| 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 | /* |
| 28 | * g723_40.c |
| 29 | * |
| 30 | * Description: |
| 31 | * |
| 32 | * g723_40_encoder(), g723_40_decoder() |
| 33 | * |
| 34 | * These routines comprise an implementation of the CCITT G.723 40Kbps |
| 35 | * ADPCM coding algorithm. Essentially, this implementation is identical to |
| 36 | * the bit level description except for a few deviations which |
| 37 | * take advantage of workstation attributes, such as hardware 2's |
| 38 | * complement arithmetic. |
| 39 | * |
| 40 | * The deviation from the bit level specification (lookup tables), |
| 41 | * preserves the bit level performance specifications. |
| 42 | * |
| 43 | * As outlined in the G.723 Recommendation, the algorithm is broken |
| 44 | * down into modules. Each section of code below is preceded by |
| 45 | * the name of the module which it is implementing. |
| 46 | * |
| 47 | */ |
| 48 | #include <wx/wxprec.h> |
| 49 | #include "g72x.h" |
| 50 | |
| 51 | /* |
| 52 | * Maps G.723_40 code word to ructeconstructed scale factor normalized log |
| 53 | * magnitude values. |
| 54 | */ |
| 55 | static short _dqlntab[32] = {-2048, -66, 28, 104, 169, 224, 274, 318, |
| 56 | 358, 395, 429, 459, 488, 514, 539, 566, |
| 57 | 566, 539, 514, 488, 459, 429, 395, 358, |
| 58 | 318, 274, 224, 169, 104, 28, -66, -2048}; |
| 59 | |
| 60 | /* Maps G.723_40 code word to log of scale factor multiplier. */ |
| 61 | static short _witab[32] = {448, 448, 768, 1248, 1280, 1312, 1856, 3200, |
| 62 | 4512, 5728, 7008, 8960, 11456, 14080, 16928, 22272, |
| 63 | 22272, 16928, 14080, 11456, 8960, 7008, 5728, 4512, |
| 64 | 3200, 1856, 1312, 1280, 1248, 768, 448, 448}; |
| 65 | |
| 66 | /* |
| 67 | * Maps G.723_40 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 | */ |
| 71 | static short _fitab[32] = {0, 0, 0, 0, 0, 0x200, 0x200, 0x200, |
| 72 | 0x200, 0x200, 0x400, 0x600, 0x800, 0xA00, 0xC00, 0xC00, |
| 73 | 0xC00, 0xC00, 0xA00, 0x800, 0x600, 0x400, 0x200, 0x200, |
| 74 | 0x200, 0x200, 0x200, 0, 0, 0, 0, 0}; |
| 75 | |
| 76 | static short qtab_723_40[15] = {-122, -16, 68, 139, 198, 250, 298, 339, |
| 77 | 378, 413, 445, 475, 502, 528, 553}; |
| 78 | |
| 79 | /* |
| 80 | * g723_40_encoder() |
| 81 | * |
| 82 | * Encodes a 16-bit linear PCM, A-law or u-law input sample and retuens |
| 83 | * the resulting 5-bit CCITT G.723 40Kbps code. |
| 84 | * Returns -1 if the input coding value is invalid. |
| 85 | */ |
| 86 | int |
| 87 | g723_40_encoder( |
| 88 | int sl, |
| 89 | int in_coding, |
| 90 | struct g72x_state *state_ptr) |
| 91 | { |
| 92 | short sei, sezi, se, sez; /* ACCUM */ |
| 93 | short d; /* SUBTA */ |
| 94 | short y; /* MIX */ |
| 95 | short sr; /* ADDB */ |
| 96 | short dqsez; /* ADDC */ |
| 97 | short dq, i; |
| 98 | |
| 99 | switch (in_coding) { /* linearize input sample to 14-bit PCM */ |
| 100 | case AUDIO_ENCODING_ALAW: |
| 101 | sl = alaw2linear(sl) >> 2; |
| 102 | break; |
| 103 | case AUDIO_ENCODING_ULAW: |
| 104 | sl = ulaw2linear(sl) >> 2; |
| 105 | break; |
| 106 | case AUDIO_ENCODING_LINEAR: |
| 107 | sl = ((short) sl) >> 2; /* sl of 14-bit dynamic range */ |
| 108 | break; |
| 109 | default: |
| 110 | return (-1); |
| 111 | } |
| 112 | |
| 113 | sezi = predictor_zero(state_ptr); |
| 114 | sez = sezi >> 1; |
| 115 | sei = sezi + predictor_pole(state_ptr); |
| 116 | se = sei >> 1; /* se = estimated signal */ |
| 117 | |
| 118 | d = sl - se; /* d = estimation difference */ |
| 119 | |
| 120 | /* quantize prediction difference */ |
| 121 | y = step_size(state_ptr); /* adaptive quantizer step size */ |
| 122 | i = quantize(d, y, qtab_723_40, 15); /* i = ADPCM code */ |
| 123 | |
| 124 | dq = reconstruct(i & 0x10, _dqlntab[i], y); /* quantized diff */ |
| 125 | |
| 126 | sr = (dq < 0) ? se - (dq & 0x7FFF) : se + dq; /* reconstructed signal */ |
| 127 | |
| 128 | dqsez = sr + sez - se; /* dqsez = pole prediction diff. */ |
| 129 | |
| 130 | update(5, y, _witab[i], _fitab[i], dq, sr, dqsez, state_ptr); |
| 131 | |
| 132 | return (i); |
| 133 | } |
| 134 | |
| 135 | /* |
| 136 | * g723_40_decoder() |
| 137 | * |
| 138 | * Decodes a 5-bit CCITT G.723 40Kbps code and returns |
| 139 | * the resulting 16-bit linear PCM, A-law or u-law sample value. |
| 140 | * -1 is returned if the output coding is unknown. |
| 141 | */ |
| 142 | int |
| 143 | g723_40_decoder( |
| 144 | int i, |
| 145 | int out_coding, |
| 146 | struct g72x_state *state_ptr) |
| 147 | { |
| 148 | short sezi, sei, sez, se; /* ACCUM */ |
| 149 | short y; /* MIX */ |
| 150 | short sr; /* ADDB */ |
| 151 | short dq; |
| 152 | short dqsez; |
| 153 | |
| 154 | i &= 0x1f; /* mask to get proper bits */ |
| 155 | sezi = predictor_zero(state_ptr); |
| 156 | sez = sezi >> 1; |
| 157 | sei = sezi + predictor_pole(state_ptr); |
| 158 | se = sei >> 1; /* se = estimated signal */ |
| 159 | |
| 160 | y = step_size(state_ptr); /* adaptive quantizer step size */ |
| 161 | dq = reconstruct(i & 0x10, _dqlntab[i], y); /* estimation diff. */ |
| 162 | |
| 163 | sr = (dq < 0) ? (se - (dq & 0x7FFF)) : (se + dq); /* reconst. signal */ |
| 164 | |
| 165 | dqsez = sr - se + sez; /* pole prediction diff. */ |
| 166 | |
| 167 | update(5, y, _witab[i], _fitab[i], dq, sr, dqsez, state_ptr); |
| 168 | |
| 169 | switch (out_coding) { |
| 170 | case AUDIO_ENCODING_ALAW: |
| 171 | return (tandem_adjust_alaw(sr, se, y, i, 0x10, qtab_723_40)); |
| 172 | case AUDIO_ENCODING_ULAW: |
| 173 | return (tandem_adjust_ulaw(sr, se, y, i, 0x10, qtab_723_40)); |
| 174 | case AUDIO_ENCODING_LINEAR: |
| 175 | return (sr << 2); /* sr was of 14-bit dynamic range */ |
| 176 | default: |
| 177 | return (-1); |
| 178 | } |
| 179 | } |