1/* 2 * This source code is a product of Sun Microsystems, Inc. and is provided 3 * for unrestricted use. Users may copy or modify this source code without 4 * charge. 5 * 6 * SUN SOURCE CODE IS PROVIDED AS IS WITH NO WARRANTIES OF ANY KIND INCLUDING 7 * THE WARRANTIES OF DESIGN, MERCHANTIBILITY AND FITNESS FOR A PARTICULAR 8 * PURPOSE, OR ARISING FROM A COURSE OF DEALING, USAGE OR TRADE PRACTICE. 9 * 10 * Sun source code is provided with no support and without any obligation on 11 * the part of Sun Microsystems, Inc. to assist in its use, correction, 12 * modification or enhancement. 13 * 14 * SUN MICROSYSTEMS, INC. SHALL HAVE NO LIABILITY WITH RESPECT TO THE 15 * INFRINGEMENT OF COPYRIGHTS, TRADE SECRETS OR ANY PATENTS BY THIS SOFTWARE 16 * OR ANY PART THEREOF. 17 * 18 * In no event will Sun Microsystems, Inc. be liable for any lost revenue 19 * or profits or other special, indirect and consequential damages, even if 20 * Sun has been advised of the possibility of such damages. 21 * 22 * Sun Microsystems, Inc. 23 * 2550 Garcia Avenue 24 * Mountain View, California 94043 25 */ 26/* 16kbps version created, used 24kbps code and changing as little as possible. 27 * G.726 specs are available from ITU's gopher or WWW site (http://www.itu.ch) 28 * If any errors are found, please contact me at mrand@tamu.edu 29 * -Marc Randolph 30 */ 31 32/* 33 * g723_16.c 34 * 35 * Description: 36 * 37 * g723_16_encoder (), g723_16_decoder () 38 * 39 * These routines comprise an implementation of the CCITT G.726 16 Kbps 40 * ADPCM coding algorithm. Essentially, this implementation is identical to 41 * the bit level description except for a few deviations which take advantage 42 * of workstation attributes, such as hardware 2's complement arithmetic. 43 * 44 */ 45 46#include "g72x.h" 47#include "g72x_priv.h" 48 49/* 50 * Maps G.723_16 code word to reconstructed scale factor normalized log 51 * magnitude values. Comes from Table 11/G.726 52 */ 53static short _dqlntab [4] = { 116, 365, 365, 116 } ; 54 55/* Maps G.723_16 code word to log of scale factor multiplier. 56 * 57 * _witab [4] is actually {-22 , 439, 439, -22}, but FILTD wants it 58 * as WI << 5 (multiplied by 32), so we'll do that here 59 */ 60static short _witab [4] = { -704, 14048, 14048, -704 } ; 61 62/* 63 * Maps G.723_16 code words to a set of values whose long and short 64 * term averages are computed and then compared to give an indication 65 * how stationary (steady state) the signal is. 66 */ 67 68/* Comes from FUNCTF */ 69static short _fitab [4] = { 0, 0xE00, 0xE00, 0 } ; 70 71/* Comes from quantizer decision level tables (Table 7/G.726) 72 */ 73static short qtab_723_16 [1] = { 261 } ; 74 75 76/* 77 * g723_16_encoder () 78 * 79 * Encodes a linear PCM, A-law or u-law input sample and returns its 2-bit code. 80 * Returns -1 if invalid input coding value. 81 */ 82int 83g723_16_encoder ( 84 int sl, 85 G72x_STATE *state_ptr) 86{ 87 short sei, sezi, se, sez ; /* ACCUM */ 88 short d ; /* SUBTA */ 89 short y ; /* MIX */ 90 short sr ; /* ADDB */ 91 short dqsez ; /* ADDC */ 92 short dq, i ; 93 94 /* linearize input sample to 14-bit PCM */ 95 sl >>= 2 ; /* sl of 14-bit dynamic range */ 96 97 sezi = predictor_zero (state_ptr) ; 98 sez = sezi >> 1 ; 99 sei = sezi + predictor_pole (state_ptr) ; 100 se = sei >> 1 ; /* se = estimated signal */ 101 102 d = sl - se ; /* d = estimation diff. */ 103 104 /* quantize prediction difference d */ 105 y = step_size (state_ptr) ; /* quantizer step size */ 106 i = quantize (d, y, qtab_723_16, 1) ; /* i = ADPCM code */ 107 108 /* Since quantize () only produces a three level output 109 * (1, 2, or 3), we must create the fourth one on our own 110 */ 111 if (i == 3) /* i code for the zero region */ 112 if ((d & 0x8000) == 0) /* If d > 0, i=3 isn't right... */ 113 i = 0 ; 114 115 dq = reconstruct (i & 2, _dqlntab [i], y) ; /* quantized diff. */ 116 117 sr = (dq < 0) ? se - (dq & 0x3FFF) : se + dq ; /* reconstructed signal */ 118 119 dqsez = sr + sez - se ; /* pole prediction diff. */ 120 121 update (2, y, _witab [i], _fitab [i], dq, sr, dqsez, state_ptr) ; 122 123 return i ; 124} 125 126/* 127 * g723_16_decoder () 128 * 129 * Decodes a 2-bit CCITT G.723_16 ADPCM code and returns 130 * the resulting 16-bit linear PCM, A-law or u-law sample value. 131 * -1 is returned if the output coding is unknown. 132 */ 133int 134g723_16_decoder ( 135 int i, 136 G72x_STATE *state_ptr) 137{ 138 short sezi, sei, sez, se ; /* ACCUM */ 139 short y ; /* MIX */ 140 short sr ; /* ADDB */ 141 short dq ; 142 short dqsez ; 143 144 i &= 0x03 ; /* mask to get proper bits */ 145 sezi = predictor_zero (state_ptr) ; 146 sez = sezi >> 1 ; 147 sei = sezi + predictor_pole (state_ptr) ; 148 se = sei >> 1 ; /* se = estimated signal */ 149 150 y = step_size (state_ptr) ; /* adaptive quantizer step size */ 151 dq = reconstruct (i & 0x02, _dqlntab [i], y) ; /* unquantize pred diff */ 152 153 sr = (dq < 0) ? (se - (dq & 0x3FFF)) : (se + dq) ; /* reconst. signal */ 154 155 dqsez = sr - se + sez ; /* pole prediction diff. */ 156 157 update (2, y, _witab [i], _fitab [i], dq, sr, dqsez, state_ptr) ; 158 159 /* sr was of 14-bit dynamic range */ 160 return (sr << 2) ; 161} 162 163