MultiMedia/mad/layer12.c

   1 /*
   2  * mad - MPEG audio decoder
   3  * Copyright (C) 2000-2001 Robert Leslie
   4  *
   5  * This program is free software; you can redistribute it and/or modify
   6  * it under the terms of the GNU General Public License as published by
   7  * the Free Software Foundation; either version 2 of the License, or
   8  * (at your option) any later version.
   9  *
  10  * This program is distributed in the hope that it will be useful,
  11  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13  * GNU General Public License for more details.
  14  *
  15  * You should have received a copy of the GNU General Public License
  16  * along with this program; if not, write to the Free Software
  17  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  18  *
  19  * $Id$
  20  */
  21
  22 # ifdef HAVE_CONFIG_H
  23 #  include "config.h"
  24 # endif
  25
  26 # include "global.h"
  27
  28 # ifdef HAVE_LIMITS_H
  29 #  include <limits.h>
  30 # else
  31 #  define CHAR_BIT  8
  32 # endif
  33
  34 # include "fixed.h"
  35 # include "bit.h"
  36 # include "stream.h"
  37 # include "frame.h"
  38 # include "layer12.h"
  39
  40 /*
  41  * scalefactor table
  42  * used in both Layer I and Layer II decoding
  43  */
  44 static
  45 mad_fixed_t const sf_table[63] = {
  46 # include "sf_table.dat"
  47 };
  48
  49 /* --- Layer I ------------------------------------------------------------- */
  50
  51 /* linear scaling table */
  52 static
  53 mad_fixed_t const linear_table[14] = {
  54   MAD_F(0x15555555),  /* 2^2  / (2^2  - 1) == 1.33333333333333 */
  55   MAD_F(0x12492492),  /* 2^3  / (2^3  - 1) == 1.14285714285714 */
  56   MAD_F(0x11111111),  /* 2^4  / (2^4  - 1) == 1.06666666666667 */
  57   MAD_F(0x10842108),  /* 2^5  / (2^5  - 1) == 1.03225806451613 */
  58   MAD_F(0x10410410),  /* 2^6  / (2^6  - 1) == 1.01587301587302 */
  59   MAD_F(0x10204081),  /* 2^7  / (2^7  - 1) == 1.00787401574803 */
  60   MAD_F(0x10101010),  /* 2^8  / (2^8  - 1) == 1.00392156862745 */
  61   MAD_F(0x10080402),  /* 2^9  / (2^9  - 1) == 1.00195694716243 */
  62   MAD_F(0x10040100),  /* 2^10 / (2^10 - 1) == 1.00097751710655 */
  63   MAD_F(0x10020040),  /* 2^11 / (2^11 - 1) == 1.00048851978505 */
  64   MAD_F(0x10010010),  /* 2^12 / (2^12 - 1) == 1.00024420024420 */
  65   MAD_F(0x10008004),  /* 2^13 / (2^13 - 1) == 1.00012208521548 */
  66   MAD_F(0x10004001),  /* 2^14 / (2^14 - 1) == 1.00006103888177 */
  67   MAD_F(0x10002000)   /* 2^15 / (2^15 - 1) == 1.00003051850948 */
  68 };
  69
  70 /*
  71  * NAME:        I_sample()
  72  * DESCRIPTION: decode one requantized Layer I sample from a bitstream
  73  */
  74 static
  75 mad_fixed_t I_sample(struct mad_bitptr *ptr, unsigned int nb)
  76 {
  77   mad_fixed_t sample;
  78
  79   sample = mad_bit_read(ptr, nb);
  80
  81   /* invert most significant bit, extend sign, then scale to fixed format */
  82
  83   sample ^= 1 << (nb - 1);
  84   sample |= -(sample & (1 << (nb - 1)));
  85
  86   sample <<= MAD_F_FRACBITS - (nb - 1);
  87
  88   /* requantize the sample */
  89
  90   /* s'' = (2^nb / (2^nb - 1)) * (s''' + 2^(-nb + 1)) */
  91
  92   sample += MAD_F_ONE >> (nb - 1);
  93
  94   return mad_f_mul(sample, linear_table[nb - 2]);
  95
  96   /* s' = factor * s'' */
  97   /* (to be performed by caller) */
  98 }
  99
 100 /*
 101  * NAME:        layer->I()
 102  * DESCRIPTION: decode a single Layer I frame
 103  */
 104 int mad_layer_I(struct mad_stream *stream, struct mad_frame *frame)
 105 {
 106   struct mad_header *header = &frame->header;
 107   unsigned int nch, bound, ch, s, sb, nb;
 108   unsigned char allocation[2][32], scalefactor[2][32];
 109
 110   nch = MAD_NCHANNELS(header);
 111
 112   bound = 32;
 113   if (header->mode == MAD_MODE_JOINT_STEREO) {
 114     header->flags |= MAD_FLAG_I_STEREO;
 115     bound = 4 + header->mode_extension * 4;
 116   }
 117
 118   /* check CRC word */
 119
 120   if (header->flags & MAD_FLAG_PROTECTION) {
 121     header->crc_check =
 122       mad_bit_crc(stream->ptr, 4 * (bound * nch + (32 - bound)),
 123                   header->crc_check);
 124
 125     if (header->crc_check != header->crc_target &&
 126         !(frame->options & MAD_OPTION_IGNORECRC)) {
 127       stream->error = MAD_ERROR_BADCRC;
 128       return -1;
 129     }
 130   }
 131
 132   /* decode bit allocations */
 133
 134   for (sb = 0; sb < bound; ++sb) {
 135     for (ch = 0; ch < nch; ++ch) {
 136       nb = mad_bit_read(&stream->ptr, 4);
 137
 138       if (nb == 15) {
 139         stream->error = MAD_ERROR_BADBITALLOC;
 140         return -1;
 141       }
 142
 143       allocation[ch][sb] = nb ? nb + 1 : 0;
 144     }
 145   }
 146
 147   for (sb = bound; sb < 32; ++sb) {
 148     nb = mad_bit_read(&stream->ptr, 4);
 149
 150     if (nb == 15) {
 151       stream->error = MAD_ERROR_BADBITALLOC;
 152       return -1;
 153     }
 154
 155     allocation[0][sb] =
 156     allocation[1][sb] = nb ? nb + 1 : 0;
 157   }
 158
 159   /* decode scalefactors */
 160
 161   for (sb = 0; sb < 32; ++sb) {
 162     for (ch = 0; ch < nch; ++ch) {
 163       if (allocation[ch][sb]) {
 164         scalefactor[ch][sb] = mad_bit_read(&stream->ptr, 6);
 165
 166         if (scalefactor[ch][sb] == 63) {
 167           stream->error = MAD_ERROR_BADSCALEFACTOR;
 168           return -1;
 169         }
 170       }
 171     }
 172   }
 173
 174   /* decode samples */
 175
 176   for (s = 0; s < 12; ++s) {
 177     for (sb = 0; sb < bound; ++sb) {
 178       for (ch = 0; ch < nch; ++ch) {
 179         nb = allocation[ch][sb];
 180         frame->sbsample[ch][s][sb] = nb ?
 181           mad_f_mul(I_sample(&stream->ptr, nb),
 182                     sf_table[scalefactor[ch][sb]]) : 0;
 183       }
 184     }
 185
 186     for (sb = bound; sb < 32; ++sb) {
 187       if ((nb = allocation[0][sb])) {
 188         mad_fixed_t sample;
 189
 190         sample = I_sample(&stream->ptr, nb);
 191
 192         for (ch = 0; ch < nch; ++ch) {
 193           frame->sbsample[ch][s][sb] =
 194             mad_f_mul(sample, sf_table[scalefactor[ch][sb]]);
 195         }
 196       }
 197       else {
 198         for (ch = 0; ch < nch; ++ch)
 199           frame->sbsample[ch][s][sb] = 0;
 200       }
 201     }
 202   }
 203
 204   return 0;
 205 }
 206
 207 /* --- Layer II ------------------------------------------------------------ */
 208
 209 /* possible quantization per subband table */
 210 static
 211 struct {
 212   unsigned int sblimit;
 213   unsigned char const offsets[30];
 214 } const sbquant_table[5] = {
 215   /* ISO/IEC 11172-3 Table B.2a */
 216   { 27, { 7, 7, 7, 6, 6, 6, 6, 6, 6, 6, 6, 3, 3, 3, 3, 3,       /* 0 */
 217           3, 3, 3, 3, 3, 3, 3, 0, 0, 0, 0 } },
 218   /* ISO/IEC 11172-3 Table B.2b */
 219   { 30, { 7, 7, 7, 6, 6, 6, 6, 6, 6, 6, 6, 3, 3, 3, 3, 3,       /* 1 */
 220           3, 3, 3, 3, 3, 3, 3, 0, 0, 0, 0, 0, 0, 0 } },
 221   /* ISO/IEC 11172-3 Table B.2c */
 222   {  8, { 5, 5, 2, 2, 2, 2, 2, 2 } },                           /* 2 */
 223   /* ISO/IEC 11172-3 Table B.2d */
 224   { 12, { 5, 5, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2 } },               /* 3 */
 225   /* ISO/IEC 13818-3 Table B.1 */
 226   { 30, { 4, 4, 4, 4, 2, 2, 2, 2, 2, 2, 2, 1, 1, 1, 1, 1,       /* 4 */
 227           1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1 } }
 228 };
 229
 230 /* bit allocation table */
 231 static
 232 struct {
 233   unsigned short nbal;
 234   unsigned short offset;
 235 } const bitalloc_table[8] = {
 236   { 2, 0 },  /* 0 */
 237   { 2, 3 },  /* 1 */
 238   { 3, 3 },  /* 2 */
 239   { 3, 1 },  /* 3 */
 240   { 4, 2 },  /* 4 */
 241   { 4, 3 },  /* 5 */
 242   { 4, 4 },  /* 6 */
 243   { 4, 5 }   /* 7 */
 244 };
 245
 246 /* offsets into quantization class table */
 247 static
 248 unsigned char const offset_table[6][15] = {
 249   { 0, 1, 16                                             },  /* 0 */
 250   { 0, 1,  2, 3, 4, 5, 16                                },  /* 1 */
 251   { 0, 1,  2, 3, 4, 5,  6, 7,  8,  9, 10, 11, 12, 13, 14 },  /* 2 */
 252   { 0, 1,  3, 4, 5, 6,  7, 8,  9, 10, 11, 12, 13, 14, 15 },  /* 3 */
 253   { 0, 1,  2, 3, 4, 5,  6, 7,  8,  9, 10, 11, 12, 13, 16 },  /* 4 */
 254   { 0, 2,  4, 5, 6, 7,  8, 9, 10, 11, 12, 13, 14, 15, 16 }   /* 5 */
 255 };
 256
 257 /* quantization class table */
 258 static
 259 struct quantclass {
 260   unsigned short nlevels;
 261   unsigned char group;
 262   unsigned char bits;
 263   mad_fixed_t C;
 264   mad_fixed_t D;
 265 } const qc_table[17] = {
 266 # include "qc_table.dat"
 267 };
 268
 269 /*
 270  * NAME:        II_samples()
 271  * DESCRIPTION: decode three requantized Layer II samples from a bitstream
 272  */
 273 static
 274 void II_samples(struct mad_bitptr *ptr,
 275                 struct quantclass const *quantclass,
 276                 mad_fixed_t output[3])
 277 {
 278   unsigned int nb, s, sample[3];
 279
 280   if ((nb = quantclass->group)) {
 281     unsigned int c, nlevels;
 282
 283     /* degrouping */
 284     c = mad_bit_read(ptr, quantclass->bits);
 285     nlevels = quantclass->nlevels;
 286
 287     for (s = 0; s < 3; ++s) {
 288       sample[s] = c % nlevels;
 289       c /= nlevels;
 290     }
 291   }
 292   else {
 293     nb = quantclass->bits;
 294
 295     for (s = 0; s < 3; ++s)
 296       sample[s] = mad_bit_read(ptr, nb);
 297   }
 298
 299   for (s = 0; s < 3; ++s) {
 300     mad_fixed_t requantized;
 301
 302     /* invert most significant bit, extend sign, then scale to fixed format */
 303
 304     requantized  = sample[s] ^ (1 << (nb - 1));
 305     requantized |= -(requantized & (1 << (nb - 1)));
 306
 307     requantized <<= MAD_F_FRACBITS - (nb - 1);
 308
 309     /* requantize the sample */
 310
 311     /* s'' = C * (s''' + D) */
 312
 313     output[s] = mad_f_mul(requantized + quantclass->D, quantclass->C);
 314
 315     /* s' = factor * s'' */
 316     /* (to be performed by caller) */
 317   }
 318 }
 319
 320 /*
 321  * NAME:        layer->II()
 322  * DESCRIPTION: decode a single Layer II frame
 323  */
 324 int mad_layer_II(struct mad_stream *stream, struct mad_frame *frame)
 325 {
 326   struct mad_header *header = &frame->header;
 327   struct mad_bitptr start;
 328   unsigned int index, sblimit, nbal, nch, bound, gr, ch, s, sb;
 329   unsigned char const *offsets;
 330   unsigned char allocation[2][32], scfsi[2][32], scalefactor[2][32][3];
 331   mad_fixed_t samples[3];
 332
 333   nch = MAD_NCHANNELS(header);
 334
 335   if (header->flags & MAD_FLAG_LSF_EXT)
 336     index = 4;
 337   else {
 338     switch (nch == 2 ? header->bitrate / 2 : header->bitrate) {
 339     case 32000:
 340     case 48000:
 341       index = (header->samplerate == 32000) ? 3 : 2;
 342       break;
 343
 344     case 56000:
 345     case 64000:
 346     case 80000:
 347       index = 0;
 348       break;
 349
 350     default:
 351       index = (header->samplerate == 48000) ? 0 : 1;
 352     }
 353   }
 354
 355   sblimit = sbquant_table[index].sblimit;
 356   offsets = sbquant_table[index].offsets;
 357
 358   bound = 32;
 359   if (header->mode == MAD_MODE_JOINT_STEREO) {
 360     header->flags |= MAD_FLAG_I_STEREO;
 361     bound = 4 + header->mode_extension * 4;
 362   }
 363
 364   if (bound > sblimit)
 365     bound = sblimit;
 366
 367   start = stream->ptr;
 368
 369   /* decode bit allocations */
 370
 371   for (sb = 0; sb < bound; ++sb) {
 372     nbal = bitalloc_table[offsets[sb]].nbal;
 373
 374     for (ch = 0; ch < nch; ++ch)
 375       allocation[ch][sb] = mad_bit_read(&stream->ptr, nbal);
 376   }
 377
 378   for (sb = bound; sb < sblimit; ++sb) {
 379     nbal = bitalloc_table[offsets[sb]].nbal;
 380
 381     allocation[0][sb] =
 382     allocation[1][sb] = mad_bit_read(&stream->ptr, nbal);
 383   }
 384
 385   /* decode scalefactor selection info */
 386
 387   for (sb = 0; sb < sblimit; ++sb) {
 388     for (ch = 0; ch < nch; ++ch) {
 389       if (allocation[ch][sb])
 390         scfsi[ch][sb] = mad_bit_read(&stream->ptr, 2);
 391     }
 392   }
 393
 394   /* check CRC word */
 395
 396   if (header->flags & MAD_FLAG_PROTECTION) {
 397     header->crc_check =
 398       mad_bit_crc(start, mad_bit_length(&start, &stream->ptr),
 399                   header->crc_check);
 400
 401     if (header->crc_check != header->crc_target &&
 402         !(frame->options & MAD_OPTION_IGNORECRC)) {
 403       stream->error = MAD_ERROR_BADCRC;
 404       return -1;
 405     }
 406   }
 407
 408   /* decode scalefactors */
 409
 410   for (sb = 0; sb < sblimit; ++sb) {
 411     for (ch = 0; ch < nch; ++ch) {
 412       if (allocation[ch][sb]) {
 413         scalefactor[ch][sb][0] = mad_bit_read(&stream->ptr, 6);
 414
 415         switch (scfsi[ch][sb]) {
 416         case 2:
 417           scalefactor[ch][sb][2] =
 418           scalefactor[ch][sb][1] =
 419           scalefactor[ch][sb][0];
 420           break;
 421
 422         case 0:
 423           scalefactor[ch][sb][1] = mad_bit_read(&stream->ptr, 6);
 424           /* fall through */
 425
 426         case 1:
 427         case 3:
 428           scalefactor[ch][sb][2] = mad_bit_read(&stream->ptr, 6);
 429         }
 430
 431         if (scfsi[ch][sb] & 1)
 432           scalefactor[ch][sb][1] = scalefactor[ch][sb][scfsi[ch][sb] - 1];
 433
 434         if (scalefactor[ch][sb][0] == 63 ||
 435             scalefactor[ch][sb][1] == 63 ||
 436             scalefactor[ch][sb][2] == 63) {
 437           stream->error = MAD_ERROR_BADSCALEFACTOR;
 438           return -1;
 439         }
 440       }
 441     }
 442   }
 443
 444   /* decode samples */
 445
 446   for (gr = 0; gr < 12; ++gr) {
 447     for (sb = 0; sb < bound; ++sb) {
 448       for (ch = 0; ch < nch; ++ch) {
 449         if ((index = allocation[ch][sb])) {
 450           index = offset_table[bitalloc_table[offsets[sb]].offset][index - 1];
 451
 452           II_samples(&stream->ptr, &qc_table[index], samples);
 453
 454           for (s = 0; s < 3; ++s) {
 455             frame->sbsample[ch][3 * gr + s][sb] =
 456               mad_f_mul(samples[s], sf_table[scalefactor[ch][sb][gr / 4]]);
 457           }
 458         }
 459         else {
 460           for (s = 0; s < 3; ++s)
 461             frame->sbsample[ch][3 * gr + s][sb] = 0;
 462         }
 463       }
 464     }
 465
 466     for (sb = bound; sb < sblimit; ++sb) {
 467       if ((index = allocation[0][sb])) {
 468         index = offset_table[bitalloc_table[offsets[sb]].offset][index - 1];
 469
 470         II_samples(&stream->ptr, &qc_table[index], samples);
 471
 472         for (ch = 0; ch < nch; ++ch) {
 473           for (s = 0; s < 3; ++s) {
 474             frame->sbsample[ch][3 * gr + s][sb] =
 475               mad_f_mul(samples[s], sf_table[scalefactor[ch][sb][gr / 4]]);
 476           }
 477         }
 478       }
 479       else {
 480         for (ch = 0; ch < nch; ++ch) {
 481           for (s = 0; s < 3; ++s)
 482             frame->sbsample[ch][3 * gr + s][sb] = 0;
 483         }
 484       }
 485     }
 486
 487     for (ch = 0; ch < nch; ++ch) {
 488       for (s = 0; s < 3; ++s) {
 489         for (sb = sblimit; sb < 32; ++sb)
 490           frame->sbsample[ch][3 * gr + s][sb] = 0;
 491       }
 492     }
 493   }
 494
 495   return 0;
 496 }