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 27#include "wx/wxprec.h" 28 29/* 30 * g721.c 31 * 32 * Description: 33 * 34 * g721_encoder(), g721_decoder() 35 * 36 * These routines comprise an implementation of the CCITT G.721 ADPCM 37 * coding algorithm. Essentially, this implementation is identical to 38 * the bit level description except for a few deviations which 39 * take advantage of work station attributes, such as hardware 2's 40 * complement arithmetic and large memory. Specifically, certain time 41 * consuming operations such as multiplications are replaced 42 * with lookup tables and software 2's complement operations are 43 * replaced with hardware 2's complement. 44 * 45 * The deviation from the bit level specification (lookup tables) 46 * preserves the bit level performance specifications. 47 * 48 * As outlined in the G.721 Recommendation, the algorithm is broken 49 * down into modules. Each section of code below is preceded by 50 * the name of the module which it is implementing. 51 * 52 */ 53#include "wx/mmedia/internal/g72x.h" 54 55static short qtab_721[7] = {-124, 80, 178, 246, 300, 349, 400}; 56/* 57 * Maps G.721 code word to reconstructed scale factor normalized log 58 * magnitude values. 59 */ 60static short _dqlntab[16] = {-2048, 4, 135, 213, 273, 323, 373, 425, 61 425, 373, 323, 273, 213, 135, 4, -2048}; 62 63/* Maps G.721 code word to log of scale factor multiplier. */ 64static short _witab[16] = {-12, 18, 41, 64, 112, 198, 355, 1122, 65 1122, 355, 198, 112, 64, 41, 18, -12}; 66/* 67 * Maps G.721 code words to a set of values whose long and short 68 * term averages are computed and then compared to give an indication 69 * how stationary (steady state) the signal is. 70 */ 71static short _fitab[16] = {0, 0, 0, 0x200, 0x200, 0x200, 0x600, 0xE00, 72 0xE00, 0x600, 0x200, 0x200, 0x200, 0, 0, 0}; 73 74/* 75 * g721_encoder() 76 * 77 * Encodes the input vale of linear PCM, A-law or u-law data sl and returns 78 * the resulting code. -1 is returned for unknown input coding value. 79 */ 80int 81g721_encoder( 82 int sl, 83 int in_coding, 84 struct g72x_state *state_ptr) 85{ 86 short sezi, se, sez; /* ACCUM */ 87 short d; /* SUBTA */ 88 short sr; /* ADDB */ 89 short y; /* MIX */ 90 short dqsez; /* ADDC */ 91 short dq, i; 92 93 switch (in_coding) { /* linearize input sample to 14-bit PCM */ 94 case AUDIO_ENCODING_ALAW: 95 sl = alaw2linear(sl) >> 2; 96 break; 97 case AUDIO_ENCODING_ULAW: 98 sl = ulaw2linear(sl) >> 2; 99 break; 100 case AUDIO_ENCODING_LINEAR: 101 sl = ((short)sl) >> 2; /* 14-bit dynamic range */ 102 break; 103 default: 104 return (-1); 105 } 106 107 sezi = predictor_zero(state_ptr); 108 sez = sezi >> 1; 109 se = (sezi + predictor_pole(state_ptr)) >> 1; /* estimated signal */ 110 111 d = sl - se; /* estimation difference */ 112 113 /* quantize the prediction difference */ 114 y = step_size(state_ptr); /* quantizer step size */ 115 i = quantize(d, y, qtab_721, 7); /* i = ADPCM code */ 116 117 dq = reconstruct(i & 8, _dqlntab[i], y); /* quantized est diff */ 118 119 sr = (dq < 0) ? se - (dq & 0x3FFF) : se + dq; /* reconst. signal */ 120 121 dqsez = sr + sez - se; /* pole prediction diff. */ 122 123 update(4, y, _witab[i] << 5, _fitab[i], dq, sr, dqsez, state_ptr); 124 125 return (i); 126} 127 128/* 129 * g721_decoder() 130 * 131 * Description: 132 * 133 * Decodes a 4-bit code of G.721 encoded data of i and 134 * returns the resulting linear PCM, A-law or u-law value. 135 * return -1 for unknown out_coding value. 136 */ 137int 138g721_decoder( 139 int i, 140 int out_coding, 141 struct g72x_state *state_ptr) 142{ 143 short sezi, sei, sez, se; /* ACCUM */ 144 short y; /* MIX */ 145 short sr; /* ADDB */ 146 short dq; 147 short dqsez; 148 149 i &= 0x0f; /* mask to get proper bits */ 150 sezi = predictor_zero(state_ptr); 151 sez = sezi >> 1; 152 sei = sezi + predictor_pole(state_ptr); 153 se = sei >> 1; /* se = estimated signal */ 154 155 y = step_size(state_ptr); /* dynamic quantizer step size */ 156 157 dq = reconstruct(i & 0x08, _dqlntab[i], y); /* quantized diff. */ 158 159 sr = (dq < 0) ? (se - (dq & 0x3FFF)) : se + dq; /* reconst. signal */ 160 161 dqsez = sr - se + sez; /* pole prediction diff. */ 162 163 update(4, y, _witab[i] << 5, _fitab[i], dq, sr, dqsez, state_ptr); 164 165 switch (out_coding) { 166 case AUDIO_ENCODING_ALAW: 167 return (tandem_adjust_alaw(sr, se, y, i, 8, qtab_721)); 168 case AUDIO_ENCODING_ULAW: 169 return (tandem_adjust_ulaw(sr, se, y, i, 8, qtab_721)); 170 case AUDIO_ENCODING_LINEAR: 171 return (sr << 2); /* sr was 14-bit dynamic range */ 172 default: 173 return (-1); 174 } 175} 176