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- /*
- * Mpeg Layer-1,2,3 audio decoder
- * ------------------------------
- * copyright (c) 1995,1996,1997 by Michael Hipp, All rights reserved.
- * See also 'README'
- * version for slower machines .. decodes only every fourth sample
- * dunno why it sounds THIS annoying (maybe we should adapt the window?)
- * absolutely not optimized for this operation
- */
- #include <stdlib.h>
- #include <math.h>
- #include <string.h>
- #include "mpg123.h"
- #define WRITE_SAMPLE(samples,sum,clip) \
- if( (sum) > 32767.0) { *(samples) = 0x7fff; (clip)++; } \
- else if( (sum) < -32768.0) { *(samples) = -0x8000; (clip)++; } \
- else { *(samples) = sum; }
- int synth_4to1_8bit(real *bandPtr,int channel,unsigned char *samples,int *pnt)
- {
- short samples_tmp[16];
- short *tmp1 = samples_tmp + channel;
- int i,ret;
- int pnt1 = 0;
- ret = synth_4to1(bandPtr,channel,(unsigned char *) samples_tmp,&pnt1);
- samples += channel + *pnt;
- for(i=0;i<8;i++) {
- *samples = conv16to8[*tmp1>>AUSHIFT];
- samples += 2;
- tmp1 += 2;
- }
- *pnt += 16;
- return ret;
- }
- int synth_4to1_8bit_mono(real *bandPtr,unsigned char *samples,int *pnt)
- {
- short samples_tmp[16];
- short *tmp1 = samples_tmp;
- int i,ret;
- int pnt1 = 0;
- ret = synth_4to1(bandPtr,0,(unsigned char *) samples_tmp,&pnt1);
- samples += *pnt;
- for(i=0;i<8;i++) {
- *samples++ = conv16to8[*tmp1>>AUSHIFT];
- tmp1 += 2;
- }
- *pnt += 8;
- return ret;
- }
- int synth_4to1_8bit_mono2stereo(real *bandPtr,unsigned char *samples,int *pnt)
- {
- short samples_tmp[16];
- short *tmp1 = samples_tmp;
- int i,ret;
- int pnt1 = 0;
- ret = synth_4to1(bandPtr,0,(unsigned char *) samples_tmp,&pnt1);
- samples += *pnt;
- for(i=0;i<8;i++) {
- *samples++ = conv16to8[*tmp1>>AUSHIFT];
- *samples++ = conv16to8[*tmp1>>AUSHIFT];
- tmp1 += 2;
- }
- *pnt += 16;
- return ret;
- }
- int synth_4to1_mono(real *bandPtr,unsigned char *samples,int *pnt)
- {
- short samples_tmp[16];
- short *tmp1 = samples_tmp;
- int i,ret;
- int pnt1 = 0;
- ret = synth_4to1(bandPtr,0,(unsigned char *) samples_tmp,&pnt1);
- samples += *pnt;
- for(i=0;i<8;i++) {
- *( (short *)samples) = *tmp1;
- samples += 2;
- tmp1 += 2;
- }
- *pnt += 16;
- return ret;
- }
- int synth_4to1_mono2stereo(real *bandPtr,unsigned char *samples,int *pnt)
- {
- int i,ret;
- ret = synth_4to1(bandPtr,0,samples,pnt);
- samples = samples + *pnt - 32;
- for(i=0;i<8;i++) {
- ((short *)samples)[1] = ((short *)samples)[0];
- samples+=4;
- }
- return ret;
- }
- int synth_4to1(real *bandPtr,int channel,unsigned char *out,int *pnt)
- {
- static real buffs[2][2][0x110];
- static const int step = 2;
- static int bo = 1;
- short *samples = (short *) (out + *pnt);
- real *b0,(*buf)[0x110];
- int clip = 0;
- int bo1;
- if(equalfile)
- do_equalizer(bandPtr,channel);
- if(!channel) {
- bo--;
- bo &= 0xf;
- buf = buffs[0];
- }
- else {
- samples++;
- buf = buffs[1];
- }
- if(bo & 0x1) {
- b0 = buf[0];
- bo1 = bo;
- dct64(buf[1]+((bo+1)&0xf),buf[0]+bo,bandPtr);
- }
- else {
- b0 = buf[1];
- bo1 = bo+1;
- dct64(buf[0]+bo,buf[1]+bo+1,bandPtr);
- }
- {
- register int j;
- real *window = decwin + 16 - bo1;
- for (j=4;j;j--,b0+=0x30,window+=0x70)
- {
- real sum;
- sum = *window++ * *b0++;
- sum -= *window++ * *b0++;
- sum += *window++ * *b0++;
- sum -= *window++ * *b0++;
- sum += *window++ * *b0++;
- sum -= *window++ * *b0++;
- sum += *window++ * *b0++;
- sum -= *window++ * *b0++;
- sum += *window++ * *b0++;
- sum -= *window++ * *b0++;
- sum += *window++ * *b0++;
- sum -= *window++ * *b0++;
- sum += *window++ * *b0++;
- sum -= *window++ * *b0++;
- sum += *window++ * *b0++;
- sum -= *window++ * *b0++;
- WRITE_SAMPLE(samples,sum,clip); samples += step;
- #if 0
- WRITE_SAMPLE(samples,sum,clip); samples += step;
- WRITE_SAMPLE(samples,sum,clip); samples += step;
- WRITE_SAMPLE(samples,sum,clip); samples += step;
- #endif
- }
- {
- real sum;
- sum = window[0x0] * b0[0x0];
- sum += window[0x2] * b0[0x2];
- sum += window[0x4] * b0[0x4];
- sum += window[0x6] * b0[0x6];
- sum += window[0x8] * b0[0x8];
- sum += window[0xA] * b0[0xA];
- sum += window[0xC] * b0[0xC];
- sum += window[0xE] * b0[0xE];
- WRITE_SAMPLE(samples,sum,clip); samples += step;
- #if 0
- WRITE_SAMPLE(samples,sum,clip); samples += step;
- WRITE_SAMPLE(samples,sum,clip); samples += step;
- WRITE_SAMPLE(samples,sum,clip); samples += step;
- #endif
- b0-=0x40,window-=0x80;
- }
- window += bo1<<1;
- for (j=3;j;j--,b0-=0x50,window-=0x70)
- {
- real sum;
- sum = -*(--window) * *b0++;
- sum -= *(--window) * *b0++;
- sum -= *(--window) * *b0++;
- sum -= *(--window) * *b0++;
- sum -= *(--window) * *b0++;
- sum -= *(--window) * *b0++;
- sum -= *(--window) * *b0++;
- sum -= *(--window) * *b0++;
- sum -= *(--window) * *b0++;
- sum -= *(--window) * *b0++;
- sum -= *(--window) * *b0++;
- sum -= *(--window) * *b0++;
- sum -= *(--window) * *b0++;
- sum -= *(--window) * *b0++;
- sum -= *(--window) * *b0++;
- sum -= *(--window) * *b0++;
- WRITE_SAMPLE(samples,sum,clip); samples += step;
- #if 0
- WRITE_SAMPLE(samples,sum,clip); samples += step;
- WRITE_SAMPLE(samples,sum,clip); samples += step;
- WRITE_SAMPLE(samples,sum,clip); samples += step;
- #endif
- }
- }
-
- *pnt += 32;
- return clip;
- }
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