| /* |
| * 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); |
| } |
| |