/* codec_adpcm.c - translate between signed linear and Dialogic ADPCM
*
* Asterisk -- A telephony toolkit for Linux.
*
* Based on frompcm.c and topcm.c from the Emiliano MIPL browser/
* interpreter. See http://www.bsdtelephony.com.mx
*
* Copyright (c) 2001 Linux Support Services, Inc. All rights reserved.
*
* Karl Sackett <krs@linux-support.net>, 2001-3-21
*
* This program is free software, distributed under the terms of
* the GNU General Public License
*/
#include <asterisk/lock.h>
#include <asterisk/logger.h>
#include <asterisk/module.h>
#include <asterisk/translate.h>
#include <asterisk/channel.h>
#include <fcntl.h>
#include <netinet/in.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#define BUFFER_SIZE 8096 /* size for the translation buffers */
AST_MUTEX_DEFINE_STATIC(localuser_lock);
static int localusecnt = 0;
static char *tdesc = "Adaptive Differential PCM Coder/Decoder";
/* Sample frame data */
#include "slin_adpcm_ex.h"
#include "adpcm_slin_ex.h"
/*
* Step size index shift table
*/
static short indsft[8] = { -1, -1, -1, -1, 2, 4, 6, 8 };
/*
* Step size table, where stpsz[i]=floor[16*(11/10)^i]
*/
static short stpsz[49] = {
16, 17, 19, 21, 23, 25, 28, 31, 34, 37, 41, 45, 50, 55, 60, 66, 73,
80, 88, 97, 107, 118, 130, 143, 157, 173, 190, 209, 230, 253, 279,
307, 337, 371, 408, 449, 494, 544, 598, 658, 724, 796, 876, 963,
1060, 1166, 1282, 1411, 1552
};
/*
* Nibble to bit map
*/
static short nbl2bit[16][4] = {
{1, 0, 0, 0}, {1, 0, 0, 1}, {1, 0, 1, 0}, {1, 0, 1, 1},
{1, 1, 0, 0}, {1, 1, 0, 1}, {1, 1, 1, 0}, {1, 1, 1, 1},
{-1, 0, 0, 0}, {-1, 0, 0, 1}, {-1, 0, 1, 0}, {-1, 0, 1, 1},
{-1, 1, 0, 0}, {-1, 1, 0, 1}, {-1, 1, 1, 0}, {-1, 1, 1, 1}
};
/*
* Decode(encoded)
* Decodes the encoded nibble from the adpcm file.
*
* Results:
* Returns the encoded difference.
*
* Side effects:
* Sets the index to the step size table for the next encode.
*/
static inline void
decode (unsigned char encoded, short *ssindex, short *signal, unsigned char *rkey, unsigned char *next)
{
short diff, step;
step = stpsz[*ssindex];
diff = step * nbl2bit[encoded][1] +
(step >> 1) * nbl2bit[encoded][2] +
(step >> 2) * nbl2bit[encoded][3] +
(step >> 3);
if (nbl2bit[encoded][2] && (step & 0x1))
diff++;
diff *= nbl2bit[encoded][0];
if ( *next & 0x1 )
*signal -= 8;
else if ( *next & 0x2 )
*signal += 8;
*signal += diff;
if (*signal > 2047)
*signal = 2047;
else if (*signal < -2047)
*signal = -2047;
*next = 0;
#ifdef AUTO_RETURN
if( encoded & 0x7 )
*rkey = 0;
else if ( ++(*rkey) == 24 ) {
*rkey = 0;
if (*signal > 0)
*next = 0x1;
else if (*signal < 0)
*next = 0x2;
}
#endif
*ssindex = *ssindex + indsft[(encoded & 7)];
if (*ssindex < 0)
*ssindex = 0;
else if (*ssindex > 48)
*ssindex = 48;
}
/*
* Adpcm
* Takes a signed linear signal and encodes it as ADPCM
* For more information see http://support.dialogic.com/appnotes/adpcm.pdf
*
* Results:
* Foo.
*
* Side effects:
* signal gets updated with each pass.
*/
static inline unsigned char
adpcm (short csig, short *ssindex, short *signal, unsigned char *rkey, unsigned char *next)
{
short diff, step;
unsigned char encoded;
step = stpsz[*ssindex];
/*
* Clip csig if too large or too small
*/
csig >>= 4;
diff = csig - *signal;
if (diff < 0)
{
encoded = 8;
diff = -diff;
}
else
encoded = 0;
if (diff >= step)
{
encoded |= 4;
diff -= step;
}
step >>= 1;
if (diff >= step)
{
encoded |= 2;
diff -= step;
}
step >>= 1;
if (diff >= step)
encoded |= 1;
decode (encoded, ssindex, signal, rkey, next);
return (encoded);
}
/*
* Private workspace for translating signed linear signals to ADPCM.
*/
struct adpcm_encoder_pvt
{
struct ast_frame f;
char offset[AST_FRIENDLY_OFFSET]; /* Space to build offset */
short inbuf[BUFFER_SIZE]; /* Unencoded signed linear values */
unsigned char outbuf[BUFFER_SIZE]; /* Encoded ADPCM, two nibbles to a word */
short ssindex;
short signal;
unsigned char zero_count;
unsigned char next_flag;
int tail;
};
/*
* Private workspace for translating ADPCM signals to signed linear.
*/
struct adpcm_decoder_pvt
{
struct ast_frame f;
char offset[AST_FRIENDLY_OFFSET]; /* Space to build offset */
short outbuf[BUFFER_SIZE]; /* Decoded signed linear values */
short ssindex;
short signal;
unsigned char zero_count;
unsigned char next_flag;
int tail;
};
/*
* AdpcmToLin_New
* Create a new instance of adpcm_decoder_pvt.
*
* Results:
* Returns a pointer to the new instance.
*
* Side effects:
* None.
*/
static struct ast_translator_pvt *
adpcmtolin_new (void)
{
struct adpcm_decoder_pvt *tmp;
tmp = malloc (sizeof (struct adpcm_decoder_pvt));
if (tmp)
{
memset(tmp, 0, sizeof(*tmp));
tmp->tail = 0;
localusecnt++;
ast_update_use_count ();
}
return (struct ast_translator_pvt *) tmp;
}
/*
* LinToAdpcm_New
* Create a new instance of adpcm_encoder_pvt.
*
* Results:
* Returns a pointer to the new instance.
*
* Side effects:
* None.
*/
static struct ast_translator_pvt *
lintoadpcm_new (void)
{
struct adpcm_encoder_pvt *tmp;
tmp = malloc (sizeof (struct adpcm_encoder_pvt));
if (tmp)
{
memset(tmp, 0, sizeof(*tmp));
localusecnt++;
ast_update_use_count ();
tmp->tail = 0;
}
return (struct ast_translator_pvt *) tmp;
}
/*
* AdpcmToLin_FrameIn
* Fill an input buffer with packed 4-bit ADPCM values if there is room
* left.
*
* Results:
* Foo
*
* Side effects:
* tmp->tail is the number of packed values in the buffer.
*/
static int
adpcmtolin_framein (struct ast_translator_pvt *pvt, struct ast_frame *f)
{
struct adpcm_decoder_pvt *tmp = (struct adpcm_decoder_pvt *) pvt;
int x;
unsigned char *b;
if (f->datalen * 4 > sizeof(tmp->outbuf)) {
ast_log(LOG_WARNING, "Out of buffer space\n");
return -1;
}
b = f->data;
for (x=0;x<f->datalen;x++) {
decode((b[x] >> 4) & 0xf, &tmp->ssindex, &tmp->signal, &tmp->zero_count, &tmp->next_flag);
tmp->outbuf[tmp->tail++] = tmp->signal << 4;
decode(b[x] & 0x0f, &tmp->ssindex, &tmp->signal, &tmp->zero_count, &tmp->next_flag);
tmp->outbuf[tmp->tail++] = tmp->signal << 4;
}
return 0;
}
/*
* AdpcmToLin_FrameOut
* Convert 4-bit ADPCM encoded signals to 16-bit signed linear.
*
* Results:
* Converted signals are placed in tmp->f.data, tmp->f.datalen
* and tmp->f.samples are calculated.
*
* Side effects:
* None.
*/
static struct ast_frame *
adpcmtolin_frameout (struct ast_translator_pvt *pvt)
{
struct adpcm_decoder_pvt *tmp = (struct adpcm_decoder_pvt *) pvt;
if (!tmp->tail)
return NULL;
tmp->f.frametype = AST_FRAME_VOICE;
tmp->f.subclass = AST_FORMAT_SLINEAR;
tmp->f.datalen = tmp->tail *2;
tmp->f.samples = tmp->tail;
tmp->f.mallocd = 0;
tmp->f.offset = AST_FRIENDLY_OFFSET;
tmp->f.src = __PRETTY_FUNCTION__;
tmp->f.data = tmp->outbuf;
tmp->tail = 0;
return &tmp->f;
}
/*
* LinToAdpcm_FrameIn
* Fill an input buffer with 16-bit signed linear PCM values.
*
* Results:
* None.
*
* Side effects:
* tmp->tail is number of signal values in the input buffer.
*/
static int
lintoadpcm_framein (struct ast_translator_pvt *pvt, struct ast_frame *f)
{
struct adpcm_encoder_pvt *tmp = (struct adpcm_encoder_pvt *) pvt;
if ((tmp->tail + f->datalen / 2) < (sizeof (tmp->inbuf) / 2))
{
memcpy (&tmp->inbuf[tmp->tail], f->data, f->datalen);
tmp->tail += f->datalen / 2;
}
else
{
ast_log (LOG_WARNING, "Out of buffer space\n");
return -1;
}
return 0;
}
/*
* LinToAdpcm_FrameOut
* Convert a buffer of raw 16-bit signed linear PCM to a buffer
* of 4-bit ADPCM packed two to a byte (Big Endian).
*
* Results:
* Foo
*
* Side effects:
* Leftover inbuf data gets packed, tail gets updated.
*/
static struct ast_frame *
lintoadpcm_frameout (struct ast_translator_pvt *pvt)
{
struct adpcm_encoder_pvt *tmp = (struct adpcm_encoder_pvt *) pvt;
unsigned char adpcm0, adpcm1;
int i_max, i;
if (tmp->tail < 2) return NULL;
i_max = (tmp->tail / 2) * 2;
tmp->outbuf[0] = tmp->ssindex & 0xff;
tmp->outbuf[1] = (tmp->signal >> 8) & 0xff;
tmp->outbuf[2] = (tmp->signal & 0xff);
tmp->outbuf[3] = tmp->zero_count;
tmp->outbuf[4] = tmp->next_flag;
for (i = 0; i < i_max; i+=2)
{
adpcm0 = adpcm (tmp->inbuf[i], &tmp->ssindex, &tmp->signal, &tmp->zero_count, &tmp->next_flag);
adpcm1 = adpcm (tmp->inbuf[i+1], &tmp->ssindex, &tmp->signal, &tmp->zero_count, &tmp->next_flag);
tmp->outbuf[i/2] = (adpcm0 << 4) | adpcm1;
};
tmp->f.frametype = AST_FRAME_VOICE;
tmp->f.subclass = AST_FORMAT_ADPCM;
tmp->f.samples = i_max;
tmp->f.mallocd = 0;
tmp->f.offset = AST_FRIENDLY_OFFSET;
tmp->f.src = __PRETTY_FUNCTION__;
tmp->f.data = tmp->outbuf;
tmp->f.datalen = i_max / 2;
/*
* If there is a signal left over (there should be no more than
* one) move it to the beginning of the input buffer.
*/
if (tmp->tail == i_max)
tmp->tail = 0;
else
{
tmp->inbuf[0] = tmp->inbuf[tmp->tail];
tmp->tail = 1;
}
return &tmp->f;
}
/*
* AdpcmToLin_Sample
*/
static struct ast_frame *
adpcmtolin_sample (void)
{
static struct ast_frame f;
f.frametype = AST_FRAME_VOICE;
f.subclass = AST_FORMAT_ADPCM;
f.datalen = sizeof (adpcm_slin_ex);
f.samples = sizeof(adpcm_slin_ex) * 2;
f.mallocd = 0;
f.offset = 0;
f.src = __PRETTY_FUNCTION__;
f.data = adpcm_slin_ex;
return &f;
}
/*
* LinToAdpcm_Sample
*/
static struct ast_frame *
lintoadpcm_sample (void)
{
static struct ast_frame f;
f.frametype = AST_FRAME_VOICE;
f.subclass = AST_FORMAT_SLINEAR;
f.datalen = sizeof (slin_adpcm_ex);
/* Assume 8000 Hz */
f.samples = sizeof (slin_adpcm_ex) / 2;
f.mallocd = 0;
f.offset = 0;
f.src = __PRETTY_FUNCTION__;
f.data = slin_adpcm_ex;
return &f;
}
/*
* Adpcm_Destroy
* Destroys a private workspace.
*
* Results:
* It's gone!
*
* Side effects:
* None.
*/
static void
adpcm_destroy (struct ast_translator_pvt *pvt)
{
free (pvt);
localusecnt--;
ast_update_use_count ();
}
/*
* The complete translator for ADPCMToLin.
*/
static struct ast_translator adpcmtolin = {
"adpcmtolin",
AST_FORMAT_ADPCM,
AST_FORMAT_SLINEAR,
adpcmtolin_new,
adpcmtolin_framein,
adpcmtolin_frameout,
adpcm_destroy,
/* NULL */
adpcmtolin_sample
};
/*
* The complete translator for LinToADPCM.
*/
static struct ast_translator lintoadpcm = {
"lintoadpcm",
AST_FORMAT_SLINEAR,
AST_FORMAT_ADPCM,
lintoadpcm_new,
lintoadpcm_framein,
lintoadpcm_frameout,
adpcm_destroy,
/* NULL */
lintoadpcm_sample
};
int
unload_module (void)
{
int res;
ast_mutex_lock (&localuser_lock);
res = ast_unregister_translator (&lintoadpcm);
if (!res)
res = ast_unregister_translator (&adpcmtolin);
if (localusecnt)
res = -1;
ast_mutex_unlock (&localuser_lock);
return res;
}
int
load_module (void)
{
int res;
res = ast_register_translator (&adpcmtolin);
if (!res)
res = ast_register_translator (&lintoadpcm);
else
ast_unregister_translator (&adpcmtolin);
return res;
}
/*
* Return a description of this module.
*/
char *
description (void)
{
return tdesc;
}
int
usecount (void)
{
int res;
STANDARD_USECOUNT (res);
return res;
}
char *
key ()
{
return ASTERISK_GPL_KEY;
}