159 lines
4.5 KiB
C
159 lines
4.5 KiB
C
/*
|
|
* This source code is a product of Sun Microsystems, Inc. and is provided
|
|
* for unrestricted use. Users may copy or modify this source code without
|
|
* charge.
|
|
*
|
|
* SUN SOURCE CODE IS PROVIDED AS IS WITH NO WARRANTIES OF ANY KIND INCLUDING
|
|
* THE WARRANTIES OF DESIGN, MERCHANTIBILITY AND FITNESS FOR A PARTICULAR
|
|
* PURPOSE, OR ARISING FROM A COURSE OF DEALING, USAGE OR TRADE PRACTICE.
|
|
*
|
|
* Sun source code is provided with no support and without any obligation on
|
|
* the part of Sun Microsystems, Inc. to assist in its use, correction,
|
|
* modification or enhancement.
|
|
*
|
|
* SUN MICROSYSTEMS, INC. SHALL HAVE NO LIABILITY WITH RESPECT TO THE
|
|
* INFRINGEMENT OF COPYRIGHTS, TRADE SECRETS OR ANY PATENTS BY THIS SOFTWARE
|
|
* OR ANY PART THEREOF.
|
|
*
|
|
* In no event will Sun Microsystems, Inc. be liable for any lost revenue
|
|
* or profits or other special, indirect and consequential damages, even if
|
|
* Sun has been advised of the possibility of such damages.
|
|
*
|
|
* Sun Microsystems, Inc.
|
|
* 2550 Garcia Avenue
|
|
* Mountain View, California 94043
|
|
*/
|
|
|
|
/*
|
|
* g723_24.c
|
|
*
|
|
* Description:
|
|
*
|
|
* g723_24_encoder(), g723_24_decoder()
|
|
*
|
|
* These routines comprise an implementation of the CCITT G.723 24 Kbps
|
|
* ADPCM coding algorithm. Essentially, this implementation is identical to
|
|
* the bit level description except for a few deviations which take advantage
|
|
* of workstation attributes, such as hardware 2's complement arithmetic.
|
|
*
|
|
*/
|
|
#include "g72x.h"
|
|
|
|
/*
|
|
* Maps G.723_24 code word to reconstructed scale factor normalized log
|
|
* magnitude values.
|
|
*/
|
|
static short _dqlntab[8] = {-2048, 135, 273, 373, 373, 273, 135, -2048};
|
|
|
|
/* Maps G.723_24 code word to log of scale factor multiplier. */
|
|
static short _witab[8] = {-128, 960, 4384, 18624, 18624, 4384, 960, -128};
|
|
|
|
/*
|
|
* Maps G.723_24 code words to a set of values whose long and short
|
|
* term averages are computed and then compared to give an indication
|
|
* how stationary (steady state) the signal is.
|
|
*/
|
|
static short _fitab[8] = {0, 0x200, 0x400, 0xE00, 0xE00, 0x400, 0x200, 0};
|
|
|
|
static short qtab_723_24[3] = {8, 218, 331};
|
|
|
|
/*
|
|
* g723_24_encoder()
|
|
*
|
|
* Encodes a linear PCM, A-law or u-law input sample and returns its 3-bit code.
|
|
* Returns -1 if invalid input coding value.
|
|
*/
|
|
int
|
|
g723_24_encoder(
|
|
int sl,
|
|
int in_coding,
|
|
struct g72x_state *state_ptr)
|
|
{
|
|
short sei, sezi, se, sez; /* ACCUM */
|
|
short d; /* SUBTA */
|
|
short y; /* MIX */
|
|
short sr; /* ADDB */
|
|
short dqsez; /* ADDC */
|
|
short dq, i;
|
|
|
|
switch (in_coding) { /* linearize input sample to 14-bit PCM */
|
|
case AUDIO_ENCODING_ALAW:
|
|
sl = alaw2linear(sl) >> 2;
|
|
break;
|
|
case AUDIO_ENCODING_ULAW:
|
|
sl = ulaw2linear(sl) >> 2;
|
|
break;
|
|
case AUDIO_ENCODING_LINEAR:
|
|
sl >>= 2; /* sl of 14-bit dynamic range */
|
|
break;
|
|
default:
|
|
return (-1);
|
|
}
|
|
|
|
sezi = predictor_zero(state_ptr);
|
|
sez = sezi >> 1;
|
|
sei = sezi + predictor_pole(state_ptr);
|
|
se = sei >> 1; /* se = estimated signal */
|
|
|
|
d = sl - se; /* d = estimation diff. */
|
|
|
|
/* quantize prediction difference d */
|
|
y = step_size(state_ptr); /* quantizer step size */
|
|
i = quantize(d, y, qtab_723_24, 3); /* i = ADPCM code */
|
|
dq = reconstruct(i & 4, _dqlntab[i], y); /* quantized diff. */
|
|
|
|
sr = (dq < 0) ? se - (dq & 0x3FFF) : se + dq; /* reconstructed signal */
|
|
|
|
dqsez = sr + sez - se; /* pole prediction diff. */
|
|
|
|
update(3, y, _witab[i], _fitab[i], dq, sr, dqsez, state_ptr);
|
|
|
|
return (i);
|
|
}
|
|
|
|
/*
|
|
* g723_24_decoder()
|
|
*
|
|
* Decodes a 3-bit CCITT G.723_24 ADPCM code and returns
|
|
* the resulting 16-bit linear PCM, A-law or u-law sample value.
|
|
* -1 is returned if the output coding is unknown.
|
|
*/
|
|
int
|
|
g723_24_decoder(
|
|
int i,
|
|
int out_coding,
|
|
struct g72x_state *state_ptr)
|
|
{
|
|
short sezi, sei, sez, se; /* ACCUM */
|
|
short y; /* MIX */
|
|
short sr; /* ADDB */
|
|
short dq;
|
|
short dqsez;
|
|
|
|
i &= 0x07; /* mask to get proper bits */
|
|
sezi = predictor_zero(state_ptr);
|
|
sez = sezi >> 1;
|
|
sei = sezi + predictor_pole(state_ptr);
|
|
se = sei >> 1; /* se = estimated signal */
|
|
|
|
y = step_size(state_ptr); /* adaptive quantizer step size */
|
|
dq = reconstruct(i & 0x04, _dqlntab[i], y); /* unquantize pred diff */
|
|
|
|
sr = (dq < 0) ? (se - (dq & 0x3FFF)) : (se + dq); /* reconst. signal */
|
|
|
|
dqsez = sr - se + sez; /* pole prediction diff. */
|
|
|
|
update(3, y, _witab[i], _fitab[i], dq, sr, dqsez, state_ptr);
|
|
|
|
switch (out_coding) {
|
|
case AUDIO_ENCODING_ALAW:
|
|
return (tandem_adjust_alaw(sr, se, y, i, 4, qtab_723_24));
|
|
case AUDIO_ENCODING_ULAW:
|
|
return (tandem_adjust_ulaw(sr, se, y, i, 4, qtab_723_24));
|
|
case AUDIO_ENCODING_LINEAR:
|
|
return (sr << 2); /* sr was of 14-bit dynamic range */
|
|
default:
|
|
return (-1);
|
|
}
|
|
}
|