Layer2.cpp
上传用户：tuheem
上传日期：2007-05-01
资源大小：21889k
文件大小：7k
- #include "mpg123.h"
- #include "l2tables.h"
- static int grp_3tab[32 * 3] = { 0, };
- static int grp_5tab[128 * 3] = { 0, };
- static int grp_9tab[1024 * 3] = { 0, };
- real muls[27][64];
- /**
- *
- **/
- void init_layer2(void)
- {
- static double mulmul[27] = {
- 0.0 , -2.0/3.0 , 2.0/3.0 ,
- 2.0/7.0 , 2.0/15.0 , 2.0/31.0, 2.0/63.0 , 2.0/127.0 , 2.0/255.0 ,
- 2.0/511.0 , 2.0/1023.0 , 2.0/2047.0 , 2.0/4095.0 , 2.0/8191.0 ,
- 2.0/16383.0 , 2.0/32767.0 , 2.0/65535.0 ,
- -4.0/5.0 , -2.0/5.0 , 2.0/5.0, 4.0/5.0 ,
- -8.0/9.0 , -4.0/9.0 , -2.0/9.0 , 2.0/9.0 , 4.0/9.0 , 8.0/9.0 };
- static int base[3][9] = {
- { 1 , 0, 2 , } ,
- { 17, 18, 0 , 19, 20 , } ,
- { 21, 1, 22, 23, 0, 24, 25, 2, 26 } };
- int i,j,k,l,len;
- real *table;
- static int tablen[3] = { 3 , 5 , 9 };
- static int *itable,*tables[3] = { grp_3tab , grp_5tab , grp_9tab };
- for(i=0;i<3;i++) {
- itable = tables[i];
- len = tablen[i];
- for(j=0;j<len;j++) {
- for(k=0;k<len;k++) {
- for(l=0;l<len;l++) {
- *itable++ = base[i][l];
- *itable++ = base[i][k];
- *itable++ = base[i][j];
- }
- }
- }
- }
- for(k=0;k<27;k++) {
- double m=mulmul[k];
- table = muls[k];
- for(j=3,i=0;i<63;i++,j--)
- *table++ = m * pow(2.0,(double) j / 3.0);
- *table++ = 0.0;
- }
- }
- /**
- *
- **/
- static void II_step_one (unsigned int *bit_alloc,int *scale,struct frame *fr)
- {
- int stereo = fr->stereo-1;
- int sblimit = fr->II_sblimit;
- int jsbound = fr->jsbound;
- int sblimit2 = fr->II_sblimit<<stereo;
- struct al_table *alloc1 = (struct al_table *) fr->alloc;
- int i;
- static unsigned int scfsi_buf[64];
- unsigned int *scfsi,*bita;
- int sc,step;
- bita = bit_alloc;
- if (stereo) {
- for (i=jsbound;i;i--,alloc1+=(1<<step)) {
- *bita++ = (char) getbits(step=alloc1->bits);
- *bita++ = (char) getbits(step);
- }
- for (i=sblimit-jsbound;i;i--,alloc1+=(1<<step)) {
- bita[0] = (char) getbits(step=alloc1->bits);
- bita[1] = bita[0];
- bita+=2;
- }
- bita = bit_alloc;
- scfsi=scfsi_buf;
- for (i=sblimit2;i;i--)
- if (*bita++)
- *scfsi++ = (char) getbits_fast(2);
- } else { /* mono */
- for (i=sblimit;i;i--,alloc1+=(1<<step))
- *bita++ = (char) getbits(step=alloc1->bits);
- bita = bit_alloc;
- scfsi=scfsi_buf;
- for (i=sblimit;i;i--)
- if (*bita++)
- *scfsi++ = (char) getbits_fast(2);
- }
- bita = bit_alloc;
- scfsi=scfsi_buf;
- for (i=sblimit2;i;i--) {
- if (*bita++) {
- switch (*scfsi++) {
- case 0:
- *scale++ = getbits_fast(6);
- *scale++ = getbits_fast(6);
- *scale++ = getbits_fast(6);
- break;
- case 1 :
- *scale++ = sc = getbits_fast(6);
- *scale++ = sc;
- *scale++ = getbits_fast(6);
- break;
- case 2:
- *scale++ = sc = getbits_fast(6);
- *scale++ = sc;
- *scale++ = sc;
- break;
- case 3:
- default:
- *scale++ = getbits_fast(6);
- *scale++ = sc = getbits_fast(6);
- *scale++ = sc;
- break;
- }
- }
- }
- }
- /**
- *
- **/
- static void II_step_two (unsigned int *bit_alloc,real fraction[2][4][SBLIMIT],int *scale,struct frame *fr,int x1)
- {
- int i,j,k,ba;
- int stereo = fr->stereo;
- int sblimit = fr->II_sblimit;
- int jsbound = fr->jsbound;
- struct al_table *alloc2,*alloc1 = (struct al_table *) fr->alloc;
- unsigned int *bita=bit_alloc;
- int d1,step;
- for (i=0;i<jsbound;i++,alloc1+=(1<<step)) {
- step = alloc1->bits;
- for (j=0;j<stereo;j++) {
- if ((ba=*bita++)) {
- k=(alloc2 = alloc1+ba)->bits;
- if( (d1=alloc2->d) < 0) {
- real cm=muls[k][scale[x1]];
- fraction[j][0][i] = ((real) ((int)getbits(k) + d1)) * cm;
- fraction[j][1][i] = ((real) ((int)getbits(k) + d1)) * cm;
- fraction[j][2][i] = ((real) ((int)getbits(k) + d1)) * cm;
- } else {
- static int *table[] = { 0,0,0,grp_3tab,0,grp_5tab,0,0,0,grp_9tab };
- unsigned int idx,*tab,m=scale[x1];
- idx = (unsigned int) getbits(k);
- tab = (unsigned int *) (table[d1] + idx + idx + idx);
- fraction[j][0][i] = muls[*tab++][m];
- fraction[j][1][i] = muls[*tab++][m];
- fraction[j][2][i] = muls[*tab][m];
- }
- scale+=3;
- } else
- fraction[j][0][i] = fraction[j][1][i] = fraction[j][2][i] = 0.0;
- }
- }
- for (i=jsbound;i<sblimit;i++,alloc1+=(1<<step)) {
- step = alloc1->bits;
- bita++;
- if ((ba=*bita++)) {
- k=(alloc2 = alloc1+ba)->bits;
- if( (d1=alloc2->d) < 0) {
- real cm;
- cm=muls[k][scale[x1+3]];
- fraction[1][0][i] = (fraction[0][0][i] = (real) ((int)getbits(k) + d1) ) * cm;
- fraction[1][1][i] = (fraction[0][1][i] = (real) ((int)getbits(k) + d1) ) * cm;
- fraction[1][2][i] = (fraction[0][2][i] = (real) ((int)getbits(k) + d1) ) * cm;
- cm=muls[k][scale[x1]];
- fraction[0][0][i] *= cm; fraction[0][1][i] *= cm; fraction[0][2][i] *= cm;
- } else {
- static int *table[] = { 0,0,0,grp_3tab,0,grp_5tab,0,0,0,grp_9tab };
- unsigned int idx,*tab,m1,m2;
- m1 = scale[x1]; m2 = scale[x1+3];
- idx = (unsigned int) getbits(k);
- tab = (unsigned int *) (table[d1] + idx + idx + idx);
- fraction[0][0][i] = muls[*tab][m1]; fraction[1][0][i] = muls[*tab++][m2];
- fraction[0][1][i] = muls[*tab][m1]; fraction[1][1][i] = muls[*tab++][m2];
- fraction[0][2][i] = muls[*tab][m1]; fraction[1][2][i] = muls[*tab][m2];
- }
- scale+=6;
- } else
- fraction[0][0][i] = fraction[0][1][i] = fraction[0][2][i] = fraction[1][0][i] = fraction[1][1][i] = fraction[1][2][i] = 0.0;
- }
- for(i=sblimit;i<SBLIMIT;i++)
- for (j=0;j<stereo;j++)
- fraction[j][0][i] = fraction[j][1][i] = fraction[j][2][i] = 0.0;
- }
- /**
- *
- **/
- static void II_select_table(struct frame *fr)
- {
- static int translate[3][2][16] =
- { { { 0,2,2,2,2,2,2,0,0,0,1,1,1,1,1,0 } ,
- { 0,2,2,0,0,0,1,1,1,1,1,1,1,1,1,0 } } ,
- { { 0,2,2,2,2,2,2,0,0,0,0,0,0,0,0,0 } ,
- { 0,2,2,0,0,0,0,0,0,0,0,0,0,0,0,0 } } ,
- { { 0,3,3,3,3,3,3,0,0,0,1,1,1,1,1,0 } ,
- { 0,3,3,0,0,0,1,1,1,1,1,1,1,1,1,0 } } };
- int table,sblim;
- static struct al_table *tables[5] =
- { alloc_0, alloc_1, alloc_2, alloc_3 , alloc_4 };
- static int sblims[5] = { 27 , 30 , 8, 12 , 30 };
- if(fr->lsf)
- table = 4;
- else
- table = translate[fr->sampling_frequency][2-fr->stereo][fr->bitrate_index];
- sblim = sblims[table];
- fr->alloc = tables[table];
- fr->II_sblimit = sblim;
- }
- /**
- *
- **/
- int do_layer2 (struct frame *fr,unsigned char *pcm_sample,int *pcm_point)
- {
- int clip=0;
- int i,j;
- int stereo = fr->stereo;
- real fraction[2][4][SBLIMIT];
- unsigned int bit_alloc[64];
- int scale[192];
- int single = fr->single;
- II_select_table(fr);
- fr->jsbound = (fr->mode == MPG_MD_JOINT_STEREO) ?
- (fr->mode_ext<<2)+4 : fr->II_sblimit;
- if(stereo == 1 || single == 3)
- single = 0;
- II_step_one(bit_alloc, scale, fr);
- if(single >= 0) {
- for (i=0;i<SCALE_BLOCK;i++) {
- II_step_two(bit_alloc,fraction,scale,fr,i>>2);
-
- for (j=0;j<3;j++)
- clip += synth_1to1_mono(fraction[0][j],pcm_sample,pcm_point);
- }
- } else {
- for (i=0;i<SCALE_BLOCK;i++) {
- II_step_two(bit_alloc,fraction,scale,fr,i>>2);
- for (j=0;j<3;j++) {
- int p1 = *pcm_point;
- clip += synth_1to1(fraction[0][j],0,pcm_sample,&p1);
- clip += synth_1to1(fraction[1][j],1,pcm_sample,pcm_point);
- }
- }
- }
- return clip;
- }
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