/******************************************************************
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"
/*----------------------------------------------------------------*
* 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));
}
/*----------------------------------------------------------------*
* 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
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));
}
}
/*----------------------------------------------------------------*
* 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];
SimpleAnalysis(lsf, data, iLBCenc_inst);
SimplelsfQ(lsfdeq, lsf_index, lsf, iLBCenc_inst->lpc_n);
LSF_check(lsfdeq, LPC_FILTERORDER, iLBCenc_inst->lpc_n);
SimpleInterpolateLSF(syntdenum, weightdenum,
lsf, lsfdeq, iLBCenc_inst->lsfold,
iLBCenc_inst->lsfdeqold, LPC_FILTERORDER, iLBCenc_inst);
}