layer2.c 9.03 KB
Newer Older
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18
/*
 * Mpeg Layer-2 audio decoder
 * --------------------------
 * copyright (c) 1995 by Michael Hipp, All rights reserved. See also 'README'
 * This file has been copied from mpglib.
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
19
 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA
20 21 22 23 24 25 26 27 28 29 30 31 32
 */

#include "mpg123.h"
#include "l2tables.h"

static int grp_3tab[32 * 3] = { 0, };   /* used: 27 */
static int grp_5tab[128 * 3] = { 0, };  /* used: 125 */
static int grp_9tab[1024 * 3] = { 0, }; /* used: 729 */

real muls[27][64];	/* also used by layer 1 */

void init_layer2(void)
{
33
  static const double mulmul[27] = {
34 35 36 37 38 39
    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 };
40
  static const int base[3][9] = {
41 42 43 44 45
     { 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;
46
  static const int tablen[3] = { 3 , 5 , 9 };
47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73
  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;
  }
}


74
static void II_step_one(unsigned int *bit_alloc,int *scale,struct frame *fr)
75 76 77 78 79
{
    int stereo = fr->stereo-1;
    int sblimit = fr->II_sblimit;
    int jsbound = fr->jsbound;
    int sblimit2 = fr->II_sblimit<<stereo;
80
    const struct al_table *alloc1 = fr->alloc;
81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146
    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;
          default:              /* case 3 */
                *scale++ = getbits_fast(6);
                *scale++ = sc = getbits_fast(6);
                *scale++ = sc;
                break;
        }

}

147 148
static void II_step_two(unsigned int *bit_alloc, real fraction[2][4][SBLIMIT],
                        int *scale, struct frame *fr, int x1)
149 150 151 152 153
{
    int i,j,k,ba;
    int stereo = fr->stereo;
    int sblimit = fr->II_sblimit;
    int jsbound = fr->jsbound;
154
    const struct al_table *alloc2,*alloc1 = fr->alloc;
155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176
    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];
177
            idx = getbits(k);
178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211
            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++;	/* channel 1 and channel 2 bitalloc are the same */
      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];
212
          idx = getbits(k);
213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241
          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;
      }
/*
   should we use individual scalefac for channel 2 or
   is the current way the right one , where we just copy channel 1 to
   channel 2 ??
   The current 'strange' thing is, that we throw away the scalefac
   values for the second channel ...!!
-> changed .. now we use the scalefac values of channel one !!
*/
    }

    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)
{
242
  static const int translate[3][2][16] =
243 244 245 246 247 248 249 250
   { { { 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;
251
  static const struct al_table *tables[5] =
252
       { alloc_0, alloc_1, alloc_2, alloc_3 , alloc_4 };
253
  static const int sblims[5] = { 27 , 30 , 8, 12 , 30 };
254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288

  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]; /* pick_table clears unused subbands */
  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);

  for (i=0;i<SCALE_BLOCK;i++)
  {
    II_step_two(bit_alloc,fraction,scale,fr,i>>2);
    for (j=0;j<3;j++) {
      if(single >= 0) {
289
        clip += synth_1to1_mono(fr->mp,fraction[0][j],pcm_sample,pcm_point);
290 291 292
      }
      else {
        int p1 = *pcm_point;
293 294
        clip += synth_1to1(fr->mp,fraction[0][j],0,pcm_sample,&p1);
        clip += synth_1to1(fr->mp,fraction[1][j],1,pcm_sample,pcm_point);
295 296 297 298 299 300 301
      }

    }
  }

  return clip;
}