Alexandre Lision | 7c6f4a6 | 2013-09-05 13:27:01 -0400 | [diff] [blame] | 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 | */ |
| 53 | static 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 | */ |
| 60 | static 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 */ |
| 69 | static short _fitab[4] = {0, 0xE00, 0xE00, 0}; |
| 70 | |
| 71 | /* Comes from quantizer decision level tables (Table 7/G.726) |
| 72 | */ |
| 73 | static 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 | */ |
| 82 | int |
| 83 | g723_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 | */ |
| 133 | int |
| 134 | g723_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 | |