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Diffstat (limited to 'src/ccitt-adpcm/g723_40.c')
| -rw-r--r-- | src/ccitt-adpcm/g723_40.c | 178 |
1 files changed, 178 insertions, 0 deletions
diff --git a/src/ccitt-adpcm/g723_40.c b/src/ccitt-adpcm/g723_40.c new file mode 100644 index 0000000..4858baf --- /dev/null +++ b/src/ccitt-adpcm/g723_40.c @@ -0,0 +1,178 @@ +/* + * 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_40.c + * + * Description: + * + * g723_40_encoder(), g723_40_decoder() + * + * These routines comprise an implementation of the CCITT G.723 40Kbps + * 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. + * + * The deviation from the bit level specification (lookup tables), + * preserves the bit level performance specifications. + * + * As outlined in the G.723 Recommendation, the algorithm is broken + * down into modules. Each section of code below is preceded by + * the name of the module which it is implementing. + * + */ +#include "g72x.h" + +/* + * Maps G.723_40 code word to ructeconstructed scale factor normalized log + * magnitude values. + */ +static short _dqlntab[32] = {-2048, -66, 28, 104, 169, 224, 274, 318, + 358, 395, 429, 459, 488, 514, 539, 566, + 566, 539, 514, 488, 459, 429, 395, 358, + 318, 274, 224, 169, 104, 28, -66, -2048}; + +/* Maps G.723_40 code word to log of scale factor multiplier. */ +static short _witab[32] = {448, 448, 768, 1248, 1280, 1312, 1856, 3200, + 4512, 5728, 7008, 8960, 11456, 14080, 16928, 22272, + 22272, 16928, 14080, 11456, 8960, 7008, 5728, 4512, + 3200, 1856, 1312, 1280, 1248, 768, 448, 448}; + +/* + * Maps G.723_40 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[32] = {0, 0, 0, 0, 0, 0x200, 0x200, 0x200, + 0x200, 0x200, 0x400, 0x600, 0x800, 0xA00, 0xC00, 0xC00, + 0xC00, 0xC00, 0xA00, 0x800, 0x600, 0x400, 0x200, 0x200, + 0x200, 0x200, 0x200, 0, 0, 0, 0, 0}; + +static short qtab_723_40[15] = {-122, -16, 68, 139, 198, 250, 298, 339, + 378, 413, 445, 475, 502, 528, 553}; + +/* + * g723_40_encoder() + * + * Encodes a 16-bit linear PCM, A-law or u-law input sample and retuens + * the resulting 5-bit CCITT G.723 40Kbps code. + * Returns -1 if the input coding value is invalid. + */ +int +g723_40_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 difference */ + + /* quantize prediction difference */ + y = step_size(state_ptr); /* adaptive quantizer step size */ + i = quantize(d, y, qtab_723_40, 15); /* i = ADPCM code */ + + dq = reconstruct(i & 0x10, _dqlntab[i], y); /* quantized diff */ + + sr = (dq < 0) ? se - (dq & 0x7FFF) : se + dq; /* reconstructed signal */ + + dqsez = sr + sez - se; /* dqsez = pole prediction diff. */ + + update(5, y, _witab[i], _fitab[i], dq, sr, dqsez, state_ptr); + + return (i); +} + +/* + * g723_40_decoder() + * + * Decodes a 5-bit CCITT G.723 40Kbps 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_40_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 &= 0x1f; /* 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 & 0x10, _dqlntab[i], y); /* estimation diff. */ + + sr = (dq < 0) ? (se - (dq & 0x7FFF)) : (se + dq); /* reconst. signal */ + + dqsez = sr - se + sez; /* pole prediction diff. */ + + update(5, 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, 0x10, qtab_723_40)); + case AUDIO_ENCODING_ULAW: + return (tandem_adjust_ulaw(sr, se, y, i, 0x10, qtab_723_40)); + case AUDIO_ENCODING_LINEAR: + return (sr << 2); /* sr was of 14-bit dynamic range */ + default: + return (-1); + } +} |