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Diffstat (limited to 'gr-vocoder/lib/g7xx/g723_24.c')
| -rw-r--r-- | gr-vocoder/lib/g7xx/g723_24.c | 158 |
1 files changed, 158 insertions, 0 deletions
diff --git a/gr-vocoder/lib/g7xx/g723_24.c b/gr-vocoder/lib/g7xx/g723_24.c new file mode 100644 index 000000000..452f4daeb --- /dev/null +++ b/gr-vocoder/lib/g7xx/g723_24.c @@ -0,0 +1,158 @@ +/* + * 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); + } +} |