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Diffstat (limited to 'libs/libsndfile/src/G72x/g723_16.c')
| -rw-r--r-- | libs/libsndfile/src/G72x/g723_16.c | 169 |
1 files changed, 169 insertions, 0 deletions
diff --git a/libs/libsndfile/src/G72x/g723_16.c b/libs/libsndfile/src/G72x/g723_16.c new file mode 100644 index 0000000000..0c3174501c --- /dev/null +++ b/libs/libsndfile/src/G72x/g723_16.c @@ -0,0 +1,169 @@ +/* + * 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 + */ +/* 16kbps version created, used 24kbps code and changing as little as possible. + * G.726 specs are available from ITU's gopher or WWW site (http://www.itu.ch) + * If any errors are found, please contact me at mrand@tamu.edu + * -Marc Randolph + */ + +/* + * g723_16.c + * + * Description: + * + * g723_16_encoder(), g723_16_decoder() + * + * These routines comprise an implementation of the CCITT G.726 16 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" +#include "g72x_priv.h" + +/* + * Maps G.723_16 code word to reconstructed scale factor normalized log + * magnitude values. Comes from Table 11/G.726 + */ +static short _dqlntab[4] = { 116, 365, 365, 116}; + +/* Maps G.723_16 code word to log of scale factor multiplier. + * + * _witab[4] is actually {-22 , 439, 439, -22}, but FILTD wants it + * as WI << 5 (multiplied by 32), so we'll do that here + */ +static short _witab[4] = {-704, 14048, 14048, -704}; + +/* + * Maps G.723_16 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. + */ + +/* Comes from FUNCTF */ +static short _fitab[4] = {0, 0xE00, 0xE00, 0}; + +/* Comes from quantizer decision level tables (Table 7/G.726) + */ +static short qtab_723_16[1] = {261}; + + +/* + * g723_16_encoder() + * + * Encodes a linear PCM, A-law or u-law input sample and returns its 2-bit code. + * Returns -1 if invalid input coding value. + */ +int +g723_16_encoder( + int sl, + 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; + + /* linearize input sample to 14-bit PCM */ + sl >>= 2; /* sl of 14-bit dynamic range */ + + 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_16, 1); /* i = ADPCM code */ + + /* Since quantize() only produces a three level output + * (1, 2, or 3), we must create the fourth one on our own + */ + if (i == 3) /* i code for the zero region */ + if ((d & 0x8000) == 0) /* If d > 0, i=3 isn't right... */ + i = 0; + + dq = reconstruct(i & 2, _dqlntab[i], y); /* quantized diff. */ + + sr = (dq < 0) ? se - (dq & 0x3FFF) : se + dq; /* reconstructed signal */ + + dqsez = sr + sez - se; /* pole prediction diff. */ + + update(2, y, _witab[i], _fitab[i], dq, sr, dqsez, state_ptr); + + return (i); +} + +/* + * g723_16_decoder() + * + * Decodes a 2-bit CCITT G.723_16 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_16_decoder( + int i, + G72x_STATE *state_ptr) +{ + short sezi, sei, sez, se; /* ACCUM */ + short y; /* MIX */ + short sr; /* ADDB */ + short dq; + short dqsez; + + i &= 0x03; /* 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 & 0x02, _dqlntab[i], y); /* unquantize pred diff */ + + sr = (dq < 0) ? (se - (dq & 0x3FFF)) : (se + dq); /* reconst. signal */ + + dqsez = sr - se + sez; /* pole prediction diff. */ + + update(2, y, _witab[i], _fitab[i], dq, sr, dqsez, state_ptr); + + /* sr was of 14-bit dynamic range */ + return (sr << 2); +} +/* +** Do not edit or modify anything in this comment block. +** The arch-tag line is a file identity tag for the GNU Arch +** revision control system. +** +** arch-tag: ae265466-c3fc-4f83-bb32-edae488a5ca5 +*/ + |