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| 2 | pj | 1 | /* |
| 2 | * Mpeg Layer-1,2,3 audio decoder |
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| 3 | * ------------------------------ |
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| 4 | * copyright (c) 1995 by Michael Hipp, All rights reserved. See also 'README' |
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| 5 | * version for slower machines .. decodes only every second sample |
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| 6 | * sounds like 24000,22050 or 16000 kHz .. (depending on original sample freq.) |
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| 7 | * |
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| 8 | */ |
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| 9 | |||
| 10 | #include <stdlib.h> |
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| 11 | #include <math.h> |
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| 12 | #include <string.h> |
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| 13 | |||
| 14 | #include "mpg123.h" |
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| 15 | |||
| 16 | #define WRITE_SAMPLE(samples,sum,clip) \ |
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| 17 | if( (sum) > 32767.0) { *(samples) = 0x7fff; (clip)++; } \ |
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| 18 | else if( (sum) < -32768.0) { *(samples) = -0x8000; (clip)++; } \ |
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| 19 | else { *(samples) = sum; } |
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| 20 | |||
| 21 | int synth_2to1_8bit(real *bandPtr,int channel,unsigned char *samples) |
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| 22 | { |
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| 23 | short samples_tmp[32]; |
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| 24 | short *tmp1 = samples_tmp + channel; |
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| 25 | int i,ret; |
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| 26 | |||
| 27 | samples += channel; |
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| 28 | ret = synth_2to1(bandPtr,channel,(unsigned char *) samples_tmp); |
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| 29 | |||
| 30 | for(i=0;i<16;i++) { |
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| 31 | *samples = conv16to8[*tmp1>>4]; |
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| 32 | samples += 2; |
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| 33 | tmp1 += 2; |
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| 34 | } |
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| 35 | |||
| 36 | return ret; |
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| 37 | } |
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| 38 | |||
| 39 | int synth_2to1_8bit_mono(real *bandPtr,unsigned char *samples) |
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| 40 | { |
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| 41 | short samples_tmp[32]; |
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| 42 | short *tmp1 = samples_tmp; |
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| 43 | int i,ret; |
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| 44 | |||
| 45 | ret = synth_2to1(bandPtr,0,(unsigned char *) samples_tmp); |
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| 46 | |||
| 47 | for(i=0;i<16;i++) { |
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| 48 | *samples++ = conv16to8[*tmp1>>4]; |
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| 49 | *samples++ = conv16to8[*tmp1>>4]; |
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| 50 | tmp1 += 2; |
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| 51 | } |
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| 52 | |||
| 53 | return ret; |
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| 54 | } |
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| 55 | |||
| 56 | int synth_2to1_mono(real *bandPtr,unsigned char *samples) |
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| 57 | { |
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| 58 | int i,ret = synth_2to1(bandPtr,0,samples); |
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| 59 | for(i=0;i<16;i++) { |
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| 60 | ((short *)samples)[1] = ((short *)samples)[0]; |
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| 61 | samples+=4; |
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| 62 | } |
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| 63 | return ret; |
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| 64 | } |
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| 65 | |||
| 66 | int synth_2to1(real *bandPtr,int channel,unsigned char *out) |
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| 67 | { |
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| 68 | static real buffs[2][2][0x110]; |
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| 69 | static const int step = 2; |
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| 70 | static int bo = 1; |
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| 71 | short *samples = (short *) out; |
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| 72 | |||
| 73 | real *b0,(*buf)[0x110]; |
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| 74 | int clip = 0; |
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| 75 | int bo1; |
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| 76 | |||
| 77 | if(!channel) { |
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| 78 | bo--; |
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| 79 | bo &= 0xf; |
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| 80 | buf = buffs[0]; |
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| 81 | } |
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| 82 | else { |
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| 83 | samples++; |
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| 84 | buf = buffs[1]; |
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| 85 | } |
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| 86 | |||
| 87 | if(bo & 0x1) { |
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| 88 | b0 = buf[0]; |
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| 89 | bo1 = bo; |
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| 90 | dct64(buf[1]+((bo+1)&0xf),buf[0]+bo,bandPtr); |
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| 91 | } |
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| 92 | else { |
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| 93 | b0 = buf[1]; |
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| 94 | bo1 = bo+1; |
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| 95 | dct64(buf[0]+bo,buf[1]+bo+1,bandPtr); |
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| 96 | } |
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| 97 | |||
| 98 | { |
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| 99 | register int j; |
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| 100 | real *window = decwin + 16 - bo1; |
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| 101 | |||
| 102 | for (j=8;j;j--,b0+=0x10,window+=0x30) |
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| 103 | { |
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| 104 | real sum; |
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| 105 | sum = *window++ * *b0++; |
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| 106 | sum -= *window++ * *b0++; |
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| 107 | sum += *window++ * *b0++; |
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| 108 | sum -= *window++ * *b0++; |
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| 109 | sum += *window++ * *b0++; |
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| 110 | sum -= *window++ * *b0++; |
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| 111 | sum += *window++ * *b0++; |
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| 112 | sum -= *window++ * *b0++; |
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| 113 | sum += *window++ * *b0++; |
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| 114 | sum -= *window++ * *b0++; |
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| 115 | sum += *window++ * *b0++; |
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| 116 | sum -= *window++ * *b0++; |
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| 117 | sum += *window++ * *b0++; |
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| 118 | sum -= *window++ * *b0++; |
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| 119 | sum += *window++ * *b0++; |
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| 120 | sum -= *window++ * *b0++; |
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| 121 | |||
| 122 | WRITE_SAMPLE(samples,sum,clip); samples += step; |
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| 123 | #if 0 |
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| 124 | WRITE_SAMPLE(samples,sum,clip); samples += step; |
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| 125 | #endif |
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| 126 | } |
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| 127 | |||
| 128 | { |
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| 129 | real sum; |
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| 130 | sum = window[0x0] * b0[0x0]; |
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| 131 | sum += window[0x2] * b0[0x2]; |
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| 132 | sum += window[0x4] * b0[0x4]; |
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| 133 | sum += window[0x6] * b0[0x6]; |
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| 134 | sum += window[0x8] * b0[0x8]; |
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| 135 | sum += window[0xA] * b0[0xA]; |
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| 136 | sum += window[0xC] * b0[0xC]; |
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| 137 | sum += window[0xE] * b0[0xE]; |
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| 138 | WRITE_SAMPLE(samples,sum,clip); samples += step; |
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| 139 | #if 0 |
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| 140 | WRITE_SAMPLE(samples,sum,clip); samples += step; |
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| 141 | #endif |
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| 142 | b0-=0x20,window-=0x40; |
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| 143 | } |
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| 144 | window += bo1<<1; |
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| 145 | |||
| 146 | for (j=7;j;j--,b0-=0x30,window-=0x30) |
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| 147 | { |
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| 148 | real sum; |
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| 149 | sum = -*(--window) * *b0++; |
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| 150 | sum -= *(--window) * *b0++; |
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| 151 | sum -= *(--window) * *b0++; |
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| 152 | sum -= *(--window) * *b0++; |
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| 153 | sum -= *(--window) * *b0++; |
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| 154 | sum -= *(--window) * *b0++; |
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| 155 | sum -= *(--window) * *b0++; |
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| 156 | sum -= *(--window) * *b0++; |
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| 157 | sum -= *(--window) * *b0++; |
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| 158 | sum -= *(--window) * *b0++; |
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| 159 | sum -= *(--window) * *b0++; |
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| 160 | sum -= *(--window) * *b0++; |
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| 161 | sum -= *(--window) * *b0++; |
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| 162 | sum -= *(--window) * *b0++; |
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| 163 | sum -= *(--window) * *b0++; |
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| 164 | sum -= *(--window) * *b0++; |
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| 165 | |||
| 166 | WRITE_SAMPLE(samples,sum,clip); samples += step; |
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| 167 | #if 0 |
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| 168 | WRITE_SAMPLE(samples,sum,clip); samples += step; |
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| 169 | #endif |
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| 170 | } |
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| 171 | } |
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| 172 | |||
| 173 | return clip; |
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| 174 | } |
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| 175 | |||
| 176 |