <3,0,0> |
|
|
----------------------------------+---------------+---------------+
|
|
Position 22 sample segment | 1 <1,0,0> | 1 <1,0,0> |
|
|
----------------------------------+---------------+---------------+
|
|
Scale Factor State Coder | 6 <6,0,0> | 6 <6,0,0> |
|
|
----------------------------------+---------------+---------------+
|
|
Sample 0 | 3 <0,1,2> | 3 <0,1,2> |
|
|
Quantized Sample 1 | 3 <0,1,2> | 3 <0,1,2> |
|
|
Residual : | : : | : : |
|
|
State : | : : | : : |
|
|
Samples : | : : | : : |
|
|
Sample 56 | 3 <0,1,2> | 3 <0,1,2> |
|
|
Sample 57 | NA | 3 <0,1,2> |
|
|
------------------+---------------+---------------+
|
|
Sum | 171 <0,57,114>| 174 <0,58,116>|
|
|
----------------------------------+---------------+---------------+
|
|
Stage 1 | 7 <6,0,1> | 7 <4,2,1> |
|
|
CB for 22/23 Stage 2 | 7 <0,0,7> | 7 <0,0,7> |
|
|
sample block Stage 3 | 7 <0,0,7> | 7 <0,0,7> |
|
|
------------------+---------------+---------------+
|
|
Sum | 21 <6,0,15> | 21 <4,2,15> |
|
|
----------------------------------+---------------+---------------+
|
|
Stage 1 | 5 <2,0,3> | 5 <1,1,3> |
|
|
Gain for 22/23 Stage 2 | 4 <1,1,2> | 4 <1,1,2> |
|
|
sample block Stage 3 | 3 <0,0,3> | 3 <0,0,3> |
|
|
------------------+---------------+---------------+
|
|
Sum | 12 <3,1,8> | 12 <2,2,8> |
|
|
----------------------------------+---------------+---------------+
|
|
Stage 1 | 8 <7,0,1> | 8 <6,1,1> |
|
|
sub-block 1 Stage 2 | 7 <0,0,7> | 7 <0,0,7> |
|
|
Stage 3 | 7 <0,0,7> | 7 <0,0,7> |
|
|
------------------+---------------+---------------+
|
|
|
|
|
|
|
|
Andersen, et al. Experimental [Page 30]
|
|
|
|
RFC 3951 Internet Low Bit Rate Codec December 2004
|
|
|
|
|
|
Stage 1 | 8 <0,0,8> | 8 <0,7,1> |
|
|
sub-block 2 Stage 2 | 8 <0,0,8> | 8 <0,0,8> |
|
|
Indices Stage 3 | 8 <0,0,8> | 8 <0,0,8> |
|
|
for CB ------------------+---------------+---------------+
|
|
sub-blocks Stage 1 | NA | 8 <0,7,1> |
|
|
sub-block 3 Stage 2 | NA | 8 <0,0,8> |
|
|
Stage 3 | NA | 8 <0,0,8> |
|
|
------------------+---------------+---------------+
|
|
Stage 1 | NA | 8 <0,7,1> |
|
|
sub-block 4 Stage 2 | NA | 8 <0,0,8> |
|
|
Stage 3 | NA | 8 <0,0,8> |
|
|
------------------+---------------+---------------+
|
|
Sum | 46 <7,0,39> | 94 <6,22,66> |
|
|
----------------------------------+---------------+---------------+
|
|
Stage 1 | 5 <1,2,2> | 5 <1,2,2> |
|
|
sub-block 1 Stage 2 | 4 <1,1,2> | 4 <1,2,1> |
|
|
Stage 3 | 3 <0,0,3> | 3 <0,0,3> |
|
|
------------------+---------------+---------------+
|
|
Stage 1 | 5 <1,1,3> | 5 <0,2,3> |
|
|
sub-block 2 Stage 2 | 4 <0,2,2> | 4 <0,2,2> |
|
|
Stage 3 | 3 <0,0,3> | 3 <0,0,3> |
|
|
Gains for ------------------+---------------+---------------+
|
|
sub-blocks Stage 1 | NA | 5 <0,1,4> |
|
|
sub-block 3 Stage 2 | NA | 4 <0,1,3> |
|
|
Stage 3 | NA | 3 <0,0,3> |
|
|
------------------+---------------+---------------+
|
|
Stage 1 | NA | 5 <0,1,4> |
|
|
sub-block 4 Stage 2 | NA | 4 <0,1,3> |
|
|
Stage 3 | NA | 3 <0,0,3> |
|
|
------------------+---------------+---------------+
|
|
Sum | 24 <3,6,15> | 48 <2,12,34> |
|
|
----------------------------------+---------------+---------------+
|
|
Empty frame indicator | 1 <0,0,1> | 1 <0,0,1> |
|
|
-------------------------------------------------------------------
|
|
SUM 304 <48,64,192> 400 <64,96,240>
|
|
|
|
Table 3.2. The bitstream definition for iLBC for both the 20 ms
|
|
frame size mode and the 30 ms frame size mode.
|
|
|
|
When packetized into the payload, the bits MUST be sorted as follows:
|
|
All the class 1 bits in the order (from top to bottom) as specified
|
|
in the table, all the class 2 bits (from top to bottom), and all the
|
|
class 3 bits in the same sequential order. The last bit, the empty
|
|
frame indicator, SHOULD be set to zero by the encoder. If this bit
|
|
is set to 1 the decoder SHOULD treat the data as a lost frame. For
|
|
example, this bit can be set to 1 to indicate lost frame for file
|
|
storage format, as in [1].
|
|
|
|
|
|
|
|
|
|
Andersen, et al. Experimental [Page 31]
|
|
|
|
RFC 3951 Internet Low Bit Rate Codec December 2004
|
|
|
|
|
|
4. Decoder Principles
|
|
|
|
This section describes the principles of each component of the
|
|
decoder algorithm.
|
|
|
|
+-------------+ +--------+ +---------------+
|
|
payload -> | 1. Get para | -> | 2. LPC | -> | 3. Sc Dequant | ->
|
|
+-------------+ +--------+ +---------------+
|
|
|
|
+-------------+ +------------------+
|
|
-> | 4. Mem setup| -> | 5. Construct res |------->
|
|
| +-------------+ +------------------- |
|
|
---------<-----------<-----------<------------
|
|
Sub-frame 0...2/4 (20 ms/30 ms)
|
|
|
|
+----------------+ +----------+
|
|
-> | 6. Enhance res | -> | 7. Synth | ------------>
|
|
+----------------+ +----------+
|
|
|
|
+-----------------+
|
|
-> | 8. Post Process | ----------------> decoded speech
|
|
+-----------------+
|
|
|
|
Figure 4.1. Flow chart of the iLBC decoder. If a frame was lost,
|
|
steps 1 to 5 SHOULD be replaced by a PLC algorithm.
|
|
|
|
1. Extract the parameters from the bitstream.
|
|
|
|
2. Decode the LPC and interpolate (section 4.1).
|
|
|
|
3. Construct the 57/58-sample start state (section 4.2).
|
|
|
|
4. Set up the memory by using data from the decoded residual. This
|
|
memory is used for codebook construction. For blocks preceding
|
|
the start state, both the decoded residual and the target are time
|
|
reversed. Sub-frames are decoded in the same order as they were
|
|
encoded.
|
|
|
|
5. Construct the residuals of this sub-frame (gain[0]*cbvec[0] +
|
|
gain[1]*cbvec[1] + gain[2]*cbvec[2]). Repeat 4 and 5 until the
|
|
residual of all sub-blocks has been constructed.
|
|
|
|
6. Enhance the residual with the post filter (section 4.6).
|
|
|
|
7. Synthesis of the residual (section 4.7).
|
|
|
|
8. Post process with HP filter, if desired (section 4.8).
|
|
|
|
|
|
|
|
|
|
Andersen, et al. Experimental [Page 32]
|
|
|
|
RFC 3951 Internet Low Bit Rate Codec December 2004
|
|
|
|
|
|
4.1. LPC Filter Reconstruction
|
|
|
|
The decoding of the LP filter parameters is very straightforward.
|
|
For a set of three/six indices, the corresponding LSF vector(s) are
|
|
found by simple table lookup. For each of the LSF vectors, the three
|
|
split vectors are concatenated to obtain qlsf1 and qlsf2,
|
|
respectively (in the 20 ms mode only one LSF vector, qlsf, is
|
|
constructed). The next step is the stability check described in
|
|
section 3.2.5 followed by the interpolation scheme described in
|
|
section 3.2.6 (3.2.7 for 20 ms frames). The only difference is that
|
|
only the quantized LSFs are known at the decoder, and hence the
|
|
unquantized LSFs are not processed.
|
|
|
|
A reference implementation of the LPC filter reconstruction is given
|
|
in Appendix A.36.
|
|
|
|
4.2. Start State Reconstruction
|
|
|
|
The scalar encoded STATE_SHORT_LEN=58 (STATE_SHORT_LEN=57 in the 20
|
|
ms mode) state samples are reconstructed by 1) forming a set of
|
|
samples (by table lookup) from the index stream idxVec[n], 2)
|
|
multiplying the set with 1/scal=(10^qmax)/4.5, 3) time reversing the
|
|
57/58 samples, 4) filtering the time reversed block with the
|
|
dispersion (all-pass) filter used in the encoder (as described in
|
|
section 3.5.2); this compensates for the phase distortion of the
|
|
earlier filter operation, and 5 reversing the 57/58 samples from the
|
|
previous step.
|
|
|
|
in(0..(STATE_SHORT_LEN-1)) = time reversed samples from table
|
|
look-up,
|
|
idxVecDec((STATE_SHORT_LEN-1)..0)
|
|
|
|
in(STATE_SHORT_LEN..(2*STATE_SHORT_LEN-1)) = 0
|
|
|
|
Pk(z) = A~rk(z)/A~k(z), where
|
|
___
|
|
\
|
|
A~rk(z)= z^(-LPC_FILTERORDER) + > a~ki*z^(i-(LPC_FILTERORDER-1))
|
|
/__
|
|
i=0...(LPC_FILTERORDER-1)
|
|
|
|
and A~k(z) is taken from the block where the start state begins
|
|
|
|
in -> Pk(z) -> filtered
|
|
|
|
out(k) = filtered(STATE_SHORT_LEN-1-k) +
|
|
filtered(2*STATE_SHORT_LEN-1-k),
|
|
k=0..(STATE_SHORT_LEN-1)
|
|
|
|
|
|
|
|
Andersen, et al. Experimental [Page 33]
|
|
|
|
RFC 3951 Internet Low Bit Rate Codec December 2004
|
|
|
|
|
|
The remaining 23/22 samples in the state are reconstructed by the
|
|
same adaptive codebook technique described in section 4.3. The
|
|
location bit determines whether these are the first or the last 23/22
|
|
samples of the 80-sample state vector. If the remaining 23/22
|
|
samples are the first samples, then the scalar encoded
|
|
STATE_SHORT_LEN state samples are time-reversed before initialization
|
|
of the adaptive codebook memory vector.
|
|
|
|
A reference implementation of the start state reconstruction is given
|
|
in Appendix A.44.
|
|
|
|
4.3. Excitation Decoding Loop
|
|
|
|
The decoding of the LPC excitation vector proceeds in the same order
|
|
in which the residual was encoded at the encoder. That is, after the
|
|
decoding of the entire 80-sample state vector, the forward sub-blocks
|
|
(corresponding to samples occurring after the state vector samples)
|
|
are decoded, and then the backward sub-blocks (corresponding to
|
|
samples occurring before the state vector) are decoded, resulting in
|
|
a fully decoded block of excitation signal samples.
|
|
|
|
In particular, each sub-block is decoded by using the multistage
|
|
adaptive codebook decoding module described in section 4.4. This
|
|
module relies upon an adaptive codebook memory constructed before
|
|
each run of the adaptive codebook decoding. The construction of the
|
|
adaptive codebook memory in the decoder is identical to the method
|
|
outlined in section 3.6.3, except that it is done on the codebook
|
|
memory without perceptual weighting.
|
|
|
|
For the initial forward sub-block, the last STATE_LEN=80 samples of
|
|
the length CB_LMEM=147 adaptive codebook memory are filled with the
|
|
samples of the state vector. For subsequent forward sub-blocks, the
|
|
first SUBL=40 samples of the adaptive codebook memory are discarded,
|
|
the remaining samples are shifted by SUBL samples toward the
|
|
beginning of the vector, and the newly decoded SUBL=40 samples are
|
|
placed at the end of the adaptive codebook memory. For backward
|
|
sub-blocks, the construction is similar, except that every vector of
|
|
samples involved is first time reversed.
|
|
|
|
A reference implementation of the excitation decoding loop is found
|
|
in Appendix A.5.
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
Andersen, et al. Experimental [Page 34]
|
|
|
|
RFC 3951 Internet Low Bit Rate Codec December 2004
|
|
|
|
|
|
4.4. Multistage Adaptive Codebook Decoding
|
|
|
|
The Multistage Adaptive Codebook Decoding module is used at both the
|
|
sender (encoder) and the receiver (decoder) ends to produce a
|
|
synthetic signal in the residual domain that is eventually used to
|
|
produce synthetic speech. The module takes the index values used to
|
|
construct vectors that are scaled and summed together to produce a
|
|
synthetic signal that is the output of the module.
|
|
|
|
4.4.1. Construction of the Decoded Excitation Signal
|
|
|
|
The unpacked index values provided at the input to the module are
|
|
references to extended codebooks, which are constructed as described
|
|
in section 3.6.3, except that they are based on the codebook memory
|
|
without the perceptual weighting. The unpacked three indices are
|
|
used to look up three codebook vectors. The unpacked three gain
|
|
indices are used to decode the corresponding 3 gains. In this
|
|
decoding, the successive rescaling, as described in section 3.6.4.2,
|
|
is applied.
|
|
|
|
A reference implementation of the adaptive codebook decoding is
|
|
listed in Appendix A.32.
|
|
|
|
4.5. Packet Loss Concealment
|
|
|
|
If packet loss occurs, the decoder receives a signal saying that
|
|
information regarding a block is lost. For such blocks it is
|
|
RECOMMENDED to use a Packet Loss Concealment (PLC) unit to create a
|
|
decoded signal that masks the effect of that packet loss. In the
|
|
following we will describe an example of a PLC unit that can be used
|
|
with the iLBC codec. As the PLC unit is used only at the decoder,
|
|
the PLC unit does not affect interoperability between
|
|
implementations. Other PLC implementations MAY therefore be used.
|
|
|
|
The PLC described operates on the LP filters and the excitation
|
|
signals and is based on the following principles:
|
|
|
|
4.5.1. Block Received Correctly and Previous Block Also Received
|
|
|
|
If the block is received correctly, the PLC only records state
|
|
information of the current block that can be used in case the next
|
|
block is lost. The LP filter coefficients for each sub-block and the
|
|
entire decoded excitation signal are all saved in the decoder state
|
|
structure. All of this information will be needed if the following
|
|
block is lost.
|
|
|
|
|
|
|
|
|
|
|
|
|
|
Andersen, et al. Experimental [Page 35]
|
|
|
|
RFC 3951 Internet Low Bit Rate Codec December 2004
|
|
|
|
|
|
4.5.2. Block Not Received
|
|
|
|
If the block is not received, the block substitution is based on a
|
|
pitch-synchronous repetition of the excitation signal, which is
|
|
filtered by the last LP filter of the previous block. The previous
|
|
block's information is stored in the decoder state structure.
|
|
|
|
A correlation analysis is performed on the previous block's
|
|
excitation signal in order to detect the amount of pitch periodicity
|
|
and a pitch value. The correlation measure is also used to decide on
|
|
the voicing level (the degree to which the previous block's
|
|
excitation was a voiced or roughly periodic signal). The excitation
|
|
in the previous block is used to create an excitation for the block
|
|
to be substituted, such that the pitch of the previous block is
|
|
maintained. Therefore, the new excitation is constructed in a
|
|
pitch-synchronous manner. In order to avoid a buzzy-sounding
|
|
substituted block, a random excitation is mixed with the new pitch
|
|
periodic excitation, and the relative use of the two components is
|
|
computed from the correlation measure (voicing level).
|
|
|
|
For the block to be substituted, the newly constructed excitation
|
|
signal is then passed through the LP filter to produce the speech
|
|
that will be substituted for the lost block.
|
|
|
|
For several consecutive lost blocks, the packet loss concealment
|
|
continues in a similar manner. The correlation measure of the last
|
|
block received is still used along with the same pitch value. The LP
|
|
filters of the last block received are also used again. The energy
|
|
of the substituted excitation for consecutive lost blocks is
|
|
decreased, leading to a dampened excitation, and therefore to
|
|
dampened speech.
|
|
|
|
4.5.3. Block Received Correctly When Previous Block Not Received
|
|
|
|
For the case in which a block is received correctly when the previous
|
|
block was not, the correctly received block's directly decoded speech
|
|
(based solely on the received block) is not used as the actual
|
|
output. The reason for this is that the directly decoded speech does
|
|
not necessarily smoothly merge into the synthetic speech generated
|
|
for the previous lost block. If the two signals are not smoothly
|
|
merged, an audible discontinuity is accidentally produced.
|
|
Therefore, a correlation analysis between the two blocks of
|
|
excitation signal (the excitation of the previous concealed block and
|
|
that of the current received block) is performed to find the best
|
|
phase match. Then a simple overlap-add procedure is performed to
|
|
merge the previous excitation smoothly into the current block's
|
|
excitation.
|
|
|
|
|
|
|
|
|
|
Andersen, et al. Experimental [Page 36]
|
|
|
|
RFC 3951 Internet Low Bit Rate Codec December 2004
|
|
|
|
|
|
The exact implementation of the packet loss concealment does not
|
|
influence interoperability of the codec.
|
|
|
|
A reference implementation of the packet loss concealment is
|
|
suggested in Appendix A.14. Exact compliance with this suggested
|
|
algorithm is not needed for a reference implementation to be fully
|
|
compatible with the overall codec specification.
|
|
|
|
4.6. Enhancement
|
|
|
|
The decoder contains an enhancement unit that operates on the
|
|
reconstructed excitation signal. The enhancement unit increases the
|
|
perceptual quality of the reconstructed signal by reducing the
|
|
speech-correlated noise in the voiced speech segments. Compared to
|
|
traditional postfilters, the enhancer has an advantage in that it can
|
|
only modify the excitation signal slightly. This means that there is
|
|
no risk of over enhancement. The enhancer works very similarly for
|
|
both the 20 ms frame size mode and the 30 ms frame size mode.
|
|
|
|
For the mode with 20 ms frame size, the enhancer uses a memory of six
|
|
80-sample excitation blocks prior in time plus the two new 80-sample
|
|
excitation blocks. For each block of 160 new unenhanced excitation
|
|
samples, 160 enhanced excitation samples are produced. The enhanced
|
|
excitation is 40-sample delayed compared to the unenhanced
|
|
excitation, as the enhancer algorithm uses lookahead.
|
|
|
|
For the mode with 30 ms frame size, the enhancer uses a memory of
|
|
five 80-sample excitation blocks prior in time plus the three new
|
|
80-sample excitation blocks. For each block of 240 new unenhanced
|
|
excitation samples, 240 enhanced excitation samples are produced.
|
|
The enhanced excitation is 80-sample delayed compared to the
|
|
unenhanced excitation, as the enhancer algorithm uses lookahead.
|
|
|
|
Outline of Enhancer
|
|
|
|
The speech enhancement unit operates on sub-blocks of 80 samples,
|
|
which means that there are two/three 80 sample sub-blocks per frame.
|
|
Each of these two/three sub-blocks is enhanced separately, but in an
|
|
analogous manner.
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
Andersen, et al. Experimental [Page 37]
|
|
|
|
RFC 3951 Internet Low Bit Rate Codec December 2004
|
|
|
|
|
|
unenhanced residual
|
|
|
|
|
| +---------------+ +--------------+
|
|
+-> | 1. Pitch Est | -> | 2. Find PSSQ | -------->
|
|
+---------------+ | +--------------+
|
|
+-----<-------<------<--+
|
|
+------------+ enh block 0..1/2 |
|
|
-> | 3. Smooth | |
|
|
+------------+ |
|
|
\ |
|
|
/\ |
|
|
/ \ Already |
|
|
/ 4. \----------->----------->-----------+ |
|
|
\Crit/ Fulfilled | |
|
|
\? / v |
|
|
\/ | |
|
|
\ +-----------------+ +---------+ | |
|
|
Not +->| 5. Use Constr. | -> | 6. Mix | ----->
|
|
Fulfilled +-----------------+ +---------+
|
|
|
|
---------------> enhanced residual
|
|
|
|
Figure 4.2. Flow chart of the enhancer.
|
|
|
|
1. Pitch estimation of each of the two/three new 80-sample blocks.
|
|
|
|
2. Find the pitch-period-synchronous sequence n (for block k) by a
|
|
search around the estimated pitch value. Do this for n=1,2,3,
|
|
-1,-2,-3.
|
|
|
|
3. Calculate the smoothed residual generated by the six pitch-
|
|
period-synchronous sequences from prior step.
|
|
|
|
4. Check if the smoothed residual satisfies the criterion (section
|
|
4.6.4).
|
|
|
|
5. Use constraint to calculate mixing factor (section 4.6.5).
|
|
|
|
6. Mix smoothed signal with unenhanced residual (pssq(n) n=0).
|
|
|
|
The main idea of the enhancer is to find three 80 sample blocks
|
|
before and three 80-sample blocks after the analyzed unenhanced sub-
|
|
block and to use these to improve the quality of the excitation in
|
|
that sub-block. The six blocks are chosen so that they have the
|
|
highest possible correlation with the unenhanced sub-block that is
|
|
being enhanced. In other words, the six blocks are pitch-period-
|
|
synchronous sequences to the unenhanced sub-block.
|
|
|
|
|
|
|
|
|
|
Andersen, et al. Experimental [Page 38]
|
|
|
|
RFC 3951 Internet Low Bit Rate Codec December 2004
|
|
|
|
|
|
A linear combination of the six pitch-period-synchronous sequences is
|
|
calculated that approximates the sub-block. If the squared error
|
|
between the approximation and the unenhanced sub-block is small
|
|
enough, the enhanced residual is set equal to this approximation.
|
|
For the cases when the squared error criterion is not fulfilled, a
|
|
linear combination of the approximation and the unenhanced residual
|
|
forms the enhanced residual.
|
|
|
|
4.6.1. Estimating the Pitch
|
|
|
|
Pitch estimates are needed to determine the locations of the pitch-
|
|
period-synchronous sequences in a complexity-efficient way. For each
|
|
of the new two/three sub-blocks, a pitch estimate is calculated by
|
|
finding the maximum correlation in the range from lag 20 to lag 120.
|
|
These pitch estimates are used to narrow down the search for the best
|
|
possible pitch-period-synchronous sequences.
|
|
|
|
4.6.2. Determination of the Pitch-Synchronous Sequences
|
|
|
|
Upon receiving the pitch estimates from the prior step, the enhancer
|
|
analyzes and enhances one 80-sample sub-block at a time. The pitch-
|
|
period-synchronous-sequences pssq(n) can be viewed as vectors of
|
|
length 80 samples each shifted n*lag samples from the current sub-
|
|
block. The six pitch-period-synchronous-sequences, pssq(-3) to
|
|
pssq(-1) and pssq(1) to pssq(3), are found one at a time by the steps
|
|
below:
|
|
|
|
1) Calculate the estimate of the position of the pssq(n). For
|
|
pssq(n) in front of pssq(0) (n > 0), the location of the pssq(n)
|
|
is estimated by moving one pitch estimate forward in time from the
|
|
exact location of pssq(n-1). Similarly, pssq(n) behind pssq(0) (n
|
|
< 0) is estimated by moving one pitch estimate backward in time
|
|
from the exact location of pssq(n+1). If the estimated pssq(n)
|
|
vector location is totally within the enhancer memory (Figure
|
|
4.3), steps 2, 3, and 4 are performed, otherwise the pssq(n) is
|
|
set to zeros.
|
|
|
|
2) Compute the correlation between the unenhanced excitation and
|
|
vectors around the estimated location interval of pssq(n). The
|
|
correlation is calculated in the interval estimated location +/- 2
|
|
samples. This results in five correlation values.
|
|
|
|
3) The five correlation values are upsampled by a factor of 4, by
|
|
using four simple upsampling filters (MA filters with coefficients
|
|
upsFilter1.. upsFilter4). Within these the maximum value is
|
|
found, which specifies the best pitch-period with a resolution of
|
|
a quarter of a sample.
|
|
|
|
|
|
|
|
|
|
Andersen, et al. Experimental [Page 39]
|
|
|
|
RFC 3951 Internet Low Bit Rate Codec December 2004
|
|
|
|
|
|
upsFilter1[7]={0.000000 0.000000 0.000000 1.000000
|
|
0.000000 0.000000 0.000000}
|
|
upsFilter2[7]={0.015625 -0.076904 0.288330 0.862061
|
|
-0.106445 0.018799 -0.015625}
|
|
upsFilter3[7]={0.023682 -0.124268 0.601563 0.601563
|
|
-0.124268 0.023682 -0.023682}
|
|
upsFilter4[7]={0.018799 -0.106445 0.862061 0.288330
|
|
-0.076904 0.015625 -0.018799}
|
|
|
|
4) Generate the pssq(n) vector by upsampling of the excitation memory
|
|
and extracting the sequence that corresponds to the lag delay that
|
|
was calculated in prior step.
|
|
|
|
With the steps above, all the pssq(n) can be found in an iterative
|
|
manner, first moving backward in time from pssq(0) and then forward
|
|
in time from pssq(0).
|
|
|
|
|
|
0 159 319 479 639
|
|
+---------------------------------------------------------------+
|
|
| -5 | -4 | -3 | -2 | -1 | 0 | 1 | 2 |
|
|
+---------------------------------------------------------------+
|
|
|pssq 0 |
|
|
|pssq -1| |pssq 1 |
|
|
|pssq -2| |pssq 2 |
|
|
|pssq -3| |pssq 3 |
|
|
|
|
Figure 4.3. Enhancement for 20 ms frame size.
|
|
|
|
Figure 4.3 depicts pitch-period-synchronous sequences in the
|
|
enhancement of the first 80 sample block in the 20 ms frame size
|
|
mode. The unenhanced signal input is stored in the last two sub-
|
|
blocks (1 - 2), and the six other sub-blocks contain unenhanced
|
|
residual prior-in-time. We perform the enhancement algorithm on two
|
|
blocks of 80 samples, where the first of the two blocks consists of
|
|
the last 40 samples of sub-block 0 and the first 40 samples of sub-
|
|
block 1. The second 80-sample block consists of the last 40 samples
|
|
of sub-block 1 and the first 40 samples of sub-block 2.
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
Andersen, et al. Experimental [Page 40]
|
|
|
|
RFC 3951 Internet Low Bit Rate Codec December 2004
|
|
|
|
|
|
0 159 319 479 639
|
|
+---------------------------------------------------------------+
|
|
| -4 | -3 | -2 | -1 | 0 | 1 | 2 | 3 |
|
|
+---------------------------------------------------------------+
|
|
|pssq 0 |
|
|
|pssq -1| |pssq 1 |
|
|
|pssq -2| |pssq 2 |
|
|
|pssq -3| |pssq 3 |
|
|
|
|
Figure 4.4. Enhancement for 30 ms frame size.
|
|
|
|
Figure 4.4 depicts pitch-period-synchronous sequences in the
|
|
enhancement of the first 80-sample block in the 30 ms frame size
|
|
mode. The unenhanced signal input is stored in the last three sub-
|
|
blocks (1 - 3). The five other sub-blocks contain unenhanced
|
|
residual prior-in-time. The enhancement algorithm is performed on
|
|
the three 80 sample sub-blocks 0, 1, and 2.
|
|
|
|
4.6.3. Calculation of the Smoothed Excitation
|
|
|
|
A linear combination of the six pssq(n) (n!=0) form a smoothed
|
|
approximation, z, of pssq(0). Most of the weight is put on the
|
|
sequences that are close to pssq(0), as these are likely to be most
|
|
similar to pssq(0). The smoothed vector is also rescaled so that the
|
|
energy of z is the same as the energy of pssq(0).
|
|
|
|
___
|
|
\
|
|
y = > pssq(i) * pssq_weight(i)
|
|
/__
|
|
i=-3,-2,-1,1,2,3
|
|
|
|
pssq_weight(i) = 0.5*(1-cos(2*pi*(i+4)/(2*3+2)))
|
|
|
|
z = C * y, where C = ||pssq(0)||/||y||
|
|
|
|
4.6.4. Enhancer Criterion
|
|
|
|
The criterion of the enhancer is that the enhanced excitation is not
|
|
allowed to differ much from the unenhanced excitation. This
|
|
criterion is checked for each 80-sample sub-block.
|
|
|
|
e < (b * ||pssq(0)||^2), where b=0.05 and (Constraint 1)
|
|
|
|
e = (pssq(0)-z)*(pssq(0)-z), and "*" means the dot product
|
|
|
|
|
|
|
|
|
|
|
|
|
|
Andersen, et al. Experimental [Page 41]
|
|
|
|
RFC 3951 Internet Low Bit Rate Codec December 2004
|
|
|
|
|
|
4.6.5. Enhancing the excitation
|
|
|
|
From the criterion in the previous section, it is clear that the
|
|
excitation is not allowed to change much. The purpose of this
|
|
constraint is to prevent the creation of an enhanced signal
|
|
significantly different from the original signal. This also means
|
|
that the constraint limits the numerical size of the errors that the
|
|
enhancement procedure can make. That is especially important in
|
|
unvoiced segments and background noise segments for which increased
|
|
periodicity could lead to lower perceived quality.
|
|
|
|
When the constraint in the prior section is not met, the enhanced
|
|
residual is instead calculated through a constrained optimization by
|
|
using the Lagrange multiplier technique. The new constraint is that
|
|
|
|
e = (b * ||pssq(0)||^2) (Constraint 2)
|
|
|
|
We distinguish two solution regions for the optimization: 1) the
|
|
region where the first constraint is fulfilled and 2) the region
|
|
where the first constraint is not fulfilled and the second constraint
|
|
must be used.
|
|
|
|
In the first case, where the second constraint is not needed, the
|
|
optimized re-estimated vector is simply z, the energy-scaled version
|
|
of y.
|
|
|
|
In the second case, where the second constraint is activated and
|
|
becomes an equality constraint, we have
|
|
|
|
z= A*y + B*pssq(0)
|
|
|
|
where
|
|
|
|
A = sqrt((b-b^2/4)*(w00*w00)/ (w11*w00 + w10*w10)) and
|
|
|
|
w11 = pssq(0)*pssq(0)
|
|
w00 = y*y
|
|
w10 = y*pssq(0) (* symbolizes the dot product)
|
|
|
|
and
|
|
|
|
B = 1 - b/2 - A * w10/w00
|
|
|
|
Appendix A.16 contains a listing of a reference implementation for
|
|
the enhancement method.
|
|
|
|
|
|
|
|
|
|
|
|
|
|
Andersen, et al. Experimental [Page 42]
|
|
|
|
RFC 3951 Internet Low Bit Rate Codec December 2004
|
|
|
|
|
|
4.7. Synthesis Filtering
|
|
|
|
Upon decoding or PLC of the LP excitation block, the decoded speech
|
|
block is obtained by running the decoded LP synthesis filter,
|
|
1/A~k(z), over the block. The synthesis filters have to be shifted
|
|
to compensate for the delay in the enhancer. For 20 ms frame size
|
|
mode, they SHOULD be shifted one 40-sample sub-block, and for 30 ms
|
|
frame size mode, they SHOULD be shifted two 40-sample sub-blocks.
|
|
The LP coefficients SHOULD be changed at the first sample of every
|
|
sub-block while keeping the filter state. For PLC blocks, one
|
|
solution is to apply the last LP coefficients of the last decoded
|
|
speech block for all sub-blocks.
|
|
|
|
The reference implementation for the synthesis filtering can be found
|
|
in Appendix A.48.
|
|
|
|
4.8. Post Filtering
|
|
|
|
If desired, the decoded block can be filtered by a high-pass filter.
|
|
This removes the low frequencies of the decoded signal. A reference
|
|
implementation of this, with cutoff at 65 Hz, is shown in Appendix
|
|
A.30.
|
|
|
|
5. Security Considerations
|
|
|
|
This algorithm for the coding of speech signals is not subject to any
|
|
known security consideration; however, its RTP payload format [1] is
|
|
subject to several considerations, which are addressed there.
|
|
Confidentiality of the media streams is achieved by encryption;
|
|
therefore external mechanisms, such as SRTP [5], MAY be used for that
|
|
purpose.
|
|
|
|
6. Evaluation of the iLBC Implementations
|
|
|
|
It is possible and suggested to evaluate certain iLBC implementation
|
|
by utilizing methodology and tools available at
|
|
http://www.ilbcfreeware.org/evaluation.html
|
|
|
|
7. References
|
|
|
|
7.1. Normative References
|
|
|
|
[1] Duric, A. and S. Andersen, "Real-time Transport Protocol (RTP)
|
|
Payload Format for internet Low Bit Rate Codec (iLBC) Speech",
|
|
RFC 3952, December 2004.
|
|
|
|
[2] Bradner, S., "Key words for use in RFCs to Indicate Requirement
|
|
Levels", BCP 14, RFC 2119, March 1997.
|
|
|
|
|
|
|
|
Andersen, et al. Experimental [Page 43]
|
|
|
|
RFC 3951 Internet Low Bit Rate Codec December 2004
|
|
|
|
|
|
[3] PacketCable(TM) Audio/Video Codecs Specification, Cable
|
|
Television Laboratories, Inc.
|
|
|
|
7.2. Informative References
|
|
|
|
[4] ITU-T Recommendation G.711, available online from the ITU
|
|
bookstore at http://www.itu.int.
|
|
|
|
[5] Baugher, M., McGrew, D., Naslund, M., Carrara, E., and K. Norman,
|
|
"The Secure Real Time Transport Protocol (SRTP)", RFC 3711, March
|
|
2004.
|
|
|
|
8. Acknowledgements
|
|
|
|
This extensive work, besides listed authors, has the following
|
|
authors, who could not have been listed among "official" authors (due
|
|
to IESG restrictions in the number of authors who can be listed):
|
|
|
|
Manohar N. Murthi (Department of Electrical and Computer
|
|
Engineering, University of Miami), Fredrik Galschiodt, Julian
|
|
Spittka, and Jan Skoglund (Global IP Sound).
|
|
|
|
The authors are deeply indebted to the following people and thank
|
|
them sincerely:
|
|
|
|
Henry Sinnreich, Patrik Faltstrom, Alan Johnston, and Jean-
|
|
Francois Mule for great support of the iLBC initiative and for
|
|
valuable feedback and comments.
|
|
|
|
Peter Vary, Frank Mertz, and Christoph Erdmann (RWTH Aachen);
|
|
Vladimir Cuperman (Niftybox LLC); Thomas Eriksson (Chalmers Univ
|
|
of Tech), and Gernot Kubin (TU Graz), for thorough review of the
|
|
iLBC document and their valuable feedback and remarks.
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
Andersen, et al. Experimental [Page 44]
|
|
|
|
RFC 3951 Internet Low Bit Rate Codec December 2004
|
|
|
|
|
|
APPENDIX A. Reference Implementation
|
|
|
|
This appendix contains the complete c-code for a reference
|
|
implementation of encoder and decoder for the specified codec.
|
|
|
|
The c-code consists of the following files with highest-level
|
|
functions:
|
|
|
|
iLBC_test.c: main function for evaluation purpose
|
|
iLBC_encode.h: encoder header
|
|
iLBC_encode.c: encoder function
|
|
iLBC_decode.h: decoder header
|
|
iLBC_decode.c: decoder function
|
|
|
|
The following files contain global defines and constants:
|
|
|
|
iLBC_define.h: global defines
|
|
constants.h: global constants header
|
|
constants.c: global constants memory allocations
|
|
|
|
The following files contain subroutines:
|
|
|
|
anaFilter.h: lpc analysis filter header
|
|
anaFilter.c: lpc analysis filter function
|
|
createCB.h: codebook construction header
|
|
createCB.c: codebook construction function
|
|
doCPLC.h: packet loss concealment header
|
|
doCPLC.c: packet loss concealment function
|
|
enhancer.h: signal enhancement header
|
|
enhancer.c: signal enhancement function
|
|
filter.h: general filter header
|
|
filter.c: general filter functions
|
|
FrameClassify.h: start state classification header
|
|
FrameClassify.c: start state classification function
|
|
gainquant.h: gain quantization header
|
|
gainquant.c: gain quantization function
|
|
getCBvec.h: codebook vector construction header
|
|
getCBvec.c: codebook vector construction function
|
|
helpfun.h: general purpose header
|
|
helpfun.c: general purpose functions
|
|
hpInput.h: input high pass filter header
|
|
hpInput.c: input high pass filter function
|
|
hpOutput.h: output high pass filter header
|
|
hpOutput.c: output high pass filter function
|
|
iCBConstruct.h: excitation decoding header
|
|
iCBConstruct.c: excitation decoding function
|
|
iCBSearch.h: excitation encoding header
|
|
iCBSearch.c: excitation encoding function
|
|
|
|
|
|
|
|
Andersen, et al. Experimental [Page 45]
|
|
|
|
RFC 3951 Internet Low Bit Rate Codec December 2004
|
|
|
|
|
|
LPCdecode.h: lpc decoding header
|
|
LPCdecode.c: lpc decoding function
|
|
LPCencode.h: lpc encoding header
|
|
LPCencode.c: lpc encoding function
|
|
lsf.h: line spectral frequencies header
|
|
lsf.c: line spectral frequencies functions
|
|
packing.h: bitstream packetization header
|
|
packing.c: bitstream packetization functions
|
|
StateConstructW.h: state decoding header
|
|
StateConstructW.c: state decoding functions
|
|
StateSearchW.h: state encoding header
|
|
StateSearchW.c: state encoding function
|
|
syntFilter.h: lpc synthesis filter header
|
|
syntFilter.c: lpc synthesis filter function
|
|
|
|
The implementation is portable and should work on many different
|
|
platforms. However, it is not difficult to optimize the
|
|
implementation on particular platforms, an exercise left to the
|
|
reader.
|
|
|
|
A.1. iLBC_test.c
|
|
|
|
/******************************************************************
|
|
|
|
iLBC Speech Coder ANSI-C Source Code
|
|
|
|
iLBC_test.c
|
|
|
|
Copyright (C) The Internet Society (2004).
|
|
All Rights Reserved.
|
|
|
|
******************************************************************/
|
|
|
|
#include <math.h>
|
|
#include <stdlib.h>
|
|
#include <stdio.h>
|
|
#include <string.h>
|
|
#include "iLBC_define.h"
|
|
#include "iLBC_encode.h"
|
|
#include "iLBC_decode.h"
|
|
|
|
/* Runtime statistics */
|
|
#include <time.h>
|
|
|
|
#define ILBCNOOFWORDS_MAX (NO_OF_BYTES_30MS/2)
|
|
|
|
/*----------------------------------------------------------------*
|
|
* Encoder interface function
|
|
|
|
|
|
|
|
Andersen, et al. Experimental [Page 46]
|
|
|
|
RFC 3951 Internet Low Bit Rate Codec December 2004
|
|
|
|
|
|
*---------------------------------------------------------------*/
|
|
|
|
short encode( /* (o) Number of bytes encoded */
|
|
iLBC_Enc_Inst_t *iLBCenc_inst,
|
|
/* (i/o) Encoder instance */
|
|
short *encoded_data, /* (o) The encoded bytes */
|
|
short *data /* (i) The signal block to encode*/
|
|
){
|
|
float block[BLOCKL_MAX];
|
|
int k;
|
|
|
|
/* convert signal to float */
|
|
|
|
for (k=0; k<iLBCenc_inst->blockl; k++)
|
|
block[k] = (float)data[k];
|
|
|
|
/* do the actual encoding */
|
|
|
|
iLBC_encode((unsigned char *)encoded_data, block, iLBCenc_inst);
|
|
|
|
|
|
return (iLBCenc_inst->no_of_bytes);
|
|
}
|
|
|
|
/*----------------------------------------------------------------*
|
|
* Decoder interface function
|
|
*---------------------------------------------------------------*/
|
|
|
|
short decode( /* (o) Number of decoded samples */
|
|
iLBC_Dec_Inst_t *iLBCdec_inst, /* (i/o) Decoder instance */
|
|
short *decoded_data, /* (o) Decoded signal block*/
|
|
short *encoded_data, /* (i) Encoded bytes */
|
|
short mode /* (i) 0=PL, 1=Normal */
|
|
){
|
|
int k;
|
|
float decblock[BLOCKL_MAX], dtmp;
|
|
|
|
/* check if mode is valid */
|
|
|
|
if (mode<0 || mode>1) {
|
|
printf("\nERROR - Wrong mode - 0, 1 allowed\n"); exit(3);}
|
|
|
|
/* do actual decoding of block */
|
|
|
|
iLBC_decode(decblock, (unsigned char *)encoded_data,
|
|
iLBCdec_inst, mode);
|
|
|
|
/* convert to short */
|
|
|
|
|
|
|
|
Andersen, et al. Experimental [Page 47]
|
|
|
|
RFC 3951 Internet Low Bit Rate Codec December 2004
|
|
|
|
|
|
for (k=0; k<iLBCdec_inst->blockl; k++){
|
|
dtmp=decblock[k];
|
|
|
|
if (dtmp<MIN_SAMPLE)
|
|
dtmp=MIN_SAMPLE;
|
|
else if (dtmp>MAX_SAMPLE)
|
|
dtmp=MAX_SAMPLE;
|
|
decoded_data[k] = (short) dtmp;
|
|
}
|
|
|
|
return (iLBCdec_inst->blockl);
|
|
}
|
|
|
|
/*---------------------------------------------------------------*
|
|
* Main program to test iLBC encoding and decoding
|
|
*
|
|
* Usage:
|
|
* exefile_name.exe <infile> <bytefile> <outfile> <channel>
|
|
*
|
|
* <infile> : Input file, speech for encoder (16-bit pcm file)
|
|
* <bytefile> : Bit stream output from the encoder
|
|
* <outfile> : Output file, decoded speech (16-bit pcm file)
|
|
* <channel> : Bit error file, optional (16-bit)
|
|
* 1 - Packet received correctly
|
|
* 0 - Packet Lost
|
|
*
|
|
*--------------------------------------------------------------*/
|
|
|
|
int main(int argc, char* argv[])
|
|
{
|
|
|
|
/* Runtime statistics */
|
|
|
|
float starttime;
|
|
float runtime;
|
|
float outtime;
|
|
|
|
FILE *ifileid,*efileid,*ofileid, *cfileid;
|
|
short data[BLOCKL_MAX];
|
|
short encoded_data[ILBCNOOFWORDS_MAX], decoded_data[BLOCKL_MAX];
|
|
int len;
|
|
short pli, mode;
|
|
int blockcount = 0;
|
|
int packetlosscount = 0;
|
|
|
|
/* Create structs */
|
|
iLBC_Enc_Inst_t Enc_Inst;
|
|
iLBC_Dec_Inst_t Dec_Inst;
|
|
|
|
|
|
|
|
Andersen, et al. Experimental [Page 48]
|
|
|
|
RFC 3951 Internet Low Bit Rate Codec December 2004
|
|
|
|
|
|
/* get arguments and open files */
|
|
|
|
if ((argc!=5) && (argc!=6)) {
|
|
fprintf(stderr,
|
|
"\n*-----------------------------------------------*\n");
|
|
fprintf(stderr,
|
|
" %s <20,30> input encoded decoded (channel)\n\n",
|
|
argv[0]);
|
|
fprintf(stderr,
|
|
" mode : Frame size for the encoding/decoding\n");
|
|
fprintf(stderr,
|
|
" 20 - 20 ms\n");
|
|
fprintf(stderr,
|
|
" 30 - 30 ms\n");
|
|
fprintf(stderr,
|
|
" input : Speech for encoder (16-bit pcm file)\n");
|
|
fprintf(stderr,
|
|
" encoded : Encoded bit stream\n");
|
|
fprintf(stderr,
|
|
" decoded : Decoded speech (16-bit pcm file)\n");
|
|
fprintf(stderr,
|
|
" channel : Packet loss pattern, optional (16-bit)\n");
|
|
fprintf(stderr,
|
|
" 1 - Packet received correctly\n");
|
|
fprintf(stderr,
|
|
" 0 - Packet Lost\n");
|
|
fprintf(stderr,
|
|
"*-----------------------------------------------*\n\n");
|
|
exit(1);
|
|
}
|
|
mode=atoi(argv[1]);
|
|
if (mode != 20 && mode != 30) {
|
|
fprintf(stderr,"Wrong mode %s, must be 20, or 30\n",
|
|
argv[1]);
|
|
exit(2);
|
|
}
|
|
if ( (ifileid=fopen(argv[2],"rb")) == NULL) {
|
|
fprintf(stderr,"Cannot open input file %s\n", argv[2]);
|
|
exit(2);}
|
|
if ( (efileid=fopen(argv[3],"wb")) == NULL) {
|
|
fprintf(stderr, "Cannot open encoded file %s\n",
|
|
argv[3]); exit(1);}
|
|
if ( (ofileid=fopen(argv[4],"wb")) == NULL) {
|
|
fprintf(stderr, "Cannot open decoded file %s\n",
|
|
argv[4]); exit(1);}
|
|
if (argc==6) {
|
|
if( (cfileid=fopen(argv[5],"rb")) == NULL) {
|
|
fprintf(stderr, "Cannot open channel file %s\n",
|
|
|
|
|
|
|
|
Andersen, et al. Experimental [Page 49]
|
|
|
|
RFC 3951 Internet Low Bit Rate Codec December 2004
|
|
|
|
|
|
argv[5]);
|
|
exit(1);
|
|
}
|
|
} else {
|
|
cfileid=NULL;
|
|
}
|
|
|
|
/* print info */
|
|
|
|
fprintf(stderr, "\n");
|
|
fprintf(stderr,
|
|
"*---------------------------------------------------*\n");
|
|
fprintf(stderr,
|
|
"* *\n");
|
|
fprintf(stderr,
|
|
"* iLBC test program *\n");
|
|
fprintf(stderr,
|
|
"* *\n");
|
|
fprintf(stderr,
|
|
"* *\n");
|
|
fprintf(stderr,
|
|
"*---------------------------------------------------*\n");
|
|
fprintf(stderr,"\nMode : %2d ms\n", mode);
|
|
fprintf(stderr,"Input file : %s\n", argv[2]);
|
|
fprintf(stderr,"Encoded file : %s\n", argv[3]);
|
|
fprintf(stderr,"Output file : %s\n", argv[4]);
|
|
if (argc==6) {
|
|
fprintf(stderr,"Channel file : %s\n", argv[5]);
|
|
}
|
|
fprintf(stderr,"\n");
|
|
|
|
/* Initialization */
|
|
|
|
initEncode(&Enc_Inst, mode);
|
|
initDecode(&Dec_Inst, mode, 1);
|
|
|
|
/* Runtime statistics */
|
|
|
|
starttime=clock()/(float)CLOCKS_PER_SEC;
|
|
|
|
/* loop over input blocks */
|
|
|
|
while (fread(data,sizeof(short),Enc_Inst.blockl,ifileid)==
|
|
Enc_Inst.blockl) {
|
|
|
|
blockcount++;
|
|
|
|
/* encoding */
|
|
|
|
|
|
|
|
Andersen, et al. Experimental [Page 50]
|
|
|
|
RFC 3951 Internet Low Bit Rate Codec December 2004
|
|
|
|
|
|
fprintf(stderr, "--- Encoding block %i --- ",blockcount);
|
|
len=encode(&Enc_Inst, encoded_data, data);
|
|
fprintf(stderr, "\r");
|
|
|
|
/* write byte file */
|
|
|
|
fwrite(encoded_data, sizeof(unsigned char), len, efileid);
|
|
|
|
/* get channel data if provided */
|
|
if (argc==6) {
|
|
if (fread(&pli, sizeof(short), 1, cfileid)) {
|
|
if ((pli!=0)&&(pli!=1)) {
|
|
fprintf(stderr, "Error in channel file\n");
|
|
exit(0);
|
|
}
|
|
if (pli==0) {
|
|
/* Packet loss -> remove info from frame */
|
|
memset(encoded_data, 0,
|
|
sizeof(short)*ILBCNOOFWORDS_MAX);
|
|
packetlosscount++;
|
|
}
|
|
} else {
|
|
fprintf(stderr, "Error. Channel file too short\n");
|
|
exit(0);
|
|
}
|
|
} else {
|
|
pli=1;
|
|
}
|
|
|
|
/* decoding */
|
|
|
|
fprintf(stderr, "--- Decoding block %i --- ",blockcount);
|
|
|
|
len=decode(&Dec_Inst, decoded_data, encoded_data, pli);
|
|
fprintf(stderr, "\r");
|
|
|
|
/* write output file */
|
|
|
|
fwrite(decoded_data,sizeof(short),len,ofileid);
|
|
}
|
|
|
|
/* Runtime statistics */
|
|
|
|
runtime = (float)(clock()/(float)CLOCKS_PER_SEC-starttime);
|
|
outtime = (float)((float)blockcount*(float)mode/1000.0);
|
|
printf("\n\nLength of speech file: %.1f s\n", outtime);
|
|
printf("Packet loss : %.1f%%\n",
|
|
100.0*(float)packetlosscount/(float)blockcount);
|
|
|
|
|
|
|
|
Andersen, et al. Experimental [Page 51]
|
|
|
|
RFC 3951 Internet Low Bit Rate Codec December 2004
|
|
|
|
|
|
printf("Time to run iLBC :");
|
|
printf(" %.1f s (%.1f %% of realtime)\n\n", runtime,
|
|
(100*runtime/outtime));
|
|
|
|
/* close files */
|
|
|
|
fclose(ifileid); fclose(efileid); fclose(ofileid);
|
|
if (argc==6) {
|
|
fclose(cfileid);
|
|
}
|
|
return(0);
|
|
}
|
|
|
|
A.2. iLBC_encode.h
|
|
|
|
/******************************************************************
|
|
|
|
iLBC Speech Coder ANSI-C Source Code
|
|
|
|
iLBC_encode.h
|
|
|
|
Copyright (C) The Internet Society (2004).
|
|
All Rights Reserved.
|
|
|
|
******************************************************************/
|
|
|
|
#ifndef __iLBC_ILBCENCODE_H
|
|
#define __iLBC_ILBCENCODE_H
|
|
|
|
#include "iLBC_define.h"
|
|
|
|
short initEncode( /* (o) Number of bytes
|
|
encoded */
|
|
iLBC_Enc_Inst_t *iLBCenc_inst, /* (i/o) Encoder instance */
|
|
int mode /* (i) frame size mode */
|
|
);
|
|
|
|
void iLBC_encode(
|
|
|
|
unsigned char *bytes, /* (o) encoded data bits iLBC */
|
|
float *block, /* (o) speech vector to
|
|
encode */
|
|
iLBC_Enc_Inst_t *iLBCenc_inst /* (i/o) the general encoder
|
|
state */
|
|
);
|
|
|
|
#endif
|
|
|
|
|
|
|
|
|
|
Andersen, et al. Experimental [Page 52]
|
|
|
|
RFC 3951 Internet Low Bit Rate Codec December 2004
|
|
|
|
|
|
A.3. iLBC_encode.c
|
|
|
|
/******************************************************************
|
|
|
|
iLBC Speech Coder ANSI-C Source Code
|
|
|
|
iLBC_encode.c
|
|
|
|
Copyright (C) The Internet Society (2004).
|
|
All Rights Reserved.
|
|
|
|
******************************************************************/
|
|
|
|
#include <math.h>
|
|
#include <stdlib.h>
|
|
#include <string.h>
|
|
|
|
#include "iLBC_define.h"
|
|
#include "LPCencode.h"
|
|
#include "FrameClassify.h"
|
|
#include "StateSearchW.h"
|
|
#include "StateConstructW.h"
|
|
#include "helpfun.h"
|
|
#include "constants.h"
|
|
#include "packing.h"
|
|
#include "iCBSearch.h"
|
|
#include "iCBConstruct.h"
|
|
#include "hpInput.h"
|
|
#include "anaFilter.h"
|
|
#include "syntFilter.h"
|
|
|
|
/*----------------------------------------------------------------*
|
|
* Initiation of encoder instance.
|
|
*---------------------------------------------------------------*/
|
|
|
|
short initEncode( /* (o) Number of bytes
|
|
encoded */
|
|
iLBC_Enc_Inst_t *iLBCenc_inst, /* (i/o) Encoder instance */
|
|
int mode /* (i) frame size mode */
|
|
){
|
|
iLBCenc_inst->mode = mode;
|
|
if (mode==30) {
|
|
iLBCenc_inst->blockl = BLOCKL_30MS;
|
|
iLBCenc_inst->nsub = NSUB_30MS;
|
|
iLBCenc_inst->nasub = NASUB_30MS;
|
|
iLBCenc_inst->lpc_n = LPC_N_30MS;
|
|
iLBCenc_inst->no_of_bytes = NO_OF_BYTES_30MS;
|
|
iLBCenc_inst->no_of_words = NO_OF_WORDS_30MS;
|
|
|
|
|
|
|
|
Andersen, et al. Experimental [Page 53]
|
|
|
|
RFC 3951 Internet Low Bit Rate Codec December 2004
|
|
|
|
|
|
iLBCenc_inst->state_short_len=STATE_SHORT_LEN_30MS;
|
|
/* ULP init */
|
|
iLBCenc_inst->ULP_inst=&ULP_30msTbl;
|
|
}
|
|
else if (mode==20) {
|
|
iLBCenc_inst->blockl = BLOCKL_20MS;
|
|
iLBCenc_inst->nsub = NSUB_20MS;
|
|
iLBCenc_inst->nasub = NASUB_20MS;
|
|
iLBCenc_inst->lpc_n = LPC_N_20MS;
|
|
iLBCenc_inst->no_of_bytes = NO_OF_BYTES_20MS;
|
|
iLBCenc_inst->no_of_words = NO_OF_WORDS_20MS;
|
|
iLBCenc_inst->state_short_len=STATE_SHORT_LEN_20MS;
|
|
/* ULP init */
|
|
iLBCenc_inst->ULP_inst=&ULP_20msTbl;
|
|
}
|
|
else {
|
|
exit(2);
|
|
}
|
|
|
|
memset((*iLBCenc_inst).anaMem, 0,
|
|
LPC_FILTERORDER*sizeof(float));
|
|
memcpy((*iLBCenc_inst).lsfold, lsfmeanTbl,
|
|
LPC_FILTERORDER*sizeof(float));
|
|
memcpy((*iLBCenc_inst).lsfdeqold, lsfmeanTbl,
|
|
LPC_FILTERORDER*sizeof(float));
|
|
memset((*iLBCenc_inst).lpc_buffer, 0,
|
|
(LPC_LOOKBACK+BLOCKL_MAX)*sizeof(float));
|
|
memset((*iLBCenc_inst).hpimem, 0, 4*sizeof(float));
|
|
|
|
return (iLBCenc_inst->no_of_bytes);
|
|
}
|
|
|
|
/*----------------------------------------------------------------*
|
|
* main encoder function
|
|
*---------------------------------------------------------------*/
|
|
|
|
void iLBC_encode(
|
|
unsigned char *bytes, /* (o) encoded data bits iLBC */
|
|
float *block, /* (o) speech vector to
|
|
encode */
|
|
iLBC_Enc_Inst_t *iLBCenc_inst /* (i/o) the general encoder
|
|
state */
|
|
){
|
|
|
|
float data[BLOCKL_MAX];
|
|
float residual[BLOCKL_MAX], reverseResidual[BLOCKL_MAX];
|
|
|
|
int start, idxForMax, idxVec[STATE_LEN];
|
|
|
|
|
|
|
|
Andersen, et al. Experimental [Page 54]
|
|
|
|
RFC 3951 Internet Low Bit Rate Codec December 2004
|
|
|
|
|
|
float reverseDecresidual[BLOCKL_MAX], mem[CB_MEML];
|
|
int n, k, meml_gotten, Nfor, Nback, i, pos;
|
|
int gain_index[CB_NSTAGES*NASUB_MAX],
|
|
extra_gain_index[CB_NSTAGES];
|
|
int cb_index[CB_NSTAGES*NASUB_MAX],extra_cb_index[CB_NSTAGES];
|
|
int lsf_i[LSF_NSPLIT*LPC_N_MAX];
|
|
unsigned char *pbytes;
|
|
int diff, start_pos, state_first;
|
|
float en1, en2;
|
|
int index, ulp, firstpart;
|
|
int subcount, subframe;
|
|
float weightState[LPC_FILTERORDER];
|
|
float syntdenum[NSUB_MAX*(LPC_FILTERORDER+1)];
|
|
float weightdenum[NSUB_MAX*(LPC_FILTERORDER+1)];
|
|
float decresidual[BLOCKL_MAX];
|
|
|
|
/* high pass filtering of input signal if such is not done
|
|
prior to calling this function */
|
|
|
|
hpInput(block, iLBCenc_inst->blockl,
|
|
data, (*iLBCenc_inst).hpimem);
|
|
|
|
/* otherwise simply copy */
|
|
|
|
/*memcpy(data,block,iLBCenc_inst->blockl*sizeof(float));*/
|
|
|
|
/* LPC of hp filtered input data */
|
|
|
|
LPCencode(syntdenum, weightdenum, lsf_i, data, iLBCenc_inst);
|
|
|
|
|
|
/* inverse filter to get residual */
|
|
|
|
for (n=0; n<iLBCenc_inst->nsub; n++) {
|
|
anaFilter(&data[n*SUBL], &syntdenum[n*(LPC_FILTERORDER+1)],
|
|
SUBL, &residual[n*SUBL], iLBCenc_inst->anaMem);
|
|
}
|
|
|
|
/* find state location */
|
|
|
|
start = FrameClassify(iLBCenc_inst, residual);
|
|
|
|
/* check if state should be in first or last part of the
|
|
two subframes */
|
|
|
|
diff = STATE_LEN - iLBCenc_inst->state_short_len;
|
|
en1 = 0;
|
|
index = (start-1)*SUBL;
|
|
|
|
|
|
|
|
Andersen, et al. Experimental [Page 55]
|
|
|
|
RFC 3951 Internet Low Bit Rate Codec December 2004
|
|
|
|
|
|
for (i = 0; i < iLBCenc_inst->state_short_len; i++) {
|
|
en1 += residual[index+i]*residual[index+i];
|
|
}
|
|
en2 = 0;
|
|
index = (start-1)*SUBL+diff;
|
|
for (i = 0; i < iLBCenc_inst->state_short_len; i++) {
|
|
en2 += residual[index+i]*residual[index+i];
|
|
}
|
|
|
|
|
|
if (en1 > en2) {
|
|
state_first = 1;
|
|
start_pos = (start-1)*SUBL;
|
|
} else {
|
|
state_first = 0;
|
|
start_pos = (start-1)*SUBL + diff;
|
|
}
|
|
|
|
/* scalar quantization of state */
|
|
|
|
StateSearchW(iLBCenc_inst, &residual[start_pos],
|
|
&syntdenum[(start-1)*(LPC_FILTERORDER+1)],
|
|
&weightdenum[(start-1)*(LPC_FILTERORDER+1)], &idxForMax,
|
|
idxVec, iLBCenc_inst->state_short_len, state_first);
|
|
|
|
StateConstructW(idxForMax, idxVec,
|
|
&syntdenum[(start-1)*(LPC_FILTERORDER+1)],
|
|
&decresidual[start_pos], iLBCenc_inst->state_short_len);
|
|
|
|
/* predictive quantization in state */
|
|
|
|
if (state_first) { /* put adaptive part in the end */
|
|
|
|
/* setup memory */
|
|
|
|
memset(mem, 0,
|
|
(CB_MEML-iLBCenc_inst->state_short_len)*sizeof(float));
|
|
memcpy(mem+CB_MEML-iLBCenc_inst->state_short_len,
|
|
decresidual+start_pos,
|
|
iLBCenc_inst->state_short_len*sizeof(float));
|
|
memset(weightState, 0, LPC_FILTERORDER*sizeof(float));
|
|
|
|
/* encode sub-frames */
|
|
|
|
iCBSearch(iLBCenc_inst, extra_cb_index, extra_gain_index,
|
|
&residual[start_pos+iLBCenc_inst->state_short_len],
|
|
mem+CB_MEML-stMemLTbl,
|
|
stMemLTbl, diff, CB_NSTAGES,
|
|
|
|
|
|
|
|
Andersen, et al. Experimental [Page 56]
|
|
|
|
RFC 3951 Internet Low Bit Rate Codec December 2004
|
|
|
|
|
|
&weightdenum[start*(LPC_FILTERORDER+1)],
|
|
weightState, 0);
|
|
|
|
/* construct decoded vector */
|
|
|
|
iCBConstruct(
|
|
&decresidual[start_pos+iLBCenc_inst->state_short_len],
|
|
extra_cb_index, extra_gain_index,
|
|
mem+CB_MEML-stMemLTbl,
|
|
stMemLTbl, diff, CB_NSTAGES);
|
|
|
|
}
|
|
else { /* put adaptive part in the beginning */
|
|
|
|
/* create reversed vectors for prediction */
|
|
|
|
for (k=0; k<diff; k++) {
|
|
reverseResidual[k] = residual[(start+1)*SUBL-1
|
|
-(k+iLBCenc_inst->state_short_len)];
|
|
}
|
|
|
|
/* setup memory */
|
|
|
|
meml_gotten = iLBCenc_inst->state_short_len;
|
|
for (k=0; k<meml_gotten; k++) {
|
|
mem[CB_MEML-1-k] = decresidual[start_pos + k];
|
|
}
|
|
memset(mem, 0, (CB_MEML-k)*sizeof(float));
|
|
memset(weightState, 0, LPC_FILTERORDER*sizeof(float));
|
|
|
|
/* encode sub-frames */
|
|
|
|
iCBSearch(iLBCenc_inst, extra_cb_index, extra_gain_index,
|
|
reverseResidual, mem+CB_MEML-stMemLTbl, stMemLTbl,
|
|
diff, CB_NSTAGES,
|
|
&weightdenum[(start-1)*(LPC_FILTERORDER+1)],
|
|
weightState, 0);
|
|
|
|
/* construct decoded vector */
|
|
|
|
iCBConstruct(reverseDecresidual, extra_cb_index,
|
|
extra_gain_index, mem+CB_MEML-stMemLTbl, stMemLTbl,
|
|
diff, CB_NSTAGES);
|
|
|
|
/* get decoded residual from reversed vector */
|
|
|
|
for (k=0; k<diff; k++) {
|
|
decresidual[start_pos-1-k] = reverseDecresidual[k];
|
|
|
|
|
|
|
|
Andersen, et al. Experimental [Page 57]
|
|
|
|
RFC 3951 Internet Low Bit Rate Codec December 2004
|
|
|
|
|
|
}
|
|
}
|
|
|
|
/* counter for predicted sub-frames */
|
|
|
|
subcount=0;
|
|
|
|
/* forward prediction of sub-frames */
|
|
|
|
Nfor = iLBCenc_inst->nsub-start-1;
|
|
|
|
|
|
if ( Nfor > 0 ) {
|
|
|
|
/* setup memory */
|
|
|
|
memset(mem, 0, (CB_MEML-STATE_LEN)*sizeof(float));
|
|
memcpy(mem+CB_MEML-STATE_LEN, decresidual+(start-1)*SUBL,
|
|
STATE_LEN*sizeof(float));
|
|
memset(weightState, 0, LPC_FILTERORDER*sizeof(float));
|
|
|
|
/* loop over sub-frames to encode */
|
|
|
|
for (subframe=0; subframe<Nfor; subframe++) {
|
|
|
|
/* encode sub-frame */
|
|
|
|
iCBSearch(iLBCenc_inst, cb_index+subcount*CB_NSTAGES,
|
|
gain_index+subcount*CB_NSTAGES,
|
|
&residual[(start+1+subframe)*SUBL],
|
|
mem+CB_MEML-memLfTbl[subcount],
|
|
memLfTbl[subcount], SUBL, CB_NSTAGES,
|
|
&weightdenum[(start+1+subframe)*
|
|
(LPC_FILTERORDER+1)],
|
|
weightState, subcount+1);
|
|
|
|
/* construct decoded vector */
|
|
|
|
iCBConstruct(&decresidual[(start+1+subframe)*SUBL],
|
|
cb_index+subcount*CB_NSTAGES,
|
|
gain_index+subcount*CB_NSTAGES,
|
|
mem+CB_MEML-memLfTbl[subcount],
|
|
memLfTbl[subcount], SUBL, CB_NSTAGES);
|
|
|
|
/* update memory */
|
|
|
|
memcpy(mem, mem+SUBL, (CB_MEML-SUBL)*sizeof(float));
|
|
memcpy(mem+CB_MEML-SUBL,
|
|
|
|
|
|
|
|
Andersen, et al. Experimental [Page 58]
|
|
|
|
RFC 3951 Internet Low Bit Rate Codec December 2004
|
|
|
|
|
|
&decresidual[(start+1+subframe)*SUBL],
|
|
SUBL*sizeof(float));
|
|
memset(weightState, 0, LPC_FILTERORDER*sizeof(float));
|
|
|
|
subcount++;
|
|
}
|
|
}
|
|
|
|
|
|
/* backward prediction of sub-frames */
|
|
|
|
Nback = start-1;
|
|
|
|
|
|
if ( Nback > 0 ) {
|
|
|
|
/* create reverse order vectors */
|
|
|
|
for (n=0; n<Nback; n++) {
|
|
for (k=0; k<SUBL; k++) {
|
|
reverseResidual[n*SUBL+k] =
|
|
residual[(start-1)*SUBL-1-n*SUBL-k];
|
|
reverseDecresidual[n*SUBL+k] =
|
|
decresidual[(start-1)*SUBL-1-n*SUBL-k];
|
|
}
|
|
}
|
|
|
|
/* setup memory */
|
|
|
|
meml_gotten = SUBL*(iLBCenc_inst->nsub+1-start);
|
|
|
|
|
|
if ( meml_gotten > CB_MEML ) {
|
|
meml_gotten=CB_MEML;
|
|
}
|
|
for (k=0; k<meml_gotten; k++) {
|
|
mem[CB_MEML-1-k] = decresidual[(start-1)*SUBL + k];
|
|
}
|
|
memset(mem, 0, (CB_MEML-k)*sizeof(float));
|
|
memset(weightState, 0, LPC_FILTERORDER*sizeof(float));
|
|
|
|
/* loop over sub-frames to encode */
|
|
|
|
for (subframe=0; subframe<Nback; subframe++) {
|
|
|
|
/* encode sub-frame */
|
|
|
|
iCBSearch(iLBCenc_inst, cb_index+subcount*CB_NSTAGES,
|
|
|
|
|
|
|
|
Andersen, et al. Experimental [Page 59]
|
|
|
|
RFC 3951 Internet Low Bit Rate Codec December 2004
|
|
|
|
|
|
gain_index+subcount*CB_NSTAGES,
|
|
&reverseResidual[subframe*SUBL],
|
|
mem+CB_MEML-memLfTbl[subcount],
|
|
memLfTbl[subcount], SUBL, CB_NSTAGES,
|
|
&weightdenum[(start-2-subframe)*
|
|
(LPC_FILTERORDER+1)],
|
|
weightState, subcount+1);
|
|
|
|
/* construct decoded vector */
|
|
|
|
iCBConstruct(&reverseDecresidual[subframe*SUBL],
|
|
cb_index+subcount*CB_NSTAGES,
|
|
gain_index+subcount*CB_NSTAGES,
|
|
mem+CB_MEML-memLfTbl[subcount],
|
|
memLfTbl[subcount], SUBL, CB_NSTAGES);
|
|
|
|
/* update memory */
|
|
|
|
memcpy(mem, mem+SUBL, (CB_MEML-SUBL)*sizeof(float));
|
|
memcpy(mem+CB_MEML-SUBL,
|
|
&reverseDecresidual[subframe*SUBL],
|
|
SUBL*sizeof(float));
|
|
memset(weightState, 0, LPC_FILTERORDER*sizeof(float));
|
|
|
|
subcount++;
|
|
|
|
}
|
|
|
|
/* get decoded residual from reversed vector */
|
|
|
|
for (i=0; i<SUBL*Nback; i++) {
|
|
decresidual[SUBL*Nback - i - 1] =
|
|
reverseDecresidual[i];
|
|
}
|
|
}
|
|
/* end encoding part */
|
|
|
|
/* adjust index */
|
|
index_conv_enc(cb_index);
|
|
|
|
/* pack bytes */
|
|
|
|
pbytes=bytes;
|
|
pos=0;
|
|
|
|
/* loop over the 3 ULP classes */
|
|
|
|
for (ulp=0; ulp<3; ulp++) {
|
|
|
|
|
|
|
|
Andersen, et al. Experimental [Page 60]
|
|
|
|
RFC 3951 Internet Low Bit Rate Codec December 2004
|
|
|
|
|
|
|
|
/* LSF */
|
|
for (k=0; k<LSF_NSPLIT*iLBCenc_inst->lpc_n; k++) {
|
|
packsplit(&lsf_i[k], &firstpart, &lsf_i[k],
|
|
iLBCenc_inst->ULP_inst->lsf_bits[k][ulp],
|
|
iLBCenc_inst->ULP_inst->lsf_bits[k][ulp]+
|
|
iLBCenc_inst->ULP_inst->lsf_bits[k][ulp+1]+
|
|
iLBCenc_inst->ULP_inst->lsf_bits[k][ulp+2]);
|
|
dopack( &pbytes, firstpart,
|
|
iLBCenc_inst->ULP_inst->lsf_bits[k][ulp], &pos);
|
|
}
|
|
|
|
/* Start block info */
|
|
|
|
packsplit(&start, &firstpart, &start,
|
|
iLBCenc_inst->ULP_inst->start_bits[ulp],
|
|
iLBCenc_inst->ULP_inst->start_bits[ulp]+
|
|
iLBCenc_inst->ULP_inst->start_bits[ulp+1]+
|
|
iLBCenc_inst->ULP_inst->start_bits[ulp+2]);
|
|
dopack( &pbytes, firstpart,
|
|
iLBCenc_inst->ULP_inst->start_bits[ulp], &pos);
|
|
|
|
packsplit(&state_first, &firstpart, &state_first,
|
|
iLBCenc_inst->ULP_inst->startfirst_bits[ulp],
|
|
iLBCenc_inst->ULP_inst->startfirst_bits[ulp]+
|
|
iLBCenc_inst->ULP_inst->startfirst_bits[ulp+1]+
|
|
iLBCenc_inst->ULP_inst->startfirst_bits[ulp+2]);
|
|
dopack( &pbytes, firstpart,
|
|
iLBCenc_inst->ULP_inst->startfirst_bits[ulp], &pos);
|
|
|
|
packsplit(&idxForMax, &firstpart, &idxForMax,
|
|
iLBCenc_inst->ULP_inst->scale_bits[ulp],
|
|
iLBCenc_inst->ULP_inst->scale_bits[ulp]+
|
|
iLBCenc_inst->ULP_inst->scale_bits[ulp+1]+
|
|
iLBCenc_inst->ULP_inst->scale_bits[ulp+2]);
|
|
dopack( &pbytes, firstpart,
|
|
iLBCenc_inst->ULP_inst->scale_bits[ulp], &pos);
|
|
|
|
for (k=0; k<iLBCenc_inst->state_short_len; k++) {
|
|
packsplit(idxVec+k, &firstpart, idxVec+k,
|
|
iLBCenc_inst->ULP_inst->state_bits[ulp],
|
|
iLBCenc_inst->ULP_inst->state_bits[ulp]+
|
|
iLBCenc_inst->ULP_inst->state_bits[ulp+1]+
|
|
iLBCenc_inst->ULP_inst->state_bits[ulp+2]);
|
|
dopack( &pbytes, firstpart,
|
|
iLBCenc_inst->ULP_inst->state_bits[ulp], &pos);
|
|
}
|
|
|
|
|
|
|
|
|
|
Andersen, et al. Experimental [Page 61]
|
|
|
|
RFC 3951 Internet Low Bit Rate Codec December 2004
|
|
|
|
|
|
/* 23/22 (20ms/30ms) sample block */
|
|
|
|
for (k=0;k<CB_NSTAGES;k++) {
|
|
packsplit(extra_cb_index+k, &firstpart,
|
|
extra_cb_index+k,
|
|
iLBCenc_inst->ULP_inst->extra_cb_index[k][ulp],
|
|
iLBCenc_inst->ULP_inst->extra_cb_index[k][ulp]+
|
|
iLBCenc_inst->ULP_inst->extra_cb_index[k][ulp+1]+
|
|
iLBCenc_inst->ULP_inst->extra_cb_index[k][ulp+2]);
|
|
dopack( &pbytes, firstpart,
|
|
iLBCenc_inst->ULP_inst->extra_cb_index[k][ulp],
|
|
&pos);
|
|
}
|
|
|
|
for (k=0;k<CB_NSTAGES;k++) {
|
|
packsplit(extra_gain_index+k, &firstpart,
|
|
extra_gain_index+k,
|
|
iLBCenc_inst->ULP_inst->extra_cb_gain[k][ulp],
|
|
iLBCenc_inst->ULP_inst->extra_cb_gain[k][ulp]+
|
|
iLBCenc_inst->ULP_inst->extra_cb_gain[k][ulp+1]+
|
|
iLBCenc_inst->ULP_inst->extra_cb_gain[k][ulp+2]);
|
|
dopack( &pbytes, firstpart,
|
|
iLBCenc_inst->ULP_inst->extra_cb_gain[k][ulp],
|
|
&pos);
|
|
}
|
|
|
|
/* The two/four (20ms/30ms) 40 sample sub-blocks */
|
|
|
|
for (i=0; i<iLBCenc_inst->nasub; i++) {
|
|
for (k=0; k<CB_NSTAGES; k++) {
|
|
packsplit(cb_index+i*CB_NSTAGES+k, &firstpart,
|
|
cb_index+i*CB_NSTAGES+k,
|
|
iLBCenc_inst->ULP_inst->cb_index[i][k][ulp],
|
|
iLBCenc_inst->ULP_inst->cb_index[i][k][ulp]+
|
|
iLBCenc_inst->ULP_inst->cb_index[i][k][ulp+1]+
|
|
iLBCenc_inst->ULP_inst->cb_index[i][k][ulp+2]);
|
|
dopack( &pbytes, firstpart,
|
|
iLBCenc_inst->ULP_inst->cb_index[i][k][ulp],
|
|
&pos);
|
|
}
|
|
}
|
|
|
|
for (i=0; i<iLBCenc_inst->nasub; i++) {
|
|
for (k=0; k<CB_NSTAGES; k++) {
|
|
packsplit(gain_index+i*CB_NSTAGES+k, &firstpart,
|
|
gain_index+i*CB_NSTAGES+k,
|
|
iLBCenc_inst->ULP_inst->cb_gain[i][k][ulp],
|
|
iLBCenc_inst->ULP_inst->cb_gain[i][k][ulp]+
|
|
|
|
|
|
|
|
Andersen, et al. Experimental [Page 62]
|
|
|
|
RFC 3951 Internet Low Bit Rate Codec December 2004
|
|
|
|
|
|
iLBCenc_inst->ULP_inst->cb_gain[i][k][ulp+1]+
|
|
iLBCenc_inst->ULP_inst->cb_gain[i][k][ulp+2]);
|
|
dopack( &pbytes, firstpart,
|
|
iLBCenc_inst->ULP_inst->cb_gain[i][k][ulp],
|
|
&pos);
|
|
}
|
|
}
|
|
}
|
|
|
|
/* set the last bit to zero (otherwise the decoder
|
|
will treat it as a lost frame) */
|
|
dopack( &pbytes, 0, 1, &pos);
|
|
}
|
|
|
|
A.4. iLBC_decode.h
|
|
|
|
/******************************************************************
|
|
|
|
iLBC Speech Coder ANSI-C Source Code
|
|
|
|
iLBC_decode.h
|
|
|
|
Copyright (C) The Internet Society (2004).
|
|
All Rights Reserved.
|
|
|
|
******************************************************************/
|
|
|
|
#ifndef __iLBC_ILBCDECODE_H
|
|
#define __iLBC_ILBCDECODE_H
|
|
|
|
#include "iLBC_define.h"
|
|
|
|
short initDecode( /* (o) Number of decoded
|
|
samples */
|
|
iLBC_Dec_Inst_t *iLBCdec_inst, /* (i/o) Decoder instance */
|
|
int mode, /* (i) frame size mode */
|
|
int use_enhancer /* (i) 1 to use enhancer
|
|
0 to run without
|
|
enhancer */
|
|
);
|
|
|
|
void iLBC_decode(
|
|
float *decblock, /* (o) decoded signal block */
|
|
unsigned char *bytes, /* (i) encoded signal bits */
|
|
iLBC_Dec_Inst_t *iLBCdec_inst, /* (i/o) the decoder state
|
|
structure */
|
|
int mode /* (i) 0: bad packet, PLC,
|
|
1: normal */
|
|
|
|
|
|
|
|
Andersen, et al. Experimental [Page 63]
|
|
|
|
RFC 3951 Internet Low Bit Rate Codec December 2004
|
|
|
|
|
|
);
|
|
|
|
#endif
|
|
|
|
A.5. iLBC_decode.c
|
|
|
|
/******************************************************************
|
|
|
|
iLBC Speech Coder ANSI-C Source Code
|
|
|
|
iLBC_decode.c
|
|
|
|
Copyright (C) The Internet Society (2004).
|
|
All Rights Reserved.
|
|
|
|
******************************************************************/
|
|
|
|
#include <math.h>
|
|
#include <stdlib.h>
|
|
|
|
#include "iLBC_define.h"
|
|
#include "StateConstructW.h"
|
|
#include "LPCdecode.h"
|
|
#include "iCBConstruct.h"
|
|
#include "doCPLC.h"
|
|
#include "helpfun.h"
|
|
#include "constants.h"
|
|
#include "packing.h"
|
|
#include "string.h"
|
|
#include "enhancer.h"
|
|
#include "hpOutput.h"
|
|
#include "syntFilter.h"
|
|
|
|
/*----------------------------------------------------------------*
|
|
* Initiation of decoder instance.
|
|
*---------------------------------------------------------------*/
|
|
|
|
short initDecode( /* (o) Number of decoded
|
|
samples */
|
|
iLBC_Dec_Inst_t *iLBCdec_inst, /* (i/o) Decoder instance */
|
|
int mode, /* (i) frame size mode */
|
|
int use_enhancer /* (i) 1 to use enhancer
|
|
0 to run without
|
|
enhancer */
|
|
){
|
|
int i;
|
|
|
|
iLBCdec_inst->mode = mode;
|
|
|
|
|
|
|
|
Andersen, et al. Experimental [Page 64]
|
|
|
|
RFC 3951 Internet Low Bit Rate Codec December 2004
|
|
|
|
|
|
if (mode==30) {
|
|
iLBCdec_inst->blockl = BLOCKL_30MS;
|
|
iLBCdec_inst->nsub = NSUB_30MS;
|
|
iLBCdec_inst->nasub = NASUB_30MS;
|
|
iLBCdec_inst->lpc_n = LPC_N_30MS;
|
|
iLBCdec_inst->no_of_bytes = NO_OF_BYTES_30MS;
|
|
iLBCdec_inst->no_of_words = NO_OF_WORDS_30MS;
|
|
iLBCdec_inst->state_short_len=STATE_SHORT_LEN_30MS;
|
|
/* ULP init */
|
|
iLBCdec_inst->ULP_inst=&ULP_30msTbl;
|
|
}
|
|
else if (mode==20) {
|
|
iLBCdec_inst->blockl = BLOCKL_20MS;
|
|
iLBCdec_inst->nsub = NSUB_20MS;
|
|
iLBCdec_inst->nasub = NASUB_20MS;
|
|
iLBCdec_inst->lpc_n = LPC_N_20MS;
|
|
iLBCdec_inst->no_of_bytes = NO_OF_BYTES_20MS;
|
|
iLBCdec_inst->no_of_words = NO_OF_WORDS_20MS;
|
|
iLBCdec_inst->state_short_len=STATE_SHORT_LEN_20MS;
|
|
/* ULP init */
|
|
iLBCdec_inst->ULP_inst=&ULP_20msTbl;
|
|
}
|
|
else {
|
|
exit(2);
|
|
}
|
|
|
|
memset(iLBCdec_inst->syntMem, 0,
|
|
LPC_FILTERORDER*sizeof(float));
|
|
memcpy((*iLBCdec_inst).lsfdeqold, lsfmeanTbl,
|
|
LPC_FILTERORDER*sizeof(float));
|
|
|
|
memset(iLBCdec_inst->old_syntdenum, 0,
|
|
((LPC_FILTERORDER + 1)*NSUB_MAX)*sizeof(float));
|
|
for (i=0; i<NSUB_MAX; i++)
|
|
iLBCdec_inst->old_syntdenum[i*(LPC_FILTERORDER+1)]=1.0;
|
|
|
|
iLBCdec_inst->last_lag = 20;
|
|
|
|
iLBCdec_inst->prevLag = 120;
|
|
iLBCdec_inst->per = 0.0;
|
|
iLBCdec_inst->consPLICount = 0;
|
|
iLBCdec_inst->prevPLI = 0;
|
|
iLBCdec_inst->prevLpc[0] = 1.0;
|
|
memset(iLBCdec_inst->prevLpc+1,0,
|
|
LPC_FILTERORDER*sizeof(float));
|
|
memset(iLBCdec_inst->prevResidual, 0, BLOCKL_MAX*sizeof(float));
|
|
iLBCdec_inst->seed=777;
|
|
|
|
|
|
|
|
|
|
Andersen, et al. Experimental [Page 65]
|
|
|
|
RFC 3951 Internet Low Bit Rate Codec December 2004
|
|
|
|
|
|
memset(iLBCdec_inst->hpomem, 0, 4*sizeof(float));
|
|
|
|
iLBCdec_inst->use_enhancer = use_enhancer;
|
|
memset(iLBCdec_inst->enh_buf, 0, ENH_BUFL*sizeof(float));
|
|
for (i=0;i<ENH_NBLOCKS_TOT;i++)
|
|
iLBCdec_inst->enh_period[i]=(float)40.0;
|
|
|
|
iLBCdec_inst->prev_enh_pl = 0;
|
|
|
|
return (iLBCdec_inst->blockl);
|
|
}
|
|
|
|
/*----------------------------------------------------------------*
|
|
* frame residual decoder function (subroutine to iLBC_decode)
|
|
*---------------------------------------------------------------*/
|
|
|
|
void Decode(
|
|
iLBC_Dec_Inst_t *iLBCdec_inst, /* (i/o) the decoder state
|
|
structure */
|
|
float *decresidual, /* (o) decoded residual frame */
|
|
int start, /* (i) location of start
|
|
state */
|
|
int idxForMax, /* (i) codebook index for the
|
|
maximum value */
|
|
int *idxVec, /* (i) codebook indexes for the
|
|
samples in the start
|
|
state */
|
|
float *syntdenum, /* (i) the decoded synthesis
|
|
filter coefficients */
|
|
int *cb_index, /* (i) the indexes for the
|
|
adaptive codebook */
|
|
int *gain_index, /* (i) the indexes for the
|
|
corresponding gains */
|
|
int *extra_cb_index, /* (i) the indexes for the
|
|
adaptive codebook part
|
|
of start state */
|
|
int *extra_gain_index, /* (i) the indexes for the
|
|
corresponding gains */
|
|
int state_first /* (i) 1 if non adaptive part
|
|
of start state comes
|
|
first 0 if that part
|
|
comes last */
|
|
){
|
|
float reverseDecresidual[BLOCKL_MAX], mem[CB_MEML];
|
|
int k, meml_gotten, Nfor, Nback, i;
|
|
int diff, start_pos;
|
|
int subcount, subframe;
|
|
|
|
|
|
|
|
|
|
Andersen, et al. Experimental [Page 66]
|
|
|
|
RFC 3951 Internet Low Bit Rate Codec December 2004
|
|
|
|
|
|
diff = STATE_LEN - iLBCdec_inst->state_short_len;
|
|
|
|
if (state_first == 1) {
|
|
start_pos = (start-1)*SUBL;
|
|
} else {
|
|
start_pos = (start-1)*SUBL + diff;
|
|
}
|
|
|
|
/* decode scalar part of start state */
|
|
|
|
StateConstructW(idxForMax, idxVec,
|
|
&syntdenum[(start-1)*(LPC_FILTERORDER+1)],
|
|
&decresidual[start_pos], iLBCdec_inst->state_short_len);
|
|
|
|
|
|
if (state_first) { /* put adaptive part in the end */
|
|
|
|
/* setup memory */
|
|
|
|
memset(mem, 0,
|
|
(CB_MEML-iLBCdec_inst->state_short_len)*sizeof(float));
|
|
memcpy(mem+CB_MEML-iLBCdec_inst->state_short_len,
|
|
decresidual+start_pos,
|
|
iLBCdec_inst->state_short_len*sizeof(float));
|
|
|
|
/* construct decoded vector */
|
|
|
|
iCBConstruct(
|
|
&decresidual[start_pos+iLBCdec_inst->state_short_len],
|
|
extra_cb_index, extra_gain_index, mem+CB_MEML-stMemLTbl,
|
|
stMemLTbl, diff, CB_NSTAGES);
|
|
|
|
}
|
|
else {/* put adaptive part in the beginning */
|
|
|
|
/* create reversed vectors for prediction */
|
|
|
|
for (k=0; k<diff; k++) {
|
|
reverseDecresidual[k] =
|
|
decresidual[(start+1)*SUBL-1-
|
|
(k+iLBCdec_inst->state_short_len)];
|
|
}
|
|
|
|
/* setup memory */
|
|
|
|
meml_gotten = iLBCdec_inst->state_short_len;
|
|
for (k=0; k<meml_gotten; k++){
|
|
mem[CB_MEML-1-k] = decresidual[start_pos + k];
|
|
|
|
|
|
|
|
Andersen, et al. Experimental [Page 67]
|
|
|
|
RFC 3951 Internet Low Bit Rate Codec December 2004
|
|
|
|
|
|
}
|
|
memset(mem, 0, (CB_MEML-k)*sizeof(float));
|
|
|
|
/* construct decoded vector */
|
|
|
|
iCBConstruct(reverseDecresidual, extra_cb_index,
|
|
extra_gain_index, mem+CB_MEML-stMemLTbl, stMemLTbl,
|
|
diff, CB_NSTAGES);
|
|
|
|
/* get decoded residual from reversed vector */
|
|
|
|
for (k=0; k<diff; k++) {
|
|
decresidual[start_pos-1-k] = reverseDecresidual[k];
|
|
}
|
|
}
|
|
|
|
/* counter for predicted sub-frames */
|
|
|
|
subcount=0;
|
|
|
|
/* forward prediction of sub-frames */
|
|
|
|
Nfor = iLBCdec_inst->nsub-start-1;
|
|
|
|
if ( Nfor > 0 ){
|
|
|
|
/* setup memory */
|
|
|
|
memset(mem, 0, (CB_MEML-STATE_LEN)*sizeof(float));
|
|
memcpy(mem+CB_MEML-STATE_LEN, decresidual+(start-1)*SUBL,
|
|
STATE_LEN*sizeof(float));
|
|
|
|
/* loop over sub-frames to encode */
|
|
|
|
for (subframe=0; subframe<Nfor; subframe++) {
|
|
|
|
/* construct decoded vector */
|
|
|
|
iCBConstruct(&decresidual[(start+1+subframe)*SUBL],
|
|
cb_index+subcount*CB_NSTAGES,
|
|
gain_index+subcount*CB_NSTAGES,
|
|
mem+CB_MEML-memLfTbl[subcount],
|
|
memLfTbl[subcount], SUBL, CB_NSTAGES);
|
|
|
|
/* update memory */
|
|
|
|
memcpy(mem, mem+SUBL, (CB_MEML-SUBL)*sizeof(float));
|
|
memcpy(mem+CB_MEML-SUBL,
|
|
|
|
|
|
|
|
Andersen, et al. Experimental [Page 68]
|
|
|
|
RFC 3951 Internet Low Bit Rate Codec December 2004
|
|
|
|
|
|
&decresidual[(start+1+subframe)*SUBL],
|
|
SUBL*sizeof(float));
|
|
|
|
subcount++;
|
|
|
|
}
|
|
|
|
}
|
|
|
|
/* backward prediction of sub-frames */
|
|
|
|
Nback = start-1;
|
|
|
|
if ( Nback > 0 ) {
|
|
|
|
/* setup memory */
|
|
|
|
meml_gotten = SUBL*(iLBCdec_inst->nsub+1-start);
|
|
|
|
if ( meml_gotten > CB_MEML ) {
|
|
meml_gotten=CB_MEML;
|
|
}
|
|
for (k=0; k<meml_gotten; k++) {
|
|
mem[CB_MEML-1-k] = decresidual[(start-1)*SUBL + k];
|
|
}
|
|
memset(mem, 0, (CB_MEML-k)*sizeof(float));
|
|
|
|
/* loop over subframes to decode */
|
|
|
|
for (subframe=0; subframe<Nback; subframe++) {
|
|
|
|
/* construct decoded vector */
|
|
|
|
iCBConstruct(&reverseDecresidual[subframe*SUBL],
|
|
cb_index+subcount*CB_NSTAGES,
|
|
gain_index+subcount*CB_NSTAGES,
|
|
mem+CB_MEML-memLfTbl[subcount], memLfTbl[subcount],
|
|
SUBL, CB_NSTAGES);
|
|
|
|
/* update memory */
|
|
|
|
memcpy(mem, mem+SUBL, (CB_MEML-SUBL)*sizeof(float));
|
|
memcpy(mem+CB_MEML-SUBL,
|
|
&reverseDecresidual[subframe*SUBL],
|
|
SUBL*sizeof(float));
|
|
|
|
subcount++;
|
|
}
|
|
|
|
|
|
|
|
Andersen, et al. Experimental [Page 69]
|
|
|
|
RFC 3951 Internet Low Bit Rate Codec December 2004
|
|
|
|
|
|
/* get decoded residual from reversed vector */
|
|
|
|
for (i=0; i<SUBL*Nback; i++)
|
|
decresidual[SUBL*Nback - i - 1] =
|
|
reverseDecresidual[i];
|
|
}
|
|
}
|
|
|
|
/*----------------------------------------------------------------*
|
|
* main decoder function
|
|
*---------------------------------------------------------------*/
|
|
|
|
void iLBC_decode(
|
|
float *decblock, /* (o) decoded signal block */
|
|
unsigned char *bytes, /* (i) encoded signal bits */
|
|
iLBC_Dec_Inst_t *iLBCdec_inst, /* (i/o) the decoder state
|
|
structure */
|
|
int mode /* (i) 0: bad packet, PLC,
|
|
1: normal */
|
|
){
|
|
float data[BLOCKL_MAX];
|
|
float lsfdeq[LPC_FILTERORDER*LPC_N_MAX];
|
|
float PLCresidual[BLOCKL_MAX], PLClpc[LPC_FILTERORDER + 1];
|
|
float zeros[BLOCKL_MAX], one[LPC_FILTERORDER + 1];
|
|
int k, i, start, idxForMax, pos, lastpart, ulp;
|
|
int lag, ilag;
|
|
float cc, maxcc;
|
|
int idxVec[STATE_LEN];
|
|
int check;
|
|
int gain_index[NASUB_MAX*CB_NSTAGES],
|
|
extra_gain_index[CB_NSTAGES];
|
|
int cb_index[CB_NSTAGES*NASUB_MAX], extra_cb_index[CB_NSTAGES];
|
|
int lsf_i[LSF_NSPLIT*LPC_N_MAX];
|
|
int state_first;
|
|
int last_bit;
|
|
unsigned char *pbytes;
|
|
float weightdenum[(LPC_FILTERORDER + 1)*NSUB_MAX];
|
|
int order_plus_one;
|
|
float syntdenum[NSUB_MAX*(LPC_FILTERORDER+1)];
|
|
float decresidual[BLOCKL_MAX];
|
|
|
|
if (mode>0) { /* the data are good */
|
|
|
|
/* decode data */
|
|
|
|
pbytes=bytes;
|
|
pos=0;
|
|
|
|
|
|
|
|
|
|
Andersen, et al. Experimental [Page 70]
|
|
|
|
RFC 3951 Internet Low Bit Rate Codec December 2004
|
|
|
|
|
|
/* Set everything to zero before decoding */
|
|
|
|
for (k=0; k<LSF_NSPLIT*LPC_N_MAX; k++) {
|
|
lsf_i[k]=0;
|
|
}
|
|
start=0;
|
|
state_first=0;
|
|
idxForMax=0;
|
|
for (k=0; k<iLBCdec_inst->state_short_len; k++) {
|
|
idxVec[k]=0;
|
|
}
|
|
for (k=0; k<CB_NSTAGES; k++) {
|
|
extra_cb_index[k]=0;
|
|
}
|
|
for (k=0; k<CB_NSTAGES; k++) {
|
|
extra_gain_index[k]=0;
|
|
}
|
|
for (i=0; i<iLBCdec_inst->nasub; i++) {
|
|
for (k=0; k<CB_NSTAGES; k++) {
|
|
cb_index[i*CB_NSTAGES+k]=0;
|
|
}
|
|
}
|
|
for (i=0; i<iLBCdec_inst->nasub; i++) {
|
|
for (k=0; k<CB_NSTAGES; k++) {
|
|
gain_index[i*CB_NSTAGES+k]=0;
|
|
}
|
|
}
|
|
|
|
/* loop over ULP classes */
|
|
|
|
for (ulp=0; ulp<3; ulp++) {
|
|
|
|
/* LSF */
|
|
for (k=0; k<LSF_NSPLIT*iLBCdec_inst->lpc_n; k++){
|
|
unpack( &pbytes, &lastpart,
|
|
iLBCdec_inst->ULP_inst->lsf_bits[k][ulp], &pos);
|
|
packcombine(&lsf_i[k], lastpart,
|
|
iLBCdec_inst->ULP_inst->lsf_bits[k][ulp]);
|
|
}
|
|
|
|
/* Start block info */
|
|
|
|
unpack( &pbytes, &lastpart,
|
|
iLBCdec_inst->ULP_inst->start_bits[ulp], &pos);
|
|
packcombine(&start, lastpart,
|
|
iLBCdec_inst->ULP_inst->start_bits[ulp]);
|
|
|
|
unpack( &pbytes, &lastpart,
|
|
|
|
|
|
|
|
Andersen, et al. Experimental [Page 71]
|
|
|
|
RFC 3951 Internet Low Bit Rate Codec December 2004
|
|
|
|
|
|
iLBCdec_inst->ULP_inst->startfirst_bits[ulp], &pos);
|
|
packcombine(&state_first, lastpart,
|
|
iLBCdec_inst->ULP_inst->startfirst_bits[ulp]);
|
|
|
|
unpack( &pbytes, &lastpart,
|
|
iLBCdec_inst->ULP_inst->scale_bits[ulp], &pos);
|
|
packcombine(&idxForMax, lastpart,
|
|
iLBCdec_inst->ULP_inst->scale_bits[ulp]);
|
|
|
|
for (k=0; k<iLBCdec_inst->state_short_len; k++) {
|
|
unpack( &pbytes, &lastpart,
|
|
iLBCdec_inst->ULP_inst->state_bits[ulp], &pos);
|
|
packcombine(idxVec+k, lastpart,
|
|
iLBCdec_inst->ULP_inst->state_bits[ulp]);
|
|
}
|
|
|
|
/* 23/22 (20ms/30ms) sample block */
|
|
|
|
for (k=0; k<CB_NSTAGES; k++) {
|
|
unpack( &pbytes, &lastpart,
|
|
iLBCdec_inst->ULP_inst->extra_cb_index[k][ulp],
|
|
&pos);
|
|
packcombine(extra_cb_index+k, lastpart,
|
|
iLBCdec_inst->ULP_inst->extra_cb_index[k][ulp]);
|
|
}
|
|
for (k=0; k<CB_NSTAGES; k++) {
|
|
unpack( &pbytes, &lastpart,
|
|
iLBCdec_inst->ULP_inst->extra_cb_gain[k][ulp],
|
|
&pos);
|
|
packcombine(extra_gain_index+k, lastpart,
|
|
iLBCdec_inst->ULP_inst->extra_cb_gain[k][ulp]);
|
|
}
|
|
|
|
/* The two/four (20ms/30ms) 40 sample sub-blocks */
|
|
|
|
for (i=0; i<iLBCdec_inst->nasub; i++) {
|
|
for (k=0; k<CB_NSTAGES; k++) {
|
|
unpack( &pbytes, &lastpart,
|
|
iLBCdec_inst->ULP_inst->cb_index[i][k][ulp],
|
|
&pos);
|
|
packcombine(cb_index+i*CB_NSTAGES+k, lastpart,
|
|
iLBCdec_inst->ULP_inst->cb_index[i][k][ulp]);
|
|
}
|
|
}
|
|
|
|
for (i=0; i<iLBCdec_inst->nasub; i++) {
|
|
for (k=0; k<CB_NSTAGES; k++) {
|
|
unpack( &pbytes, &lastpart,
|
|
|
|
|
|
|
|
Andersen, et al. Experimental [Page 72]
|
|
|
|
RFC 3951 Internet Low Bit Rate Codec December 2004
|
|
|
|
|
|
iLBCdec_inst->ULP_inst->cb_gain[i][k][ulp],
|
|
&pos);
|
|
packcombine(gain_index+i*CB_NSTAGES+k, lastpart,
|
|
iLBCdec_inst->ULP_inst->cb_gain[i][k][ulp]);
|
|
}
|
|
}
|
|
}
|
|
/* Extract last bit. If it is 1 this indicates an
|
|
empty/lost frame */
|
|
unpack( &pbytes, &last_bit, 1, &pos);
|
|
|
|
/* Check for bit errors or empty/lost frames */
|
|
if (start<1)
|
|
mode = 0;
|
|
if (iLBCdec_inst->mode==20 && start>3)
|
|
mode = 0;
|
|
if (iLBCdec_inst->mode==30 && start>5)
|
|
mode = 0;
|
|
if (last_bit==1)
|
|
mode = 0;
|
|
|
|
if (mode==1) { /* No bit errors was detected,
|
|
continue decoding */
|
|
|
|
/* adjust index */
|
|
index_conv_dec(cb_index);
|
|
|
|
/* decode the lsf */
|
|
|
|
SimplelsfDEQ(lsfdeq, lsf_i, iLBCdec_inst->lpc_n);
|
|
check=LSF_check(lsfdeq, LPC_FILTERORDER,
|
|
iLBCdec_inst->lpc_n);
|
|
DecoderInterpolateLSF(syntdenum, weightdenum,
|
|
lsfdeq, LPC_FILTERORDER, iLBCdec_inst);
|
|
|
|
Decode(iLBCdec_inst, decresidual, start, idxForMax,
|
|
idxVec, syntdenum, cb_index, gain_index,
|
|
extra_cb_index, extra_gain_index,
|
|
state_first);
|
|
|
|
/* preparing the plc for a future loss! */
|
|
|
|
doThePLC(PLCresidual, PLClpc, 0, decresidual,
|
|
syntdenum +
|
|
(LPC_FILTERORDER + 1)*(iLBCdec_inst->nsub - 1),
|
|
(*iLBCdec_inst).last_lag, iLBCdec_inst);
|
|
|
|
|
|
|
|
|
|
|
|
Andersen, et al. Experimental [Page 73]
|
|
|
|
RFC 3951 Internet Low Bit Rate Codec December 2004
|
|
|
|
|
|
memcpy(decresidual, PLCresidual,
|
|
iLBCdec_inst->blockl*sizeof(float));
|
|
}
|
|
|
|
}
|
|
|
|
if (mode == 0) {
|
|
/* the data is bad (either a PLC call
|
|
* was made or a severe bit error was detected)
|
|
*/
|
|
|
|
/* packet loss conceal */
|
|
|
|
memset(zeros, 0, BLOCKL_MAX*sizeof(float));
|
|
|
|
one[0] = 1;
|
|
memset(one+1, 0, LPC_FILTERORDER*sizeof(float));
|
|
|
|
start=0;
|
|
|
|
doThePLC(PLCresidual, PLClpc, 1, zeros, one,
|
|
(*iLBCdec_inst).last_lag, iLBCdec_inst);
|
|
memcpy(decresidual, PLCresidual,
|
|
iLBCdec_inst->blockl*sizeof(float));
|
|
|
|
order_plus_one = LPC_FILTERORDER + 1;
|
|
for (i = 0; i < iLBCdec_inst->nsub; i++) {
|
|
memcpy(syntdenum+(i*order_plus_one), PLClpc,
|
|
order_plus_one*sizeof(float));
|
|
}
|
|
}
|
|
|
|
if (iLBCdec_inst->use_enhancer == 1) {
|
|
|
|
/* post filtering */
|
|
|
|
iLBCdec_inst->last_lag =
|
|
enhancerInterface(data, decresidual, iLBCdec_inst);
|
|
|
|
/* synthesis filtering */
|
|
|
|
if (iLBCdec_inst->mode==20) {
|
|
/* Enhancer has 40 samples delay */
|
|
i=0;
|
|
syntFilter(data + i*SUBL,
|
|
iLBCdec_inst->old_syntdenum +
|
|
(i+iLBCdec_inst->nsub-1)*(LPC_FILTERORDER+1),
|
|
SUBL, iLBCdec_inst->syntMem);
|
|
|
|
|
|
|
|
Andersen, et al. Experimental [Page 74]
|
|
|
|
RFC 3951 Internet Low Bit Rate Codec December 2004
|
|
|
|
|
|
for (i=1; i < iLBCdec_inst->nsub; i++) {
|
|
syntFilter(data + i*SUBL,
|
|
syntdenum + (i-1)*(LPC_FILTERORDER+1),
|
|
SUBL, iLBCdec_inst->syntMem);
|
|
}
|
|
} else if (iLBCdec_inst->mode==30) {
|
|
/* Enhancer has 80 samples delay */
|
|
for (i=0; i < 2; i++) {
|
|
syntFilter(data + i*SUBL,
|
|
iLBCdec_inst->old_syntdenum +
|
|
(i+iLBCdec_inst->nsub-2)*(LPC_FILTERORDER+1),
|
|
SUBL, iLBCdec_inst->syntMem);
|
|
}
|
|
for (i=2; i < iLBCdec_inst->nsub; i++) {
|
|
syntFilter(data + i*SUBL,
|
|
syntdenum + (i-2)*(LPC_FILTERORDER+1), SUBL,
|
|
iLBCdec_inst->syntMem);
|
|
}
|
|
}
|
|
|
|
} else {
|
|
|
|
/* Find last lag */
|
|
lag = 20;
|
|
maxcc = xCorrCoef(&decresidual[BLOCKL_MAX-ENH_BLOCKL],
|
|
&decresidual[BLOCKL_MAX-ENH_BLOCKL-lag], ENH_BLOCKL);
|
|
|
|
for (ilag=21; ilag<120; ilag++) {
|
|
cc = xCorrCoef(&decresidual[BLOCKL_MAX-ENH_BLOCKL],
|
|
&decresidual[BLOCKL_MAX-ENH_BLOCKL-ilag],
|
|
ENH_BLOCKL);
|
|
|
|
if (cc > maxcc) {
|
|
maxcc = cc;
|
|
lag = ilag;
|
|
}
|
|
}
|
|
iLBCdec_inst->last_lag = lag;
|
|
|
|
/* copy data and run synthesis filter */
|
|
|
|
memcpy(data, decresidual,
|
|
iLBCdec_inst->blockl*sizeof(float));
|
|
for (i=0; i < iLBCdec_inst->nsub; i++) {
|
|
syntFilter(data + i*SUBL,
|
|
syntdenum + i*(LPC_FILTERORDER+1), SUBL,
|
|
iLBCdec_inst->syntMem);
|
|
}
|
|
|
|
|
|
|
|
Andersen, et al. Experimental [Page 75]
|
|
|
|
RFC 3951 Internet Low Bit Rate Codec December 2004
|
|
|
|
|
|
}
|
|
|
|
/* high pass filtering on output if desired, otherwise
|
|
copy to out */
|
|
|
|
hpOutput(data, iLBCdec_inst->blockl,
|
|
decblock,iLBCdec_inst->hpomem);
|
|
|
|
/* memcpy(decblock,data,iLBCdec_inst->blockl*sizeof(float));*/
|
|
|
|
memcpy(iLBCdec_inst->old_syntdenum, syntdenum,
|
|
|
|
iLBCdec_inst->nsub*(LPC_FILTERORDER+1)*sizeof(float));
|
|
|
|
iLBCdec_inst->prev_enh_pl=0;
|
|
|
|
if (mode==0) { /* PLC was used */
|
|
iLBCdec_inst->prev_enh_pl=1;
|
|
}
|
|
}
|
|
|
|
A.6. iLBC_define.h
|
|
|
|
/******************************************************************
|
|
|
|
iLBC Speech Coder ANSI-C Source Code
|
|
|
|
iLBC_define.h
|
|
|
|
Copyright (C) The Internet Society (2004).
|
|
All Rights Reserved.
|
|
|
|
******************************************************************/
|
|
#include <string.h>
|
|
|
|
#ifndef __iLBC_ILBCDEFINE_H
|
|
#define __iLBC_ILBCDEFINE_H
|
|
|
|
/* general codec settings */
|
|
|
|
#define FS (float)8000.0
|
|
#define BLOCKL_20MS 160
|
|
#define BLOCKL_30MS 240
|
|
#define BLOCKL_MAX 240
|
|
#define NSUB_20MS 4
|
|
#define NSUB_30MS 6
|
|
#define NSUB_MAX 6
|
|
#define NASUB_20MS 2
|
|
|
|
|
|
|
|
Andersen, et al. Experimental [Page 76]
|
|
|
|
RFC 3951 Internet Low Bit Rate Codec December 2004
|
|
|
|
|
|
#define NASUB_30MS 4
|
|
#define NASUB_MAX 4
|
|
#define SUBL 40
|
|
#define STATE_LEN 80
|
|
#define STATE_SHORT_LEN_30MS 58
|
|
#define STATE_SHORT_LEN_20MS 57
|
|
|
|
/* LPC settings */
|
|
|
|
#define LPC_FILTERORDER 10
|
|
#define LPC_CHIRP_SYNTDENUM (float)0.9025
|
|
#define LPC_CHIRP_WEIGHTDENUM (float)0.4222
|
|
#define LPC_LOOKBACK 60
|
|
#define LPC_N_20MS 1
|
|
#define LPC_N_30MS 2
|
|
#define LPC_N_MAX 2
|
|
#define LPC_ASYMDIFF 20
|
|
#define LPC_BW (float)60.0
|
|
#define LPC_WN (float)1.0001
|
|
#define LSF_NSPLIT 3
|
|
#define LSF_NUMBER_OF_STEPS 4
|
|
#define LPC_HALFORDER (LPC_FILTERORDER/2)
|
|
|
|
/* cb settings */
|
|
|
|
#define CB_NSTAGES 3
|
|
#define CB_EXPAND 2
|
|
#define CB_MEML 147
|
|
#define CB_FILTERLEN 2*4
|
|
#define CB_HALFFILTERLEN 4
|
|
#define CB_RESRANGE 34
|
|
#define CB_MAXGAIN (float)1.3
|
|
|
|
/* enhancer */
|
|
|
|
#define ENH_BLOCKL 80 /* block length */
|
|
#define ENH_BLOCKL_HALF (ENH_BLOCKL/2)
|
|
#define ENH_HL 3 /* 2*ENH_HL+1 is number blocks
|
|
in said second sequence */
|
|
#define ENH_SLOP 2 /* max difference estimated and
|
|
correct pitch period */
|
|
#define ENH_PLOCSL 20 /* pitch-estimates and pitch-
|
|
locations buffer length */
|
|
#define ENH_OVERHANG 2
|
|
#define ENH_UPS0 4 /* upsampling rate */
|
|
#define ENH_FL0 3 /* 2*FLO+1 is the length of
|
|
each filter */
|
|
#define ENH_VECTL (ENH_BLOCKL+2*ENH_FL0)
|
|
|
|
|
|
|
|
Andersen, et al. Experimental [Page 77]
|
|
|
|
RFC 3951 Internet Low Bit Rate Codec December 2004
|
|
|
|
|
|
#define ENH_CORRDIM (2*ENH_SLOP+1)
|
|
#define ENH_NBLOCKS (BLOCKL_MAX/ENH_BLOCKL)
|
|
#define ENH_NBLOCKS_EXTRA 5
|
|
#define ENH_NBLOCKS_TOT 8 /* ENH_NBLOCKS +
|
|
ENH_NBLOCKS_EXTRA */
|
|
#define ENH_BUFL (ENH_NBLOCKS_TOT)*ENH_BLOCKL
|
|
#define ENH_ALPHA0 (float)0.05
|
|
|
|
/* Down sampling */
|
|
|
|
#define FILTERORDER_DS 7
|
|
#define DELAY_DS 3
|
|
#define FACTOR_DS 2
|
|
|
|
/* bit stream defs */
|
|
|
|
#define NO_OF_BYTES_20MS 38
|
|
#define NO_OF_BYTES_30MS 50
|
|
#define NO_OF_WORDS_20MS 19
|
|
#define NO_OF_WORDS_30MS 25
|
|
#define STATE_BITS 3
|
|
#define BYTE_LEN 8
|
|
#define ULP_CLASSES 3
|
|
|
|
/* help parameters */
|
|
|
|
#define FLOAT_MAX (float)1.0e37
|
|
#define EPS (float)2.220446049250313e-016
|
|
#define PI (float)3.14159265358979323846
|
|
#define MIN_SAMPLE -32768
|
|
#define MAX_SAMPLE 32767
|
|
#define TWO_PI (float)6.283185307
|
|
#define PI2 (float)0.159154943
|
|
|
|
/* type definition encoder instance */
|
|
typedef struct iLBC_ULP_Inst_t_ {
|
|
int lsf_bits[6][ULP_CLASSES+2];
|
|
int start_bits[ULP_CLASSES+2];
|
|
int startfirst_bits[ULP_CLASSES+2];
|
|
int scale_bits[ULP_CLASSES+2];
|
|
int state_bits[ULP_CLASSES+2];
|
|
int extra_cb_index[CB_NSTAGES][ULP_CLASSES+2];
|
|
int extra_cb_gain[CB_NSTAGES][ULP_CLASSES+2];
|
|
int cb_index[NSUB_MAX][CB_NSTAGES][ULP_CLASSES+2];
|
|
int cb_gain[NSUB_MAX][CB_NSTAGES][ULP_CLASSES+2];
|
|
} iLBC_ULP_Inst_t;
|
|
|
|
/* type definition encoder instance */
|
|
|
|
|
|
|
|
Andersen, et al. Experimental [Page 78]
|
|
|
|
RFC 3951 Internet Low Bit Rate Codec December 2004
|
|
|
|
|
|
typedef struct iLBC_Enc_Inst_t_ {
|
|
|
|
/* flag for frame size mode */
|
|
int mode;
|
|
|
|
/* basic parameters for different frame sizes */
|
|
int blockl;
|
|
int nsub;
|
|
int nasub;
|
|
int no_of_bytes, no_of_words;
|
|
int lpc_n;
|
|
int state_short_len;
|
|
const iLBC_ULP_Inst_t *ULP_inst;
|
|
|
|
/* analysis filter state */
|
|
float anaMem[LPC_FILTERORDER];
|
|
|
|
/* old lsf parameters for interpolation */
|
|
float lsfold[LPC_FILTERORDER];
|
|
float lsfdeqold[LPC_FILTERORDER];
|
|
|
|
/* signal buffer for LP analysis */
|
|
float lpc_buffer[LPC_LOOKBACK + BLOCKL_MAX];
|
|
|
|
/* state of input HP filter */
|
|
float hpimem[4];
|
|
|
|
} iLBC_Enc_Inst_t;
|
|
|
|
/* type definition decoder instance */
|
|
typedef struct iLBC_Dec_Inst_t_ {
|
|
|
|
/* flag for frame size mode */
|
|
int mode;
|
|
|
|
/* basic parameters for different frame sizes */
|
|
int blockl;
|
|
int nsub;
|
|
int nasub;
|
|
int no_of_bytes, no_of_words;
|
|
int lpc_n;
|
|
int state_short_len;
|
|
const iLBC_ULP_Inst_t *ULP_inst;
|
|
|
|
/* synthesis filter state */
|
|
float syntMem[LPC_FILTERORDER];
|
|
|
|
/* old LSF for interpolation */
|
|
|
|
|
|
|
|
Andersen, et al. Experimental [Page 79]
|
|
|
|
RFC 3951 Internet Low Bit Rate Codec December 2004
|
|
|
|
|
|
float lsfdeqold[LPC_FILTERORDER];
|
|
|
|
/* pitch lag estimated in enhancer and used in PLC */
|
|
int last_lag;
|
|
|
|
/* PLC state information */
|
|
int prevLag, consPLICount, prevPLI, prev_enh_pl;
|
|
float prevLpc[LPC_FILTERORDER+1];
|
|
float prevResidual[NSUB_MAX*SUBL];
|
|
float per;
|
|
unsigned long seed;
|
|
|
|
/* previous synthesis filter parameters */
|
|
float old_syntdenum[(LPC_FILTERORDER + 1)*NSUB_MAX];
|
|
|
|
/* state of output HP filter */
|
|
float hpomem[4];
|
|
|
|
/* enhancer state information */
|
|
int use_enhancer;
|
|
float enh_buf[ENH_BUFL];
|
|
float enh_period[ENH_NBLOCKS_TOT];
|
|
|
|
} iLBC_Dec_Inst_t;
|
|
|
|
#endif
|
|
|
|
A.7. constants.h
|
|
|
|
/******************************************************************
|
|
|
|
iLBC Speech Coder ANSI-C Source Code
|
|
|
|
constants.h
|
|
|
|
Copyright (C) The Internet Society (2004).
|
|
All Rights Reserved.
|
|
|
|
******************************************************************/
|
|
|
|
#ifndef __iLBC_CONSTANTS_H
|
|
#define __iLBC_CONSTANTS_H
|
|
|
|
#include "iLBC_define.h"
|
|
|
|
|
|
/* ULP bit allocation */
|
|
|
|
|
|
|
|
|
|
Andersen, et al. Experimental [Page 80]
|
|
|
|
RFC 3951 Internet Low Bit Rate Codec December 2004
|
|
|
|
|
|
extern const iLBC_ULP_Inst_t ULP_20msTbl;
|
|
extern const iLBC_ULP_Inst_t ULP_30msTbl;
|
|
|
|
/* high pass filters */
|
|
|
|
extern float hpi_zero_coefsTbl[];
|
|
extern float hpi_pole_coefsTbl[];
|
|
extern float hpo_zero_coefsTbl[];
|
|
extern float hpo_pole_coefsTbl[];
|
|
|
|
/* low pass filters */
|
|
extern float lpFilt_coefsTbl[];
|
|
|
|
/* LPC analysis and quantization */
|
|
|
|
extern float lpc_winTbl[];
|
|
extern float lpc_asymwinTbl[];
|
|
extern float lpc_lagwinTbl[];
|
|
extern float lsfCbTbl[];
|
|
extern float lsfmeanTbl[];
|
|
extern int dim_lsfCbTbl[];
|
|
extern int size_lsfCbTbl[];
|
|
extern float lsf_weightTbl_30ms[];
|
|
extern float lsf_weightTbl_20ms[];
|
|
|
|
/* state quantization tables */
|
|
|
|
extern float state_sq3Tbl[];
|
|
extern float state_frgqTbl[];
|
|
|
|
/* gain quantization tables */
|
|
|
|
extern float gain_sq3Tbl[];
|
|
extern float gain_sq4Tbl[];
|
|
extern float gain_sq5Tbl[];
|
|
|
|
/* adaptive codebook definitions */
|
|
|
|
extern int search_rangeTbl[5][CB_NSTAGES];
|
|
extern int memLfTbl[];
|
|
extern int stMemLTbl;
|
|
extern float cbfiltersTbl[CB_FILTERLEN];
|
|
|
|
/* enhancer definitions */
|
|
|
|
extern float polyphaserTbl[];
|
|
extern float enh_plocsTbl[];
|
|
|
|
|
|
|
|
|
|
Andersen, et al. Experimental [Page 81]
|
|
|
|
RFC 3951 Internet Low Bit Rate Codec December 2004
|
|
|
|
|
|
#endif
|
|
|
|
A.8. constants.c
|
|
|
|
/******************************************************************
|
|
|
|
iLBC Speech Coder ANSI-C Source Code
|
|
|
|
constants.c
|
|
|
|
Copyright (C) The Internet Society (2004).
|
|
All Rights Reserved.
|
|
|
|
******************************************************************/
|
|
|
|
#include "iLBC_define.h"
|
|
|
|
/* ULP bit allocation */
|
|
|
|
/* 20 ms frame */
|
|
|
|
const iLBC_ULP_Inst_t ULP_20msTbl = {
|
|
/* LSF */
|
|
{ {6,0,0,0,0}, {7,0,0,0,0}, {7,0,0,0,0},
|
|
{0,0,0,0,0}, {0,0,0,0,0}, {0,0,0,0,0}},
|
|
/* Start state location, gain and samples */
|
|
{2,0,0,0,0},
|
|
{1,0,0,0,0},
|
|
{6,0,0,0,0},
|
|
{0,1,2,0,0},
|
|
/* extra CB index and extra CB gain */
|
|
{{6,0,1,0,0}, {0,0,7,0,0}, {0,0,7,0,0}},
|
|
{{2,0,3,0,0}, {1,1,2,0,0}, {0,0,3,0,0}},
|
|
/* CB index and CB gain */
|
|
{ {{7,0,1,0,0}, {0,0,7,0,0}, {0,0,7,0,0}},
|
|
{{0,0,8,0,0}, {0,0,8,0,0}, {0,0,8,0,0}},
|
|
{{0,0,0,0,0}, {0,0,0,0,0}, {0,0,0,0,0}},
|
|
{{0,0,0,0,0}, {0,0,0,0,0}, {0,0,0,0,0}}},
|
|
{ {{1,2,2,0,0}, {1,1,2,0,0}, {0,0,3,0,0}},
|
|
{{1,1,3,0,0}, {0,2,2,0,0}, {0,0,3,0,0}},
|
|
{{0,0,0,0,0}, {0,0,0,0,0}, {0,0,0,0,0}},
|
|
{{0,0,0,0,0}, {0,0,0,0,0}, {0,0,0,0,0}}}
|
|
};
|
|
|
|
/* 30 ms frame */
|
|
|
|
const iLBC_ULP_Inst_t ULP_30msTbl = {
|
|
/* LSF */
|
|
|
|
|
|
|
|
Andersen, et al. Experimental [Page 82]
|
|
|
|
RFC 3951 Internet Low Bit Rate Codec December 2004
|
|
|
|
|
|
{ {6,0,0,0,0}, {7,0,0,0,0}, {7,0,0,0,0},
|
|
{6,0,0,0,0}, {7,0,0,0,0}, {7,0,0,0,0}},
|
|
/* Start state location, gain and samples */
|
|
{3,0,0,0,0},
|
|
{1,0,0,0,0},
|
|
{6,0,0,0,0},
|
|
{0,1,2,0,0},
|
|
/* extra CB index and extra CB gain */
|
|
{{4,2,1,0,0}, {0,0,7,0,0}, {0,0,7,0,0}},
|
|
{{1,1,3,0,0}, {1,1,2,0,0}, {0,0,3,0,0}},
|
|
/* CB index and CB gain */
|
|
{ {{6,1,1,0,0}, {0,0,7,0,0}, {0,0,7,0,0}},
|
|
{{0,7,1,0,0}, {0,0,8,0,0}, {0,0,8,0,0}},
|
|
{{0,7,1,0,0}, {0,0,8,0,0}, {0,0,8,0,0}},
|
|
{{0,7,1,0,0}, {0,0,8,0,0}, {0,0,8,0,0}}},
|
|
{ {{1,2,2,0,0}, {1,2,1,0,0}, {0,0,3,0,0}},
|
|
{{0,2,3,0,0}, {0,2,2,0,0}, {0,0,3,0,0}},
|
|
{{0,1,4,0,0}, {0,1,3,0,0}, {0,0,3,0,0}},
|
|
{{0,1,4,0,0}, {0,1,3,0,0}, {0,0,3,0,0}}}
|
|
};
|
|
|
|
/* HP Filters */
|
|
|
|
float hpi_zero_coefsTbl[3] = {
|
|
(float)0.92727436, (float)-1.8544941, (float)0.92727436
|
|
};
|
|
float hpi_pole_coefsTbl[3] = {
|
|
(float)1.0, (float)-1.9059465, (float)0.9114024
|
|
};
|
|
float hpo_zero_coefsTbl[3] = {
|
|
(float)0.93980581, (float)-1.8795834, (float)0.93980581
|
|
};
|
|
float hpo_pole_coefsTbl[3] = {
|
|
(float)1.0, (float)-1.9330735, (float)0.93589199
|
|
};
|
|
|
|
/* LP Filter */
|
|
|
|
float lpFilt_coefsTbl[FILTERORDER_DS]={
|
|
(float)-0.066650, (float)0.125000, (float)0.316650,
|
|
(float)0.414063, (float)0.316650,
|
|
(float)0.125000, (float)-0.066650
|
|
};
|
|
|
|
/* State quantization tables */
|
|
|
|
float state_sq3Tbl[8] = {
|
|
(float)-3.719849, (float)-2.177490, (float)-1.130005,
|
|
|
|
|
|
|
|
Andersen, et al. Experimental [Page 83]
|
|
|
|
RFC 3951 Internet Low Bit Rate Codec December 2004
|
|
|
|
|
|
(float)-0.309692, (float)0.444214, (float)1.329712,
|
|
(float)2.436279, (float)3.983887
|
|
};
|
|
|
|
float state_frgqTbl[64] = {
|
|
(float)1.000085, (float)1.071695, (float)1.140395,
|
|
(float)1.206868, (float)1.277188, (float)1.351503,
|
|
(float)1.429380, (float)1.500727, (float)1.569049,
|
|
(float)1.639599, (float)1.707071, (float)1.781531,
|
|
(float)1.840799, (float)1.901550, (float)1.956695,
|
|
(float)2.006750, (float)2.055474, (float)2.102787,
|
|
(float)2.142819, (float)2.183592, (float)2.217962,
|
|
(float)2.257177, (float)2.295739, (float)2.332967,
|
|
(float)2.369248, (float)2.402792, (float)2.435080,
|
|
(float)2.468598, (float)2.503394, (float)2.539284,
|
|
(float)2.572944, (float)2.605036, (float)2.636331,
|
|
(float)2.668939, (float)2.698780, (float)2.729101,
|
|
(float)2.759786, (float)2.789834, (float)2.818679,
|
|
(float)2.848074, (float)2.877470, (float)2.906899,
|
|
(float)2.936655, (float)2.967804, (float)3.000115,
|
|
(float)3.033367, (float)3.066355, (float)3.104231,
|
|
(float)3.141499, (float)3.183012, (float)3.222952,
|
|
(float)3.265433, (float)3.308441, (float)3.350823,
|
|
(float)3.395275, (float)3.442793, (float)3.490801,
|
|
(float)3.542514, (float)3.604064, (float)3.666050,
|
|
(float)3.740994, (float)3.830749, (float)3.938770,
|
|
(float)4.101764
|
|
};
|
|
|
|
/* CB tables */
|
|
|
|
int search_rangeTbl[5][CB_NSTAGES]={{58,58,58}, {108,44,44},
|
|
{108,108,108}, {108,108,108}, {108,108,108}};
|
|
int stMemLTbl=85;
|
|
int memLfTbl[NASUB_MAX]={147,147,147,147};
|
|
|
|
/* expansion filter(s) */
|
|
|
|
float cbfiltersTbl[CB_FILTERLEN]={
|
|
(float)-0.034180, (float)0.108887, (float)-0.184326,
|
|
(float)0.806152, (float)0.713379, (float)-0.144043,
|
|
(float)0.083740, (float)-0.033691
|
|
};
|
|
|
|
/* Gain Quantization */
|
|
|
|
float gain_sq3Tbl[8]={
|
|
(float)-1.000000, (float)-0.659973, (float)-0.330017,
|
|
|
|
|
|
|
|
Andersen, et al. Experimental [Page 84]
|
|
|
|
RFC 3951 Internet Low Bit Rate Codec December 2004
|
|
|
|
|
|
(float)0.000000, (float)0.250000, (float)0.500000,
|
|
(float)0.750000, (float)1.00000};
|
|
|
|
float gain_sq4Tbl[16]={
|
|
(float)-1.049988, (float)-0.900024, (float)-0.750000,
|
|
(float)-0.599976, (float)-0.450012, (float)-0.299988,
|
|
(float)-0.150024, (float)0.000000, (float)0.150024,
|
|
(float)0.299988, (float)0.450012, (float)0.599976,
|
|
(float)0.750000, (float)0.900024, (float)1.049988,
|
|
(float)1.200012};
|
|
|
|
float gain_sq5Tbl[32]={
|
|
(float)0.037476, (float)0.075012, (float)0.112488,
|
|
(float)0.150024, (float)0.187500, (float)0.224976,
|
|
(float)0.262512, (float)0.299988, (float)0.337524,
|
|
(float)0.375000, (float)0.412476, (float)0.450012,
|
|
(float)0.487488, (float)0.525024, (float)0.562500,
|
|
(float)0.599976, (float)0.637512, (float)0.674988,
|
|
(float)0.712524, (float)0.750000, (float)0.787476,
|
|
(float)0.825012, (float)0.862488, (float)0.900024,
|
|
(float)0.937500, (float)0.974976, (float)1.012512,
|
|
(float)1.049988, (float)1.087524, (float)1.125000,
|
|
(float)1.162476, (float)1.200012};
|
|
|
|
/* Enhancer - Upsampling a factor 4 (ENH_UPS0 = 4) */
|
|
float polyphaserTbl[ENH_UPS0*(2*ENH_FL0+1)]={
|
|
(float)0.000000, (float)0.000000, (float)0.000000,
|
|
(float)1.000000,
|
|
(float)0.000000, (float)0.000000, (float)0.000000,
|
|
(float)0.015625, (float)-0.076904, (float)0.288330,
|
|
(float)0.862061,
|
|
(float)-0.106445, (float)0.018799, (float)-0.015625,
|
|
(float)0.023682, (float)-0.124268, (float)0.601563,
|
|
(float)0.601563,
|
|
(float)-0.124268, (float)0.023682, (float)-0.023682,
|
|
(float)0.018799, (float)-0.106445, (float)0.862061,
|
|
(float)0.288330,
|
|
(float)-0.076904, (float)0.015625, (float)-0.018799};
|
|
|
|
float enh_plocsTbl[ENH_NBLOCKS_TOT] = {(float)40.0, (float)120.0,
|
|
(float)200.0, (float)280.0, (float)360.0,
|
|
(float)440.0, (float)520.0, (float)600.0};
|
|
|
|
/* LPC analysis and quantization */
|
|
|
|
int dim_lsfCbTbl[LSF_NSPLIT] = {3, 3, 4};
|
|
int size_lsfCbTbl[LSF_NSPLIT] = {64,128,128};
|
|
|
|
|
|
|
|
|
|
Andersen, et al. Experimental [Page 85]
|
|
|
|
RFC 3951 Internet Low Bit Rate Codec December 2004
|
|
|
|
|
|
float lsfmeanTbl[LPC_FILTERORDER] = {
|
|
(float)0.281738, (float)0.445801, (float)0.663330,
|
|
(float)0.962524, (float)1.251831, (float)1.533081,
|
|
(float)1.850586, (float)2.137817, (float)2.481445,
|
|
(float)2.777344};
|
|
|
|
float lsf_weightTbl_30ms[6] = {(float)(1.0/2.0), (float)1.0,
|
|
(float)(2.0/3.0),
|
|
(float)(1.0/3.0), (float)0.0, (float)0.0};
|
|
|
|
float lsf_weightTbl_20ms[4] = {(float)(3.0/4.0), (float)(2.0/4.0),
|
|
(float)(1.0/4.0), (float)(0.0)};
|
|
|
|
/* Hanning LPC window */
|
|
float lpc_winTbl[BLOCKL_MAX]={
|
|
(float)0.000183, (float)0.000671, (float)0.001526,
|
|
(float)0.002716, (float)0.004242, (float)0.006104,
|
|
(float)0.008301, (float)0.010834, (float)0.013702,
|
|
(float)0.016907, (float)0.020416, (float)0.024261,
|
|
(float)0.028442, (float)0.032928, (float)0.037750,
|
|
(float)0.042877, (float)0.048309, (float)0.054047,
|
|
(float)0.060089, (float)0.066437, (float)0.073090,
|
|
(float)0.080017, (float)0.087219, (float)0.094727,
|
|
(float)0.102509, (float)0.110535, (float)0.118835,
|
|
(float)0.127411, (float)0.136230, (float)0.145294,
|
|
(float)0.154602, (float)0.164154, (float)0.173920,
|
|
(float)0.183899, (float)0.194122, (float)0.204529,
|
|
(float)0.215149, (float)0.225952, (float)0.236938,
|
|
(float)0.248108, (float)0.259460, (float)0.270966,
|
|
(float)0.282654, (float)0.294464, (float)0.306396,
|
|
(float)0.318481, (float)0.330688, (float)0.343018,
|
|
(float)0.355438, (float)0.367981, (float)0.380585,
|
|
(float)0.393280, (float)0.406067, (float)0.418884,
|
|
(float)0.431763, (float)0.444702, (float)0.457672,
|
|
(float)0.470673, (float)0.483704, (float)0.496735,
|
|
(float)0.509766, (float)0.522797, (float)0.535828,
|
|
(float)0.548798, (float)0.561768, (float)0.574677,
|
|
(float)0.587524, (float)0.600342, (float)0.613068,
|
|
(float)0.625732, (float)0.638306, (float)0.650787,
|
|
(float)0.663147, (float)0.675415, (float)0.687561,
|
|
(float)0.699585, (float)0.711487, (float)0.723206,
|
|
(float)0.734802, (float)0.746216, (float)0.757477,
|
|
(float)0.768585, (float)0.779480, (float)0.790192,
|
|
(float)0.800720, (float)0.811005, (float)0.821106,
|
|
(float)0.830994, (float)0.840668, (float)0.850067,
|
|
(float)0.859253, (float)0.868225, (float)0.876892,
|
|
(float)0.885345, (float)0.893524, (float)0.901428,
|
|
(float)0.909058, (float)0.916412, (float)0.923492,
|
|
|
|
|
|
|
|
Andersen, et al. Experimental [Page 86]
|
|
|
|
RFC 3951 Internet Low Bit Rate Codec December 2004
|
|
|
|
|
|
(float)0.930267, (float)0.936768, (float)0.942963,
|
|
(float)0.948853, (float)0.954437, (float)0.959717,
|
|
(float)0.964691, (float)0.969360, (float)0.973694,
|
|
(float)0.977692, (float)0.981384, (float)0.984741,
|
|
(float)0.987762, (float)0.990479, (float)0.992828,
|
|
(float)0.994873, (float)0.996552, (float)0.997925,
|
|
(float)0.998932, (float)0.999603, (float)0.999969,
|
|
(float)0.999969, (float)0.999603, (float)0.998932,
|
|
(float)0.997925, (float)0.996552, (float)0.994873,
|
|
(float)0.992828, (float)0.990479, (float)0.987762,
|
|
(float)0.984741, (float)0.981384, (float)0.977692,
|
|
(float)0.973694, (float)0.969360, (float)0.964691,
|
|
(float)0.959717, (float)0.954437, (float)0.948853,
|
|
(float)0.942963, (float)0.936768, (float)0.930267,
|
|
(float)0.923492, (float)0.916412, (float)0.909058,
|
|
(float)0.901428, (float)0.893524, (float)0.885345,
|
|
(float)0.876892, (float)0.868225, (float)0.859253,
|
|
(float)0.850067, (float)0.840668, (float)0.830994,
|
|
(float)0.821106, (float)0.811005, (float)0.800720,
|
|
(float)0.790192, (float)0.779480, (float)0.768585,
|
|
(float)0.757477, (float)0.746216, (float)0.734802,
|
|
(float)0.723206, (float)0.711487, (float)0.699585,
|
|
(float)0.687561, (float)0.675415, (float)0.663147,
|
|
(float)0.650787, (float)0.638306, (float)0.625732,
|
|
(float)0.613068, (float)0.600342, (float)0.587524,
|
|
(float)0.574677, (float)0.561768, (float)0.548798,
|
|
(float)0.535828, (float)0.522797, (float)0.509766,
|
|
(float)0.496735, (float)0.483704, (float)0.470673,
|
|
(float)0.457672, (float)0.444702, (float)0.431763,
|
|
(float)0.418884, (float)0.406067, (float)0.393280,
|
|
(float)0.380585, (float)0.367981, (float)0.355438,
|
|
(float)0.343018, (float)0.330688, (float)0.318481,
|
|
(float)0.306396, (float)0.294464, (float)0.282654,
|
|
(float)0.270966, (float)0.259460, (float)0.248108,
|
|
(float)0.236938, (float)0.225952, (float)0.215149,
|
|
(float)0.204529, (float)0.194122, (float)0.183899,
|
|
(float)0.173920, (float)0.164154, (float)0.154602,
|
|
(float)0.145294, (float)0.136230, (float)0.127411,
|
|
(float)0.118835, (float)0.110535, (float)0.102509,
|
|
(float)0.094727, (float)0.087219, (float)0.080017,
|
|
(float)0.073090, (float)0.066437, (float)0.060089,
|
|
(float)0.054047, (float)0.048309, (float)0.042877,
|
|
(float)0.037750, (float)0.032928, (float)0.028442,
|
|
(float)0.024261, (float)0.020416, (float)0.016907,
|
|
(float)0.013702, (float)0.010834, (float)0.008301,
|
|
(float)0.006104, (float)0.004242, (float)0.002716,
|
|
(float)0.001526, (float)0.000671, (float)0.000183
|
|
};
|
|
|
|
|
|
|
|
Andersen, et al. Experimental [Page 87]
|
|
|
|
RFC 3951 Internet Low Bit Rate Codec December 2004
|
|
|
|
|
|
/* Asymmetric LPC window */
|
|
float lpc_asymwinTbl[BLOCKL_MAX]={
|
|
(float)0.000061, (float)0.000214, (float)0.000458,
|
|
(float)0.000824, (float)0.001282, (float)0.001831,
|
|
(float)0.002472, (float)0.003235, (float)0.004120,
|
|
(float)0.005066, (float)0.006134, (float)0.007294,
|
|
(float)0.008545, (float)0.009918, (float)0.011383,
|
|
(float)0.012939, (float)0.014587, (float)0.016357,
|
|
(float)0.018219, (float)0.020172, (float)0.022217,
|
|
(float)0.024353, (float)0.026611, (float)0.028961,
|
|
(float)0.031372, (float)0.033905, (float)0.036530,
|
|
(float)0.039276, (float)0.042084, (float)0.044983,
|
|
(float)0.047974, (float)0.051086, (float)0.054260,
|
|
(float)0.057526, (float)0.060883, (float)0.064331,
|
|
(float)0.067871, (float)0.071503, (float)0.075226,
|
|
(float)0.079010, (float)0.082916, (float)0.086884,
|
|
(float)0.090942, (float)0.095062, (float)0.099304,
|
|
(float)0.103607, (float)0.107971, (float)0.112427,
|
|
(float)0.116974, (float)0.121582, (float)0.126282,
|
|
(float)0.131073, (float)0.135895, (float)0.140839,
|
|
(float)0.145813, (float)0.150879, (float)0.156006,
|
|
(float)0.161224, (float)0.166504, (float)0.171844,
|
|
(float)0.177246, (float)0.182709, (float)0.188263,
|
|
(float)0.193848, (float)0.199524, (float)0.205231,
|
|
(float)0.211029, (float)0.216858, (float)0.222778,
|
|
(float)0.228729, (float)0.234741, (float)0.240814,
|
|
(float)0.246918, (float)0.253082, (float)0.259308,
|
|
(float)0.265564, (float)0.271881, (float)0.278259,
|
|
(float)0.284668, (float)0.291107, (float)0.297607,
|
|
(float)0.304138, (float)0.310730, (float)0.317322,
|
|
(float)0.323975, (float)0.330658, (float)0.337372,
|
|
(float)0.344147, (float)0.350922, (float)0.357727,
|
|
(float)0.364594, (float)0.371460, (float)0.378357,
|
|
(float)0.385284, (float)0.392212, (float)0.399170,
|
|
(float)0.406158, (float)0.413177, (float)0.420197,
|
|
(float)0.427246, (float)0.434296, (float)0.441376,
|
|
(float)0.448456, (float)0.455536, (float)0.462646,
|
|
(float)0.469757, (float)0.476868, (float)0.483978,
|
|
(float)0.491089, (float)0.498230, (float)0.505341,
|
|
(float)0.512451, (float)0.519592, (float)0.526703,
|
|
(float)0.533813, (float)0.540924, (float)0.548004,
|
|
(float)0.555084, (float)0.562164, (float)0.569244,
|
|
(float)0.576294, (float)0.583313, (float)0.590332,
|
|
(float)0.597321, (float)0.604309, (float)0.611267,
|
|
(float)0.618195, (float)0.625092, (float)0.631989,
|
|
(float)0.638855, (float)0.645660, (float)0.652466,
|
|
(float)0.659241, (float)0.665985, (float)0.672668,
|
|
(float)0.679352, (float)0.685974, (float)0.692566,
|
|
|
|
|
|
|
|
Andersen, et al. Experimental [Page 88]
|
|
|
|
RFC 3951 Internet Low Bit Rate Codec December 2004
|
|
|
|
|
|
(float)0.699127, (float)0.705658, (float)0.712128,
|
|
(float)0.718536, (float)0.724945, (float)0.731262,
|
|
(float)0.737549, (float)0.743805, (float)0.750000,
|
|
(float)0.756134, (float)0.762238, (float)0.768280,
|
|
(float)0.774261, (float)0.780182, (float)0.786072,
|
|
(float)0.791870, (float)0.797638, (float)0.803314,
|
|
(float)0.808960, (float)0.814514, (float)0.820038,
|
|
(float)0.825470, (float)0.830841, (float)0.836151,
|
|
(float)0.841400, (float)0.846558, (float)0.851654,
|
|
(float)0.856689, (float)0.861633, (float)0.866516,
|
|
(float)0.871338, (float)0.876068, (float)0.880737,
|
|
(float)0.885315, (float)0.889801, (float)0.894226,
|
|
(float)0.898560, (float)0.902832, (float)0.907013,
|
|
(float)0.911102, (float)0.915100, (float)0.919037,
|
|
(float)0.922882, (float)0.926636, (float)0.930328,
|
|
(float)0.933899, (float)0.937408, (float)0.940796,
|
|
(float)0.944122, (float)0.947357, (float)0.950470,
|
|
(float)0.953522, (float)0.956482, (float)0.959351,
|
|
(float)0.962097, (float)0.964783, (float)0.967377,
|
|
(float)0.969849, (float)0.972229, (float)0.974518,
|
|
(float)0.976715, (float)0.978821, (float)0.980835,
|
|
(float)0.982727, (float)0.984528, (float)0.986237,
|
|
(float)0.987854, (float)0.989380, (float)0.990784,
|
|
(float)0.992096, (float)0.993317, (float)0.994415,
|
|
(float)0.995422, (float)0.996338, (float)0.997162,
|
|
(float)0.997864, (float)0.998474, (float)0.998962,
|
|
(float)0.999390, (float)0.999695, (float)0.999878,
|
|
(float)0.999969, (float)0.999969, (float)0.996918,
|
|
(float)0.987701, (float)0.972382, (float)0.951050,
|
|
(float)0.923889, (float)0.891022, (float)0.852631,
|
|
(float)0.809021, (float)0.760406, (float)0.707092,
|
|
(float)0.649445, (float)0.587799, (float)0.522491,
|
|
(float)0.453979, (float)0.382690, (float)0.309021,
|
|
(float)0.233459, (float)0.156433, (float)0.078461
|
|
};
|
|
|
|
/* Lag window for LPC */
|
|
float lpc_lagwinTbl[LPC_FILTERORDER + 1]={
|
|
(float)1.000100, (float)0.998890, (float)0.995569,
|
|
(float)0.990057, (float)0.982392,
|
|
(float)0.972623, (float)0.960816, (float)0.947047,
|
|
(float)0.931405, (float)0.913989, (float)0.894909};
|
|
|
|
/* LSF quantization*/
|
|
float lsfCbTbl[64 * 3 + 128 * 3 + 128 * 4] = {
|
|
(float)0.155396, (float)0.273193, (float)0.451172,
|
|
(float)0.390503, (float)0.648071, (float)1.002075,
|
|
(float)0.440186, (float)0.692261, (float)0.955688,
|
|
|
|
|
|
|
|
Andersen, et al. Experimental [Page 89]
|
|
|
|
RFC 3951 Internet Low Bit Rate Codec December 2004
|
|
|
|
|
|
(float)0.343628, (float)0.642334, (float)1.071533,
|
|
(float)0.318359, (float)0.491577, (float)0.670532,
|
|
(float)0.193115, (float)0.375488, (float)0.725708,
|
|
(float)0.364136, (float)0.510376, (float)0.658691,
|
|
(float)0.297485, (float)0.527588, (float)0.842529,
|
|
(float)0.227173, (float)0.365967, (float)0.563110,
|
|
(float)0.244995, (float)0.396729, (float)0.636475,
|
|
(float)0.169434, (float)0.300171, (float)0.520264,
|
|
(float)0.312866, (float)0.464478, (float)0.643188,
|
|
(float)0.248535, (float)0.429932, (float)0.626099,
|
|
(float)0.236206, (float)0.491333, (float)0.817139,
|
|
(float)0.334961, (float)0.625122, (float)0.895752,
|
|
(float)0.343018, (float)0.518555, (float)0.698608,
|
|
(float)0.372803, (float)0.659790, (float)0.945435,
|
|
(float)0.176880, (float)0.316528, (float)0.581421,
|
|
(float)0.416382, (float)0.625977, (float)0.805176,
|
|
(float)0.303223, (float)0.568726, (float)0.915039,
|
|
(float)0.203613, (float)0.351440, (float)0.588135,
|
|
(float)0.221191, (float)0.375000, (float)0.614746,
|
|
(float)0.199951, (float)0.323364, (float)0.476074,
|
|
(float)0.300781, (float)0.433350, (float)0.566895,
|
|
(float)0.226196, (float)0.354004, (float)0.507568,
|
|
(float)0.300049, (float)0.508179, (float)0.711670,
|
|
(float)0.312012, (float)0.492676, (float)0.763428,
|
|
(float)0.329956, (float)0.541016, (float)0.795776,
|
|
(float)0.373779, (float)0.604614, (float)0.928833,
|
|
(float)0.210571, (float)0.452026, (float)0.755249,
|
|
(float)0.271118, (float)0.473267, (float)0.662476,
|
|
(float)0.285522, (float)0.436890, (float)0.634399,
|
|
(float)0.246704, (float)0.565552, (float)0.859009,
|
|
(float)0.270508, (float)0.406250, (float)0.553589,
|
|
(float)0.361450, (float)0.578491, (float)0.813843,
|
|
(float)0.342651, (float)0.482788, (float)0.622437,
|
|
(float)0.340332, (float)0.549438, (float)0.743164,
|
|
(float)0.200439, (float)0.336304, (float)0.540894,
|
|
(float)0.407837, (float)0.644775, (float)0.895142,
|
|
(float)0.294678, (float)0.454834, (float)0.699097,
|
|
(float)0.193115, (float)0.344482, (float)0.643188,
|
|
(float)0.275757, (float)0.420776, (float)0.598755,
|
|
(float)0.380493, (float)0.608643, (float)0.861084,
|
|
(float)0.222778, (float)0.426147, (float)0.676514,
|
|
(float)0.407471, (float)0.700195, (float)1.053101,
|
|
(float)0.218384, (float)0.377197, (float)0.669922,
|
|
(float)0.313232, (float)0.454102, (float)0.600952,
|
|
(float)0.347412, (float)0.571533, (float)0.874146,
|
|
(float)0.238037, (float)0.405396, (float)0.729492,
|
|
(float)0.223877, (float)0.412964, (float)0.822021,
|
|
(float)0.395264, (float)0.582153, (float)0.743896,
|
|
|
|
|
|
|
|
Andersen, et al. Experimental [Page 90]
|
|
|
|
RFC 3951 Internet Low Bit Rate Codec December 2004
|
|
|
|
|
|
(float)0.247925, (float)0.485596, (float)0.720581,
|
|
(float)0.229126, (float)0.496582, (float)0.907715,
|
|
(float)0.260132, (float)0.566895, (float)1.012695,
|
|
(float)0.337402, (float)0.611572, (float)0.978149,
|
|
(float)0.267822, (float)0.447632, (float)0.769287,
|
|
(float)0.250610, (float)0.381714, (float)0.530029,
|
|
(float)0.430054, (float)0.805054, (float)1.221924,
|
|
(float)0.382568, (float)0.544067, (float)0.701660,
|
|
(float)0.383545, (float)0.710327, (float)1.149170,
|
|
(float)0.271362, (float)0.529053, (float)0.775513,
|
|
(float)0.246826, (float)0.393555, (float)0.588623,
|
|
(float)0.266846, (float)0.422119, (float)0.676758,
|
|
(float)0.311523, (float)0.580688, (float)0.838623,
|
|
(float)1.331177, (float)1.576782, (float)1.779541,
|
|
(float)1.160034, (float)1.401978, (float)1.768188,
|
|
(float)1.161865, (float)1.525146, (float)1.715332,
|
|
(float)0.759521, (float)0.913940, (float)1.119873,
|
|
(float)0.947144, (float)1.121338, (float)1.282471,
|
|
(float)1.015015, (float)1.557007, (float)1.804932,
|
|
(float)1.172974, (float)1.402100, (float)1.692627,
|
|
(float)1.087524, (float)1.474243, (float)1.665405,
|
|
(float)0.899536, (float)1.105225, (float)1.406250,
|
|
(float)1.148438, (float)1.484741, (float)1.796265,
|
|
(float)0.785645, (float)1.209839, (float)1.567749,
|
|
(float)0.867798, (float)1.166504, (float)1.450684,
|
|
(float)0.922485, (float)1.229858, (float)1.420898,
|
|
(float)0.791260, (float)1.123291, (float)1.409546,
|
|
(float)0.788940, (float)0.966064, (float)1.340332,
|
|
(float)1.051147, (float)1.272827, (float)1.556641,
|
|
(float)0.866821, (float)1.181152, (float)1.538818,
|
|
(float)0.906738, (float)1.373535, (float)1.607910,
|
|
(float)1.244751, (float)1.581421, (float)1.933838,
|
|
(float)0.913940, (float)1.337280, (float)1.539673,
|
|
(float)0.680542, (float)0.959229, (float)1.662720,
|
|
(float)0.887207, (float)1.430542, (float)1.800781,
|
|
(float)0.912598, (float)1.433594, (float)1.683960,
|
|
(float)0.860474, (float)1.060303, (float)1.455322,
|
|
(float)1.005127, (float)1.381104, (float)1.706909,
|
|
(float)0.800781, (float)1.363892, (float)1.829102,
|
|
(float)0.781860, (float)1.124390, (float)1.505981,
|
|
(float)1.003662, (float)1.471436, (float)1.684692,
|
|
(float)0.981323, (float)1.309570, (float)1.618042,
|
|
(float)1.228760, (float)1.554321, (float)1.756470,
|
|
(float)0.734375, (float)0.895752, (float)1.225586,
|
|
(float)0.841797, (float)1.055664, (float)1.249268,
|
|
(float)0.920166, (float)1.119385, (float)1.486206,
|
|
(float)0.894409, (float)1.539063, (float)1.828979,
|
|
(float)1.283691, (float)1.543335, (float)1.858276,
|
|
|
|
|
|
|
|
Andersen, et al. Experimental [Page 91]
|
|
|
|
RFC 3951 Internet Low Bit Rate Codec December 2004
|
|
|
|
|
|
(float)0.676025, (float)0.933105, (float)1.490845,
|
|
(float)0.821289, (float)1.491821, (float)1.739868,
|
|
(float)0.923218, (float)1.144653, (float)1.580566,
|
|
(float)1.057251, (float)1.345581, (float)1.635864,
|
|
(float)0.888672, (float)1.074951, (float)1.353149,
|
|
(float)0.942749, (float)1.195435, (float)1.505493,
|
|
(float)1.492310, (float)1.788086, (float)2.039673,
|
|
(float)1.070313, (float)1.634399, (float)1.860962,
|
|
(float)1.253296, (float)1.488892, (float)1.686035,
|
|
(float)0.647095, (float)0.864014, (float)1.401855,
|
|
(float)0.866699, (float)1.254883, (float)1.453369,
|
|
(float)1.063965, (float)1.532593, (float)1.731323,
|
|
(float)1.167847, (float)1.521484, (float)1.884033,
|
|
(float)0.956055, (float)1.502075, (float)1.745605,
|
|
(float)0.928711, (float)1.288574, (float)1.479614,
|
|
(float)1.088013, (float)1.380737, (float)1.570801,
|
|
(float)0.905029, (float)1.186768, (float)1.371948,
|
|
(float)1.057861, (float)1.421021, (float)1.617432,
|
|
(float)1.108276, (float)1.312500, (float)1.501465,
|
|
(float)0.979492, (float)1.416992, (float)1.624268,
|
|
(float)1.276001, (float)1.661011, (float)2.007935,
|
|
(float)0.993042, (float)1.168579, (float)1.331665,
|
|
(float)0.778198, (float)0.944946, (float)1.235962,
|
|
(float)1.223755, (float)1.491333, (float)1.815674,
|
|
(float)0.852661, (float)1.350464, (float)1.722290,
|
|
(float)1.134766, (float)1.593140, (float)1.787354,
|
|
(float)1.051392, (float)1.339722, (float)1.531006,
|
|
(float)0.803589, (float)1.271240, (float)1.652100,
|
|
(float)0.755737, (float)1.143555, (float)1.639404,
|
|
(float)0.700928, (float)0.837280, (float)1.130371,
|
|
(float)0.942749, (float)1.197876, (float)1.669800,
|
|
(float)0.993286, (float)1.378296, (float)1.566528,
|
|
(float)0.801025, (float)1.095337, (float)1.298950,
|
|
(float)0.739990, (float)1.032959, (float)1.383667,
|
|
(float)0.845703, (float)1.072266, (float)1.543823,
|
|
(float)0.915649, (float)1.072266, (float)1.224487,
|
|
(float)1.021973, (float)1.226196, (float)1.481323,
|
|
(float)0.999878, (float)1.204102, (float)1.555908,
|
|
(float)0.722290, (float)0.913940, (float)1.340210,
|
|
(float)0.673340, (float)0.835938, (float)1.259521,
|
|
(float)0.832397, (float)1.208374, (float)1.394165,
|
|
(float)0.962158, (float)1.576172, (float)1.912842,
|
|
(float)1.166748, (float)1.370850, (float)1.556763,
|
|
(float)0.946289, (float)1.138550, (float)1.400391,
|
|
(float)1.035034, (float)1.218262, (float)1.386475,
|
|
(float)1.393799, (float)1.717773, (float)2.000244,
|
|
(float)0.972656, (float)1.260986, (float)1.760620,
|
|
(float)1.028198, (float)1.288452, (float)1.484619,
|
|
|
|
|
|
|
|
Andersen, et al. Experimental [Page 92]
|
|
|
|
RFC 3951 Internet Low Bit Rate Codec December 2004
|
|
|
|
|
|
(float)0.773560, (float)1.258057, (float)1.756714,
|
|
(float)1.080322, (float)1.328003, (float)1.742676,
|
|
(float)0.823975, (float)1.450806, (float)1.917725,
|
|
(float)0.859009, (float)1.016602, (float)1.191895,
|
|
(float)0.843994, (float)1.131104, (float)1.645020,
|
|
(float)1.189697, (float)1.702759, (float)1.894409,
|
|
(float)1.346680, (float)1.763184, (float)2.066040,
|
|
(float)0.980469, (float)1.253784, (float)1.441650,
|
|
(float)1.338135, (float)1.641968, (float)1.932739,
|
|
(float)1.223267, (float)1.424194, (float)1.626465,
|
|
(float)0.765747, (float)1.004150, (float)1.579102,
|
|
(float)1.042847, (float)1.269165, (float)1.647461,
|
|
(float)0.968750, (float)1.257568, (float)1.555786,
|
|
(float)0.826294, (float)0.993408, (float)1.275146,
|
|
(float)0.742310, (float)0.950439, (float)1.430542,
|
|
(float)1.054321, (float)1.439819, (float)1.828003,
|
|
(float)1.072998, (float)1.261719, (float)1.441895,
|
|
(float)0.859375, (float)1.036377, (float)1.314819,
|
|
(float)0.895752, (float)1.267212, (float)1.605591,
|
|
(float)0.805420, (float)0.962891, (float)1.142334,
|
|
(float)0.795654, (float)1.005493, (float)1.468506,
|
|
(float)1.105347, (float)1.313843, (float)1.584839,
|
|
(float)0.792236, (float)1.221802, (float)1.465698,
|
|
(float)1.170532, (float)1.467651, (float)1.664063,
|
|
(float)0.838257, (float)1.153198, (float)1.342163,
|
|
(float)0.968018, (float)1.198242, (float)1.391235,
|
|
(float)1.250122, (float)1.623535, (float)1.823608,
|
|
(float)0.711670, (float)1.058350, (float)1.512085,
|
|
(float)1.204834, (float)1.454468, (float)1.739136,
|
|
(float)1.137451, (float)1.421753, (float)1.620117,
|
|
(float)0.820435, (float)1.322754, (float)1.578247,
|
|
(float)0.798706, (float)1.005005, (float)1.213867,
|
|
(float)0.980713, (float)1.324951, (float)1.512939,
|
|
(float)1.112305, (float)1.438843, (float)1.735596,
|
|
(float)1.135498, (float)1.356689, (float)1.635742,
|
|
(float)1.101318, (float)1.387451, (float)1.686523,
|
|
(float)0.849854, (float)1.276978, (float)1.523438,
|
|
(float)1.377930, (float)1.627563, (float)1.858154,
|
|
(float)0.884888, (float)1.095459, (float)1.287476,
|
|
(float)1.289795, (float)1.505859, (float)1.756592,
|
|
(float)0.817505, (float)1.384155, (float)1.650513,
|
|
(float)1.446655, (float)1.702148, (float)1.931885,
|
|
(float)0.835815, (float)1.023071, (float)1.385376,
|
|
(float)0.916626, (float)1.139038, (float)1.335327,
|
|
(float)0.980103, (float)1.174072, (float)1.453735,
|
|
(float)1.705688, (float)2.153809, (float)2.398315, (float)2.743408,
|
|
(float)1.797119, (float)2.016846, (float)2.445679, (float)2.701904,
|
|
(float)1.990356, (float)2.219116, (float)2.576416, (float)2.813477,
|
|
|
|
|
|
|
|
Andersen, et al. Experimental [Page 93]
|
|
|
|
RFC 3951 Internet Low Bit Rate Codec December 2004
|
|
|
|
|
|
(float)1.849365, (float)2.190918, (float)2.611572, (float)2.835083,
|
|
(float)1.657959, (float)1.854370, (float)2.159058, (float)2.726196,
|
|
(float)1.437744, (float)1.897705, (float)2.253174, (float)2.655396,
|
|
(float)2.028687, (float)2.247314, (float)2.542358, (float)2.875854,
|
|
(float)1.736938, (float)1.922119, (float)2.185913, (float)2.743408,
|
|
(float)1.521606, (float)1.870972, (float)2.526855, (float)2.786987,
|
|
(float)1.841431, (float)2.050659, (float)2.463623, (float)2.857666,
|
|
(float)1.590088, (float)2.067261, (float)2.427979, (float)2.794434,
|
|
(float)1.746826, (float)2.057373, (float)2.320190, (float)2.800781,
|
|
(float)1.734619, (float)1.940552, (float)2.306030, (float)2.826416,
|
|
(float)1.786255, (float)2.204468, (float)2.457520, (float)2.795288,
|
|
(float)1.861084, (float)2.170532, (float)2.414551, (float)2.763672,
|
|
(float)2.001465, (float)2.307617, (float)2.552734, (float)2.811890,
|
|
(float)1.784424, (float)2.124146, (float)2.381592, (float)2.645508,
|
|
(float)1.888794, (float)2.135864, (float)2.418579, (float)2.861206,
|
|
(float)2.301147, (float)2.531250, (float)2.724976, (float)2.913086,
|
|
(float)1.837769, (float)2.051270, (float)2.261963, (float)2.553223,
|
|
(float)2.012939, (float)2.221191, (float)2.440186, (float)2.678101,
|
|
(float)1.429565, (float)1.858276, (float)2.582275, (float)2.845703,
|
|
(float)1.622803, (float)1.897705, (float)2.367310, (float)2.621094,
|
|
(float)1.581543, (float)1.960449, (float)2.515869, (float)2.736450,
|
|
(float)1.419434, (float)1.933960, (float)2.394653, (float)2.746704,
|
|
(float)1.721924, (float)2.059570, (float)2.421753, (float)2.769653,
|
|
(float)1.911011, (float)2.220703, (float)2.461060, (float)2.740723,
|
|
(float)1.581177, (float)1.860840, (float)2.516968, (float)2.874634,
|
|
(float)1.870361, (float)2.098755, (float)2.432373, (float)2.656494,
|
|
(float)2.059692, (float)2.279785, (float)2.495605, (float)2.729370,
|
|
(float)1.815674, (float)2.181519, (float)2.451538, (float)2.680542,
|
|
(float)1.407959, (float)1.768311, (float)2.343018, (float)2.668091,
|
|
(float)2.168701, (float)2.394653, (float)2.604736, (float)2.829346,
|
|
(float)1.636230, (float)1.865723, (float)2.329102, (float)2.824219,
|
|
(float)1.878906, (float)2.139526, (float)2.376709, (float)2.679810,
|
|
(float)1.765381, (float)1.971802, (float)2.195435, (float)2.586914,
|
|
(float)2.164795, (float)2.410889, (float)2.673706, (float)2.903198,
|
|
(float)2.071899, (float)2.331055, (float)2.645874, (float)2.907104,
|
|
(float)2.026001, (float)2.311523, (float)2.594849, (float)2.863892,
|
|
(float)1.948975, (float)2.180786, (float)2.514893, (float)2.797852,
|
|
(float)1.881836, (float)2.130859, (float)2.478149, (float)2.804199,
|
|
(float)2.238159, (float)2.452759, (float)2.652832, (float)2.868286,
|
|
(float)1.897949, (float)2.101685, (float)2.524292, (float)2.880127,
|
|
(float)1.856445, (float)2.074585, (float)2.541016, (float)2.791748,
|
|
(float)1.695557, (float)2.199097, (float)2.506226, (float)2.742676,
|
|
(float)1.612671, (float)1.877075, (float)2.435425, (float)2.732910,
|
|
(float)1.568848, (float)1.786499, (float)2.194580, (float)2.768555,
|
|
(float)1.953369, (float)2.164551, (float)2.486938, (float)2.874023,
|
|
(float)1.388306, (float)1.725342, (float)2.384521, (float)2.771851,
|
|
(float)2.115356, (float)2.337769, (float)2.592896, (float)2.864014,
|
|
(float)1.905762, (float)2.111328, (float)2.363525, (float)2.789307,
|
|
|
|
|
|
|
|
Andersen, et al. Experimental [Page 94]
|
|
|
|
RFC 3951 Internet Low Bit Rate Codec December 2004
|
|
|
|
|
|
(float)1.882568, (float)2.332031, (float)2.598267, (float)2.827637,
|
|
(float)1.683594, (float)2.088745, (float)2.361938, (float)2.608643,
|
|
(float)1.874023, (float)2.182129, (float)2.536133, (float)2.766968,
|
|
(float)1.861938, (float)2.070435, (float)2.309692, (float)2.700562,
|
|
(float)1.722168, (float)2.107422, (float)2.477295, (float)2.837646,
|
|
(float)1.926880, (float)2.184692, (float)2.442627, (float)2.663818,
|
|
(float)2.123901, (float)2.337280, (float)2.553101, (float)2.777466,
|
|
(float)1.588135, (float)1.911499, (float)2.212769, (float)2.543945,
|
|
(float)2.053955, (float)2.370850, (float)2.712158, (float)2.939941,
|
|
(float)2.210449, (float)2.519653, (float)2.770386, (float)2.958618,
|
|
(float)2.199463, (float)2.474731, (float)2.718262, (float)2.919922,
|
|
(float)1.960083, (float)2.175415, (float)2.608032, (float)2.888794,
|
|
(float)1.953735, (float)2.185181, (float)2.428223, (float)2.809570,
|
|
(float)1.615234, (float)2.036499, (float)2.576538, (float)2.834595,
|
|
(float)1.621094, (float)2.028198, (float)2.431030, (float)2.664673,
|
|
(float)1.824951, (float)2.267456, (float)2.514526, (float)2.747925,
|
|
(float)1.994263, (float)2.229126, (float)2.475220, (float)2.833984,
|
|
(float)1.746338, (float)2.011353, (float)2.588257, (float)2.826904,
|
|
(float)1.562866, (float)2.135986, (float)2.471680, (float)2.687256,
|
|
(float)1.748901, (float)2.083496, (float)2.460938, (float)2.686279,
|
|
(float)1.758057, (float)2.131470, (float)2.636597, (float)2.891602,
|
|
(float)2.071289, (float)2.299072, (float)2.550781, (float)2.814331,
|
|
(float)1.839600, (float)2.094360, (float)2.496460, (float)2.723999,
|
|
(float)1.882202, (float)2.088257, (float)2.636841, (float)2.923096,
|
|
(float)1.957886, (float)2.153198, (float)2.384399, (float)2.615234,
|
|
(float)1.992920, (float)2.351196, (float)2.654419, (float)2.889771,
|
|
(float)2.012817, (float)2.262451, (float)2.643799, (float)2.903076,
|
|
(float)2.025635, (float)2.254761, (float)2.508423, (float)2.784058,
|
|
(float)2.316040, (float)2.589355, (float)2.794189, (float)2.963623,
|
|
(float)1.741211, (float)2.279541, (float)2.578491, (float)2.816284,
|
|
(float)1.845337, (float)2.055786, (float)2.348511, (float)2.822021,
|
|
(float)1.679932, (float)1.926514, (float)2.499756, (float)2.835693,
|
|
(float)1.722534, (float)1.946899, (float)2.448486, (float)2.728760,
|
|
(float)1.829834, (float)2.043213, (float)2.580444, (float)2.867676,
|
|
(float)1.676636, (float)2.071655, (float)2.322510, (float)2.704834,
|
|
(float)1.791504, (float)2.113525, (float)2.469727, (float)2.784058,
|
|
(float)1.977051, (float)2.215088, (float)2.497437, (float)2.726929,
|
|
(float)1.800171, (float)2.106689, (float)2.357788, (float)2.738892,
|
|
(float)1.827759, (float)2.170166, (float)2.525879, (float)2.852417,
|
|
(float)1.918335, (float)2.132813, (float)2.488403, (float)2.728149,
|
|
(float)1.916748, (float)2.225098, (float)2.542603, (float)2.857666,
|
|
(float)1.761230, (float)1.976074, (float)2.507446, (float)2.884521,
|
|
(float)2.053711, (float)2.367432, (float)2.608032, (float)2.837646,
|
|
(float)1.595337, (float)2.000977, (float)2.307129, (float)2.578247,
|
|
(float)1.470581, (float)2.031250, (float)2.375854, (float)2.647583,
|
|
(float)1.801392, (float)2.128052, (float)2.399780, (float)2.822876,
|
|
(float)1.853638, (float)2.066650, (float)2.429199, (float)2.751465,
|
|
(float)1.956299, (float)2.163696, (float)2.394775, (float)2.734253,
|
|
|
|
|
|
|
|
Andersen, et al. Experimental [Page 95]
|
|
|
|
RFC 3951 Internet Low Bit Rate Codec December 2004
|
|
|
|
|
|
(float)1.963623, (float)2.275757, (float)2.585327, (float)2.865234,
|
|
(float)1.887451, (float)2.105469, (float)2.331787, (float)2.587402,
|
|
(float)2.120117, (float)2.443359, (float)2.733887, (float)2.941406,
|
|
(float)1.506348, (float)1.766968, (float)2.400513, (float)2.851807,
|
|
(float)1.664551, (float)1.981079, (float)2.375732, (float)2.774414,
|
|
(float)1.720703, (float)1.978882, (float)2.391479, (float)2.640991,
|
|
(float)1.483398, (float)1.814819, (float)2.434448, (float)2.722290,
|
|
(float)1.769043, (float)2.136597, (float)2.563721, (float)2.774414,
|
|
(float)1.810791, (float)2.049316, (float)2.373901, (float)2.613647,
|
|
(float)1.788330, (float)2.005981, (float)2.359131, (float)2.723145,
|
|
(float)1.785156, (float)1.993164, (float)2.399780, (float)2.832520,
|
|
(float)1.695313, (float)2.022949, (float)2.522583, (float)2.745117,
|
|
(float)1.584106, (float)1.965576, (float)2.299927, (float)2.715576,
|
|
(float)1.894897, (float)2.249878, (float)2.655884, (float)2.897705,
|
|
(float)1.720581, (float)1.995728, (float)2.299438, (float)2.557007,
|
|
(float)1.619385, (float)2.173950, (float)2.574219, (float)2.787964,
|
|
(float)1.883179, (float)2.220459, (float)2.474365, (float)2.825073,
|
|
(float)1.447632, (float)2.045044, (float)2.555542, (float)2.744873,
|
|
(float)1.502686, (float)2.156616, (float)2.653320, (float)2.846558,
|
|
(float)1.711548, (float)1.944092, (float)2.282959, (float)2.685791,
|
|
(float)1.499756, (float)1.867554, (float)2.341064, (float)2.578857,
|
|
(float)1.916870, (float)2.135132, (float)2.568237, (float)2.826050,
|
|
(float)1.498047, (float)1.711182, (float)2.223267, (float)2.755127,
|
|
(float)1.808716, (float)1.997559, (float)2.256470, (float)2.758545,
|
|
(float)2.088501, (float)2.402710, (float)2.667358, (float)2.890259,
|
|
(float)1.545044, (float)1.819214, (float)2.324097, (float)2.692993,
|
|
(float)1.796021, (float)2.012573, (float)2.505737, (float)2.784912,
|
|
(float)1.786499, (float)2.041748, (float)2.290405, (float)2.650757,
|
|
(float)1.938232, (float)2.264404, (float)2.529053, (float)2.796143
|
|
};
|
|
|
|
A.9. anaFilter.h
|
|
|
|
/******************************************************************
|
|
|
|
iLBC Speech Coder ANSI-C Source Code
|
|
|
|
anaFilter.h
|
|
|
|
Copyright (C) The Internet Society (2004).
|
|
All Rights Reserved.
|
|
|
|
******************************************************************/
|
|
|
|
#ifndef __iLBC_ANAFILTER_H
|
|
#define __iLBC_ANAFILTER_H
|
|
|
|
void anaFilter(
|
|
|
|
|
|
|
|
Andersen, et al. Experimental [Page 96]
|
|
|
|
RFC 3951 Internet Low Bit Rate Codec December 2004
|
|
|
|
|
|
float *In, /* (i) Signal to be filtered */
|
|
float *a, /* (i) LP parameters */
|
|
int len,/* (i) Length of signal */
|
|
float *Out, /* (o) Filtered signal */
|
|
float *mem /* (i/o) Filter state */
|
|
);
|
|
|
|
#endif
|
|
|
|
A.10. anaFilter.c
|
|
|
|
/******************************************************************
|
|
|
|
iLBC Speech Coder ANSI-C Source Code
|
|
|
|
anaFilter.c
|
|
|
|
Copyright (C) The Internet Society (2004).
|
|
All Rights Reserved.
|
|
|
|
******************************************************************/
|
|
|
|
#include <string.h>
|
|
#include "iLBC_define.h"
|
|
|
|
/*----------------------------------------------------------------*
|
|
* LP analysis filter.
|
|
*---------------------------------------------------------------*/
|
|
|
|
void anaFilter(
|
|
float *In, /* (i) Signal to be filtered */
|
|
float *a, /* (i) LP parameters */
|
|
int len,/* (i) Length of signal */
|
|
float *Out, /* (o) Filtered signal */
|
|
float *mem /* (i/o) Filter state */
|
|
){
|
|
int i, j;
|
|
float *po, *pi, *pm, *pa;
|
|
|
|
po = Out;
|
|
|
|
/* Filter first part using memory from past */
|
|
|
|
for (i=0; i<LPC_FILTERORDER; i++) {
|
|
pi = &In[i];
|
|
pm = &mem[LPC_FILTERORDER-1];
|
|
pa = a;
|
|
*po=0.0;
|
|
|
|
|
|
|
|
Andersen, et al. Experimental [Page 97]
|
|
|
|
RFC 3951 Internet Low Bit Rate Codec December 2004
|
|
|
|
|
|
for (j=0; j<=i; j++) {
|
|
*po+=(*pa++)*(*pi--);
|
|
}
|
|
for (j=i+1; j<LPC_FILTERORDER+1; j++) {
|
|
|
|
*po+=(*pa++)*(*pm--);
|
|
}
|
|
po++;
|
|
}
|
|
|
|
/* Filter last part where the state is entirely
|
|
in the input vector */
|
|
|
|
for (i=LPC_FILTERORDER; i<len; i++) {
|
|
pi = &In[i];
|
|
pa = a;
|
|
*po=0.0;
|
|
for (j=0; j<LPC_FILTERORDER+1; j++) {
|
|
*po+=(*pa++)*(*pi--);
|
|
}
|
|
po++;
|
|
}
|
|
|
|
/* Update state vector */
|
|
|
|
memcpy(mem, &In[len-LPC_FILTERORDER],
|
|
LPC_FILTERORDER*sizeof(float));
|
|
}
|
|
|
|
A.11. createCB.h
|
|
|
|
/******************************************************************
|
|
|
|
iLBC Speech Coder ANSI-C Source Code
|
|
|
|
createCB.h
|
|
|
|
Copyright (C) The Internet Society (2004).
|
|
All Rights Reserved.
|
|
|
|
******************************************************************/
|
|
|
|
#ifndef __iLBC_CREATECB_H
|
|
#define __iLBC_CREATECB_H
|
|
|
|
void filteredCBvecs(
|
|
float *cbvectors, /* (o) Codebook vector for the
|
|
higher section */
|
|
|
|
|
|
|
|
Andersen, et al. Experimental [Page 98]
|
|
|
|
RFC 3951 Internet Low Bit Rate Codec December 2004
|
|
|
|
|
|
float *mem, /* (i) Buffer to create codebook
|
|
vectors from */
|
|
int lMem /* (i) Length of buffer */
|
|
);
|
|
|
|
void searchAugmentedCB(
|
|
int low, /* (i) Start index for the search */
|
|
int high, /* (i) End index for the search */
|
|
int stage, /* (i) Current stage */
|
|
int startIndex, /* (i) CB index for the first
|
|
augmented vector */
|
|
float *target, /* (i) Target vector for encoding */
|
|
float *buffer, /* (i) Pointer to the end of the
|
|
buffer for augmented codebook
|
|
construction */
|
|
float *max_measure, /* (i/o) Currently maximum measure */
|
|
int *best_index,/* (o) Currently the best index */
|
|
float *gain, /* (o) Currently the best gain */
|
|
float *energy, /* (o) Energy of augmented
|
|
codebook vectors */
|
|
float *invenergy/* (o) Inv energy of aug codebook
|
|
vectors */
|
|
);
|
|
|
|
void createAugmentedVec(
|
|
int index, /* (i) Index for the aug vector
|
|
to be created */
|
|
float *buffer, /* (i) Pointer to the end of the
|
|
buffer for augmented codebook
|
|
construction */
|
|
float *cbVec /* (o) The constructed codebook vector */
|
|
);
|
|
|
|
#endif
|
|
|
|
A.12. createCB.c
|
|
|
|
|
|
/******************************************************************
|
|
|
|
iLBC Speech Coder ANSI-C Source Code
|
|
|
|
createCB.c
|
|
|
|
Copyright (C) The Internet Society (2004).
|
|
All Rights Reserved.
|
|
|
|
******************************************************************/
|
|
|
|
|
|
|
|
Andersen, et al. Experimental [Page 99]
|
|
|
|
RFC 3951 Internet Low Bit Rate Codec December 2004
|
|
|
|
|
|
#include "iLBC_define.h"
|
|
#include "constants.h"
|
|
#include <string.h>
|
|
#include <math.h>
|
|
|
|
/*----------------------------------------------------------------*
|
|
* Construct an additional codebook vector by filtering the
|
|
* initial codebook buffer. This vector is then used to expand
|
|
* the codebook with an additional section.
|
|
*---------------------------------------------------------------*/
|
|
|
|
void filteredCBvecs(
|
|
float *cbvectors, /* (o) Codebook vectors for the
|
|
higher section */
|
|
float *mem, /* (i) Buffer to create codebook
|
|
vector from */
|
|
int lMem /* (i) Length of buffer */
|
|
){
|
|
int j, k;
|
|
float *pp, *pp1;
|
|
float tempbuff2[CB_MEML+CB_FILTERLEN];
|
|
float *pos;
|
|
|
|
memset(tempbuff2, 0, (CB_HALFFILTERLEN-1)*sizeof(float));
|
|
memcpy(&tempbuff2[CB_HALFFILTERLEN-1], mem, lMem*sizeof(float));
|
|
memset(&tempbuff2[lMem+CB_HALFFILTERLEN-1], 0,
|
|
(CB_HALFFILTERLEN+1)*sizeof(float));
|
|
|
|
/* Create codebook vector for higher section by filtering */
|
|
|
|
/* do filtering */
|
|
pos=cbvectors;
|
|
memset(pos, 0, lMem*sizeof(float));
|
|
for (k=0; k<lMem; k++) {
|
|
pp=&tempbuff2[k];
|
|
pp1=&cbfiltersTbl[CB_FILTERLEN-1];
|
|
for (j=0;j<CB_FILTERLEN;j++) {
|
|
(*pos)+=(*pp++)*(*pp1--);
|
|
}
|
|
pos++;
|
|
}
|
|
}
|
|
|
|
/*----------------------------------------------------------------*
|
|
* Search the augmented part of the codebook to find the best
|
|
* measure.
|
|
*----------------------------------------------------------------*/
|
|
|
|
|
|
|
|
|
|
Andersen, et al. Experimental [Page 100]
|
|
|
|
RFC 3951 Internet Low Bit Rate Codec December 2004
|
|
|
|
|
|
void searchAugmentedCB(
|
|
int low, /* (i) Start index for the search */
|
|
int high, /* (i) End index for the search */
|
|
int stage, /* (i) Current stage */
|
|
int startIndex, /* (i) Codebook index for the first
|
|
aug vector */
|
|
float *target, /* (i) Target vector for encoding */
|
|
float *buffer, /* (i) Pointer to the end of the buffer for
|
|
augmented codebook construction */
|
|
float *max_measure, /* (i/o) Currently maximum measure */
|
|
int *best_index,/* (o) Currently the best index */
|
|
float *gain, /* (o) Currently the best gain */
|
|
float *energy, /* (o) Energy of augmented codebook
|
|
vectors */
|
|
float *invenergy/* (o) Inv energy of augmented codebook
|
|
vectors */
|
|
) {
|
|
int icount, ilow, j, tmpIndex;
|
|
float *pp, *ppo, *ppi, *ppe, crossDot, alfa;
|
|
float weighted, measure, nrjRecursive;
|
|
float ftmp;
|
|
|
|
/* Compute the energy for the first (low-5)
|
|
noninterpolated samples */
|
|
nrjRecursive = (float) 0.0;
|
|
pp = buffer - low + 1;
|
|
for (j=0; j<(low-5); j++) {
|
|
nrjRecursive += ( (*pp)*(*pp) );
|
|
pp++;
|
|
}
|
|
ppe = buffer - low;
|
|
|
|
|
|
for (icount=low; icount<=high; icount++) {
|
|
|
|
/* Index of the codebook vector used for retrieving
|
|
energy values */
|
|
tmpIndex = startIndex+icount-20;
|
|
|
|
ilow = icount-4;
|
|
|
|
/* Update the energy recursively to save complexity */
|
|
nrjRecursive = nrjRecursive + (*ppe)*(*ppe);
|
|
ppe--;
|
|
energy[tmpIndex] = nrjRecursive;
|
|
|
|
/* Compute cross dot product for the first (low-5)
|
|
samples */
|
|
|
|
|
|
|
|
Andersen, et al. Experimental [Page 101]
|
|
|
|
RFC 3951 Internet Low Bit Rate Codec December 2004
|
|
|
|
|
|
crossDot = (float) 0.0;
|
|
pp = buffer-icount;
|
|
for (j=0; j<ilow; j++) {
|
|
crossDot += target[j]*(*pp++);
|
|
}
|
|
|
|
/* interpolation */
|
|
alfa = (float) 0.2;
|
|
ppo = buffer-4;
|
|
ppi = buffer-icount-4;
|
|
for (j=ilow; j<icount; j++) {
|
|
weighted = ((float)1.0-alfa)*(*ppo)+alfa*(*ppi);
|
|
ppo++;
|
|
ppi++;
|
|
energy[tmpIndex] += weighted*weighted;
|
|
crossDot += target[j]*weighted;
|
|
alfa += (float)0.2;
|
|
}
|
|
|
|
/* Compute energy and cross dot product for the
|
|
remaining samples */
|
|
pp = buffer - icount;
|
|
for (j=icount; j<SUBL; j++) {
|
|
energy[tmpIndex] += (*pp)*(*pp);
|
|
crossDot += target[j]*(*pp++);
|
|
}
|
|
|
|
if (energy[tmpIndex]>0.0) {
|
|
invenergy[tmpIndex]=(float)1.0/(energy[tmpIndex]+EPS);
|
|
} else {
|
|
invenergy[tmpIndex] = (float) 0.0;
|
|
}
|
|
|
|
if (stage==0) {
|
|
measure = (float)-10000000.0;
|
|
|
|
if (crossDot > 0.0) {
|
|
measure = crossDot*crossDot*invenergy[tmpIndex];
|
|
}
|
|
}
|
|
else {
|
|
measure = crossDot*crossDot*invenergy[tmpIndex];
|
|
}
|
|
|
|
/* check if measure is better */
|
|
ftmp = crossDot*invenergy[tmpIndex];
|
|
|
|
if ((measure>*max_measure) && (fabs(ftmp)<CB_MAXGAIN)) {
|
|
|
|
|
|
|
|
Andersen, et al. Experimental [Page 102]
|
|
|
|
RFC 3951 Internet Low Bit Rate Codec December 2004
|
|
|
|
|
|
*best_index = tmpIndex;
|
|
*max_measure = measure;
|
|
*gain = ftmp;
|
|
}
|
|
}
|
|
}
|
|
|
|
|
|
/*----------------------------------------------------------------*
|
|
* Recreate a specific codebook vector from the augmented part.
|
|
*
|
|
*----------------------------------------------------------------*/
|
|
|
|
void createAugmentedVec(
|
|
int index, /* (i) Index for the augmented vector
|
|
to be created */
|
|
float *buffer, /* (i) Pointer to the end of the buffer for
|
|
augmented codebook construction */
|
|
float *cbVec/* (o) The constructed codebook vector */
|
|
) {
|
|
int ilow, j;
|
|
float *pp, *ppo, *ppi, alfa, alfa1, weighted;
|
|
|
|
ilow = index-5;
|
|
|
|
/* copy the first noninterpolated part */
|
|
|
|
pp = buffer-index;
|
|
memcpy(cbVec,pp,sizeof(float)*index);
|
|
|
|
/* interpolation */
|
|
|
|
alfa1 = (float)0.2;
|
|
alfa = 0.0;
|
|
ppo = buffer-5;
|
|
ppi = buffer-index-5;
|
|
for (j=ilow; j<index; j++) {
|
|
weighted = ((float)1.0-alfa)*(*ppo)+alfa*(*ppi);
|
|
ppo++;
|
|
ppi++;
|
|
cbVec[j] = weighted;
|
|
alfa += alfa1;
|
|
}
|
|
|
|
/* copy the second noninterpolated part */
|
|
|
|
pp = buffer - index;
|
|
memcpy(cbVec+index,pp,sizeof(float)*(SUBL-index));
|
|
|
|
|
|
|
|
Andersen, et al. Experimental [Page 103]
|
|
|
|
RFC 3951 Internet Low Bit Rate Codec December 2004
|
|
|
|
|
|
}
|
|
|
|
A.13. doCPLC.h
|
|
|
|
/******************************************************************
|
|
|
|
iLBC Speech Coder ANSI-C Source Code
|
|
|
|
doCPLC.h
|
|
|
|
Copyright (C) The Internet Society (2004).
|
|
All Rights Reserved.
|
|
|
|
******************************************************************/
|
|
|
|
#ifndef __iLBC_DOLPC_H
|
|
#define __iLBC_DOLPC_H
|
|
|
|
void doThePLC(
|
|
float *PLCresidual, /* (o) concealed residual */
|
|
float *PLClpc, /* (o) concealed LP parameters */
|
|
int PLI, /* (i) packet loss indicator
|
|
0 - no PL, 1 = PL */
|
|
float *decresidual, /* (i) decoded residual */
|
|
float *lpc, /* (i) decoded LPC (only used for no PL) */
|
|
int inlag, /* (i) pitch lag */
|
|
iLBC_Dec_Inst_t *iLBCdec_inst
|
|
/* (i/o) decoder instance */
|
|
);
|
|
|
|
#endif
|
|
|
|
A.14. doCPLC.c
|
|
|
|
/******************************************************************
|
|
|
|
iLBC Speech Coder ANSI-C Source Code
|
|
|
|
doCPLC.c
|
|
|
|
Copyright (C) The Internet Society (2004).
|
|
All Rights Reserved.
|
|
|
|
******************************************************************/
|
|
|
|
#include <math.h>
|
|
#include <string.h>
|
|
#include <stdio.h>
|
|
|
|
|
|
|
|
Andersen, et al. Experimental [Page 104]
|
|
|
|
RFC 3951 Internet Low Bit Rate Codec December 2004
|
|
|
|
|
|
#include "iLBC_define.h"
|
|
|
|
/*----------------------------------------------------------------*
|
|
* Compute cross correlation and pitch gain for pitch prediction
|
|
* of last subframe at given lag.
|
|
*---------------------------------------------------------------*/
|
|
|
|
void compCorr(
|
|
float *cc, /* (o) cross correlation coefficient */
|
|
float *gc, /* (o) gain */
|
|
float *pm,
|
|
float *buffer, /* (i) signal buffer */
|
|
int lag, /* (i) pitch lag */
|
|
int bLen, /* (i) length of buffer */
|
|
int sRange /* (i) correlation search length */
|
|
){
|
|
int i;
|
|
float ftmp1, ftmp2, ftmp3;
|
|
|
|
/* Guard against getting outside buffer */
|
|
if ((bLen-sRange-lag)<0) {
|
|
sRange=bLen-lag;
|
|
}
|
|
|
|
ftmp1 = 0.0;
|
|
ftmp2 = 0.0;
|
|
ftmp3 = 0.0;
|
|
for (i=0; i<sRange; i++) {
|
|
ftmp1 += buffer[bLen-sRange+i] *
|
|
buffer[bLen-sRange+i-lag];
|
|
ftmp2 += buffer[bLen-sRange+i-lag] *
|
|
buffer[bLen-sRange+i-lag];
|
|
ftmp3 += buffer[bLen-sRange+i] *
|
|
buffer[bLen-sRange+i];
|
|
}
|
|
|
|
if (ftmp2 > 0.0) {
|
|
*cc = ftmp1*ftmp1/ftmp2;
|
|
*gc = (float)fabs(ftmp1/ftmp2);
|
|
*pm=(float)fabs(ftmp1)/
|
|
((float)sqrt(ftmp2)*(float)sqrt(ftmp3));
|
|
}
|
|
else {
|
|
*cc = 0.0;
|
|
*gc = 0.0;
|
|
*pm=0.0;
|
|
}
|
|
}
|
|
|
|
|
|
|
|
Andersen, et al. Experimental [Page 105]
|
|
|
|
RFC 3951 Internet Low Bit Rate Codec December 2004
|
|
|
|
|
|
/*----------------------------------------------------------------*
|
|
* Packet loss concealment routine. Conceals a residual signal
|
|
* and LP parameters. If no packet loss, update state.
|
|
*---------------------------------------------------------------*/
|
|
|
|
void doThePLC(
|
|
float *PLCresidual, /* (o) concealed residual */
|
|
float *PLClpc, /* (o) concealed LP parameters */
|
|
int PLI, /* (i) packet loss indicator
|
|
0 - no PL, 1 = PL */
|
|
float *decresidual, /* (i) decoded residual */
|
|
float *lpc, /* (i) decoded LPC (only used for no PL) */
|
|
int inlag, /* (i) pitch lag */
|
|
iLBC_Dec_Inst_t *iLBCdec_inst
|
|
/* (i/o) decoder instance */
|
|
){
|
|
int lag=20, randlag;
|
|
float gain, maxcc;
|
|
float use_gain;
|
|
float gain_comp, maxcc_comp, per, max_per;
|
|
int i, pick, use_lag;
|
|
float ftmp, randvec[BLOCKL_MAX], pitchfact, energy;
|
|
|
|
/* Packet Loss */
|
|
|
|
if (PLI == 1) {
|
|
|
|
iLBCdec_inst->consPLICount += 1;
|
|
|
|
/* if previous frame not lost,
|
|
determine pitch pred. gain */
|
|
|
|
if (iLBCdec_inst->prevPLI != 1) {
|
|
|
|
/* Search around the previous lag to find the
|
|
best pitch period */
|
|
|
|
lag=inlag-3;
|
|
compCorr(&maxcc, &gain, &max_per,
|
|
iLBCdec_inst->prevResidual,
|
|
lag, iLBCdec_inst->blockl, 60);
|
|
for (i=inlag-2;i<=inlag+3;i++) {
|
|
compCorr(&maxcc_comp, &gain_comp, &per,
|
|
iLBCdec_inst->prevResidual,
|
|
i, iLBCdec_inst->blockl, 60);
|
|
|
|
if (maxcc_comp>maxcc) {
|
|
maxcc=maxcc_comp;
|
|
|
|
|
|
|
|
Andersen, et al. Experimental [Page 106]
|
|
|
|
RFC 3951 Internet Low Bit Rate Codec December 2004
|
|
|
|
|
|
gain=gain_comp;
|
|
lag=i;
|
|
max_per=per;
|
|
}
|
|
}
|
|
|
|
}
|
|
|
|
/* previous frame lost, use recorded lag and periodicity */
|
|
|
|
else {
|
|
lag=iLBCdec_inst->prevLag;
|
|
max_per=iLBCdec_inst->per;
|
|
}
|
|
|
|
/* downscaling */
|
|
|
|
use_gain=1.0;
|
|
if (iLBCdec_inst->consPLICount*iLBCdec_inst->blockl>320)
|
|
use_gain=(float)0.9;
|
|
else if (iLBCdec_inst->consPLICount*
|
|
iLBCdec_inst->blockl>2*320)
|
|
use_gain=(float)0.7;
|
|
else if (iLBCdec_inst->consPLICount*
|
|
iLBCdec_inst->blockl>3*320)
|
|
use_gain=(float)0.5;
|
|
else if (iLBCdec_inst->consPLICount*
|
|
iLBCdec_inst->blockl>4*320)
|
|
use_gain=(float)0.0;
|
|
|
|
/* mix noise and pitch repeatition */
|
|
ftmp=(float)sqrt(max_per);
|
|
if (ftmp>(float)0.7)
|
|
pitchfact=(float)1.0;
|
|
else if (ftmp>(float)0.4)
|
|
pitchfact=(ftmp-(float)0.4)/((float)0.7-(float)0.4);
|
|
else
|
|
pitchfact=0.0;
|
|
|
|
|
|
/* avoid repetition of same pitch cycle */
|
|
use_lag=lag;
|
|
if (lag<80) {
|
|
use_lag=2*lag;
|
|
}
|
|
|
|
/* compute concealed residual */
|
|
|
|
|
|
|
|
|
|
Andersen, et al. Experimental [Page 107]
|
|
|
|
RFC 3951 Internet Low Bit Rate Codec December 2004
|
|
|
|
|
|
energy = 0.0;
|
|
for (i=0; i<iLBCdec_inst->blockl; i++) {
|
|
|
|
/* noise component */
|
|
|
|
iLBCdec_inst->seed=(iLBCdec_inst->seed*69069L+1) &
|
|
(0x80000000L-1);
|
|
randlag = 50 + ((signed long) iLBCdec_inst->seed)%70;
|
|
pick = i - randlag;
|
|
|
|
if (pick < 0) {
|
|
randvec[i] =
|
|
iLBCdec_inst->prevResidual[
|
|
iLBCdec_inst->blockl+pick];
|
|
} else {
|
|
randvec[i] = randvec[pick];
|
|
}
|
|
|
|
/* pitch repeatition component */
|
|
pick = i - use_lag;
|
|
|
|
if (pick < 0) {
|
|
PLCresidual[i] =
|
|
iLBCdec_inst->prevResidual[
|
|
iLBCdec_inst->blockl+pick];
|
|
} else {
|
|
PLCresidual[i] = PLCresidual[pick];
|
|
}
|
|
|
|
/* mix random and periodicity component */
|
|
|
|
if (i<80)
|
|
PLCresidual[i] = use_gain*(pitchfact *
|
|
PLCresidual[i] +
|
|
((float)1.0 - pitchfact) * randvec[i]);
|
|
else if (i<160)
|
|
PLCresidual[i] = (float)0.95*use_gain*(pitchfact *
|
|
PLCresidual[i] +
|
|
((float)1.0 - pitchfact) * randvec[i]);
|
|
else
|
|
PLCresidual[i] = (float)0.9*use_gain*(pitchfact *
|
|
PLCresidual[i] +
|
|
((float)1.0 - pitchfact) * randvec[i]);
|
|
|
|
energy += PLCresidual[i] * PLCresidual[i];
|
|
}
|
|
|
|
/* less than 30 dB, use only noise */
|
|
|
|
|
|
|
|
Andersen, et al. Experimental [Page 108]
|
|
|
|
RFC 3951 Internet Low Bit Rate Codec December 2004
|
|
|
|
|
|
|
|
if (sqrt(energy/(float)iLBCdec_inst->blockl) < 30.0) {
|
|
gain=0.0;
|
|
for (i=0; i<iLBCdec_inst->blockl; i++) {
|
|
PLCresidual[i] = randvec[i];
|
|
}
|
|
}
|
|
|
|
/* use old LPC */
|
|
|
|
memcpy(PLClpc,iLBCdec_inst->prevLpc,
|
|
(LPC_FILTERORDER+1)*sizeof(float));
|
|
|
|
}
|
|
|
|
/* no packet loss, copy input */
|
|
|
|
else {
|
|
memcpy(PLCresidual, decresidual,
|
|
iLBCdec_inst->blockl*sizeof(float));
|
|
memcpy(PLClpc, lpc, (LPC_FILTERORDER+1)*sizeof(float));
|
|
iLBCdec_inst->consPLICount = 0;
|
|
}
|
|
|
|
/* update state */
|
|
|
|
if (PLI) {
|
|
iLBCdec_inst->prevLag = lag;
|
|
iLBCdec_inst->per=max_per;
|
|
}
|
|
|
|
iLBCdec_inst->prevPLI = PLI;
|
|
memcpy(iLBCdec_inst->prevLpc, PLClpc,
|
|
(LPC_FILTERORDER+1)*sizeof(float));
|
|
memcpy(iLBCdec_inst->prevResidual, PLCresidual,
|
|
iLBCdec_inst->blockl*sizeof(float));
|
|
}
|
|
|
|
A.15. enhancer.h
|
|
|
|
/******************************************************************
|
|
|
|
iLBC Speech Coder ANSI-C Source Code
|
|
|
|
enhancer.h
|
|
|
|
Copyright (C) The Internet Society (2004).
|
|
All Rights Reserved.
|
|
|
|
|
|
|
|
Andersen, et al. Experimental [Page 109]
|
|
|
|
RFC 3951 Internet Low Bit Rate Codec December 2004
|
|
|
|
|
|
******************************************************************/
|
|
|
|
#ifndef __ENHANCER_H
|
|
#define __ENHANCER_H
|
|
|
|
#include "iLBC_define.h"
|
|
|
|
float xCorrCoef(
|
|
float *target, /* (i) first array */
|
|
float *regressor, /* (i) second array */
|
|
int subl /* (i) dimension arrays */
|
|
);
|
|
|
|
int enhancerInterface(
|
|
float *out, /* (o) the enhanced residual signal */
|
|
float *in, /* (i) the residual signal to enhance */
|
|
iLBC_Dec_Inst_t *iLBCdec_inst
|
|
/* (i/o) the decoder state structure */
|
|
);
|
|
|
|
#endif
|
|
|
|
A.16. enhancer.c
|
|
|
|
/******************************************************************
|
|
|
|
iLBC Speech Coder ANSI-C Source Code
|
|
|
|
enhancer.c
|
|
|
|
Copyright (C) The Internet Society (2004).
|
|
All Rights Reserved.
|
|
|
|
******************************************************************/
|
|
|
|
#include <math.h>
|
|
#include <string.h>
|
|
#include "iLBC_define.h"
|
|
#include "constants.h"
|
|
#include "filter.h"
|
|
|
|
/*----------------------------------------------------------------*
|
|
* Find index in array such that the array element with said
|
|
* index is the element of said array closest to "value"
|
|
* according to the squared-error criterion
|
|
*---------------------------------------------------------------*/
|
|
|
|
void NearestNeighbor(
|
|
|
|
|
|
|
|
Andersen, et al. Experimental [Page 110]
|
|
|
|
RFC 3951 Internet Low Bit Rate Codec December 2004
|
|
|
|
|
|
int *index, /* (o) index of array element closest
|
|
to value */
|
|
float *array, /* (i) data array */
|
|
float value,/* (i) value */
|
|
int arlength/* (i) dimension of data array */
|
|
){
|
|
int i;
|
|
float bestcrit,crit;
|
|
|
|
crit=array[0]-value;
|
|
bestcrit=crit*crit;
|
|
*index=0;
|
|
for (i=1; i<arlength; i++) {
|
|
crit=array[i]-value;
|
|
crit=crit*crit;
|
|
|
|
if (crit<bestcrit) {
|
|
bestcrit=crit;
|
|
*index=i;
|
|
}
|
|
}
|
|
}
|
|
|
|
/*----------------------------------------------------------------*
|
|
* compute cross correlation between sequences
|
|
*---------------------------------------------------------------*/
|
|
|
|
void mycorr1(
|
|
float* corr, /* (o) correlation of seq1 and seq2 */
|
|
float* seq1, /* (i) first sequence */
|
|
int dim1, /* (i) dimension first seq1 */
|
|
const float *seq2, /* (i) second sequence */
|
|
int dim2 /* (i) dimension seq2 */
|
|
){
|
|
int i,j;
|
|
|
|
for (i=0; i<=dim1-dim2; i++) {
|
|
corr[i]=0.0;
|
|
for (j=0; j<dim2; j++) {
|
|
corr[i] += seq1[i+j] * seq2[j];
|
|
}
|
|
}
|
|
}
|
|
|
|
/*----------------------------------------------------------------*
|
|
* upsample finite array assuming zeros outside bounds
|
|
*---------------------------------------------------------------*/
|
|
|
|
|
|
|
|
|
|
Andersen, et al. Experimental [Page 111]
|
|
|
|
RFC 3951 Internet Low Bit Rate Codec December 2004
|
|
|
|
|
|
void enh_upsample(
|
|
float* useq1, /* (o) upsampled output sequence */
|
|
float* seq1,/* (i) unupsampled sequence */
|
|
int dim1, /* (i) dimension seq1 */
|
|
int hfl /* (i) polyphase filter length=2*hfl+1 */
|
|
){
|
|
float *pu,*ps;
|
|
int i,j,k,q,filterlength,hfl2;
|
|
const float *polyp[ENH_UPS0]; /* pointers to
|
|
polyphase columns */
|
|
const float *pp;
|
|
|
|
/* define pointers for filter */
|
|
|
|
filterlength=2*hfl+1;
|
|
|
|
if ( filterlength > dim1 ) {
|
|
hfl2=(int) (dim1/2);
|
|
for (j=0; j<ENH_UPS0; j++) {
|
|
polyp[j]=polyphaserTbl+j*filterlength+hfl-hfl2;
|
|
}
|
|
hfl=hfl2;
|
|
filterlength=2*hfl+1;
|
|
}
|
|
else {
|
|
for (j=0; j<ENH_UPS0; j++) {
|
|
polyp[j]=polyphaserTbl+j*filterlength;
|
|
}
|
|
}
|
|
|
|
/* filtering: filter overhangs left side of sequence */
|
|
|
|
pu=useq1;
|
|
for (i=hfl; i<filterlength; i++) {
|
|
for (j=0; j<ENH_UPS0; j++) {
|
|
*pu=0.0;
|
|
pp = polyp[j];
|
|
ps = seq1+i;
|
|
for (k=0; k<=i; k++) {
|
|
*pu += *ps-- * *pp++;
|
|
}
|
|
pu++;
|
|
}
|
|
}
|
|
|
|
/* filtering: simple convolution=inner products */
|
|
|
|
for (i=filterlength; i<dim1; i++) {
|
|
|
|
|
|
|
|
Andersen, et al. Experimental [Page 112]
|
|
|
|
RFC 3951 Internet Low Bit Rate Codec December 2004
|
|
|
|
|
|
for (j=0;j<ENH_UPS0; j++){
|
|
*pu=0.0;
|
|
pp = polyp[j];
|
|
ps = seq1+i;
|
|
for (k=0; k<filterlength; k++) {
|
|
*pu += *ps-- * *pp++;
|
|
}
|
|
pu++;
|
|
}
|
|
}
|
|
|
|
/* filtering: filter overhangs right side of sequence */
|
|
|
|
for (q=1; q<=hfl; q++) {
|
|
for (j=0; j<ENH_UPS0; j++) {
|
|
*pu=0.0;
|
|
pp = polyp[j]+q;
|
|
ps = seq1+dim1-1;
|
|
for (k=0; k<filterlength-q; k++) {
|
|
*pu += *ps-- * *pp++;
|
|
}
|
|
pu++;
|
|
}
|
|
}
|
|
}
|
|
|
|
|
|
/*----------------------------------------------------------------*
|
|
* find segment starting near idata+estSegPos that has highest
|
|
* correlation with idata+centerStartPos through
|
|
* idata+centerStartPos+ENH_BLOCKL-1 segment is found at a
|
|
* resolution of ENH_UPSO times the original of the original
|
|
* sampling rate
|
|
*---------------------------------------------------------------*/
|
|
|
|
void refiner(
|
|
float *seg, /* (o) segment array */
|
|
float *updStartPos, /* (o) updated start point */
|
|
float* idata, /* (i) original data buffer */
|
|
int idatal, /* (i) dimension of idata */
|
|
int centerStartPos, /* (i) beginning center segment */
|
|
float estSegPos,/* (i) estimated beginning other segment */
|
|
float period /* (i) estimated pitch period */
|
|
){
|
|
int estSegPosRounded,searchSegStartPos,searchSegEndPos,corrdim;
|
|
int tloc,tloc2,i,st,en,fraction;
|
|
float vect[ENH_VECTL],corrVec[ENH_CORRDIM],maxv;
|
|
float corrVecUps[ENH_CORRDIM*ENH_UPS0];
|
|
|
|
|
|
|
|
Andersen, et al. Experimental [Page 113]
|
|
|
|
RFC 3951 Internet Low Bit Rate Codec December 2004
|
|
|
|
|
|
/* defining array bounds */
|
|
|
|
estSegPosRounded=(int)(estSegPos - 0.5);
|
|
|
|
searchSegStartPos=estSegPosRounded-ENH_SLOP;
|
|
|
|
if (searchSegStartPos<0) {
|
|
searchSegStartPos=0;
|
|
}
|
|
searchSegEndPos=estSegPosRounded+ENH_SLOP;
|
|
|
|
if (searchSegEndPos+ENH_BLOCKL >= idatal) {
|
|
searchSegEndPos=idatal-ENH_BLOCKL-1;
|
|
}
|
|
corrdim=searchSegEndPos-searchSegStartPos+1;
|
|
|
|
/* compute upsampled correlation (corr33) and find
|
|
location of max */
|
|
|
|
mycorr1(corrVec,idata+searchSegStartPos,
|
|
corrdim+ENH_BLOCKL-1,idata+centerStartPos,ENH_BLOCKL);
|
|
enh_upsample(corrVecUps,corrVec,corrdim,ENH_FL0);
|
|
tloc=0; maxv=corrVecUps[0];
|
|
for (i=1; i<ENH_UPS0*corrdim; i++) {
|
|
|
|
if (corrVecUps[i]>maxv) {
|
|
tloc=i;
|
|
maxv=corrVecUps[i];
|
|
}
|
|
}
|
|
|
|
/* make vector can be upsampled without ever running outside
|
|
bounds */
|
|
|
|
*updStartPos= (float)searchSegStartPos +
|
|
(float)tloc/(float)ENH_UPS0+(float)1.0;
|
|
tloc2=(int)(tloc/ENH_UPS0);
|
|
|
|
if (tloc>tloc2*ENH_UPS0) {
|
|
tloc2++;
|
|
}
|
|
st=searchSegStartPos+tloc2-ENH_FL0;
|
|
|
|
if (st<0) {
|
|
memset(vect,0,-st*sizeof(float));
|
|
memcpy(&vect[-st],idata, (ENH_VECTL+st)*sizeof(float));
|
|
}
|
|
else {
|
|
|
|
|
|
|
|
Andersen, et al. Experimental [Page 114]
|
|
|
|
RFC 3951 Internet Low Bit Rate Codec December 2004
|
|
|
|
|
|
en=st+ENH_VECTL;
|
|
|
|
if (en>idatal) {
|
|
memcpy(vect, &idata[st],
|
|
(ENH_VECTL-(en-idatal))*sizeof(float));
|
|
memset(&vect[ENH_VECTL-(en-idatal)], 0,
|
|
(en-idatal)*sizeof(float));
|
|
}
|
|
else {
|
|
memcpy(vect, &idata[st], ENH_VECTL*sizeof(float));
|
|
}
|
|
}
|
|
fraction=tloc2*ENH_UPS0-tloc;
|
|
|
|
/* compute the segment (this is actually a convolution) */
|
|
|
|
mycorr1(seg,vect,ENH_VECTL,polyphaserTbl+(2*ENH_FL0+1)*fraction,
|
|
2*ENH_FL0+1);
|
|
}
|
|
|
|
/*----------------------------------------------------------------*
|
|
* find the smoothed output data
|
|
*---------------------------------------------------------------*/
|
|
|
|
void smath(
|
|
float *odata, /* (o) smoothed output */
|
|
float *sseq,/* (i) said second sequence of waveforms */
|
|
int hl, /* (i) 2*hl+1 is sseq dimension */
|
|
float alpha0/* (i) max smoothing energy fraction */
|
|
){
|
|
int i,k;
|
|
float w00,w10,w11,A,B,C,*psseq,err,errs;
|
|
float surround[BLOCKL_MAX]; /* shape contributed by other than
|
|
current */
|
|
float wt[2*ENH_HL+1]; /* waveform weighting to get
|
|
surround shape */
|
|
float denom;
|
|
|
|
/* create shape of contribution from all waveforms except the
|
|
current one */
|
|
|
|
for (i=1; i<=2*hl+1; i++) {
|
|
wt[i-1] = (float)0.5*(1 - (float)cos(2*PI*i/(2*hl+2)));
|
|
}
|
|
wt[hl]=0.0; /* for clarity, not used */
|
|
for (i=0; i<ENH_BLOCKL; i++) {
|
|
surround[i]=sseq[i]*wt[0];
|
|
}
|
|
|
|
|
|
|
|
Andersen, et al. Experimental [Page 115]
|
|
|
|
RFC 3951 Internet Low Bit Rate Codec December 2004
|
|
|
|
|
|
for (k=1; k<hl; k++) {
|
|
psseq=sseq+k*ENH_BLOCKL;
|
|
for(i=0;i<ENH_BLOCKL; i++) {
|
|
surround[i]+=psseq[i]*wt[k];
|
|
}
|
|
}
|
|
for (k=hl+1; k<=2*hl; k++) {
|
|
psseq=sseq+k*ENH_BLOCKL;
|
|
for(i=0;i<ENH_BLOCKL; i++) {
|
|
surround[i]+=psseq[i]*wt[k];
|
|
}
|
|
}
|
|
|
|
/* compute some inner products */
|
|
|
|
w00 = w10 = w11 = 0.0;
|
|
psseq=sseq+hl*ENH_BLOCKL; /* current block */
|
|
for (i=0; i<ENH_BLOCKL;i++) {
|
|
w00+=psseq[i]*psseq[i];
|
|
w11+=surround[i]*surround[i];
|
|
w10+=surround[i]*psseq[i];
|
|
}
|
|
|
|
if (fabs(w11) < 1.0) {
|
|
w11=1.0;
|
|
}
|
|
C = (float)sqrt( w00/w11);
|
|
|
|
/* first try enhancement without power-constraint */
|
|
|
|
errs=0.0;
|
|
psseq=sseq+hl*ENH_BLOCKL;
|
|
for (i=0; i<ENH_BLOCKL; i++) {
|
|
odata[i]=C*surround[i];
|
|
err=psseq[i]-odata[i];
|
|
errs+=err*err;
|
|
}
|
|
|
|
/* if constraint violated by first try, add constraint */
|
|
|
|
if (errs > alpha0 * w00) {
|
|
if ( w00 < 1) {
|
|
w00=1;
|
|
}
|
|
denom = (w11*w00-w10*w10)/(w00*w00);
|
|
|
|
if (denom > 0.0001) { /* eliminates numerical problems
|
|
for if smooth */
|
|
|
|
|
|
|
|
Andersen, et al. Experimental [Page 116]
|
|
|
|
RFC 3951 Internet Low Bit Rate Codec December 2004
|
|
|
|
|
|
A = (float)sqrt( (alpha0- alpha0*alpha0/4)/denom);
|
|
B = -alpha0/2 - A * w10/w00;
|
|
B = B+1;
|
|
}
|
|
else { /* essentially no difference between cycles;
|
|
smoothing not needed */
|
|
A= 0.0;
|
|
B= 1.0;
|
|
}
|
|
|
|
/* create smoothed sequence */
|
|
|
|
psseq=sseq+hl*ENH_BLOCKL;
|
|
for (i=0; i<ENH_BLOCKL; i++) {
|
|
odata[i]=A*surround[i]+B*psseq[i];
|
|
}
|
|
}
|
|
}
|
|
|
|
/*----------------------------------------------------------------*
|
|
* get the pitch-synchronous sample sequence
|
|
*---------------------------------------------------------------*/
|
|
|
|
void getsseq(
|
|
float *sseq, /* (o) the pitch-synchronous sequence */
|
|
float *idata, /* (i) original data */
|
|
int idatal, /* (i) dimension of data */
|
|
int centerStartPos, /* (i) where current block starts */
|
|
float *period, /* (i) rough-pitch-period array */
|
|
float *plocs, /* (i) where periods of period array
|
|
are taken */
|
|
int periodl, /* (i) dimension period array */
|
|
int hl /* (i) 2*hl+1 is the number of sequences */
|
|
){
|
|
int i,centerEndPos,q;
|
|
float blockStartPos[2*ENH_HL+1];
|
|
int lagBlock[2*ENH_HL+1];
|
|
float plocs2[ENH_PLOCSL];
|
|
float *psseq;
|
|
|
|
centerEndPos=centerStartPos+ENH_BLOCKL-1;
|
|
|
|
/* present */
|
|
|
|
NearestNeighbor(lagBlock+hl,plocs,
|
|
(float)0.5*(centerStartPos+centerEndPos),periodl);
|
|
|
|
blockStartPos[hl]=(float)centerStartPos;
|
|
|
|
|
|
|
|
Andersen, et al. Experimental [Page 117]
|
|
|
|
RFC 3951 Internet Low Bit Rate Codec December 2004
|
|
|
|
|
|
psseq=sseq+ENH_BLOCKL*hl;
|
|
memcpy(psseq, idata+centerStartPos, ENH_BLOCKL*sizeof(float));
|
|
|
|
/* past */
|
|
|
|
for (q=hl-1; q>=0; q--) {
|
|
blockStartPos[q]=blockStartPos[q+1]-period[lagBlock[q+1]];
|
|
NearestNeighbor(lagBlock+q,plocs,
|
|
blockStartPos[q]+
|
|
ENH_BLOCKL_HALF-period[lagBlock[q+1]], periodl);
|
|
|
|
|
|
if (blockStartPos[q]-ENH_OVERHANG>=0) {
|
|
refiner(sseq+q*ENH_BLOCKL, blockStartPos+q, idata,
|
|
idatal, centerStartPos, blockStartPos[q],
|
|
period[lagBlock[q+1]]);
|
|
} else {
|
|
psseq=sseq+q*ENH_BLOCKL;
|
|
memset(psseq, 0, ENH_BLOCKL*sizeof(float));
|
|
}
|
|
}
|
|
|
|
/* future */
|
|
|
|
for (i=0; i<periodl; i++) {
|
|
plocs2[i]=plocs[i]-period[i];
|
|
}
|
|
for (q=hl+1; q<=2*hl; q++) {
|
|
NearestNeighbor(lagBlock+q,plocs2,
|
|
blockStartPos[q-1]+ENH_BLOCKL_HALF,periodl);
|
|
|
|
blockStartPos[q]=blockStartPos[q-1]+period[lagBlock[q]];
|
|
if (blockStartPos[q]+ENH_BLOCKL+ENH_OVERHANG<idatal) {
|
|
refiner(sseq+ENH_BLOCKL*q, blockStartPos+q, idata,
|
|
idatal, centerStartPos, blockStartPos[q],
|
|
period[lagBlock[q]]);
|
|
}
|
|
else {
|
|
psseq=sseq+q*ENH_BLOCKL;
|
|
memset(psseq, 0, ENH_BLOCKL*sizeof(float));
|
|
}
|
|
}
|
|
}
|
|
|
|
/*----------------------------------------------------------------*
|
|
* perform enhancement on idata+centerStartPos through
|
|
* idata+centerStartPos+ENH_BLOCKL-1
|
|
*---------------------------------------------------------------*/
|
|
|
|
|
|
|
|
Andersen, et al. Experimental [Page 118]
|
|
|
|
RFC 3951 Internet Low Bit Rate Codec December 2004
|
|
|
|
|
|
void enhancer(
|
|
float *odata, /* (o) smoothed block, dimension blockl */
|
|
float *idata, /* (i) data buffer used for enhancing */
|
|
int idatal, /* (i) dimension idata */
|
|
int centerStartPos, /* (i) first sample current block
|
|
within idata */
|
|
float alpha0, /* (i) max correction-energy-fraction
|
|
(in [0,1]) */
|
|
float *period, /* (i) pitch period array */
|
|
float *plocs, /* (i) locations where period array
|
|
values valid */
|
|
int periodl /* (i) dimension of period and plocs */
|
|
){
|
|
float sseq[(2*ENH_HL+1)*ENH_BLOCKL];
|
|
|
|
/* get said second sequence of segments */
|
|
|
|
getsseq(sseq,idata,idatal,centerStartPos,period,
|
|
plocs,periodl,ENH_HL);
|
|
|
|
/* compute the smoothed output from said second sequence */
|
|
|
|
smath(odata,sseq,ENH_HL,alpha0);
|
|
|
|
}
|
|
|
|
/*----------------------------------------------------------------*
|
|
* cross correlation
|
|
*---------------------------------------------------------------*/
|
|
|
|
float xCorrCoef(
|
|
float *target, /* (i) first array */
|
|
float *regressor, /* (i) second array */
|
|
int subl /* (i) dimension arrays */
|
|
){
|
|
int i;
|
|
float ftmp1, ftmp2;
|
|
|
|
ftmp1 = 0.0;
|
|
ftmp2 = 0.0;
|
|
for (i=0; i<subl; i++) {
|
|
ftmp1 += target[i]*regressor[i];
|
|
ftmp2 += regressor[i]*regressor[i];
|
|
}
|
|
|
|
if (ftmp1 > 0.0) {
|
|
return (float)(ftmp1*ftmp1/ftmp2);
|
|
}
|
|
|
|
|
|
|
|
Andersen, et al. Experimental [Page 119]
|
|
|
|
RFC 3951 Internet Low Bit Rate Codec December 2004
|
|
|
|
|
|
else {
|
|
return (float)0.0;
|
|
}
|
|
}
|
|
|
|
/*----------------------------------------------------------------*
|
|
* interface for enhancer
|
|
*---------------------------------------------------------------*/
|
|
|
|
int enhancerInterface(
|
|
float *out, /* (o) enhanced signal */
|
|
float *in, /* (i) unenhanced signal */
|
|
iLBC_Dec_Inst_t *iLBCdec_inst /* (i) buffers etc */
|
|
){
|
|
float *enh_buf, *enh_period;
|
|
int iblock, isample;
|
|
int lag=0, ilag, i, ioffset;
|
|
float cc, maxcc;
|
|
float ftmp1, ftmp2;
|
|
float *inPtr, *enh_bufPtr1, *enh_bufPtr2;
|
|
float plc_pred[ENH_BLOCKL];
|
|
|
|
float lpState[6], downsampled[(ENH_NBLOCKS*ENH_BLOCKL+120)/2];
|
|
int inLen=ENH_NBLOCKS*ENH_BLOCKL+120;
|
|
int start, plc_blockl, inlag;
|
|
|
|
enh_buf=iLBCdec_inst->enh_buf;
|
|
enh_period=iLBCdec_inst->enh_period;
|
|
|
|
memmove(enh_buf, &enh_buf[iLBCdec_inst->blockl],
|
|
(ENH_BUFL-iLBCdec_inst->blockl)*sizeof(float));
|
|
|
|
memcpy(&enh_buf[ENH_BUFL-iLBCdec_inst->blockl], in,
|
|
iLBCdec_inst->blockl*sizeof(float));
|
|
|
|
if (iLBCdec_inst->mode==30)
|
|
plc_blockl=ENH_BLOCKL;
|
|
else
|
|
plc_blockl=40;
|
|
|
|
/* when 20 ms frame, move processing one block */
|
|
ioffset=0;
|
|
if (iLBCdec_inst->mode==20) ioffset=1;
|
|
|
|
i=3-ioffset;
|
|
memmove(enh_period, &enh_period[i],
|
|
(ENH_NBLOCKS_TOT-i)*sizeof(float));
|
|
|
|
|
|
|
|
|
|
Andersen, et al. Experimental [Page 120]
|
|
|
|
RFC 3951 Internet Low Bit Rate Codec December 2004
|
|
|
|
|
|
/* Set state information to the 6 samples right before
|
|
the samples to be downsampled. */
|
|
|
|
memcpy(lpState,
|
|
enh_buf+(ENH_NBLOCKS_EXTRA+ioffset)*ENH_BLOCKL-126,
|
|
6*sizeof(float));
|
|
|
|
/* Down sample a factor 2 to save computations */
|
|
|
|
DownSample(enh_buf+(ENH_NBLOCKS_EXTRA+ioffset)*ENH_BLOCKL-120,
|
|
lpFilt_coefsTbl, inLen-ioffset*ENH_BLOCKL,
|
|
lpState, downsampled);
|
|
|
|
/* Estimate the pitch in the down sampled domain. */
|
|
for (iblock = 0; iblock<ENH_NBLOCKS-ioffset; iblock++) {
|
|
|
|
lag = 10;
|
|
maxcc = xCorrCoef(downsampled+60+iblock*
|
|
ENH_BLOCKL_HALF, downsampled+60+iblock*
|
|
ENH_BLOCKL_HALF-lag, ENH_BLOCKL_HALF);
|
|
for (ilag=11; ilag<60; ilag++) {
|
|
cc = xCorrCoef(downsampled+60+iblock*
|
|
ENH_BLOCKL_HALF, downsampled+60+iblock*
|
|
ENH_BLOCKL_HALF-ilag, ENH_BLOCKL_HALF);
|
|
|
|
if (cc > maxcc) {
|
|
maxcc = cc;
|
|
lag = ilag;
|
|
}
|
|
}
|
|
|
|
/* Store the estimated lag in the non-downsampled domain */
|
|
enh_period[iblock+ENH_NBLOCKS_EXTRA+ioffset] = (float)lag*2;
|
|
|
|
|
|
}
|
|
|
|
|
|
/* PLC was performed on the previous packet */
|
|
if (iLBCdec_inst->prev_enh_pl==1) {
|
|
|
|
inlag=(int)enh_period[ENH_NBLOCKS_EXTRA+ioffset];
|
|
|
|
lag = inlag-1;
|
|
maxcc = xCorrCoef(in, in+lag, plc_blockl);
|
|
for (ilag=inlag; ilag<=inlag+1; ilag++) {
|
|
cc = xCorrCoef(in, in+ilag, plc_blockl);
|
|
|
|
|
|
|
|
|
|
Andersen, et al. Experimental [Page 121]
|
|
|
|
RFC 3951 Internet Low Bit Rate Codec December 2004
|
|
|
|
|
|
if (cc > maxcc) {
|
|
maxcc = cc;
|
|
lag = ilag;
|
|
}
|
|
}
|
|
|
|
enh_period[ENH_NBLOCKS_EXTRA+ioffset-1]=(float)lag;
|
|
|
|
/* compute new concealed residual for the old lookahead,
|
|
mix the forward PLC with a backward PLC from
|
|
the new frame */
|
|
|
|
inPtr=&in[lag-1];
|
|
|
|
enh_bufPtr1=&plc_pred[plc_blockl-1];
|
|
|
|
if (lag>plc_blockl) {
|
|
start=plc_blockl;
|
|
} else {
|
|
start=lag;
|
|
}
|
|
|
|
for (isample = start; isample>0; isample--) {
|
|
*enh_bufPtr1-- = *inPtr--;
|
|
}
|
|
|
|
enh_bufPtr2=&enh_buf[ENH_BUFL-1-iLBCdec_inst->blockl];
|
|
for (isample = (plc_blockl-1-lag); isample>=0; isample--) {
|
|
*enh_bufPtr1-- = *enh_bufPtr2--;
|
|
}
|
|
|
|
/* limit energy change */
|
|
ftmp2=0.0;
|
|
ftmp1=0.0;
|
|
for (i=0;i<plc_blockl;i++) {
|
|
ftmp2+=enh_buf[ENH_BUFL-1-iLBCdec_inst->blockl-i]*
|
|
enh_buf[ENH_BUFL-1-iLBCdec_inst->blockl-i];
|
|
ftmp1+=plc_pred[i]*plc_pred[i];
|
|
}
|
|
ftmp1=(float)sqrt(ftmp1/(float)plc_blockl);
|
|
ftmp2=(float)sqrt(ftmp2/(float)plc_blockl);
|
|
if (ftmp1>(float)2.0*ftmp2 && ftmp1>0.0) {
|
|
for (i=0;i<plc_blockl-10;i++) {
|
|
plc_pred[i]*=(float)2.0*ftmp2/ftmp1;
|
|
}
|
|
for (i=plc_blockl-10;i<plc_blockl;i++) {
|
|
plc_pred[i]*=(float)(i-plc_blockl+10)*
|
|
((float)1.0-(float)2.0*ftmp2/ftmp1)/(float)(10)+
|
|
|
|
|
|
|
|
Andersen, et al. Experimental [Page 122]
|
|
|
|
RFC 3951 Internet Low Bit Rate Codec December 2004
|
|
|
|
|
|
(float)2.0*ftmp2/ftmp1;
|
|
}
|
|
}
|
|
|
|
enh_bufPtr1=&enh_buf[ENH_BUFL-1-iLBCdec_inst->blockl];
|
|
for (i=0; i<plc_blockl; i++) {
|
|
ftmp1 = (float) (i+1) / (float) (plc_blockl+1);
|
|
*enh_bufPtr1 *= ftmp1;
|
|
*enh_bufPtr1 += ((float)1.0-ftmp1)*
|
|
plc_pred[plc_blockl-1-i];
|
|
enh_bufPtr1--;
|
|
}
|
|
}
|
|
|
|
if (iLBCdec_inst->mode==20) {
|
|
/* Enhancer with 40 samples delay */
|
|
for (iblock = 0; iblock<2; iblock++) {
|
|
enhancer(out+iblock*ENH_BLOCKL, enh_buf,
|
|
ENH_BUFL, (5+iblock)*ENH_BLOCKL+40,
|
|
ENH_ALPHA0, enh_period, enh_plocsTbl,
|
|
ENH_NBLOCKS_TOT);
|
|
}
|
|
} else if (iLBCdec_inst->mode==30) {
|
|
/* Enhancer with 80 samples delay */
|
|
for (iblock = 0; iblock<3; iblock++) {
|
|
enhancer(out+iblock*ENH_BLOCKL, enh_buf,
|
|
ENH_BUFL, (4+iblock)*ENH_BLOCKL,
|
|
ENH_ALPHA0, enh_period, enh_plocsTbl,
|
|
ENH_NBLOCKS_TOT);
|
|
}
|
|
}
|
|
|
|
return (lag*2);
|
|
}
|
|
|
|
A.17. filter.h
|
|
|
|
/******************************************************************
|
|
|
|
iLBC Speech Coder ANSI-C Source Code
|
|
|
|
filter.h
|
|
|
|
Copyright (C) The Internet Society (2004).
|
|
All Rights Reserved.
|
|
|
|
******************************************************************/
|
|
|
|
|
|
|
|
|
|
Andersen, et al. Experimental [Page 123]
|
|
|
|
RFC 3951 Internet Low Bit Rate Codec December 2004
|
|
|
|
|
|
#ifndef __iLBC_FILTER_H
|
|
#define __iLBC_FILTER_H
|
|
|
|
void AllPoleFilter(
|
|
float *InOut, /* (i/o) on entrance InOut[-orderCoef] to
|
|
InOut[-1] contain the state of the
|
|
filter (delayed samples). InOut[0] to
|
|
InOut[lengthInOut-1] contain the filter
|
|
input, on en exit InOut[-orderCoef] to
|
|
InOut[-1] is unchanged and InOut[0] to
|
|
InOut[lengthInOut-1] contain filtered
|
|
samples */
|
|
float *Coef,/* (i) filter coefficients, Coef[0] is assumed
|
|
to be 1.0 */
|
|
int lengthInOut,/* (i) number of input/output samples */
|
|
int orderCoef /* (i) number of filter coefficients */
|
|
);
|
|
|
|
void AllZeroFilter(
|
|
float *In, /* (i) In[0] to In[lengthInOut-1] contain
|
|
filter input samples */
|
|
float *Coef,/* (i) filter coefficients (Coef[0] is assumed
|
|
to be 1.0) */
|
|
int lengthInOut,/* (i) number of input/output samples */
|
|
int orderCoef, /* (i) number of filter coefficients */
|
|
float *Out /* (i/o) on entrance Out[-orderCoef] to Out[-1]
|
|
contain the filter state, on exit Out[0]
|
|
to Out[lengthInOut-1] contain filtered
|
|
samples */
|
|
);
|
|
|
|
void ZeroPoleFilter(
|
|
float *In, /* (i) In[0] to In[lengthInOut-1] contain filter
|
|
input samples In[-orderCoef] to In[-1]
|
|
contain state of all-zero section */
|
|
float *ZeroCoef,/* (i) filter coefficients for all-zero
|
|
section (ZeroCoef[0] is assumed to
|
|
be 1.0) */
|
|
float *PoleCoef,/* (i) filter coefficients for all-pole section
|
|
(ZeroCoef[0] is assumed to be 1.0) */
|
|
int lengthInOut,/* (i) number of input/output samples */
|
|
int orderCoef, /* (i) number of filter coefficients */
|
|
float *Out /* (i/o) on entrance Out[-orderCoef] to Out[-1]
|
|
contain state of all-pole section. On
|
|
exit Out[0] to Out[lengthInOut-1]
|
|
contain filtered samples */
|
|
);
|
|
|
|
|
|
|
|
|
|
Andersen, et al. Experimental [Page 124]
|
|
|
|
RFC 3951 Internet Low Bit Rate Codec December 2004
|
|
|
|
|
|
void DownSample (
|
|
float *In, /* (i) input samples */
|
|
float *Coef, /* (i) filter coefficients */
|
|
int lengthIn, /* (i) number of input samples */
|
|
float *state, /* (i) filter state */
|
|
float *Out /* (o) downsampled output */
|
|
);
|
|
|
|
#endif
|
|
|
|
A.18. filter.c
|
|
|
|
/******************************************************************
|
|
|
|
iLBC Speech Coder ANSI-C Source Code
|
|
|
|
filter.c
|
|
|
|
Copyright (C) The Internet Society (2004).
|
|
All Rights Reserved.
|
|
|
|
******************************************************************/
|
|
|
|
#include "iLBC_define.h"
|
|
|
|
/*----------------------------------------------------------------*
|
|
* all-pole filter
|
|
*---------------------------------------------------------------*/
|
|
|
|
void AllPoleFilter(
|
|
float *InOut, /* (i/o) on entrance InOut[-orderCoef] to
|
|
InOut[-1] contain the state of the
|
|
filter (delayed samples). InOut[0] to
|
|
InOut[lengthInOut-1] contain the filter
|
|
input, on en exit InOut[-orderCoef] to
|
|
InOut[-1] is unchanged and InOut[0] to
|
|
InOut[lengthInOut-1] contain filtered
|
|
samples */
|
|
float *Coef,/* (i) filter coefficients, Coef[0] is assumed
|
|
to be 1.0 */
|
|
int lengthInOut,/* (i) number of input/output samples */
|
|
int orderCoef /* (i) number of filter coefficients */
|
|
){
|
|
int n,k;
|
|
|
|
for(n=0;n<lengthInOut;n++){
|
|
for(k=1;k<=orderCoef;k++){
|
|
*InOut -= Coef[k]*InOut[-k];
|
|
|
|
|
|
|
|
Andersen, et al. Experimental [Page 125]
|
|
|
|
RFC 3951 Internet Low Bit Rate Codec December 2004
|
|
|
|
|
|
}
|
|
InOut++;
|
|
}
|
|
}
|
|
|
|
/*----------------------------------------------------------------*
|
|
* all-zero filter
|
|
*---------------------------------------------------------------*/
|
|
|
|
void AllZeroFilter(
|
|
float *In, /* (i) In[0] to In[lengthInOut-1] contain
|
|
filter input samples */
|
|
float *Coef,/* (i) filter coefficients (Coef[0] is assumed
|
|
to be 1.0) */
|
|
int lengthInOut,/* (i) number of input/output samples */
|
|
int orderCoef, /* (i) number of filter coefficients */
|
|
float *Out /* (i/o) on entrance Out[-orderCoef] to Out[-1]
|
|
contain the filter state, on exit Out[0]
|
|
to Out[lengthInOut-1] contain filtered
|
|
samples */
|
|
){
|
|
int n,k;
|
|
|
|
for(n=0;n<lengthInOut;n++){
|
|
*Out = Coef[0]*In[0];
|
|
for(k=1;k<=orderCoef;k++){
|
|
*Out += Coef[k]*In[-k];
|
|
}
|
|
Out++;
|
|
In++;
|
|
}
|
|
}
|
|
|
|
/*----------------------------------------------------------------*
|
|
* pole-zero filter
|
|
*---------------------------------------------------------------*/
|
|
|
|
void ZeroPoleFilter(
|
|
float *In, /* (i) In[0] to In[lengthInOut-1] contain
|
|
filter input samples In[-orderCoef] to
|
|
In[-1] contain state of all-zero
|
|
section */
|
|
float *ZeroCoef,/* (i) filter coefficients for all-zero
|
|
section (ZeroCoef[0] is assumed to
|
|
be 1.0) */
|
|
float *PoleCoef,/* (i) filter coefficients for all-pole section
|
|
(ZeroCoef[0] is assumed to be 1.0) */
|
|
int lengthInOut,/* (i) number of input/output samples */
|
|
|
|
|
|
|
|
Andersen, et al. Experimental [Page 126]
|
|
|
|
RFC 3951 Internet Low Bit Rate Codec December 2004
|
|
|
|
|
|
int orderCoef, /* (i) number of filter coefficients */
|
|
float *Out /* (i/o) on entrance Out[-orderCoef] to Out[-1]
|
|
contain state of all-pole section. On
|
|
exit Out[0] to Out[lengthInOut-1]
|
|
contain filtered samples */
|
|
){
|
|
AllZeroFilter(In,ZeroCoef,lengthInOut,orderCoef,Out);
|
|
AllPoleFilter(Out,PoleCoef,lengthInOut,orderCoef);
|
|
}
|
|
|
|
/*----------------------------------------------------------------*
|
|
* downsample (LP filter and decimation)
|
|
*---------------------------------------------------------------*/
|
|
|
|
void DownSample (
|
|
float *In, /* (i) input samples */
|
|
float *Coef, /* (i) filter coefficients */
|
|
int lengthIn, /* (i) number of input samples */
|
|
float *state, /* (i) filter state */
|
|
float *Out /* (o) downsampled output */
|
|
){
|
|
float o;
|
|
float *Out_ptr = Out;
|
|
float *Coef_ptr, *In_ptr;
|
|
float *state_ptr;
|
|
int i, j, stop;
|
|
|
|
/* LP filter and decimate at the same time */
|
|
|
|
for (i = DELAY_DS; i < lengthIn; i+=FACTOR_DS)
|
|
{
|
|
Coef_ptr = &Coef[0];
|
|
In_ptr = &In[i];
|
|
state_ptr = &state[FILTERORDER_DS-2];
|
|
|
|
o = (float)0.0;
|
|
|
|
stop = (i < FILTERORDER_DS) ? i + 1 : FILTERORDER_DS;
|
|
|
|
for (j = 0; j < stop; j++)
|
|
{
|
|
o += *Coef_ptr++ * (*In_ptr--);
|
|
}
|
|
for (j = i + 1; j < FILTERORDER_DS; j++)
|
|
{
|
|
o += *Coef_ptr++ * (*state_ptr--);
|
|
}
|
|
|
|
|
|
|
|
|
|
Andersen, et al. Experimental [Page 127]
|
|
|
|
RFC 3951 Internet Low Bit Rate Codec December 2004
|
|
|
|
|
|
*Out_ptr++ = o;
|
|
}
|
|
|
|
/* Get the last part (use zeros as input for the future) */
|
|
|
|
for (i=(lengthIn+FACTOR_DS); i<(lengthIn+DELAY_DS);
|
|
i+=FACTOR_DS) {
|
|
|
|
o=(float)0.0;
|
|
|
|
if (i<lengthIn) {
|
|
Coef_ptr = &Coef[0];
|
|
In_ptr = &In[i];
|
|
for (j=0; j<FILTERORDER_DS; j++) {
|
|
o += *Coef_ptr++ * (*Out_ptr--);
|
|
}
|
|
} else {
|
|
Coef_ptr = &Coef[i-lengthIn];
|
|
In_ptr = &In[lengthIn-1];
|
|
for (j=0; j<FILTERORDER_DS-(i-lengthIn); j++) {
|
|
o += *Coef_ptr++ * (*In_ptr--);
|
|
}
|
|
}
|
|
*Out_ptr++ = o;
|
|
}
|
|
}
|
|
|
|
A.19. FrameClassify.h
|
|
|
|
/******************************************************************
|
|
|
|
iLBC Speech Coder ANSI-C Source Code
|
|
|
|
FrameClassify.h
|
|
|
|
Copyright (C) The Internet Society (2004).
|
|
All Rights Reserved.
|
|
|
|
******************************************************************/
|
|
|
|
#ifndef __iLBC_FRAMECLASSIFY_H
|
|
#define __iLBC_FRAMECLASSIFY_H
|
|
|
|
int FrameClassify( /* index to the max-energy sub-frame */
|
|
iLBC_Enc_Inst_t *iLBCenc_inst,
|
|
/* (i/o) the encoder state structure */
|
|
float *residual /* (i) lpc residual signal */
|
|
);
|
|
|
|
|
|
|
|
Andersen, et al. Experimental [Page 128]
|
|
|
|
RFC 3951 Internet Low Bit Rate Codec December 2004
|
|
|
|
|
|
#endif
|
|
|
|
A.20. FrameClassify.c
|
|
|
|
/******************************************************************
|
|
|
|
iLBC Speech Coder ANSI-C Source Code
|
|
|
|
FrameClassify.c
|
|
|
|
Copyright (C) The Internet Society (2004).
|
|
All Rights Reserved.
|
|
|
|
******************************************************************/
|
|
|
|
#include "iLBC_define.h"
|
|
|
|
/*---------------------------------------------------------------*
|
|
* Classification of subframes to localize start state
|
|
*--------------------------------------------------------------*/
|
|
|
|
int FrameClassify( /* index to the max-energy sub-frame */
|
|
iLBC_Enc_Inst_t *iLBCenc_inst,
|
|
/* (i/o) the encoder state structure */
|
|
float *residual /* (i) lpc residual signal */
|
|
) {
|
|
float max_ssqEn, fssqEn[NSUB_MAX], bssqEn[NSUB_MAX], *pp;
|
|
int n, l, max_ssqEn_n;
|
|
const float ssqEn_win[NSUB_MAX-1]={(float)0.8,(float)0.9,
|
|
(float)1.0,(float)0.9,(float)0.8};
|
|
const float sampEn_win[5]={(float)1.0/(float)6.0,
|
|
(float)2.0/(float)6.0, (float)3.0/(float)6.0,
|
|
(float)4.0/(float)6.0, (float)5.0/(float)6.0};
|
|
|
|
/* init the front and back energies to zero */
|
|
|
|
memset(fssqEn, 0, NSUB_MAX*sizeof(float));
|
|
memset(bssqEn, 0, NSUB_MAX*sizeof(float));
|
|
|
|
/* Calculate front of first seqence */
|
|
|
|
n=0;
|
|
pp=residual;
|
|
for (l=0; l<5; l++) {
|
|
fssqEn[n] += sampEn_win[l] * (*pp) * (*pp);
|
|
pp++;
|
|
}
|
|
for (l=5; l<SUBL; l++) {
|
|
|
|
|
|
|
|
Andersen, et al. Experimental [Page 129]
|
|
|
|
RFC 3951 Internet Low Bit Rate Codec December 2004
|
|
|
|
|
|
fssqEn[n] += (*pp) * (*pp);
|
|
pp++;
|
|
}
|
|
|
|
/* Calculate front and back of all middle sequences */
|
|
|
|
for (n=1; n<iLBCenc_inst->nsub-1; n++) {
|
|
pp=residual+n*SUBL;
|
|
for (l=0; l<5; l++) {
|
|
fssqEn[n] += sampEn_win[l] * (*pp) * (*pp);
|
|
bssqEn[n] += (*pp) * (*pp);
|
|
pp++;
|
|
}
|
|
for (l=5; l<SUBL-5; l++) {
|
|
fssqEn[n] += (*pp) * (*pp);
|
|
bssqEn[n] += (*pp) * (*pp);
|
|
pp++;
|
|
}
|
|
for (l=SUBL-5; l<SUBL; l++) {
|
|
fssqEn[n] += (*pp) * (*pp);
|
|
bssqEn[n] += sampEn_win[SUBL-l-1] * (*pp) * (*pp);
|
|
pp++;
|
|
}
|
|
}
|
|
|
|
/* Calculate back of last seqence */
|
|
|
|
n=iLBCenc_inst->nsub-1;
|
|
pp=residual+n*SUBL;
|
|
for (l=0; l<SUBL-5; l++) {
|
|
bssqEn[n] += (*pp) * (*pp);
|
|
pp++;
|
|
}
|
|
for (l=SUBL-5; l<SUBL; l++) {
|
|
bssqEn[n] += sampEn_win[SUBL-l-1] * (*pp) * (*pp);
|
|
pp++;
|
|
}
|
|
|
|
/* find the index to the weighted 80 sample with
|
|
most energy */
|
|
|
|
if (iLBCenc_inst->mode==20) l=1;
|
|
else l=0;
|
|
|
|
max_ssqEn=(fssqEn[0]+bssqEn[1])*ssqEn_win[l];
|
|
max_ssqEn_n=1;
|
|
for (n=2; n<iLBCenc_inst->nsub; n++) {
|
|
|
|
|
|
|
|
|
|
Andersen, et al. Experimental [Page 130]
|
|
|
|
RFC 3951 Internet Low Bit Rate Codec December 2004
|
|
|
|
|
|
l++;
|
|
if ((fssqEn[n-1]+bssqEn[n])*ssqEn_win[l] > max_ssqEn) {
|
|
max_ssqEn=(fssqEn[n-1]+bssqEn[n]) *
|
|
ssqEn_win[l];
|
|
max_ssqEn_n=n;
|
|
}
|
|
}
|
|
|
|
return max_ssqEn_n;
|
|
}
|
|
|
|
A.21. gainquant.h
|
|
|
|
/******************************************************************
|
|
|
|
iLBC Speech Coder ANSI-C Source Code
|
|
|
|
gainquant.h
|
|
|
|
Copyright (C) The Internet Society (2004).
|
|
All Rights Reserved.
|
|
|
|
******************************************************************/
|
|
|
|
#ifndef __iLBC_GAINQUANT_H
|
|
#define __iLBC_GAINQUANT_H
|
|
|
|
float gainquant(/* (o) quantized gain value */
|
|
float in, /* (i) gain value */
|
|
float maxIn,/* (i) maximum of gain value */
|
|
int cblen, /* (i) number of quantization indices */
|
|
int *index /* (o) quantization index */
|
|
);
|
|
|
|
float gaindequant( /* (o) quantized gain value */
|
|
int index, /* (i) quantization index */
|
|
float maxIn,/* (i) maximum of unquantized gain */
|
|
int cblen /* (i) number of quantization indices */
|
|
);
|
|
|
|
#endif
|
|
|
|
A.22. gainquant.c
|
|
|
|
/******************************************************************
|
|
|
|
iLBC Speech Coder ANSI-C Source Code
|
|
|
|
|
|
|
|
|
|
Andersen, et al. Experimental [Page 131]
|
|
|
|
RFC 3951 Internet Low Bit Rate Codec December 2004
|
|
|
|
|
|
gainquant.c
|
|
|
|
Copyright (C) The Internet Society (2004).
|
|
All Rights Reserved.
|
|
|
|
******************************************************************/
|
|
|
|
#include <string.h>
|
|
#include <math.h>
|
|
#include "constants.h"
|
|
#include "filter.h"
|
|
|
|
/*----------------------------------------------------------------*
|
|
* quantizer for the gain in the gain-shape coding of residual
|
|
*---------------------------------------------------------------*/
|
|
|
|
float gainquant(/* (o) quantized gain value */
|
|
float in, /* (i) gain value */
|
|
float maxIn,/* (i) maximum of gain value */
|
|
int cblen, /* (i) number of quantization indices */
|
|
int *index /* (o) quantization index */
|
|
){
|
|
int i, tindex;
|
|
float minmeasure,measure, *cb, scale;
|
|
|
|
/* ensure a lower bound on the scaling factor */
|
|
|
|
scale=maxIn;
|
|
|
|
if (scale<0.1) {
|
|
scale=(float)0.1;
|
|
}
|
|
|
|
/* select the quantization table */
|
|
|
|
if (cblen == 8) {
|
|
cb = gain_sq3Tbl;
|
|
} else if (cblen == 16) {
|
|
cb = gain_sq4Tbl;
|
|
} else {
|
|
cb = gain_sq5Tbl;
|
|
}
|
|
|
|
/* select the best index in the quantization table */
|
|
|
|
minmeasure=10000000.0;
|
|
tindex=0;
|
|
for (i=0; i<cblen; i++) {
|
|
|
|
|
|
|
|
Andersen, et al. Experimental [Page 132]
|
|
|
|
RFC 3951 Internet Low Bit Rate Codec December 2004
|
|
|
|
|
|
measure=(in-scale*cb[i])*(in-scale*cb[i]);
|
|
|
|
if (measure<minmeasure) {
|
|
tindex=i;
|
|
minmeasure=measure;
|
|
}
|
|
}
|
|
*index=tindex;
|
|
|
|
/* return the quantized value */
|
|
|
|
return scale*cb[tindex];
|
|
}
|
|
|
|
/*----------------------------------------------------------------*
|
|
* decoder for quantized gains in the gain-shape coding of
|
|
* residual
|
|
*---------------------------------------------------------------*/
|
|
|
|
float gaindequant( /* (o) quantized gain value */
|
|
int index, /* (i) quantization index */
|
|
float maxIn,/* (i) maximum of unquantized gain */
|
|
int cblen /* (i) number of quantization indices */
|
|
){
|
|
float scale;
|
|
|
|
/* obtain correct scale factor */
|
|
|
|
scale=(float)fabs(maxIn);
|
|
|
|
if (scale<0.1) {
|
|
scale=(float)0.1;
|
|
}
|
|
|
|
/* select the quantization table and return the decoded value */
|
|
|
|
if (cblen==8) {
|
|
return scale*gain_sq3Tbl[index];
|
|
} else if (cblen==16) {
|
|
return scale*gain_sq4Tbl[index];
|
|
}
|
|
else if (cblen==32) {
|
|
return scale*gain_sq5Tbl[index];
|
|
}
|
|
|
|
return 0.0;
|
|
}
|
|
|
|
|
|
|
|
|
|
Andersen, et al. Experimental [Page 133]
|
|
|
|
RFC 3951 Internet Low Bit Rate Codec December 2004
|
|
|
|
|
|
A.23. getCBvec.h
|
|
|
|
/******************************************************************
|
|
|
|
iLBC Speech Coder ANSI-C Source Code
|
|
|
|
getCBvec.h
|
|
|
|
Copyright (C) The Internet Society (2004).
|
|
All Rights Reserved.
|
|
|
|
******************************************************************/
|
|
|
|
#ifndef __iLBC_GETCBVEC_H
|
|
#define __iLBC_GETCBVEC_H
|
|
|
|
void getCBvec(
|
|
float *cbvec, /* (o) Constructed codebook vector */
|
|
float *mem, /* (i) Codebook buffer */
|
|
int index, /* (i) Codebook index */
|
|
int lMem, /* (i) Length of codebook buffer */
|
|
int cbveclen/* (i) Codebook vector length */
|
|
);
|
|
|
|
#endif
|
|
|
|
A.24. getCBvec.c
|
|
|
|
/******************************************************************
|
|
|
|
iLBC Speech Coder ANSI-C Source Code
|
|
|
|
getCBvec.c
|
|
|
|
Copyright (C) The Internet Society (2004).
|
|
All Rights Reserved.
|
|
|
|
******************************************************************/
|
|
|
|
#include "iLBC_define.h"
|
|
#include "constants.h"
|
|
#include <string.h>
|
|
|
|
/*----------------------------------------------------------------*
|
|
* Construct codebook vector for given index.
|
|
*---------------------------------------------------------------*/
|
|
|
|
void getCBvec(
|
|
|
|
|
|
|
|
Andersen, et al. Experimental [Page 134]
|
|
|
|
RFC 3951 Internet Low Bit Rate Codec December 2004
|
|
|
|
|
|
float *cbvec, /* (o) Constructed codebook vector */
|
|
float *mem, /* (i) Codebook buffer */
|
|
int index, /* (i) Codebook index */
|
|
int lMem, /* (i) Length of codebook buffer */
|
|
int cbveclen/* (i) Codebook vector length */
|
|
){
|
|
int j, k, n, memInd, sFilt;
|
|
float tmpbuf[CB_MEML];
|
|
int base_size;
|
|
int ilow, ihigh;
|
|
float alfa, alfa1;
|
|
|
|
/* Determine size of codebook sections */
|
|
|
|
base_size=lMem-cbveclen+1;
|
|
|
|
if (cbveclen==SUBL) {
|
|
base_size+=cbveclen/2;
|
|
}
|
|
|
|
/* No filter -> First codebook section */
|
|
|
|
if (index<lMem-cbveclen+1) {
|
|
|
|
/* first non-interpolated vectors */
|
|
|
|
k=index+cbveclen;
|
|
/* get vector */
|
|
memcpy(cbvec, mem+lMem-k, cbveclen*sizeof(float));
|
|
|
|
} else if (index < base_size) {
|
|
|
|
k=2*(index-(lMem-cbveclen+1))+cbveclen;
|
|
|
|
ihigh=k/2;
|
|
ilow=ihigh-5;
|
|
|
|
/* Copy first noninterpolated part */
|
|
|
|
memcpy(cbvec, mem+lMem-k/2, ilow*sizeof(float));
|
|
|
|
/* interpolation */
|
|
|
|
alfa1=(float)0.2;
|
|
alfa=0.0;
|
|
for (j=ilow; j<ihigh; j++) {
|
|
cbvec[j]=((float)1.0-alfa)*mem[lMem-k/2+j]+
|
|
alfa*mem[lMem-k+j];
|
|
|
|
|
|
|
|
Andersen, et al. Experimental [Page 135]
|
|
|
|
RFC 3951 Internet Low Bit Rate Codec December 2004
|
|
|
|
|
|
alfa+=alfa1;
|
|
}
|
|
|
|
/* Copy second noninterpolated part */
|
|
|
|
memcpy(cbvec+ihigh, mem+lMem-k+ihigh,
|
|
(cbveclen-ihigh)*sizeof(float));
|
|
|
|
}
|
|
|
|
/* Higher codebook section based on filtering */
|
|
|
|
else {
|
|
|
|
/* first non-interpolated vectors */
|
|
|
|
if (index-base_size<lMem-cbveclen+1) {
|
|
float tempbuff2[CB_MEML+CB_FILTERLEN+1];
|
|
float *pos;
|
|
float *pp, *pp1;
|
|
|
|
memset(tempbuff2, 0,
|
|
CB_HALFFILTERLEN*sizeof(float));
|
|
memcpy(&tempbuff2[CB_HALFFILTERLEN], mem,
|
|
lMem*sizeof(float));
|
|
memset(&tempbuff2[lMem+CB_HALFFILTERLEN], 0,
|
|
(CB_HALFFILTERLEN+1)*sizeof(float));
|
|
|
|
k=index-base_size+cbveclen;
|
|
sFilt=lMem-k;
|
|
memInd=sFilt+1-CB_HALFFILTERLEN;
|
|
|
|
/* do filtering */
|
|
pos=cbvec;
|
|
memset(pos, 0, cbveclen*sizeof(float));
|
|
for (n=0; n<cbveclen; n++) {
|
|
pp=&tempbuff2[memInd+n+CB_HALFFILTERLEN];
|
|
pp1=&cbfiltersTbl[CB_FILTERLEN-1];
|
|
for (j=0; j<CB_FILTERLEN; j++) {
|
|
(*pos)+=(*pp++)*(*pp1--);
|
|
}
|
|
pos++;
|
|
}
|
|
}
|
|
|
|
/* interpolated vectors */
|
|
|
|
else {
|
|
|
|
|
|
|
|
Andersen, et al. Experimental [Page 136]
|
|
|
|
RFC 3951 Internet Low Bit Rate Codec December 2004
|
|
|
|
|
|
float tempbuff2[CB_MEML+CB_FILTERLEN+1];
|
|
|
|
float *pos;
|
|
float *pp, *pp1;
|
|
int i;
|
|
|
|
memset(tempbuff2, 0,
|
|
CB_HALFFILTERLEN*sizeof(float));
|
|
memcpy(&tempbuff2[CB_HALFFILTERLEN], mem,
|
|
lMem*sizeof(float));
|
|
memset(&tempbuff2[lMem+CB_HALFFILTERLEN], 0,
|
|
(CB_HALFFILTERLEN+1)*sizeof(float));
|
|
|
|
k=2*(index-base_size-
|
|
(lMem-cbveclen+1))+cbveclen;
|
|
sFilt=lMem-k;
|
|
memInd=sFilt+1-CB_HALFFILTERLEN;
|
|
|
|
/* do filtering */
|
|
pos=&tmpbuf[sFilt];
|
|
memset(pos, 0, k*sizeof(float));
|
|
for (i=0; i<k; i++) {
|
|
pp=&tempbuff2[memInd+i+CB_HALFFILTERLEN];
|
|
pp1=&cbfiltersTbl[CB_FILTERLEN-1];
|
|
for (j=0; j<CB_FILTERLEN; j++) {
|
|
(*pos)+=(*pp++)*(*pp1--);
|
|
}
|
|
pos++;
|
|
}
|
|
|
|
ihigh=k/2;
|
|
ilow=ihigh-5;
|
|
|
|
/* Copy first noninterpolated part */
|
|
|
|
memcpy(cbvec, tmpbuf+lMem-k/2,
|
|
ilow*sizeof(float));
|
|
|
|
/* interpolation */
|
|
|
|
alfa1=(float)0.2;
|
|
alfa=0.0;
|
|
for (j=ilow; j<ihigh; j++) {
|
|
cbvec[j]=((float)1.0-alfa)*
|
|
tmpbuf[lMem-k/2+j]+alfa*tmpbuf[lMem-k+j];
|
|
alfa+=alfa1;
|
|
}
|
|
|
|
|
|
|
|
|
|
Andersen, et al. Experimental [Page 137]
|
|
|
|
RFC 3951 Internet Low Bit Rate Codec December 2004
|
|
|
|
|
|
/* Copy second noninterpolated part */
|
|
|
|
memcpy(cbvec+ihigh, tmpbuf+lMem-k+ihigh,
|
|
(cbveclen-ihigh)*sizeof(float));
|
|
}
|
|
}
|
|
}
|
|
|
|
A.25. helpfun.h
|
|
|
|
/******************************************************************
|
|
|
|
iLBC Speech Coder ANSI-C Source Code
|
|
|
|
helpfun.h
|
|
|
|
Copyright (C) The Internet Society (2004).
|
|
All Rights Reserved.
|
|
|
|
******************************************************************/
|
|
|
|
#ifndef __iLBC_HELPFUN_H
|
|
#define __iLBC_HELPFUN_H
|
|
|
|
void autocorr(
|
|
float *r, /* (o) autocorrelation vector */
|
|
const float *x, /* (i) data vector */
|
|
int N, /* (i) length of data vector */
|
|
int order /* largest lag for calculated
|
|
autocorrelations */
|
|
);
|
|
|
|
void window(
|
|
float *z, /* (o) the windowed data */
|
|
const float *x, /* (i) the original data vector */
|
|
const float *y, /* (i) the window */
|
|
int N /* (i) length of all vectors */
|
|
);
|
|
|
|
void levdurb(
|
|
float *a, /* (o) lpc coefficient vector starting
|
|
with 1.0 */
|
|
float *k, /* (o) reflection coefficients */
|
|
float *r, /* (i) autocorrelation vector */
|
|
int order /* (i) order of lpc filter */
|
|
);
|
|
|
|
void interpolate(
|
|
|
|
|
|
|
|
Andersen, et al. Experimental [Page 138]
|
|
|
|
RFC 3951 Internet Low Bit Rate Codec December 2004
|
|
|
|
|
|
float *out, /* (o) the interpolated vector */
|
|
float *in1, /* (i) the first vector for the
|
|
interpolation */
|
|
float *in2, /* (i) the second vector for the
|
|
interpolation */
|
|
float coef, /* (i) interpolation weights */
|
|
int length /* (i) length of all vectors */
|
|
);
|
|
|
|
void bwexpand(
|
|
float *out, /* (o) the bandwidth expanded lpc
|
|
coefficients */
|
|
float *in, /* (i) the lpc coefficients before bandwidth
|
|
expansion */
|
|
float coef, /* (i) the bandwidth expansion factor */
|
|
int length /* (i) the length of lpc coefficient vectors */
|
|
);
|
|
|
|
void vq(
|
|
float *Xq, /* (o) the quantized vector */
|
|
int *index, /* (o) the quantization index */
|
|
const float *CB,/* (i) the vector quantization codebook */
|
|
float *X, /* (i) the vector to quantize */
|
|
int n_cb, /* (i) the number of vectors in the codebook */
|
|
int dim /* (i) the dimension of all vectors */
|
|
);
|
|
|
|
void SplitVQ(
|
|
float *qX, /* (o) the quantized vector */
|
|
int *index, /* (o) a vector of indexes for all vector
|
|
codebooks in the split */
|
|
float *X, /* (i) the vector to quantize */
|
|
const float *CB,/* (i) the quantizer codebook */
|
|
int nsplit, /* the number of vector splits */
|
|
const int *dim, /* the dimension of X and qX */
|
|
const int *cbsize /* the number of vectors in the codebook */
|
|
);
|
|
|
|
|
|
void sort_sq(
|
|
float *xq, /* (o) the quantized value */
|
|
int *index, /* (o) the quantization index */
|
|
float x, /* (i) the value to quantize */
|
|
const float *cb,/* (i) the quantization codebook */
|
|
int cb_size /* (i) the size of the quantization codebook */
|
|
);
|
|
|
|
int LSF_check( /* (o) 1 for stable lsf vectors and 0 for
|
|
|
|
|
|
|
|
Andersen, et al. Experimental [Page 139]
|
|
|
|
RFC 3951 Internet Low Bit Rate Codec December 2004
|
|
|
|
|
|
nonstable ones */
|
|
float *lsf, /* (i) a table of lsf vectors */
|
|
int dim, /* (i) the dimension of each lsf vector */
|
|
int NoAn /* (i) the number of lsf vectors in the
|
|
table */
|
|
);
|
|
|
|
#endif
|
|
|
|
A.26. helpfun.c
|
|
|
|
/******************************************************************
|
|
|
|
iLBC Speech Coder ANSI-C Source Code
|
|
|
|
helpfun.c
|
|
|
|
Copyright (C) The Internet Society (2004).
|
|
All Rights Reserved.
|
|
|
|
******************************************************************/
|
|
|
|
#include <math.h>
|
|
|
|
#include "iLBC_define.h"
|
|
#include "constants.h"
|
|
|
|
/*----------------------------------------------------------------*
|
|
* calculation of auto correlation
|
|
*---------------------------------------------------------------*/
|
|
|
|
void autocorr(
|
|
float *r, /* (o) autocorrelation vector */
|
|
const float *x, /* (i) data vector */
|
|
int N, /* (i) length of data vector */
|
|
int order /* largest lag for calculated
|
|
autocorrelations */
|
|
){
|
|
int lag, n;
|
|
float sum;
|
|
|
|
for (lag = 0; lag <= order; lag++) {
|
|
sum = 0;
|
|
for (n = 0; n < N - lag; n++) {
|
|
sum += x[n] * x[n+lag];
|
|
}
|
|
r[lag] = sum;
|
|
}
|
|
|
|
|
|
|
|
Andersen, et al. Experimental [Page 140]
|
|
|
|
RFC 3951 Internet Low Bit Rate Codec December 2004
|
|
|
|
|
|
}
|
|
|
|
/*----------------------------------------------------------------*
|
|
* window multiplication
|
|
*---------------------------------------------------------------*/
|
|
|
|
void window(
|
|
float *z, /* (o) the windowed data */
|
|
const float *x, /* (i) the original data vector */
|
|
const float *y, /* (i) the window */
|
|
int N /* (i) length of all vectors */
|
|
){
|
|
int i;
|
|
|
|
for (i = 0; i < N; i++) {
|
|
z[i] = x[i] * y[i];
|
|
}
|
|
}
|
|
|
|
/*----------------------------------------------------------------*
|
|
* levinson-durbin solution for lpc coefficients
|
|
*---------------------------------------------------------------*/
|
|
|
|
void levdurb(
|
|
float *a, /* (o) lpc coefficient vector starting
|
|
with 1.0 */
|
|
float *k, /* (o) reflection coefficients */
|
|
float *r, /* (i) autocorrelation vector */
|
|
int order /* (i) order of lpc filter */
|
|
){
|
|
float sum, alpha;
|
|
int m, m_h, i;
|
|
|
|
a[0] = 1.0;
|
|
|
|
if (r[0] < EPS) { /* if r[0] <= 0, set LPC coeff. to zero */
|
|
for (i = 0; i < order; i++) {
|
|
k[i] = 0;
|
|
a[i+1] = 0;
|
|
}
|
|
} else {
|
|
a[1] = k[0] = -r[1]/r[0];
|
|
alpha = r[0] + r[1] * k[0];
|
|
for (m = 1; m < order; m++){
|
|
sum = r[m + 1];
|
|
for (i = 0; i < m; i++){
|
|
sum += a[i+1] * r[m - i];
|
|
}
|
|
|
|
|
|
|
|
Andersen, et al. Experimental [Page 141]
|
|
|
|
RFC 3951 Internet Low Bit Rate Codec December 2004
|
|
|
|
|
|
k[m] = -sum / alpha;
|
|
alpha += k[m] * sum;
|
|
m_h = (m + 1) >> 1;
|
|
for (i = 0; i < m_h; i++){
|
|
sum = a[i+1] + k[m] * a[m - i];
|
|
a[m - i] += k[m] * a[i+1];
|
|
a[i+1] = sum;
|
|
}
|
|
a[m+1] = k[m];
|
|
}
|
|
}
|
|
}
|
|
|
|
/*----------------------------------------------------------------*
|
|
* interpolation between vectors
|
|
*---------------------------------------------------------------*/
|
|
|
|
void interpolate(
|
|
float *out, /* (o) the interpolated vector */
|
|
float *in1, /* (i) the first vector for the
|
|
interpolation */
|
|
float *in2, /* (i) the second vector for the
|
|
interpolation */
|
|
float coef, /* (i) interpolation weights */
|
|
int length /* (i) length of all vectors */
|
|
){
|
|
int i;
|
|
float invcoef;
|
|
|
|
invcoef = (float)1.0 - coef;
|
|
for (i = 0; i < length; i++) {
|
|
out[i] = coef * in1[i] + invcoef * in2[i];
|
|
}
|
|
}
|
|
|
|
/*----------------------------------------------------------------*
|
|
* lpc bandwidth expansion
|
|
*---------------------------------------------------------------*/
|
|
|
|
void bwexpand(
|
|
float *out, /* (o) the bandwidth expanded lpc
|
|
coefficients */
|
|
float *in, /* (i) the lpc coefficients before bandwidth
|
|
expansion */
|
|
float coef, /* (i) the bandwidth expansion factor */
|
|
int length /* (i) the length of lpc coefficient vectors */
|
|
){
|
|
int i;
|
|
|
|
|
|
|
|
Andersen, et al. Experimental [Page 142]
|
|
|
|
RFC 3951 Internet Low Bit Rate Codec December 2004
|
|
|
|
|
|
float chirp;
|
|
|
|
chirp = coef;
|
|
|
|
out[0] = in[0];
|
|
for (i = 1; i < length; i++) {
|
|
out[i] = chirp * in[i];
|
|
chirp *= coef;
|
|
}
|
|
}
|
|
|
|
/*----------------------------------------------------------------*
|
|
* vector quantization
|
|
*---------------------------------------------------------------*/
|
|
|
|
void vq(
|
|
float *Xq, /* (o) the quantized vector */
|
|
int *index, /* (o) the quantization index */
|
|
const float *CB,/* (i) the vector quantization codebook */
|
|
float *X, /* (i) the vector to quantize */
|
|
int n_cb, /* (i) the number of vectors in the codebook */
|
|
int dim /* (i) the dimension of all vectors */
|
|
){
|
|
int i, j;
|
|
int pos, minindex;
|
|
float dist, tmp, mindist;
|
|
|
|
pos = 0;
|
|
mindist = FLOAT_MAX;
|
|
minindex = 0;
|
|
for (j = 0; j < n_cb; j++) {
|
|
dist = X[0] - CB[pos];
|
|
dist *= dist;
|
|
for (i = 1; i < dim; i++) {
|
|
tmp = X[i] - CB[pos + i];
|
|
dist += tmp*tmp;
|
|
}
|
|
|
|
if (dist < mindist) {
|
|
mindist = dist;
|
|
minindex = j;
|
|
}
|
|
pos += dim;
|
|
}
|
|
for (i = 0; i < dim; i++) {
|
|
Xq[i] = CB[minindex*dim + i];
|
|
}
|
|
*index = minindex;
|
|
|
|
|
|
|
|
Andersen, et al. Experimental [Page 143]
|
|
|
|
RFC 3951 Internet Low Bit Rate Codec December 2004
|
|
|
|
|
|
}
|
|
|
|
/*----------------------------------------------------------------*
|
|
* split vector quantization
|
|
*---------------------------------------------------------------*/
|
|
|
|
void SplitVQ(
|
|
float *qX, /* (o) the quantized vector */
|
|
int *index, /* (o) a vector of indexes for all vector
|
|
codebooks in the split */
|
|
float *X, /* (i) the vector to quantize */
|
|
const float *CB,/* (i) the quantizer codebook */
|
|
int nsplit, /* the number of vector splits */
|
|
const int *dim, /* the dimension of X and qX */
|
|
const int *cbsize /* the number of vectors in the codebook */
|
|
){
|
|
int cb_pos, X_pos, i;
|
|
|
|
cb_pos = 0;
|
|
X_pos= 0;
|
|
for (i = 0; i < nsplit; i++) {
|
|
vq(qX + X_pos, index + i, CB + cb_pos, X + X_pos,
|
|
cbsize[i], dim[i]);
|
|
X_pos += dim[i];
|
|
cb_pos += dim[i] * cbsize[i];
|
|
}
|
|
}
|
|
|
|
/*----------------------------------------------------------------*
|
|
* scalar quantization
|
|
*---------------------------------------------------------------*/
|
|
|
|
void sort_sq(
|
|
float *xq, /* (o) the quantized value */
|
|
int *index, /* (o) the quantization index */
|
|
float x, /* (i) the value to quantize */
|
|
const float *cb,/* (i) the quantization codebook */
|
|
int cb_size /* (i) the size of the quantization codebook */
|
|
){
|
|
int i;
|
|
|
|
if (x <= cb[0]) {
|
|
*index = 0;
|
|
*xq = cb[0];
|
|
} else {
|
|
i = 0;
|
|
while ((x > cb[i]) && i < cb_size - 1) {
|
|
i++;
|
|
|
|
|
|
|
|
Andersen, et al. Experimental [Page 144]
|
|
|
|
RFC 3951 Internet Low Bit Rate Codec December 2004
|
|
|
|
|
|
}
|
|
|
|
if (x > ((cb[i] + cb[i - 1])/2)) {
|
|
*index = i;
|
|
*xq = cb[i];
|
|
} else {
|
|
*index = i - 1;
|
|
*xq = cb[i - 1];
|
|
}
|
|
}
|
|
}
|
|
|
|
/*----------------------------------------------------------------*
|
|
* check for stability of lsf coefficients
|
|
*---------------------------------------------------------------*/
|
|
|
|
int LSF_check( /* (o) 1 for stable lsf vectors and 0 for
|
|
nonstable ones */
|
|
float *lsf, /* (i) a table of lsf vectors */
|
|
int dim, /* (i) the dimension of each lsf vector */
|
|
int NoAn /* (i) the number of lsf vectors in the
|
|
table */
|
|
){
|
|
int k,n,m, Nit=2, change=0,pos;
|
|
float tmp;
|
|
static float eps=(float)0.039; /* 50 Hz */
|
|
static float eps2=(float)0.0195;
|
|
static float maxlsf=(float)3.14; /* 4000 Hz */
|
|
static float minlsf=(float)0.01; /* 0 Hz */
|
|
|
|
/* LSF separation check*/
|
|
|
|
for (n=0; n<Nit; n++) { /* Run through a couple of times */
|
|
for (m=0; m<NoAn; m++) { /* Number of analyses per frame */
|
|
for (k=0; k<(dim-1); k++) {
|
|
pos=m*dim+k;
|
|
|
|
if ((lsf[pos+1]-lsf[pos])<eps) {
|
|
|
|
if (lsf[pos+1]<lsf[pos]) {
|
|
tmp=lsf[pos+1];
|
|
lsf[pos+1]= lsf[pos]+eps2;
|
|
lsf[pos]= lsf[pos+1]-eps2;
|
|
} else {
|
|
lsf[pos]-=eps2;
|
|
lsf[pos+1]+=eps2;
|
|
}
|
|
change=1;
|
|
|
|
|
|
|
|
Andersen, et al. Experimental [Page 145]
|
|
|
|
RFC 3951 Internet Low Bit Rate Codec December 2004
|
|
|
|
|
|
}
|
|
|
|
if (lsf[pos]<minlsf) {
|
|
lsf[pos]=minlsf;
|
|
change=1;
|
|
}
|
|
|
|
if (lsf[pos]>maxlsf) {
|
|
lsf[pos]=maxlsf;
|
|
change=1;
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
return change;
|
|
}
|
|
|
|
A.27. hpInput.h
|
|
|
|
/******************************************************************
|
|
|
|
iLBC Speech Coder ANSI-C Source Code
|
|
|
|
hpInput.h
|
|
|
|
Copyright (C) The Internet Society (2004).
|
|
All Rights Reserved.
|
|
|
|
******************************************************************/
|
|
|
|
#ifndef __iLBC_HPINPUT_H
|
|
#define __iLBC_HPINPUT_H
|
|
|
|
void hpInput(
|
|
float *In, /* (i) vector to filter */
|
|
int len, /* (i) length of vector to filter */
|
|
float *Out, /* (o) the resulting filtered vector */
|
|
float *mem /* (i/o) the filter state */
|
|
);
|
|
|
|
#endif
|
|
|
|
A.28. hpInput.c
|
|
|
|
/******************************************************************
|
|
|
|
iLBC Speech Coder ANSI-C Source Code
|
|
|
|
|
|
|
|
Andersen, et al. Experimental [Page 146]
|
|
|
|
RFC 3951 Internet Low Bit Rate Codec December 2004
|
|
|
|
|
|
hpInput.c
|
|
|
|
Copyright (C) The Internet Society (2004).
|
|
All Rights Reserved.
|
|
|
|
******************************************************************/
|
|
|
|
#include "constants.h"
|
|
|
|
/*----------------------------------------------------------------*
|
|
* Input high-pass filter
|
|
*---------------------------------------------------------------*/
|
|
|
|
void hpInput(
|
|
float *In, /* (i) vector to filter */
|
|
int len, /* (i) length of vector to filter */
|
|
float *Out, /* (o) the resulting filtered vector */
|
|
float *mem /* (i/o) the filter state */
|
|
){
|
|
int i;
|
|
float *pi, *po;
|
|
|
|
/* all-zero section*/
|
|
|
|
pi = &In[0];
|
|
po = &Out[0];
|
|
for (i=0; i<len; i++) {
|
|
*po = hpi_zero_coefsTbl[0] * (*pi);
|
|
*po += hpi_zero_coefsTbl[1] * mem[0];
|
|
*po += hpi_zero_coefsTbl[2] * mem[1];
|
|
|
|
mem[1] = mem[0];
|
|
mem[0] = *pi;
|
|
po++;
|
|
pi++;
|
|
|
|
}
|
|
|
|
/* all-pole section*/
|
|
|
|
po = &Out[0];
|
|
for (i=0; i<len; i++) {
|
|
*po -= hpi_pole_coefsTbl[1] * mem[2];
|
|
*po -= hpi_pole_coefsTbl[2] * mem[3];
|
|
|
|
mem[3] = mem[2];
|
|
mem[2] = *po;
|
|
po++;
|
|
|
|
|
|
|
|
Andersen, et al. Experimental [Page 147]
|
|
|
|
RFC 3951 Internet Low Bit Rate Codec December 2004
|
|
|
|
|
|
}
|
|
}
|
|
|
|
A.29. hpOutput.h
|
|
|
|
/******************************************************************
|
|
|
|
iLBC Speech Coder ANSI-C Source Code
|
|
|
|
hpOutput.h
|
|
|
|
Copyright (C) The Internet Society (2004).
|
|
All Rights Reserved.
|
|
|
|
******************************************************************/
|
|
|
|
#ifndef __iLBC_HPOUTPUT_H
|
|
#define __iLBC_HPOUTPUT_H
|
|
|
|
void hpOutput(
|
|
float *In, /* (i) vector to filter */
|
|
int len,/* (i) length of vector to filter */
|
|
float *Out, /* (o) the resulting filtered vector */
|
|
float *mem /* (i/o) the filter state */
|
|
);
|
|
|
|
#endif
|
|
|
|
A.30. hpOutput.c
|
|
|
|
/******************************************************************
|
|
|
|
iLBC Speech Coder ANSI-C Source Code
|
|
|
|
hpOutput.c
|
|
|
|
Copyright (C) The Internet Society (2004).
|
|
All Rights Reserved.
|
|
|
|
******************************************************************/
|
|
|
|
#include "constants.h"
|
|
|
|
/*----------------------------------------------------------------*
|
|
* Output high-pass filter
|
|
*---------------------------------------------------------------*/
|
|
|
|
void hpOutput(
|
|
|
|
|
|
|
|
Andersen, et al. Experimental [Page 148]
|
|
|
|
RFC 3951 Internet Low Bit Rate Codec December 2004
|
|
|
|
|
|
float *In, /* (i) vector to filter */
|
|
int len,/* (i) length of vector to filter */
|
|
float *Out, /* (o) the resulting filtered vector */
|
|
float *mem /* (i/o) the filter state */
|
|
){
|
|
int i;
|
|
float *pi, *po;
|
|
|
|
/* all-zero section*/
|
|
|
|
pi = &In[0];
|
|
po = &Out[0];
|
|
for (i=0; i<len; i++) {
|
|
*po = hpo_zero_coefsTbl[0] * (*pi);
|
|
*po += hpo_zero_coefsTbl[1] * mem[0];
|
|
*po += hpo_zero_coefsTbl[2] * mem[1];
|
|
|
|
mem[1] = mem[0];
|
|
mem[0] = *pi;
|
|
po++;
|
|
pi++;
|
|
|
|
}
|
|
|
|
/* all-pole section*/
|
|
|
|
po = &Out[0];
|
|
for (i=0; i<len; i++) {
|
|
*po -= hpo_pole_coefsTbl[1] * mem[2];
|
|
*po -= hpo_pole_coefsTbl[2] * mem[3];
|
|
|
|
mem[3] = mem[2];
|
|
mem[2] = *po;
|
|
po++;
|
|
}
|
|
}
|
|
|
|
A.31. iCBConstruct.h
|
|
|
|
/******************************************************************
|
|
|
|
iLBC Speech Coder ANSI-C Source Code
|
|
|
|
iCBConstruct.h
|
|
|
|
Copyright (C) The Internet Society (2004).
|
|
All Rights Reserved.
|
|
|
|
|
|
|
|
|
|
Andersen, et al. Experimental [Page 149]
|
|
|
|
RFC 3951 Internet Low Bit Rate Codec December 2004
|
|
|
|
|
|
******************************************************************/
|
|
|
|
#ifndef __iLBC_ICBCONSTRUCT_H
|
|
#define __iLBC_ICBCONSTRUCT_H
|
|
|
|
void index_conv_enc(
|
|
int *index /* (i/o) Codebook indexes */
|
|
);
|
|
|
|
void index_conv_dec(
|
|
int *index /* (i/o) Codebook indexes */
|
|
);
|
|
|
|
void iCBConstruct(
|
|
float *decvector, /* (o) Decoded vector */
|
|
int *index, /* (i) Codebook indices */
|
|
int *gain_index,/* (i) Gain quantization indices */
|
|
float *mem, /* (i) Buffer for codevector construction */
|
|
int lMem, /* (i) Length of buffer */
|
|
int veclen, /* (i) Length of vector */
|
|
int nStages /* (i) Number of codebook stages */
|
|
);
|
|
|
|
#endif
|
|
|
|
A.32. iCBConstruct.c
|
|
|
|
/******************************************************************
|
|
|
|
iLBC Speech Coder ANSI-C Source Code
|
|
|
|
iCBConstruct.c
|
|
|
|
Copyright (C) The Internet Society (2004).
|
|
All Rights Reserved.
|
|
|
|
******************************************************************/
|
|
|
|
#include <math.h>
|
|
|
|
#include "iLBC_define.h"
|
|
#include "gainquant.h"
|
|
#include "getCBvec.h"
|
|
|
|
/*----------------------------------------------------------------*
|
|
* Convert the codebook indexes to make the search easier
|
|
*---------------------------------------------------------------*/
|
|
|
|
|
|
|
|
|
|
Andersen, et al. Experimental [Page 150]
|
|
|
|
RFC 3951 Internet Low Bit Rate Codec December 2004
|
|
|
|
|
|
void index_conv_enc(
|
|
int *index /* (i/o) Codebook indexes */
|
|
){
|
|
int k;
|
|
|
|
for (k=1; k<CB_NSTAGES; k++) {
|
|
|
|
if ((index[k]>=108)&&(index[k]<172)) {
|
|
index[k]-=64;
|
|
} else if (index[k]>=236) {
|
|
index[k]-=128;
|
|
} else {
|
|
/* ERROR */
|
|
}
|
|
}
|
|
}
|
|
|
|
void index_conv_dec(
|
|
int *index /* (i/o) Codebook indexes */
|
|
){
|
|
int k;
|
|
|
|
for (k=1; k<CB_NSTAGES; k++) {
|
|
|
|
if ((index[k]>=44)&&(index[k]<108)) {
|
|
index[k]+=64;
|
|
} else if ((index[k]>=108)&&(index[k]<128)) {
|
|
index[k]+=128;
|
|
} else {
|
|
/* ERROR */
|
|
}
|
|
}
|
|
}
|
|
|
|
/*----------------------------------------------------------------*
|
|
* Construct decoded vector from codebook and gains.
|
|
*---------------------------------------------------------------*/
|
|
|
|
void iCBConstruct(
|
|
float *decvector, /* (o) Decoded vector */
|
|
int *index, /* (i) Codebook indices */
|
|
int *gain_index,/* (i) Gain quantization indices */
|
|
float *mem, /* (i) Buffer for codevector construction */
|
|
int lMem, /* (i) Length of buffer */
|
|
int veclen, /* (i) Length of vector */
|
|
int nStages /* (i) Number of codebook stages */
|
|
){
|
|
int j,k;
|
|
|
|
|
|
|
|
Andersen, et al. Experimental [Page 151]
|
|
|
|
RFC 3951 Internet Low Bit Rate Codec December 2004
|
|
|
|
|
|
float gain[CB_NSTAGES];
|
|
float cbvec[SUBL];
|
|
|
|
/* gain de-quantization */
|
|
|
|
gain[0] = gaindequant(gain_index[0], 1.0, 32);
|
|
if (nStages > 1) {
|
|
gain[1] = gaindequant(gain_index[1],
|
|
(float)fabs(gain[0]), 16);
|
|
}
|
|
if (nStages > 2) {
|
|
gain[2] = gaindequant(gain_index[2],
|
|
(float)fabs(gain[1]), 8);
|
|
}
|
|
|
|
/* codebook vector construction and construction of
|
|
total vector */
|
|
|
|
getCBvec(cbvec, mem, index[0], lMem, veclen);
|
|
for (j=0;j<veclen;j++){
|
|
decvector[j] = gain[0]*cbvec[j];
|
|
}
|
|
if (nStages > 1) {
|
|
for (k=1; k<nStages; k++) {
|
|
getCBvec(cbvec, mem, index[k], lMem, veclen);
|
|
for (j=0;j<veclen;j++) {
|
|
decvector[j] += gain[k]*cbvec[j];
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
A.33. iCBSearch.h
|
|
|
|
/******************************************************************
|
|
|
|
iLBC Speech Coder ANSI-C Source Code
|
|
|
|
iCBSearch.h
|
|
|
|
Copyright (C) The Internet Society (2004).
|
|
All Rights Reserved.
|
|
|
|
******************************************************************/
|
|
|
|
#ifndef __iLBC_ICBSEARCH_H
|
|
#define __iLBC_ICBSEARCH_H
|
|
|
|
|
|
|
|
|
|
Andersen, et al. Experimental [Page 152]
|
|
|
|
RFC 3951 Internet Low Bit Rate Codec December 2004
|
|
|
|
|
|
void iCBSearch(
|
|
iLBC_Enc_Inst_t *iLBCenc_inst,
|
|
/* (i) the encoder state structure */
|
|
int *index, /* (o) Codebook indices */
|
|
int *gain_index,/* (o) Gain quantization indices */
|
|
float *intarget,/* (i) Target vector for encoding */
|
|
float *mem, /* (i) Buffer for codebook construction */
|
|
int lMem, /* (i) Length of buffer */
|
|
int lTarget, /* (i) Length of vector */
|
|
int nStages, /* (i) Number of codebook stages */
|
|
float *weightDenum, /* (i) weighting filter coefficients */
|
|
float *weightState, /* (i) weighting filter state */
|
|
int block /* (i) the sub-block number */
|
|
);
|
|
|
|
#endif
|
|
|
|
A.34. iCBSearch.c
|
|
|
|
/******************************************************************
|
|
|
|
iLBC Speech Coder ANSI-C Source Code
|
|
|
|
iCBSearch.c
|
|
|
|
Copyright (C) The Internet Society (2004).
|
|
All Rights Reserved.
|
|
|
|
******************************************************************/
|
|
|
|
#include <math.h>
|
|
#include <string.h>
|
|
|
|
#include "iLBC_define.h"
|
|
#include "gainquant.h"
|
|
#include "createCB.h"
|
|
#include "filter.h"
|
|
#include "constants.h"
|
|
|
|
/*----------------------------------------------------------------*
|
|
* Search routine for codebook encoding and gain quantization.
|
|
*---------------------------------------------------------------*/
|
|
|
|
void iCBSearch(
|
|
iLBC_Enc_Inst_t *iLBCenc_inst,
|
|
/* (i) the encoder state structure */
|
|
int *index, /* (o) Codebook indices */
|
|
int *gain_index,/* (o) Gain quantization indices */
|
|
|
|
|
|
|
|
Andersen, et al. Experimental [Page 153]
|
|
|
|
RFC 3951 Internet Low Bit Rate Codec December 2004
|
|
|
|
|
|
float *intarget,/* (i) Target vector for encoding */
|
|
float *mem, /* (i) Buffer for codebook construction */
|
|
int lMem, /* (i) Length of buffer */
|
|
int lTarget, /* (i) Length of vector */
|
|
int nStages, /* (i) Number of codebook stages */
|
|
float *weightDenum, /* (i) weighting filter coefficients */
|
|
float *weightState, /* (i) weighting filter state */
|
|
int block /* (i) the sub-block number */
|
|
){
|
|
int i, j, icount, stage, best_index, range, counter;
|
|
float max_measure, gain, measure, crossDot, ftmp;
|
|
float gains[CB_NSTAGES];
|
|
float target[SUBL];
|
|
int base_index, sInd, eInd, base_size;
|
|
int sIndAug=0, eIndAug=0;
|
|
float buf[CB_MEML+SUBL+2*LPC_FILTERORDER];
|
|
float invenergy[CB_EXPAND*128], energy[CB_EXPAND*128];
|
|
float *pp, *ppi=0, *ppo=0, *ppe=0;
|
|
float cbvectors[CB_MEML];
|
|
float tene, cene, cvec[SUBL];
|
|
float aug_vec[SUBL];
|
|
|
|
memset(cvec,0,SUBL*sizeof(float));
|
|
|
|
/* Determine size of codebook sections */
|
|
|
|
base_size=lMem-lTarget+1;
|
|
|
|
if (lTarget==SUBL) {
|
|
base_size=lMem-lTarget+1+lTarget/2;
|
|
}
|
|
|
|
/* setup buffer for weighting */
|
|
|
|
memcpy(buf,weightState,sizeof(float)*LPC_FILTERORDER);
|
|
memcpy(buf+LPC_FILTERORDER,mem,lMem*sizeof(float));
|
|
memcpy(buf+LPC_FILTERORDER+lMem,intarget,lTarget*sizeof(float));
|
|
|
|
/* weighting */
|
|
|
|
AllPoleFilter(buf+LPC_FILTERORDER, weightDenum,
|
|
lMem+lTarget, LPC_FILTERORDER);
|
|
|
|
/* Construct the codebook and target needed */
|
|
|
|
memcpy(target, buf+LPC_FILTERORDER+lMem, lTarget*sizeof(float));
|
|
|
|
tene=0.0;
|
|
|
|
|
|
|
|
Andersen, et al. Experimental [Page 154]
|
|
|
|
RFC 3951 Internet Low Bit Rate Codec December 2004
|
|
|
|
|
|
for (i=0; i<lTarget; i++) {
|
|
tene+=target[i]*target[i];
|
|
}
|
|
|
|
/* Prepare search over one more codebook section. This section
|
|
is created by filtering the original buffer with a filter. */
|
|
|
|
filteredCBvecs(cbvectors, buf+LPC_FILTERORDER, lMem);
|
|
|
|
/* The Main Loop over stages */
|
|
|
|
for (stage=0; stage<nStages; stage++) {
|
|
|
|
range = search_rangeTbl[block][stage];
|
|
|
|
/* initialize search measure */
|
|
|
|
max_measure = (float)-10000000.0;
|
|
gain = (float)0.0;
|
|
best_index = 0;
|
|
|
|
/* Compute cross dot product between the target
|
|
and the CB memory */
|
|
|
|
crossDot=0.0;
|
|
pp=buf+LPC_FILTERORDER+lMem-lTarget;
|
|
for (j=0; j<lTarget; j++) {
|
|
crossDot += target[j]*(*pp++);
|
|
}
|
|
|
|
if (stage==0) {
|
|
|
|
/* Calculate energy in the first block of
|
|
'lTarget' samples. */
|
|
ppe = energy;
|
|
ppi = buf+LPC_FILTERORDER+lMem-lTarget-1;
|
|
ppo = buf+LPC_FILTERORDER+lMem-1;
|
|
|
|
*ppe=0.0;
|
|
pp=buf+LPC_FILTERORDER+lMem-lTarget;
|
|
for (j=0; j<lTarget; j++) {
|
|
*ppe+=(*pp)*(*pp++);
|
|
}
|
|
|
|
if (*ppe>0.0) {
|
|
invenergy[0] = (float) 1.0 / (*ppe + EPS);
|
|
} else {
|
|
invenergy[0] = (float) 0.0;
|
|
|
|
|
|
|
|
Andersen, et al. Experimental [Page 155]
|
|
|
|
RFC 3951 Internet Low Bit Rate Codec December 2004
|
|
|
|
|
|
}
|
|
ppe++;
|
|
|
|
measure=(float)-10000000.0;
|
|
|
|
if (crossDot > 0.0) {
|
|
measure = crossDot*crossDot*invenergy[0];
|
|
}
|
|
}
|
|
else {
|
|
measure = crossDot*crossDot*invenergy[0];
|
|
}
|
|
|
|
/* check if measure is better */
|
|
ftmp = crossDot*invenergy[0];
|
|
|
|
if ((measure>max_measure) && (fabs(ftmp)<CB_MAXGAIN)) {
|
|
best_index = 0;
|
|
max_measure = measure;
|
|
gain = ftmp;
|
|
}
|
|
|
|
/* loop over the main first codebook section,
|
|
full search */
|
|
|
|
for (icount=1; icount<range; icount++) {
|
|
|
|
/* calculate measure */
|
|
|
|
crossDot=0.0;
|
|
pp = buf+LPC_FILTERORDER+lMem-lTarget-icount;
|
|
|
|
for (j=0; j<lTarget; j++) {
|
|
crossDot += target[j]*(*pp++);
|
|
}
|
|
|
|
if (stage==0) {
|
|
*ppe++ = energy[icount-1] + (*ppi)*(*ppi) -
|
|
(*ppo)*(*ppo);
|
|
ppo--;
|
|
ppi--;
|
|
|
|
if (energy[icount]>0.0) {
|
|
invenergy[icount] =
|
|
(float)1.0/(energy[icount]+EPS);
|
|
} else {
|
|
invenergy[icount] = (float) 0.0;
|
|
}
|
|
|
|
|
|
|
|
Andersen, et al. Experimental [Page 156]
|
|
|
|
RFC 3951 Internet Low Bit Rate Codec December 2004
|
|
|
|
|
|
measure=(float)-10000000.0;
|
|
|
|
if (crossDot > 0.0) {
|
|
measure = crossDot*crossDot*invenergy[icount];
|
|
}
|
|
}
|
|
else {
|
|
measure = crossDot*crossDot*invenergy[icount];
|
|
}
|
|
|
|
/* check if measure is better */
|
|
ftmp = crossDot*invenergy[icount];
|
|
|
|
if ((measure>max_measure) && (fabs(ftmp)<CB_MAXGAIN)) {
|
|
best_index = icount;
|
|
max_measure = measure;
|
|
gain = ftmp;
|
|
}
|
|
}
|
|
|
|
/* Loop over augmented part in the first codebook
|
|
* section, full search.
|
|
* The vectors are interpolated.
|
|
*/
|
|
|
|
if (lTarget==SUBL) {
|
|
|
|
/* Search for best possible cb vector and
|
|
compute the CB-vectors' energy. */
|
|
searchAugmentedCB(20, 39, stage, base_size-lTarget/2,
|
|
target, buf+LPC_FILTERORDER+lMem,
|
|
&max_measure, &best_index, &gain, energy,
|
|
invenergy);
|
|
}
|
|
|
|
/* set search range for following codebook sections */
|
|
|
|
base_index=best_index;
|
|
|
|
/* unrestricted search */
|
|
|
|
if (CB_RESRANGE == -1) {
|
|
sInd=0;
|
|
eInd=range-1;
|
|
sIndAug=20;
|
|
eIndAug=39;
|
|
}
|
|
|
|
|
|
|
|
|
|
Andersen, et al. Experimental [Page 157]
|
|
|
|
RFC 3951 Internet Low Bit Rate Codec December 2004
|
|
|
|
|
|
/* restricted search around best index from first
|
|
codebook section */
|
|
|
|
else {
|
|
/* Initialize search indices */
|
|
sIndAug=0;
|
|
eIndAug=0;
|
|
sInd=base_index-CB_RESRANGE/2;
|
|
eInd=sInd+CB_RESRANGE;
|
|
|
|
if (lTarget==SUBL) {
|
|
|
|
if (sInd<0) {
|
|
|
|
sIndAug = 40 + sInd;
|
|
eIndAug = 39;
|
|
sInd=0;
|
|
|
|
} else if ( base_index < (base_size-20) ) {
|
|
|
|
if (eInd > range) {
|
|
sInd -= (eInd-range);
|
|
eInd = range;
|
|
}
|
|
} else { /* base_index >= (base_size-20) */
|
|
|
|
if (sInd < (base_size-20)) {
|
|
sIndAug = 20;
|
|
sInd = 0;
|
|
eInd = 0;
|
|
eIndAug = 19 + CB_RESRANGE;
|
|
|
|
if(eIndAug > 39) {
|
|
eInd = eIndAug-39;
|
|
eIndAug = 39;
|
|
}
|
|
} else {
|
|
sIndAug = 20 + sInd - (base_size-20);
|
|
eIndAug = 39;
|
|
sInd = 0;
|
|
eInd = CB_RESRANGE - (eIndAug-sIndAug+1);
|
|
}
|
|
}
|
|
|
|
} else { /* lTarget = 22 or 23 */
|
|
|
|
if (sInd < 0) {
|
|
eInd -= sInd;
|
|
|
|
|
|
|
|
Andersen, et al. Experimental [Page 158]
|
|
|
|
RFC 3951 Internet Low Bit Rate Codec December 2004
|
|
|
|
|
|
sInd = 0;
|
|
}
|
|
|
|
if(eInd > range) {
|
|
sInd -= (eInd - range);
|
|
eInd = range;
|
|
}
|
|
}
|
|
}
|
|
|
|
/* search of higher codebook section */
|
|
|
|
/* index search range */
|
|
counter = sInd;
|
|
sInd += base_size;
|
|
eInd += base_size;
|
|
|
|
|
|
if (stage==0) {
|
|
ppe = energy+base_size;
|
|
*ppe=0.0;
|
|
|
|
pp=cbvectors+lMem-lTarget;
|
|
for (j=0; j<lTarget; j++) {
|
|
*ppe+=(*pp)*(*pp++);
|
|
}
|
|
|
|
ppi = cbvectors + lMem - 1 - lTarget;
|
|
ppo = cbvectors + lMem - 1;
|
|
|
|
for (j=0; j<(range-1); j++) {
|
|
*(ppe+1) = *ppe + (*ppi)*(*ppi) - (*ppo)*(*ppo);
|
|
ppo--;
|
|
ppi--;
|
|
ppe++;
|
|
}
|
|
}
|
|
|
|
/* loop over search range */
|
|
|
|
for (icount=sInd; icount<eInd; icount++) {
|
|
|
|
/* calculate measure */
|
|
|
|
crossDot=0.0;
|
|
pp=cbvectors + lMem - (counter++) - lTarget;
|
|
|
|
for (j=0;j<lTarget;j++) {
|
|
|
|
|
|
|
|
Andersen, et al. Experimental [Page 159]
|
|
|
|
RFC 3951 Internet Low Bit Rate Codec December 2004
|
|
|
|
|
|
crossDot += target[j]*(*pp++);
|
|
}
|
|
|
|
if (energy[icount]>0.0) {
|
|
invenergy[icount] =(float)1.0/(energy[icount]+EPS);
|
|
} else {
|
|
invenergy[icount] =(float)0.0;
|
|
}
|
|
|
|
if (stage==0) {
|
|
|
|
measure=(float)-10000000.0;
|
|
|
|
if (crossDot > 0.0) {
|
|
measure = crossDot*crossDot*
|
|
invenergy[icount];
|
|
}
|
|
}
|
|
else {
|
|
measure = crossDot*crossDot*invenergy[icount];
|
|
}
|
|
|
|
/* check if measure is better */
|
|
ftmp = crossDot*invenergy[icount];
|
|
|
|
if ((measure>max_measure) && (fabs(ftmp)<CB_MAXGAIN)) {
|
|
best_index = icount;
|
|
max_measure = measure;
|
|
gain = ftmp;
|
|
}
|
|
}
|
|
|
|
/* Search the augmented CB inside the limited range. */
|
|
|
|
if ((lTarget==SUBL)&&(sIndAug!=0)) {
|
|
searchAugmentedCB(sIndAug, eIndAug, stage,
|
|
2*base_size-20, target, cbvectors+lMem,
|
|
&max_measure, &best_index, &gain, energy,
|
|
invenergy);
|
|
}
|
|
|
|
/* record best index */
|
|
|
|
index[stage] = best_index;
|
|
|
|
/* gain quantization */
|
|
|
|
if (stage==0){
|
|
|
|
|
|
|
|
Andersen, et al. Experimental [Page 160]
|
|
|
|
RFC 3951 Internet Low Bit Rate Codec December 2004
|
|
|
|
|
|
|
|
if (gain<0.0){
|
|
gain = 0.0;
|
|
}
|
|
|
|
if (gain>CB_MAXGAIN) {
|
|
gain = (float)CB_MAXGAIN;
|
|
}
|
|
gain = gainquant(gain, 1.0, 32, &gain_index[stage]);
|
|
}
|
|
else {
|
|
if (stage==1) {
|
|
gain = gainquant(gain, (float)fabs(gains[stage-1]),
|
|
16, &gain_index[stage]);
|
|
} else {
|
|
gain = gainquant(gain, (float)fabs(gains[stage-1]),
|
|
8, &gain_index[stage]);
|
|
}
|
|
}
|
|
|
|
/* Extract the best (according to measure)
|
|
codebook vector */
|
|
|
|
if (lTarget==(STATE_LEN-iLBCenc_inst->state_short_len)) {
|
|
|
|
if (index[stage]<base_size) {
|
|
pp=buf+LPC_FILTERORDER+lMem-lTarget-index[stage];
|
|
} else {
|
|
pp=cbvectors+lMem-lTarget-
|
|
index[stage]+base_size;
|
|
}
|
|
} else {
|
|
|
|
if (index[stage]<base_size) {
|
|
if (index[stage]<(base_size-20)) {
|
|
pp=buf+LPC_FILTERORDER+lMem-
|
|
lTarget-index[stage];
|
|
} else {
|
|
createAugmentedVec(index[stage]-base_size+40,
|
|
buf+LPC_FILTERORDER+lMem,aug_vec);
|
|
pp=aug_vec;
|
|
}
|
|
} else {
|
|
int filterno, position;
|
|
|
|
filterno=index[stage]/base_size;
|
|
position=index[stage]-filterno*base_size;
|
|
|
|
|
|
|
|
|
|
Andersen, et al. Experimental [Page 161]
|
|
|
|
RFC 3951 Internet Low Bit Rate Codec December 2004
|
|
|
|
|
|
|
|
if (position<(base_size-20)) {
|
|
pp=cbvectors+filterno*lMem-lTarget-
|
|
index[stage]+filterno*base_size;
|
|
} else {
|
|
createAugmentedVec(
|
|
index[stage]-(filterno+1)*base_size+40,
|
|
cbvectors+filterno*lMem,aug_vec);
|
|
pp=aug_vec;
|
|
}
|
|
}
|
|
}
|
|
|
|
/* Subtract the best codebook vector, according
|
|
to measure, from the target vector */
|
|
|
|
for (j=0;j<lTarget;j++) {
|
|
cvec[j] += gain*(*pp);
|
|
target[j] -= gain*(*pp++);
|
|
}
|
|
|
|
/* record quantized gain */
|
|
|
|
gains[stage]=gain;
|
|
|
|
}/* end of Main Loop. for (stage=0;... */
|
|
|
|
/* Gain adjustment for energy matching */
|
|
cene=0.0;
|
|
for (i=0; i<lTarget; i++) {
|
|
cene+=cvec[i]*cvec[i];
|
|
}
|
|
j=gain_index[0];
|
|
|
|
for (i=gain_index[0]; i<32; i++) {
|
|
ftmp=cene*gain_sq5Tbl[i]*gain_sq5Tbl[i];
|
|
|
|
if ((ftmp<(tene*gains[0]*gains[0])) &&
|
|
(gain_sq5Tbl[j]<(2.0*gains[0]))) {
|
|
j=i;
|
|
}
|
|
}
|
|
gain_index[0]=j;
|
|
}
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
Andersen, et al. Experimental [Page 162]
|
|
|
|
RFC 3951 Internet Low Bit Rate Codec December 2004
|
|
|
|
|
|
A.35. LPCdecode.h
|
|
|
|
/******************************************************************
|
|
|
|
iLBC Speech Coder ANSI-C Source Code
|
|
|
|
LPC_decode.h
|
|
|
|
Copyright (C) The Internet Society (2004).
|
|
All Rights Reserved.
|
|
|
|
******************************************************************/
|
|
|
|
#ifndef __iLBC_LPC_DECODE_H
|
|
#define __iLBC_LPC_DECODE_H
|
|
|
|
void LSFinterpolate2a_dec(
|
|
float *a, /* (o) lpc coefficients for a sub-frame */
|
|
float *lsf1, /* (i) first lsf coefficient vector */
|
|
float *lsf2, /* (i) second lsf coefficient vector */
|
|
float coef, /* (i) interpolation weight */
|
|
int length /* (i) length of lsf vectors */
|
|
);
|
|
|
|
void SimplelsfDEQ(
|
|
float *lsfdeq, /* (o) dequantized lsf coefficients */
|
|
int *index, /* (i) quantization index */
|
|
int lpc_n /* (i) number of LPCs */
|
|
);
|
|
|
|
void DecoderInterpolateLSF(
|
|
float *syntdenum, /* (o) synthesis filter coefficients */
|
|
float *weightdenum, /* (o) weighting denumerator
|
|
coefficients */
|
|
float *lsfdeq, /* (i) dequantized lsf coefficients */
|
|
int length, /* (i) length of lsf coefficient vector */
|
|
iLBC_Dec_Inst_t *iLBCdec_inst
|
|
/* (i) the decoder state structure */
|
|
);
|
|
|
|
#endif
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
Andersen, et al. Experimental [Page 163]
|
|
|
|
RFC 3951 Internet Low Bit Rate Codec December 2004
|
|
|
|
|
|
A.36. LPCdecode.c
|
|
|
|
/******************************************************************
|
|
|
|
iLBC Speech Coder ANSI-C Source Code
|
|
|
|
LPC_decode.c
|
|
|
|
Copyright (C) The Internet Society (2004).
|
|
All Rights Reserved.
|
|
|
|
******************************************************************/
|
|
|
|
#include <math.h>
|
|
#include <string.h>
|
|
|
|
#include "helpfun.h"
|
|
#include "lsf.h"
|
|
#include "iLBC_define.h"
|
|
#include "constants.h"
|
|
|
|
/*---------------------------------------------------------------*
|
|
* interpolation of lsf coefficients for the decoder
|
|
*--------------------------------------------------------------*/
|
|
|
|
void LSFinterpolate2a_dec(
|
|
float *a, /* (o) lpc coefficients for a sub-frame */
|
|
float *lsf1, /* (i) first lsf coefficient vector */
|
|
float *lsf2, /* (i) second lsf coefficient vector */
|
|
float coef, /* (i) interpolation weight */
|
|
int length /* (i) length of lsf vectors */
|
|
){
|
|
float lsftmp[LPC_FILTERORDER];
|
|
|
|
interpolate(lsftmp, lsf1, lsf2, coef, length);
|
|
lsf2a(a, lsftmp);
|
|
}
|
|
|
|
/*---------------------------------------------------------------*
|
|
* obtain dequantized lsf coefficients from quantization index
|
|
*--------------------------------------------------------------*/
|
|
|
|
void SimplelsfDEQ(
|
|
float *lsfdeq, /* (o) dequantized lsf coefficients */
|
|
int *index, /* (i) quantization index */
|
|
int lpc_n /* (i) number of LPCs */
|
|
){
|
|
int i, j, pos, cb_pos;
|
|
|
|
|
|
|
|
Andersen, et al. Experimental [Page 164]
|
|
|
|
RFC 3951 Internet Low Bit Rate Codec December 2004
|
|
|
|
|
|
/* decode first LSF */
|
|
|
|
pos = 0;
|
|
cb_pos = 0;
|
|
for (i = 0; i < LSF_NSPLIT; i++) {
|
|
for (j = 0; j < dim_lsfCbTbl[i]; j++) {
|
|
lsfdeq[pos + j] = lsfCbTbl[cb_pos +
|
|
(long)(index[i])*dim_lsfCbTbl[i] + j];
|
|
}
|
|
pos += dim_lsfCbTbl[i];
|
|
cb_pos += size_lsfCbTbl[i]*dim_lsfCbTbl[i];
|
|
}
|
|
|
|
if (lpc_n>1) {
|
|
|
|
/* decode last LSF */
|
|
|
|
pos = 0;
|
|
cb_pos = 0;
|
|
for (i = 0; i < LSF_NSPLIT; i++) {
|
|
for (j = 0; j < dim_lsfCbTbl[i]; j++) {
|
|
lsfdeq[LPC_FILTERORDER + pos + j] =
|
|
lsfCbTbl[cb_pos +
|
|
(long)(index[LSF_NSPLIT + i])*
|
|
dim_lsfCbTbl[i] + j];
|
|
}
|
|
pos += dim_lsfCbTbl[i];
|
|
cb_pos += size_lsfCbTbl[i]*dim_lsfCbTbl[i];
|
|
}
|
|
}
|
|
}
|
|
|
|
/*----------------------------------------------------------------*
|
|
* obtain synthesis and weighting filters form lsf coefficients
|
|
*---------------------------------------------------------------*/
|
|
|
|
void DecoderInterpolateLSF(
|
|
float *syntdenum, /* (o) synthesis filter coefficients */
|
|
float *weightdenum, /* (o) weighting denumerator
|
|
coefficients */
|
|
float *lsfdeq, /* (i) dequantized lsf coefficients */
|
|
int length, /* (i) length of lsf coefficient vector */
|
|
iLBC_Dec_Inst_t *iLBCdec_inst
|
|
/* (i) the decoder state structure */
|
|
){
|
|
int i, pos, lp_length;
|
|
float lp[LPC_FILTERORDER + 1], *lsfdeq2;
|
|
|
|
|
|
|
|
|
|
Andersen, et al. Experimental [Page 165]
|
|
|
|
RFC 3951 Internet Low Bit Rate Codec December 2004
|
|
|
|
|
|
lsfdeq2 = lsfdeq + length;
|
|
lp_length = length + 1;
|
|
|
|
if (iLBCdec_inst->mode==30) {
|
|
/* sub-frame 1: Interpolation between old and first */
|
|
|
|
LSFinterpolate2a_dec(lp, iLBCdec_inst->lsfdeqold, lsfdeq,
|
|
lsf_weightTbl_30ms[0], length);
|
|
memcpy(syntdenum,lp,lp_length*sizeof(float));
|
|
bwexpand(weightdenum, lp, LPC_CHIRP_WEIGHTDENUM,
|
|
lp_length);
|
|
|
|
/* sub-frames 2 to 6: interpolation between first
|
|
and last LSF */
|
|
|
|
pos = lp_length;
|
|
for (i = 1; i < 6; i++) {
|
|
LSFinterpolate2a_dec(lp, lsfdeq, lsfdeq2,
|
|
lsf_weightTbl_30ms[i], length);
|
|
memcpy(syntdenum + pos,lp,lp_length*sizeof(float));
|
|
bwexpand(weightdenum + pos, lp,
|
|
LPC_CHIRP_WEIGHTDENUM, lp_length);
|
|
pos += lp_length;
|
|
}
|
|
}
|
|
else {
|
|
pos = 0;
|
|
for (i = 0; i < iLBCdec_inst->nsub; i++) {
|
|
LSFinterpolate2a_dec(lp, iLBCdec_inst->lsfdeqold,
|
|
lsfdeq, lsf_weightTbl_20ms[i], length);
|
|
memcpy(syntdenum+pos,lp,lp_length*sizeof(float));
|
|
bwexpand(weightdenum+pos, lp, LPC_CHIRP_WEIGHTDENUM,
|
|
lp_length);
|
|
pos += lp_length;
|
|
}
|
|
}
|
|
|
|
/* update memory */
|
|
|
|
if (iLBCdec_inst->mode==30)
|
|
memcpy(iLBCdec_inst->lsfdeqold, lsfdeq2,
|
|
length*sizeof(float));
|
|
else
|
|
memcpy(iLBCdec_inst->lsfdeqold, lsfdeq,
|
|
length*sizeof(float));
|
|
|
|
}
|
|
|
|
|
|
|
|
|
|
Andersen, et al. Experimental [Page 166]
|
|
|
|
RFC 3951 Internet Low Bit Rate Codec December 2004
|
|
|
|
|
|
A.37. LPCencode.h
|
|
|
|
/******************************************************************
|
|
|
|
iLBC Speech Coder ANSI-C Source Code
|
|
|
|
LPCencode.h
|
|
|
|
Copyright (C) The Internet Society (2004).
|
|
All Rights Reserved.
|
|
|
|
******************************************************************/
|
|
|
|
#ifndef __iLBC_LPCENCOD_H
|
|
#define __iLBC_LPCENCOD_H
|
|
|
|
void LPCencode(
|
|
float *syntdenum, /* (i/o) synthesis filter coefficients
|
|
before/after encoding */
|
|
float *weightdenum, /* (i/o) weighting denumerator coefficients
|
|
before/after encoding */
|
|
int *lsf_index, /* (o) lsf quantization index */
|
|
float *data, /* (i) lsf coefficients to quantize */
|
|
iLBC_Enc_Inst_t *iLBCenc_inst
|
|
/* (i/o) the encoder state structure */
|
|
);
|
|
|
|
#endif
|
|
|
|
A.38. LPCencode.c
|
|
|
|
/******************************************************************
|
|
|
|
iLBC Speech Coder ANSI-C Source Code
|
|
|
|
LPCencode.c
|
|
|
|
Copyright (C) The Internet Society (2004).
|
|
All Rights Reserved.
|
|
|
|
******************************************************************/
|
|
|
|
#include <string.h>
|
|
|
|
#include "iLBC_define.h"
|
|
#include "helpfun.h"
|
|
#include "lsf.h"
|
|
#include "constants.h"
|
|
|
|
|
|
|
|
Andersen, et al. Experimental [Page 167]
|
|
|
|
RFC 3951 Internet Low Bit Rate Codec December 2004
|
|
|
|
|
|
/*----------------------------------------------------------------*
|
|
* lpc analysis (subroutine to LPCencode)
|
|
*---------------------------------------------------------------*/
|
|
|
|
void SimpleAnalysis(
|
|
float *lsf, /* (o) lsf coefficients */
|
|
float *data, /* (i) new data vector */
|
|
iLBC_Enc_Inst_t *iLBCenc_inst
|
|
/* (i/o) the encoder state structure */
|
|
){
|
|
int k, is;
|
|
float temp[BLOCKL_MAX], lp[LPC_FILTERORDER + 1];
|
|
float lp2[LPC_FILTERORDER + 1];
|
|
float r[LPC_FILTERORDER + 1];
|
|
|
|
is=LPC_LOOKBACK+BLOCKL_MAX-iLBCenc_inst->blockl;
|
|
memcpy(iLBCenc_inst->lpc_buffer+is,data,
|
|
iLBCenc_inst->blockl*sizeof(float));
|
|
|
|
/* No lookahead, last window is asymmetric */
|
|
|
|
for (k = 0; k < iLBCenc_inst->lpc_n; k++) {
|
|
|
|
is = LPC_LOOKBACK;
|
|
|
|
if (k < (iLBCenc_inst->lpc_n - 1)) {
|
|
window(temp, lpc_winTbl,
|
|
iLBCenc_inst->lpc_buffer, BLOCKL_MAX);
|
|
} else {
|
|
window(temp, lpc_asymwinTbl,
|
|
iLBCenc_inst->lpc_buffer + is, BLOCKL_MAX);
|
|
}
|
|
|
|
autocorr(r, temp, BLOCKL_MAX, LPC_FILTERORDER);
|
|
window(r, r, lpc_lagwinTbl, LPC_FILTERORDER + 1);
|
|
|
|
levdurb(lp, temp, r, LPC_FILTERORDER);
|
|
bwexpand(lp2, lp, LPC_CHIRP_SYNTDENUM, LPC_FILTERORDER+1);
|
|
|
|
a2lsf(lsf + k*LPC_FILTERORDER, lp2);
|
|
}
|
|
is=LPC_LOOKBACK+BLOCKL_MAX-iLBCenc_inst->blockl;
|
|
memmove(iLBCenc_inst->lpc_buffer,
|
|
iLBCenc_inst->lpc_buffer+LPC_LOOKBACK+BLOCKL_MAX-is,
|
|
is*sizeof(float));
|
|
}
|
|
|
|
/*----------------------------------------------------------------*
|
|
|
|
|
|
|
|
Andersen, et al. Experimental [Page 168]
|
|
|
|
RFC 3951 Internet Low Bit Rate Codec December 2004
|
|
|
|
|
|
* lsf interpolator and conversion from lsf to a coefficients
|
|
* (subroutine to SimpleInterpolateLSF)
|
|
*---------------------------------------------------------------*/
|
|
|
|
void LSFinterpolate2a_enc(
|
|
float *a, /* (o) lpc coefficients */
|
|
float *lsf1,/* (i) first set of lsf coefficients */
|
|
float *lsf2,/* (i) second set of lsf coefficients */
|
|
float coef, /* (i) weighting coefficient to use between
|
|
lsf1 and lsf2 */
|
|
long length /* (i) length of coefficient vectors */
|
|
){
|
|
float lsftmp[LPC_FILTERORDER];
|
|
|
|
interpolate(lsftmp, lsf1, lsf2, coef, length);
|
|
lsf2a(a, lsftmp);
|
|
}
|
|
|
|
/*----------------------------------------------------------------*
|
|
* lsf interpolator (subroutine to LPCencode)
|
|
*---------------------------------------------------------------*/
|
|
|
|
void SimpleInterpolateLSF(
|
|
float *syntdenum, /* (o) the synthesis filter denominator
|
|
resulting from the quantized
|
|
interpolated lsf */
|
|
float *weightdenum, /* (o) the weighting filter denominator
|
|
resulting from the unquantized
|
|
interpolated lsf */
|
|
float *lsf, /* (i) the unquantized lsf coefficients */
|
|
float *lsfdeq, /* (i) the dequantized lsf coefficients */
|
|
float *lsfold, /* (i) the unquantized lsf coefficients of
|
|
the previous signal frame */
|
|
float *lsfdeqold, /* (i) the dequantized lsf coefficients of
|
|
the previous signal frame */
|
|
int length, /* (i) should equate LPC_FILTERORDER */
|
|
iLBC_Enc_Inst_t *iLBCenc_inst
|
|
/* (i/o) the encoder state structure */
|
|
){
|
|
int i, pos, lp_length;
|
|
float lp[LPC_FILTERORDER + 1], *lsf2, *lsfdeq2;
|
|
|
|
lsf2 = lsf + length;
|
|
lsfdeq2 = lsfdeq + length;
|
|
lp_length = length + 1;
|
|
|
|
if (iLBCenc_inst->mode==30) {
|
|
/* sub-frame 1: Interpolation between old and first
|
|
|
|
|
|
|
|
Andersen, et al. Experimental [Page 169]
|
|
|
|
RFC 3951 Internet Low Bit Rate Codec December 2004
|
|
|
|
|
|
set of lsf coefficients */
|
|
|
|
LSFinterpolate2a_enc(lp, lsfdeqold, lsfdeq,
|
|
lsf_weightTbl_30ms[0], length);
|
|
memcpy(syntdenum,lp,lp_length*sizeof(float));
|
|
LSFinterpolate2a_enc(lp, lsfold, lsf,
|
|
lsf_weightTbl_30ms[0], length);
|
|
bwexpand(weightdenum, lp, LPC_CHIRP_WEIGHTDENUM, lp_length);
|
|
|
|
/* sub-frame 2 to 6: Interpolation between first
|
|
and second set of lsf coefficients */
|
|
|
|
pos = lp_length;
|
|
for (i = 1; i < iLBCenc_inst->nsub; i++) {
|
|
LSFinterpolate2a_enc(lp, lsfdeq, lsfdeq2,
|
|
lsf_weightTbl_30ms[i], length);
|
|
memcpy(syntdenum + pos,lp,lp_length*sizeof(float));
|
|
|
|
LSFinterpolate2a_enc(lp, lsf, lsf2,
|
|
lsf_weightTbl_30ms[i], length);
|
|
bwexpand(weightdenum + pos, lp,
|
|
LPC_CHIRP_WEIGHTDENUM, lp_length);
|
|
pos += lp_length;
|
|
}
|
|
}
|
|
else {
|
|
pos = 0;
|
|
for (i = 0; i < iLBCenc_inst->nsub; i++) {
|
|
LSFinterpolate2a_enc(lp, lsfdeqold, lsfdeq,
|
|
lsf_weightTbl_20ms[i], length);
|
|
memcpy(syntdenum+pos,lp,lp_length*sizeof(float));
|
|
LSFinterpolate2a_enc(lp, lsfold, lsf,
|
|
lsf_weightTbl_20ms[i], length);
|
|
bwexpand(weightdenum+pos, lp,
|
|
LPC_CHIRP_WEIGHTDENUM, lp_length);
|
|
pos += lp_length;
|
|
}
|
|
}
|
|
|
|
/* update memory */
|
|
|
|
if (iLBCenc_inst->mode==30) {
|
|
memcpy(lsfold, lsf2, length*sizeof(float));
|
|
memcpy(lsfdeqold, lsfdeq2, length*sizeof(float));
|
|
}
|
|
else {
|
|
memcpy(lsfold, lsf, length*sizeof(float));
|
|
memcpy(lsfdeqold, lsfdeq, length*sizeof(float));
|
|
|
|
|
|
|
|
Andersen, et al. Experimental [Page 170]
|
|
|
|
RFC 3951 Internet Low Bit Rate Codec December 2004
|
|
|
|
|
|
}
|
|
}
|
|
|
|
/*----------------------------------------------------------------*
|
|
* lsf quantizer (subroutine to LPCencode)
|
|
*---------------------------------------------------------------*/
|
|
|
|
void SimplelsfQ(
|
|
float *lsfdeq, /* (o) dequantized lsf coefficients
|
|
(dimension FILTERORDER) */
|
|
int *index, /* (o) quantization index */
|
|
float *lsf, /* (i) the lsf coefficient vector to be
|
|
quantized (dimension FILTERORDER ) */
|
|
int lpc_n /* (i) number of lsf sets to quantize */
|
|
){
|
|
/* Quantize first LSF with memoryless split VQ */
|
|
SplitVQ(lsfdeq, index, lsf, lsfCbTbl, LSF_NSPLIT,
|
|
dim_lsfCbTbl, size_lsfCbTbl);
|
|
|
|
if (lpc_n==2) {
|
|
/* Quantize second LSF with memoryless split VQ */
|
|
SplitVQ(lsfdeq + LPC_FILTERORDER, index + LSF_NSPLIT,
|
|
lsf + LPC_FILTERORDER, lsfCbTbl, LSF_NSPLIT,
|
|
dim_lsfCbTbl, size_lsfCbTbl);
|
|
}
|
|
}
|
|
|
|
/*----------------------------------------------------------------*
|
|
* lpc encoder
|
|
*---------------------------------------------------------------*/
|
|
|
|
void LPCencode(
|
|
float *syntdenum, /* (i/o) synthesis filter coefficients
|
|
before/after encoding */
|
|
float *weightdenum, /* (i/o) weighting denumerator
|
|
coefficients before/after
|
|
encoding */
|
|
int *lsf_index, /* (o) lsf quantization index */
|
|
float *data, /* (i) lsf coefficients to quantize */
|
|
iLBC_Enc_Inst_t *iLBCenc_inst
|
|
/* (i/o) the encoder state structure */
|
|
){
|
|
float lsf[LPC_FILTERORDER * LPC_N_MAX];
|
|
float lsfdeq[LPC_FILTERORDER * LPC_N_MAX];
|
|
int change=0;
|
|
|
|
SimpleAnalysis(lsf, data, iLBCenc_inst);
|
|
SimplelsfQ(lsfdeq, lsf_index, lsf, iLBCenc_inst->lpc_n);
|
|
|
|
|
|
|
|
Andersen, et al. Experimental [Page 171]
|
|
|
|
RFC 3951 Internet Low Bit Rate Codec December 2004
|
|
|
|
|
|
change=LSF_check(lsfdeq, LPC_FILTERORDER, iLBCenc_inst->lpc_n);
|
|
SimpleInterpolateLSF(syntdenum, weightdenum,
|
|
lsf, lsfdeq, iLBCenc_inst->lsfold,
|
|
iLBCenc_inst->lsfdeqold, LPC_FILTERORDER, iLBCenc_inst);
|
|
}
|
|
|
|
A.39. lsf.h
|
|
|
|
/******************************************************************
|
|
|
|
iLBC Speech Coder ANSI-C Source Code
|
|
|
|
lsf.h
|
|
|
|
Copyright (C) The Internet Society (2004).
|
|
All Rights Reserved.
|
|
|
|
******************************************************************/
|
|
|
|
#ifndef __iLBC_LSF_H
|
|
#define __iLBC_LSF_H
|
|
|
|
void a2lsf(
|
|
float *freq,/* (o) lsf coefficients */
|
|
float *a /* (i) lpc coefficients */
|
|
);
|
|
|
|
void lsf2a(
|
|
float *a_coef, /* (o) lpc coefficients */
|
|
float *freq /* (i) lsf coefficients */
|
|
);
|
|
|
|
#endif
|
|
|
|
A.40. lsf.c
|
|
|
|
/******************************************************************
|
|
|
|
iLBC Speech Coder ANSI-C Source Code
|
|
|
|
lsf.c
|
|
|
|
Copyright (C) The Internet Society (2004).
|
|
All Rights Reserved.
|
|
|
|
******************************************************************/
|
|
|
|
#include <string.h>
|
|
|
|
|
|
|
|
Andersen, et al. Experimental [Page 172]
|
|
|
|
RFC 3951 Internet Low Bit Rate Codec December 2004
|
|
|
|
|
|
#include <math.h>
|
|
|
|
#include "iLBC_define.h"
|
|
|
|
/*----------------------------------------------------------------*
|
|
* conversion from lpc coefficients to lsf coefficients
|
|
*---------------------------------------------------------------*/
|
|
|
|
void a2lsf(
|
|
float *freq,/* (o) lsf coefficients */
|
|
float *a /* (i) lpc coefficients */
|
|
){
|
|
float steps[LSF_NUMBER_OF_STEPS] =
|
|
{(float)0.00635, (float)0.003175, (float)0.0015875,
|
|
(float)0.00079375};
|
|
float step;
|
|
int step_idx;
|
|
int lsp_index;
|
|
float p[LPC_HALFORDER];
|
|
float q[LPC_HALFORDER];
|
|
float p_pre[LPC_HALFORDER];
|
|
float q_pre[LPC_HALFORDER];
|
|
float old_p, old_q, *old;
|
|
float *pq_coef;
|
|
float omega, old_omega;
|
|
int i;
|
|
float hlp, hlp1, hlp2, hlp3, hlp4, hlp5;
|
|
|
|
for (i=0; i<LPC_HALFORDER; i++) {
|
|
p[i] = (float)-1.0 * (a[i + 1] + a[LPC_FILTERORDER - i]);
|
|
q[i] = a[LPC_FILTERORDER - i] - a[i + 1];
|
|
}
|
|
|
|
p_pre[0] = (float)-1.0 - p[0];
|
|
p_pre[1] = - p_pre[0] - p[1];
|
|
p_pre[2] = - p_pre[1] - p[2];
|
|
p_pre[3] = - p_pre[2] - p[3];
|
|
p_pre[4] = - p_pre[3] - p[4];
|
|
p_pre[4] = p_pre[4] / 2;
|
|
|
|
q_pre[0] = (float)1.0 - q[0];
|
|
q_pre[1] = q_pre[0] - q[1];
|
|
q_pre[2] = q_pre[1] - q[2];
|
|
q_pre[3] = q_pre[2] - q[3];
|
|
q_pre[4] = q_pre[3] - q[4];
|
|
q_pre[4] = q_pre[4] / 2;
|
|
|
|
omega = 0.0;
|
|
|
|
|
|
|
|
Andersen, et al. Experimental [Page 173]
|
|
|
|
RFC 3951 Internet Low Bit Rate Codec December 2004
|
|
|
|
|
|
old_omega = 0.0;
|
|
|
|
old_p = FLOAT_MAX;
|
|
old_q = FLOAT_MAX;
|
|
|
|
/* Here we loop through lsp_index to find all the
|
|
LPC_FILTERORDER roots for omega. */
|
|
|
|
for (lsp_index = 0; lsp_index<LPC_FILTERORDER; lsp_index++) {
|
|
|
|
/* Depending on lsp_index being even or odd, we
|
|
alternatively solve the roots for the two LSP equations. */
|
|
|
|
|
|
if ((lsp_index & 0x1) == 0) {
|
|
pq_coef = p_pre;
|
|
old = &old_p;
|
|
} else {
|
|
pq_coef = q_pre;
|
|
old = &old_q;
|
|
}
|
|
|
|
/* Start with low resolution grid */
|
|
|
|
for (step_idx = 0, step = steps[step_idx];
|
|
step_idx < LSF_NUMBER_OF_STEPS;){
|
|
|
|
/* cos(10piw) + pq(0)cos(8piw) + pq(1)cos(6piw) +
|
|
pq(2)cos(4piw) + pq(3)cod(2piw) + pq(4) */
|
|
|
|
hlp = (float)cos(omega * TWO_PI);
|
|
hlp1 = (float)2.0 * hlp + pq_coef[0];
|
|
hlp2 = (float)2.0 * hlp * hlp1 - (float)1.0 +
|
|
pq_coef[1];
|
|
hlp3 = (float)2.0 * hlp * hlp2 - hlp1 + pq_coef[2];
|
|
hlp4 = (float)2.0 * hlp * hlp3 - hlp2 + pq_coef[3];
|
|
hlp5 = hlp * hlp4 - hlp3 + pq_coef[4];
|
|
|
|
|
|
if (((hlp5 * (*old)) <= 0.0) || (omega >= 0.5)){
|
|
|
|
if (step_idx == (LSF_NUMBER_OF_STEPS - 1)){
|
|
|
|
if (fabs(hlp5) >= fabs(*old)) {
|
|
freq[lsp_index] = omega - step;
|
|
} else {
|
|
freq[lsp_index] = omega;
|
|
}
|
|
|
|
|
|
|
|
Andersen, et al. Experimental [Page 174]
|
|
|
|
RFC 3951 Internet Low Bit Rate Codec December 2004
|
|
|
|
|
|
|
|
|
|
if ((*old) >= 0.0){
|
|
*old = (float)-1.0 * FLOAT_MAX;
|
|
} else {
|
|
*old = FLOAT_MAX;
|
|
}
|
|
|
|
omega = old_omega;
|
|
step_idx = 0;
|
|
|
|
step_idx = LSF_NUMBER_OF_STEPS;
|
|
} else {
|
|
|
|
if (step_idx == 0) {
|
|
old_omega = omega;
|
|
}
|
|
|
|
step_idx++;
|
|
omega -= steps[step_idx];
|
|
|
|
/* Go back one grid step */
|
|
|
|
step = steps[step_idx];
|
|
}
|
|
} else {
|
|
|
|
/* increment omega until they are of different sign,
|
|
and we know there is at least one root between omega
|
|
and old_omega */
|
|
*old = hlp5;
|
|
omega += step;
|
|
}
|
|
}
|
|
}
|
|
|
|
for (i = 0; i<LPC_FILTERORDER; i++) {
|
|
freq[i] = freq[i] * TWO_PI;
|
|
}
|
|
}
|
|
|
|
/*----------------------------------------------------------------*
|
|
* conversion from lsf coefficients to lpc coefficients
|
|
*---------------------------------------------------------------*/
|
|
|
|
void lsf2a(
|
|
float *a_coef, /* (o) lpc coefficients */
|
|
float *freq /* (i) lsf coefficients */
|
|
|
|
|
|
|
|
Andersen, et al. Experimental [Page 175]
|
|
|
|
RFC 3951 Internet Low Bit Rate Codec December 2004
|
|
|
|
|
|
){
|
|
int i, j;
|
|
float hlp;
|
|
float p[LPC_HALFORDER], q[LPC_HALFORDER];
|
|
float a[LPC_HALFORDER + 1], a1[LPC_HALFORDER],
|
|
a2[LPC_HALFORDER];
|
|
float b[LPC_HALFORDER + 1], b1[LPC_HALFORDER],
|
|
b2[LPC_HALFORDER];
|
|
|
|
for (i=0; i<LPC_FILTERORDER; i++) {
|
|
freq[i] = freq[i] * PI2;
|
|
}
|
|
|
|
/* Check input for ill-conditioned cases. This part is not
|
|
found in the TIA standard. It involves the following 2 IF
|
|
blocks. If "freq" is judged ill-conditioned, then we first
|
|
modify freq[0] and freq[LPC_HALFORDER-1] (normally
|
|
LPC_HALFORDER = 10 for LPC applications), then we adjust
|
|
the other "freq" values slightly */
|
|
|
|
|
|
if ((freq[0] <= 0.0) || (freq[LPC_FILTERORDER - 1] >= 0.5)){
|
|
|
|
|
|
if (freq[0] <= 0.0) {
|
|
freq[0] = (float)0.022;
|
|
}
|
|
|
|
|
|
if (freq[LPC_FILTERORDER - 1] >= 0.5) {
|
|
freq[LPC_FILTERORDER - 1] = (float)0.499;
|
|
}
|
|
|
|
hlp = (freq[LPC_FILTERORDER - 1] - freq[0]) /
|
|
(float) (LPC_FILTERORDER - 1);
|
|
|
|
for (i=1; i<LPC_FILTERORDER; i++) {
|
|
freq[i] = freq[i - 1] + hlp;
|
|
}
|
|
}
|
|
|
|
memset(a1, 0, LPC_HALFORDER*sizeof(float));
|
|
memset(a2, 0, LPC_HALFORDER*sizeof(float));
|
|
memset(b1, 0, LPC_HALFORDER*sizeof(float));
|
|
memset(b2, 0, LPC_HALFORDER*sizeof(float));
|
|
memset(a, 0, (LPC_HALFORDER+1)*sizeof(float));
|
|
memset(b, 0, (LPC_HALFORDER+1)*sizeof(float));
|
|
|
|
|
|
|
|
|
|
Andersen, et al. Experimental [Page 176]
|
|
|
|
RFC 3951 Internet Low Bit Rate Codec December 2004
|
|
|
|
|
|
/* p[i] and q[i] compute cos(2*pi*omega_{2j}) and
|
|
cos(2*pi*omega_{2j-1} in eqs. 4.2.2.2-1 and 4.2.2.2-2.
|
|
Note that for this code p[i] specifies the coefficients
|
|
used in .Q_A(z) while q[i] specifies the coefficients used
|
|
in .P_A(z) */
|
|
|
|
for (i=0; i<LPC_HALFORDER; i++) {
|
|
p[i] = (float)cos(TWO_PI * freq[2 * i]);
|
|
q[i] = (float)cos(TWO_PI * freq[2 * i + 1]);
|
|
}
|
|
|
|
a[0] = 0.25;
|
|
b[0] = 0.25;
|
|
|
|
for (i= 0; i<LPC_HALFORDER; i++) {
|
|
a[i + 1] = a[i] - 2 * p[i] * a1[i] + a2[i];
|
|
b[i + 1] = b[i] - 2 * q[i] * b1[i] + b2[i];
|
|
a2[i] = a1[i];
|
|
a1[i] = a[i];
|
|
b2[i] = b1[i];
|
|
b1[i] = b[i];
|
|
}
|
|
|
|
for (j=0; j<LPC_FILTERORDER; j++) {
|
|
|
|
if (j == 0) {
|
|
a[0] = 0.25;
|
|
b[0] = -0.25;
|
|
} else {
|
|
a[0] = b[0] = 0.0;
|
|
}
|
|
|
|
for (i=0; i<LPC_HALFORDER; i++) {
|
|
a[i + 1] = a[i] - 2 * p[i] * a1[i] + a2[i];
|
|
b[i + 1] = b[i] - 2 * q[i] * b1[i] + b2[i];
|
|
a2[i] = a1[i];
|
|
a1[i] = a[i];
|
|
b2[i] = b1[i];
|
|
b1[i] = b[i];
|
|
}
|
|
|
|
a_coef[j + 1] = 2 * (a[LPC_HALFORDER] + b[LPC_HALFORDER]);
|
|
}
|
|
|
|
a_coef[0] = 1.0;
|
|
}
|
|
|
|
|
|
|
|
|
|
|
|
Andersen, et al. Experimental [Page 177]
|
|
|
|
RFC 3951 Internet Low Bit Rate Codec December 2004
|
|
|
|
|
|
A.41. packing.h
|
|
|
|
/******************************************************************
|
|
|
|
iLBC Speech Coder ANSI-C Source Code
|
|
|
|
packing.h
|
|
|
|
Copyright (C) The Internet Society (2004).
|
|
All Rights Reserved.
|
|
|
|
******************************************************************/
|
|
|
|
#ifndef __PACKING_H
|
|
#define __PACKING_H
|
|
|
|
void packsplit(
|
|
int *index, /* (i) the value to split */
|
|
int *firstpart, /* (o) the value specified by most
|
|
significant bits */
|
|
int *rest, /* (o) the value specified by least
|
|
significant bits */
|
|
int bitno_firstpart, /* (i) number of bits in most
|
|
significant part */
|
|
int bitno_total /* (i) number of bits in full range
|
|
of value */
|
|
);
|
|
|
|
void packcombine(
|
|
int *index, /* (i/o) the msb value in the
|
|
combined value out */
|
|
int rest, /* (i) the lsb value */
|
|
int bitno_rest /* (i) the number of bits in the
|
|
lsb part */
|
|
);
|
|
|
|
void dopack(
|
|
unsigned char **bitstream, /* (i/o) on entrance pointer to
|
|
place in bitstream to pack
|
|
new data, on exit pointer
|
|
to place in bitstream to
|
|
pack future data */
|
|
int index, /* (i) the value to pack */
|
|
int bitno, /* (i) the number of bits that the
|
|
value will fit within */
|
|
int *pos /* (i/o) write position in the
|
|
current byte */
|
|
);
|
|
|
|
|
|
|
|
Andersen, et al. Experimental [Page 178]
|
|
|
|
RFC 3951 Internet Low Bit Rate Codec December 2004
|
|
|
|
|
|
void unpack(
|
|
unsigned char **bitstream, /* (i/o) on entrance pointer to
|
|
place in bitstream to
|
|
unpack new data from, on
|
|
exit pointer to place in
|
|
bitstream to unpack future
|
|
data from */
|
|
int *index, /* (o) resulting value */
|
|
int bitno, /* (i) number of bits used to
|
|
represent the value */
|
|
int *pos /* (i/o) read position in the
|
|
current byte */
|
|
);
|
|
|
|
#endif
|
|
|
|
A.42. packing.c
|
|
|
|
/******************************************************************
|
|
|
|
iLBC Speech Coder ANSI-C Source Code
|
|
|
|
packing.c
|
|
|
|
Copyright (C) The Internet Society (2004).
|
|
All Rights Reserved.
|
|
|
|
******************************************************************/
|
|
|
|
#include <math.h>
|
|
#include <stdlib.h>
|
|
|
|
#include "iLBC_define.h"
|
|
#include "constants.h"
|
|
#include "helpfun.h"
|
|
#include "string.h"
|
|
|
|
/*----------------------------------------------------------------*
|
|
* splitting an integer into first most significant bits and
|
|
* remaining least significant bits
|
|
*---------------------------------------------------------------*/
|
|
|
|
void packsplit(
|
|
int *index, /* (i) the value to split */
|
|
int *firstpart, /* (o) the value specified by most
|
|
significant bits */
|
|
int *rest, /* (o) the value specified by least
|
|
significant bits */
|
|
|
|
|
|
|
|
Andersen, et al. Experimental [Page 179]
|
|
|
|
RFC 3951 Internet Low Bit Rate Codec December 2004
|
|
|
|
|
|
int bitno_firstpart, /* (i) number of bits in most
|
|
significant part */
|
|
int bitno_total /* (i) number of bits in full range
|
|
of value */
|
|
){
|
|
int bitno_rest = bitno_total-bitno_firstpart;
|
|
|
|
*firstpart = *index>>(bitno_rest);
|
|
*rest = *index-(*firstpart<<(bitno_rest));
|
|
}
|
|
|
|
/*----------------------------------------------------------------*
|
|
* combining a value corresponding to msb's with a value
|
|
* corresponding to lsb's
|
|
*---------------------------------------------------------------*/
|
|
|
|
void packcombine(
|
|
int *index, /* (i/o) the msb value in the
|
|
combined value out */
|
|
int rest, /* (i) the lsb value */
|
|
int bitno_rest /* (i) the number of bits in the
|
|
lsb part */
|
|
){
|
|
*index = *index<<bitno_rest;
|
|
*index += rest;
|
|
}
|
|
|
|
/*----------------------------------------------------------------*
|
|
* packing of bits into bitstream, i.e., vector of bytes
|
|
*---------------------------------------------------------------*/
|
|
|
|
void dopack(
|
|
unsigned char **bitstream, /* (i/o) on entrance pointer to
|
|
place in bitstream to pack
|
|
new data, on exit pointer
|
|
to place in bitstream to
|
|
pack future data */
|
|
int index, /* (i) the value to pack */
|
|
int bitno, /* (i) the number of bits that the
|
|
value will fit within */
|
|
int *pos /* (i/o) write position in the
|
|
current byte */
|
|
){
|
|
int posLeft;
|
|
|
|
/* Clear the bits before starting in a new byte */
|
|
|
|
if ((*pos)==0) {
|
|
|
|
|
|
|
|
Andersen, et al. Experimental [Page 180]
|
|
|
|
RFC 3951 Internet Low Bit Rate Codec December 2004
|
|
|
|
|
|
**bitstream=0;
|
|
}
|
|
|
|
while (bitno>0) {
|
|
|
|
/* Jump to the next byte if end of this byte is reached*/
|
|
|
|
if (*pos==8) {
|
|
*pos=0;
|
|
(*bitstream)++;
|
|
**bitstream=0;
|
|
}
|
|
|
|
posLeft=8-(*pos);
|
|
|
|
/* Insert index into the bitstream */
|
|
|
|
if (bitno <= posLeft) {
|
|
**bitstream |= (unsigned char)(index<<(posLeft-bitno));
|
|
*pos+=bitno;
|
|
bitno=0;
|
|
} else {
|
|
**bitstream |= (unsigned char)(index>>(bitno-posLeft));
|
|
|
|
*pos=8;
|
|
index-=((index>>(bitno-posLeft))<<(bitno-posLeft));
|
|
|
|
bitno-=posLeft;
|
|
}
|
|
}
|
|
}
|
|
|
|
/*----------------------------------------------------------------*
|
|
* unpacking of bits from bitstream, i.e., vector of bytes
|
|
*---------------------------------------------------------------*/
|
|
|
|
void unpack(
|
|
unsigned char **bitstream, /* (i/o) on entrance pointer to
|
|
place in bitstream to
|
|
unpack new data from, on
|
|
exit pointer to place in
|
|
bitstream to unpack future
|
|
data from */
|
|
int *index, /* (o) resulting value */
|
|
int bitno, /* (i) number of bits used to
|
|
represent the value */
|
|
int *pos /* (i/o) read position in the
|
|
current byte */
|
|
|
|
|
|
|
|
Andersen, et al. Experimental [Page 181]
|
|
|
|
RFC 3951 Internet Low Bit Rate Codec December 2004
|
|
|
|
|
|
){
|
|
int BitsLeft;
|
|
|
|
*index=0;
|
|
|
|
while (bitno>0) {
|
|
|
|
/* move forward in bitstream when the end of the
|
|
byte is reached */
|
|
|
|
if (*pos==8) {
|
|
*pos=0;
|
|
(*bitstream)++;
|
|
}
|
|
|
|
BitsLeft=8-(*pos);
|
|
|
|
/* Extract bits to index */
|
|
|
|
if (BitsLeft>=bitno) {
|
|
*index+=((((**bitstream)<<(*pos)) & 0xFF)>>(8-bitno));
|
|
|
|
*pos+=bitno;
|
|
bitno=0;
|
|
} else {
|
|
|
|
if ((8-bitno)>0) {
|
|
*index+=((((**bitstream)<<(*pos)) & 0xFF)>>
|
|
(8-bitno));
|
|
*pos=8;
|
|
} else {
|
|
*index+=(((int)(((**bitstream)<<(*pos)) & 0xFF))<<
|
|
(bitno-8));
|
|
*pos=8;
|
|
}
|
|
bitno-=BitsLeft;
|
|
}
|
|
}
|
|
}
|
|
|
|
A.43. StateConstructW.h
|
|
|
|
/******************************************************************
|
|
|
|
iLBC Speech Coder ANSI-C Source Code
|
|
|
|
StateConstructW.h
|
|
|
|
|
|
|
|
|
|
Andersen, et al. Experimental [Page 182]
|
|
|
|
RFC 3951 Internet Low Bit Rate Codec December 2004
|
|
|
|
|
|
Copyright (C) The Internet Society (2004).
|
|
All Rights Reserved.
|
|
|
|
******************************************************************/
|
|
|
|
#ifndef __iLBC_STATECONSTRUCTW_H
|
|
#define __iLBC_STATECONSTRUCTW_H
|
|
|
|
void StateConstructW(
|
|
int idxForMax, /* (i) 6-bit index for the quantization of
|
|
max amplitude */
|
|
int *idxVec, /* (i) vector of quantization indexes */
|
|
float *syntDenum, /* (i) synthesis filter denumerator */
|
|
float *out, /* (o) the decoded state vector */
|
|
int len /* (i) length of a state vector */
|
|
);
|
|
|
|
#endif
|
|
|
|
A.44. StateConstructW.c
|
|
|
|
/******************************************************************
|
|
|
|
iLBC Speech Coder ANSI-C Source Code
|
|
|
|
StateConstructW.c
|
|
|
|
Copyright (C) The Internet Society (2004).
|
|
All Rights Reserved.
|
|
|
|
******************************************************************/
|
|
|
|
#include <math.h>
|
|
#include <string.h>
|
|
|
|
#include "iLBC_define.h"
|
|
#include "constants.h"
|
|
#include "filter.h"
|
|
|
|
/*----------------------------------------------------------------*
|
|
* decoding of the start state
|
|
*---------------------------------------------------------------*/
|
|
|
|
void StateConstructW(
|
|
int idxForMax, /* (i) 6-bit index for the quantization of
|
|
max amplitude */
|
|
int *idxVec, /* (i) vector of quantization indexes */
|
|
float *syntDenum, /* (i) synthesis filter denumerator */
|
|
|
|
|
|
|
|
Andersen, et al. Experimental [Page 183]
|
|
|
|
RFC 3951 Internet Low Bit Rate Codec December 2004
|
|
|
|
|
|
float *out, /* (o) the decoded state vector */
|
|
int len /* (i) length of a state vector */
|
|
){
|
|
float maxVal, tmpbuf[LPC_FILTERORDER+2*STATE_LEN], *tmp,
|
|
numerator[LPC_FILTERORDER+1];
|
|
float foutbuf[LPC_FILTERORDER+2*STATE_LEN], *fout;
|
|
int k,tmpi;
|
|
|
|
/* decoding of the maximum value */
|
|
|
|
maxVal = state_frgqTbl[idxForMax];
|
|
maxVal = (float)pow(10,maxVal)/(float)4.5;
|
|
|
|
/* initialization of buffers and coefficients */
|
|
|
|
memset(tmpbuf, 0, LPC_FILTERORDER*sizeof(float));
|
|
memset(foutbuf, 0, LPC_FILTERORDER*sizeof(float));
|
|
for (k=0; k<LPC_FILTERORDER; k++) {
|
|
numerator[k]=syntDenum[LPC_FILTERORDER-k];
|
|
}
|
|
numerator[LPC_FILTERORDER]=syntDenum[0];
|
|
tmp = &tmpbuf[LPC_FILTERORDER];
|
|
fout = &foutbuf[LPC_FILTERORDER];
|
|
|
|
/* decoding of the sample values */
|
|
|
|
for (k=0; k<len; k++) {
|
|
tmpi = len-1-k;
|
|
/* maxVal = 1/scal */
|
|
tmp[k] = maxVal*state_sq3Tbl[idxVec[tmpi]];
|
|
}
|
|
|
|
/* circular convolution with all-pass filter */
|
|
|
|
memset(tmp+len, 0, len*sizeof(float));
|
|
ZeroPoleFilter(tmp, numerator, syntDenum, 2*len,
|
|
LPC_FILTERORDER, fout);
|
|
for (k=0;k<len;k++) {
|
|
out[k] = fout[len-1-k]+fout[2*len-1-k];
|
|
}
|
|
}
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
Andersen, et al. Experimental [Page 184]
|
|
|
|
RFC 3951 Internet Low Bit Rate Codec December 2004
|
|
|
|
|
|
A.45. StateSearchW.h
|
|
|
|
/******************************************************************
|
|
|
|
iLBC Speech Coder ANSI-C Source Code
|
|
|
|
StateSearchW.h
|
|
|
|
Copyright (C) The Internet Society (2004).
|
|
All Rights Reserved.
|
|
|
|
******************************************************************/
|
|
|
|
#ifndef __iLBC_STATESEARCHW_H
|
|
#define __iLBC_STATESEARCHW_H
|
|
|
|
void AbsQuantW(
|
|
iLBC_Enc_Inst_t *iLBCenc_inst,
|
|
/* (i) Encoder instance */
|
|
float *in, /* (i) vector to encode */
|
|
float *syntDenum, /* (i) denominator of synthesis filter */
|
|
float *weightDenum, /* (i) denominator of weighting filter */
|
|
int *out, /* (o) vector of quantizer indexes */
|
|
int len, /* (i) length of vector to encode and
|
|
vector of quantizer indexes */
|
|
int state_first /* (i) position of start state in the
|
|
80 vec */
|
|
);
|
|
|
|
void StateSearchW(
|
|
iLBC_Enc_Inst_t *iLBCenc_inst,
|
|
/* (i) Encoder instance */
|
|
float *residual,/* (i) target residual vector */
|
|
float *syntDenum, /* (i) lpc synthesis filter */
|
|
float *weightDenum, /* (i) weighting filter denumerator */
|
|
int *idxForMax, /* (o) quantizer index for maximum
|
|
amplitude */
|
|
int *idxVec, /* (o) vector of quantization indexes */
|
|
int len, /* (i) length of all vectors */
|
|
int state_first /* (i) position of start state in the
|
|
80 vec */
|
|
);
|
|
|
|
|
|
#endif
|
|
|
|
|
|
|
|
|
|
|
|
|
|
Andersen, et al. Experimental [Page 185]
|
|
|
|
RFC 3951 Internet Low Bit Rate Codec December 2004
|
|
|
|
|
|
A.46. StateSearchW.c
|
|
|
|
/******************************************************************
|
|
|
|
iLBC Speech Coder ANSI-C Source Code
|
|
|
|
StateSearchW.c
|
|
|
|
Copyright (C) The Internet Society (2004).
|
|
All Rights Reserved.
|
|
|
|
******************************************************************/
|
|
|
|
#include <math.h>
|
|
#include <string.h>
|
|
|
|
#include "iLBC_define.h"
|
|
#include "constants.h"
|
|
#include "filter.h"
|
|
#include "helpfun.h"
|
|
|
|
/*----------------------------------------------------------------*
|
|
* predictive noise shaping encoding of scaled start state
|
|
* (subroutine for StateSearchW)
|
|
*---------------------------------------------------------------*/
|
|
|
|
void AbsQuantW(
|
|
iLBC_Enc_Inst_t *iLBCenc_inst,
|
|
/* (i) Encoder instance */
|
|
float *in, /* (i) vector to encode */
|
|
float *syntDenum, /* (i) denominator of synthesis filter */
|
|
float *weightDenum, /* (i) denominator of weighting filter */
|
|
int *out, /* (o) vector of quantizer indexes */
|
|
int len, /* (i) length of vector to encode and
|
|
vector of quantizer indexes */
|
|
int state_first /* (i) position of start state in the
|
|
80 vec */
|
|
){
|
|
float *syntOut;
|
|
float syntOutBuf[LPC_FILTERORDER+STATE_SHORT_LEN_30MS];
|
|
float toQ, xq;
|
|
int n;
|
|
int index;
|
|
|
|
/* initialization of buffer for filtering */
|
|
|
|
memset(syntOutBuf, 0, LPC_FILTERORDER*sizeof(float));
|
|
|
|
|
|
|
|
|
|
Andersen, et al. Experimental [Page 186]
|
|
|
|
RFC 3951 Internet Low Bit Rate Codec December 2004
|
|
|
|
|
|
/* initialization of pointer for filtering */
|
|
|
|
syntOut = &syntOutBuf[LPC_FILTERORDER];
|
|
|
|
/* synthesis and weighting filters on input */
|
|
|
|
if (state_first) {
|
|
AllPoleFilter (in, weightDenum, SUBL, LPC_FILTERORDER);
|
|
} else {
|
|
AllPoleFilter (in, weightDenum,
|
|
iLBCenc_inst->state_short_len-SUBL,
|
|
LPC_FILTERORDER);
|
|
}
|
|
|
|
/* encoding loop */
|
|
|
|
for (n=0; n<len; n++) {
|
|
|
|
/* time update of filter coefficients */
|
|
|
|
if ((state_first)&&(n==SUBL)){
|
|
syntDenum += (LPC_FILTERORDER+1);
|
|
weightDenum += (LPC_FILTERORDER+1);
|
|
|
|
/* synthesis and weighting filters on input */
|
|
AllPoleFilter (&in[n], weightDenum, len-n,
|
|
LPC_FILTERORDER);
|
|
|
|
} else if ((state_first==0)&&
|
|
(n==(iLBCenc_inst->state_short_len-SUBL))) {
|
|
syntDenum += (LPC_FILTERORDER+1);
|
|
weightDenum += (LPC_FILTERORDER+1);
|
|
|
|
/* synthesis and weighting filters on input */
|
|
AllPoleFilter (&in[n], weightDenum, len-n,
|
|
LPC_FILTERORDER);
|
|
|
|
}
|
|
|
|
/* prediction of synthesized and weighted input */
|
|
|
|
syntOut[n] = 0.0;
|
|
AllPoleFilter (&syntOut[n], weightDenum, 1,
|
|
LPC_FILTERORDER);
|
|
|
|
/* quantization */
|
|
|
|
toQ = in[n]-syntOut[n];
|
|
|
|
|
|
|
|
Andersen, et al. Experimental [Page 187]
|
|
|
|
RFC 3951 Internet Low Bit Rate Codec December 2004
|
|
|
|
|
|
sort_sq(&xq, &index, toQ, state_sq3Tbl, 8);
|
|
out[n]=index;
|
|
syntOut[n] = state_sq3Tbl[out[n]];
|
|
|
|
/* update of the prediction filter */
|
|
|
|
AllPoleFilter(&syntOut[n], weightDenum, 1,
|
|
LPC_FILTERORDER);
|
|
}
|
|
}
|
|
|
|
/*----------------------------------------------------------------*
|
|
* encoding of start state
|
|
*---------------------------------------------------------------*/
|
|
|
|
void StateSearchW(
|
|
iLBC_Enc_Inst_t *iLBCenc_inst,
|
|
/* (i) Encoder instance */
|
|
float *residual,/* (i) target residual vector */
|
|
float *syntDenum, /* (i) lpc synthesis filter */
|
|
float *weightDenum, /* (i) weighting filter denumerator */
|
|
int *idxForMax, /* (o) quantizer index for maximum
|
|
amplitude */
|
|
int *idxVec, /* (o) vector of quantization indexes */
|
|
int len, /* (i) length of all vectors */
|
|
int state_first /* (i) position of start state in the
|
|
80 vec */
|
|
){
|
|
float dtmp, maxVal;
|
|
float tmpbuf[LPC_FILTERORDER+2*STATE_SHORT_LEN_30MS];
|
|
float *tmp, numerator[1+LPC_FILTERORDER];
|
|
float foutbuf[LPC_FILTERORDER+2*STATE_SHORT_LEN_30MS], *fout;
|
|
int k;
|
|
float qmax, scal;
|
|
|
|
/* initialization of buffers and filter coefficients */
|
|
|
|
memset(tmpbuf, 0, LPC_FILTERORDER*sizeof(float));
|
|
memset(foutbuf, 0, LPC_FILTERORDER*sizeof(float));
|
|
for (k=0; k<LPC_FILTERORDER; k++) {
|
|
numerator[k]=syntDenum[LPC_FILTERORDER-k];
|
|
}
|
|
numerator[LPC_FILTERORDER]=syntDenum[0];
|
|
tmp = &tmpbuf[LPC_FILTERORDER];
|
|
fout = &foutbuf[LPC_FILTERORDER];
|
|
|
|
/* circular convolution with the all-pass filter */
|
|
|
|
|
|
|
|
|
|
Andersen, et al. Experimental [Page 188]
|
|
|
|
RFC 3951 Internet Low Bit Rate Codec December 2004
|
|
|
|
|
|
memcpy(tmp, residual, len*sizeof(float));
|
|
memset(tmp+len, 0, len*sizeof(float));
|
|
ZeroPoleFilter(tmp, numerator, syntDenum, 2*len,
|
|
LPC_FILTERORDER, fout);
|
|
for (k=0; k<len; k++) {
|
|
fout[k] += fout[k+len];
|
|
}
|
|
|
|
/* identification of the maximum amplitude value */
|
|
|
|
maxVal = fout[0];
|
|
for (k=1; k<len; k++) {
|
|
|
|
if (fout[k]*fout[k] > maxVal*maxVal){
|
|
maxVal = fout[k];
|
|
}
|
|
}
|
|
maxVal=(float)fabs(maxVal);
|
|
|
|
/* encoding of the maximum amplitude value */
|
|
|
|
if (maxVal < 10.0) {
|
|
maxVal = 10.0;
|
|
}
|
|
maxVal = (float)log10(maxVal);
|
|
sort_sq(&dtmp, idxForMax, maxVal, state_frgqTbl, 64);
|
|
|
|
/* decoding of the maximum amplitude representation value,
|
|
and corresponding scaling of start state */
|
|
|
|
maxVal=state_frgqTbl[*idxForMax];
|
|
qmax = (float)pow(10,maxVal);
|
|
scal = (float)(4.5)/qmax;
|
|
for (k=0; k<len; k++){
|
|
fout[k] *= scal;
|
|
}
|
|
|
|
/* predictive noise shaping encoding of scaled start state */
|
|
|
|
AbsQuantW(iLBCenc_inst, fout,syntDenum,
|
|
weightDenum,idxVec, len, state_first);
|
|
}
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
Andersen, et al. Experimental [Page 189]
|
|
|
|
RFC 3951 Internet Low Bit Rate Codec December 2004
|
|
|
|
|
|
A.47. syntFilter.h
|
|
|
|
/******************************************************************
|
|
|
|
iLBC Speech Coder ANSI-C Source Code
|
|
|
|
syntFilter.h
|
|
|
|
Copyright (C) The Internet Society (2004).
|
|
All Rights Reserved.
|
|
|
|
******************************************************************/
|
|
|
|
#ifndef __iLBC_SYNTFILTER_H
|
|
#define __iLBC_SYNTFILTER_H
|
|
|
|
void syntFilter(
|
|
float *Out, /* (i/o) Signal to be filtered */
|
|
float *a, /* (i) LP parameters */
|
|
int len, /* (i) Length of signal */
|
|
float *mem /* (i/o) Filter state */
|
|
);
|
|
|
|
#endif
|
|
|
|
A.48. syntFilter.c
|
|
|
|
/******************************************************************
|
|
|
|
iLBC Speech Coder ANSI-C Source Code
|
|
|
|
syntFilter.c
|
|
|
|
Copyright (C) The Internet Society (2004).
|
|
All Rights Reserved.
|
|
|
|
******************************************************************/
|
|
|
|
#include "iLBC_define.h"
|
|
|
|
/*----------------------------------------------------------------*
|
|
* LP synthesis filter.
|
|
*---------------------------------------------------------------*/
|
|
|
|
void syntFilter(
|
|
float *Out, /* (i/o) Signal to be filtered */
|
|
float *a, /* (i) LP parameters */
|
|
int len, /* (i) Length of signal */
|
|
|
|
|
|
|
|
Andersen, et al. Experimental [Page 190]
|
|
|
|
RFC 3951 Internet Low Bit Rate Codec December 2004
|
|
|
|
|
|
float *mem /* (i/o) Filter state */
|
|
){
|
|
int i, j;
|
|
float *po, *pi, *pa, *pm;
|
|
|
|
po=Out;
|
|
|
|
/* Filter first part using memory from past */
|
|
|
|
for (i=0; i<LPC_FILTERORDER; i++) {
|
|
pi=&Out[i-1];
|
|
pa=&a[1];
|
|
pm=&mem[LPC_FILTERORDER-1];
|
|
for (j=1; j<=i; j++) {
|
|
*po-=(*pa++)*(*pi--);
|
|
}
|
|
for (j=i+1; j<LPC_FILTERORDER+1; j++) {
|
|
*po-=(*pa++)*(*pm--);
|
|
}
|
|
po++;
|
|
}
|
|
|
|
/* Filter last part where the state is entirely in
|
|
the output vector */
|
|
|
|
for (i=LPC_FILTERORDER; i<len; i++) {
|
|
pi=&Out[i-1];
|
|
pa=&a[1];
|
|
for (j=1; j<LPC_FILTERORDER+1; j++) {
|
|
*po-=(*pa++)*(*pi--);
|
|
}
|
|
po++;
|
|
}
|
|
|
|
/* Update state vector */
|
|
|
|
memcpy(mem, &Out[len-LPC_FILTERORDER],
|
|
LPC_FILTERORDER*sizeof(float));
|
|
}
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
Andersen, et al. Experimental [Page 191]
|
|
|
|
RFC 3951 Internet Low Bit Rate Codec December 2004
|
|
|
|
|
|
Authors' Addresses
|
|
|
|
Soren Vang Andersen
|
|
Department of Communication Technology
|
|
Aalborg University
|
|
Fredrik Bajers Vej 7A
|
|
9200 Aalborg
|
|
Denmark
|
|
|
|
Phone: ++45 9 6358627
|
|
EMail: sva@kom.auc.dk
|
|
|
|
|
|
Alan Duric
|
|
Telio AS
|
|
Stoperigt. 2
|
|
Oslo, N-0250
|
|
Norway
|
|
|
|
Phone: +47 21673555
|
|
EMail: alan.duric@telio.no
|
|
|
|
|
|
Henrik Astrom
|
|
Global IP Sound AB
|
|
Olandsgatan 42
|
|
Stockholm, S-11663
|
|
Sweden
|
|
|
|
Phone: +46 8 54553040
|
|
EMail: henrik.astrom@globalipsound.com
|
|
|
|
|
|
Roar Hagen
|
|
Global IP Sound AB
|
|
Olandsgatan 42
|
|
Stockholm, S-11663
|
|
Sweden
|
|
|
|
Phone: +46 8 54553040
|
|
EMail: roar.hagen@globalipsound.com
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
Andersen, et al. Experimental [Page 192]
|
|
|
|
RFC 3951 Internet Low Bit Rate Codec December 2004
|
|
|
|
|
|
W. Bastiaan Kleijn
|
|
Global IP Sound AB
|
|
Olandsgatan 42
|
|
Stockholm, S-11663
|
|
Sweden
|
|
|
|
Phone: +46 8 54553040
|
|
EMail: bastiaan.kleijn@globalipsound.com
|
|
|
|
|
|
Jan Linden
|
|
Global IP Sound Inc.
|
|
900 Kearny Street, suite 500
|
|
San Francisco, CA-94133
|
|
USA
|
|
|
|
Phone: +1 415 397 2555
|
|
EMail: jan.linden@globalipsound.com
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
Andersen, et al. Experimental [Page 193]
|
|
|
|
RFC 3951 Internet Low Bit Rate Codec December 2004
|
|
|
|
|
|
Full Copyright Statement
|
|
|
|
Copyright (C) The Internet Society (2004).
|
|
|
|
This document is subject to the rights, licenses and restrictions
|
|
contained in BCP 78, and except as set forth therein, the authors
|
|
retain all their rights.
|
|
|
|
This document and the information contained herein are provided on an
|
|
"AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS
|
|
OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY AND THE INTERNET
|
|
ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS OR IMPLIED,
|
|
INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE
|
|
INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED
|
|
WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.
|
|
|
|
Intellectual Property
|
|
|
|
The IETF takes no position regarding the validity or scope of any
|
|
Intellectual Property Rights or other rights that might be claimed to
|
|
pertain to the implementation or use of the technology described in
|
|
this document or the extent to which any license under such rights
|
|
might or might not be available; nor does it represent that it has
|
|
made any independent effort to identify any such rights. Information
|
|
on the IETF's procedures with respect to rights in IETF Documents can
|
|
be found in BCP 78 and BCP 79.
|
|
|
|
Copies of IPR disclosures made to the IETF Secretariat and any
|
|
assurances of licenses to be made available, or the result of an
|
|
attempt made to obtain a general license or permission for the use of
|
|
such proprietary rights by implementers or users of this
|
|
specification can be obtained from the IETF on-line IPR repository at
|
|
http://www.ietf.org/ipr.
|
|
|
|
The IETF invites any interested party to bring to its attention any
|
|
copyrights, patents or patent applications, or other proprietary
|
|
rights that may cover technology that may be required to implement
|
|
this standard. Please address the information to the IETF at ietf-
|
|
ipr@ietf.org.
|
|
|
|
|
|
Acknowledgement
|
|
|
|
Funding for the RFC Editor function is currently provided by the
|
|
Internet Society.
|
|
|
|
|
|
|
|
|
|
|
|
|
|
Andersen, et al. Experimental [Page 194]
|