7f00235804
git-svn-id: https://svn.code.sf.net/p/fteqw/code/trunk@16 fc73d0e0-1445-4013-8a0c-d673dee63da5
163 lines
4.6 KiB
C
163 lines
4.6 KiB
C
#include "bothdefs.h"
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#ifdef VOICECHAT
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/*
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* This source code is a product of Sun Microsystems, Inc. and is provided
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* for unrestricted use. Users may copy or modify this source code without
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* charge.
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*
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* SUN SOURCE CODE IS PROVIDED AS IS WITH NO WARRANTIES OF ANY KIND INCLUDING
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* THE WARRANTIES OF DESIGN, MERCHANTIBILITY AND FITNESS FOR A PARTICULAR
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* PURPOSE, OR ARISING FROM A COURSE OF DEALING, USAGE OR TRADE PRACTICE.
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*
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* Sun source code is provided with no support and without any obligation on
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* the part of Sun Microsystems, Inc. to assist in its use, correction,
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* modification or enhancement.
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*
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* SUN MICROSYSTEMS, INC. SHALL HAVE NO LIABILITY WITH RESPECT TO THE
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* INFRINGEMENT OF COPYRIGHTS, TRADE SECRETS OR ANY PATENTS BY THIS SOFTWARE
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* OR ANY PART THEREOF.
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*
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* In no event will Sun Microsystems, Inc. be liable for any lost revenue
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* or profits or other special, indirect and consequential damages, even if
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* Sun has been advised of the possibility of such damages.
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*
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* Sun Microsystems, Inc.
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* 2550 Garcia Avenue
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* Mountain View, California 94043
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*/
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/*
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* g723_24.c
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*
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* Description:
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*
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* g723_24_encoder(), g723_24_decoder()
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*
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* These routines comprise an implementation of the CCITT G.723 24 Kbps
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* ADPCM coding algorithm. Essentially, this implementation is identical to
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* the bit level description except for a few deviations which take advantage
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* of workstation attributes, such as hardware 2's complement arithmetic.
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*
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*/
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#include "g72x.h"
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/*
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* Maps G.723_24 code word to reconstructed scale factor normalized log
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* magnitude values.
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*/
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static short _dqlntab[8] = {-2048, 135, 273, 373, 373, 273, 135, -2048};
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/* Maps G.723_24 code word to log of scale factor multiplier. */
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static short _witab[8] = {-128, 960, 4384, 18624, 18624, 4384, 960, -128};
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/*
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* Maps G.723_24 code words to a set of values whose long and short
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* term averages are computed and then compared to give an indication
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* how stationary (steady state) the signal is.
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*/
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static short _fitab[8] = {0, 0x200, 0x400, 0xE00, 0xE00, 0x400, 0x200, 0};
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static short qtab_723_24[3] = {8, 218, 331};
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/*
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* g723_24_encoder()
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*
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* Encodes a linear PCM, A-law or u-law input sample and returns its 3-bit code.
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* Returns -1 if invalid input coding value.
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*/
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int
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g723_24_encoder(
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int sl,
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int in_coding,
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struct g72x_state *state_ptr)
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{
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short sei, sezi, se, sez; /* ACCUM */
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short d; /* SUBTA */
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short y; /* MIX */
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short sr; /* ADDB */
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short dqsez; /* ADDC */
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short dq, i;
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switch (in_coding) { /* linearize input sample to 14-bit PCM */
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case AUDIO_ENCODING_ALAW:
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sl = alaw2linear((unsigned char)sl) >> 2;
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break;
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case AUDIO_ENCODING_ULAW:
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sl = ulaw2linear((unsigned char)sl) >> 2;
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break;
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case AUDIO_ENCODING_LINEAR:
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sl >>= 2; /* sl of 14-bit dynamic range */
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break;
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default:
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return (-1);
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}
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sezi = predictor_zero(state_ptr);
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sez = sezi >> 1;
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sei = sezi + predictor_pole(state_ptr);
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se = sei >> 1; /* se = estimated signal */
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d = sl - se; /* d = estimation diff. */
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/* quantize prediction difference d */
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y = step_size(state_ptr); /* quantizer step size */
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i = quantize(d, y, qtab_723_24, 3); /* i = ADPCM code */
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dq = reconstruct(i & 4, _dqlntab[i], y); /* quantized diff. */
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sr = (dq < 0) ? se - (dq & 0x3FFF) : se + dq; /* reconstructed signal */
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dqsez = sr + sez - se; /* pole prediction diff. */
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update(3, y, _witab[i], _fitab[i], dq, sr, dqsez, state_ptr);
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return (i);
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}
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/*
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* g723_24_decoder()
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*
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* Decodes a 3-bit CCITT G.723_24 ADPCM code and returns
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* the resulting 16-bit linear PCM, A-law or u-law sample value.
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* -1 is returned if the output coding is unknown.
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*/
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int
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g723_24_decoder(
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int i,
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int out_coding,
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struct g72x_state *state_ptr)
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{
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short sezi, sei, sez, se; /* ACCUM */
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short y; /* MIX */
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short sr; /* ADDB */
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short dq;
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short dqsez;
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i &= 0x07; /* mask to get proper bits */
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sezi = predictor_zero(state_ptr);
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sez = sezi >> 1;
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sei = sezi + predictor_pole(state_ptr);
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se = sei >> 1; /* se = estimated signal */
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y = step_size(state_ptr); /* adaptive quantizer step size */
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dq = reconstruct(i & 0x04, _dqlntab[i], y); /* unquantize pred diff */
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sr = (dq < 0) ? (se - (dq & 0x3FFF)) : (se + dq); /* reconst. signal */
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dqsez = sr - se + sez; /* pole prediction diff. */
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update(3, y, _witab[i], _fitab[i], dq, sr, dqsez, state_ptr);
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switch (out_coding) {
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case AUDIO_ENCODING_ALAW:
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return (tandem_adjust_alaw(sr, se, y, i, 4, qtab_723_24));
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case AUDIO_ENCODING_ULAW:
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return (tandem_adjust_ulaw(sr, se, y, i, 4, qtab_723_24));
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case AUDIO_ENCODING_LINEAR:
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return (sr << 2); /* sr was of 14-bit dynamic range */
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default:
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return (-1);
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}
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}
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#endif
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