extern/ffmpeg/libavcodec/flac.c

   1 /*
   2  * FLAC (Free Lossless Audio Codec) decoder
   3  * Copyright (c) 2003 Alex Beregszaszi
   4  *
   5  * This library is free software; you can redistribute it and/or
   6  * modify it under the terms of the GNU Lesser General Public
   7  * License as published by the Free Software Foundation; either
   8  * version 2 of the License, or (at your option) any later version.
   9  *
  10  * This library 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 GNU
  13  * Lesser General Public License for more details.
  14  *
  15  * You should have received a copy of the GNU Lesser General Public
  16  * License along with this library; if not, write to the Free Software
  17  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  18  */
  19
  20 /**
  21  * @file flac.c
  22  * FLAC (Free Lossless Audio Codec) decoder
  23  * @author Alex Beregszaszi
  24  *
  25  * For more information on the FLAC format, visit:
  26  *  http://flac.sourceforge.net/
  27  *
  28  * This decoder can be used in 1 of 2 ways: Either raw FLAC data can be fed
  29  * through, starting from the initial 'fLaC' signature; or by passing the
  30  * 34-byte streaminfo structure through avctx->extradata[_size] followed
  31  * by data starting with the 0xFFF8 marker.
  32  */
  33
  34 #include <limits.h>
  35
  36 #include "avcodec.h"
  37 #include "bitstream.h"
  38 #include "golomb.h"
  39 #include "crc.h"
  40
  41 #undef NDEBUG
  42 #include <assert.h>
  43
  44 #define MAX_CHANNELS 8
  45 #define MAX_BLOCKSIZE 65535
  46 #define FLAC_STREAMINFO_SIZE 34
  47
  48 enum decorrelation_type {
  49     INDEPENDENT,
  50     LEFT_SIDE,
  51     RIGHT_SIDE,
  52     MID_SIDE,
  53 };
  54
  55 typedef struct FLACContext {
  56     AVCodecContext *avctx;
  57     GetBitContext gb;
  58
  59     int min_blocksize, max_blocksize;
  60     int min_framesize, max_framesize;
  61     int samplerate, channels;
  62     int blocksize/*, last_blocksize*/;
  63     int bps, curr_bps;
  64     enum decorrelation_type decorrelation;
  65
  66     int32_t *decoded[MAX_CHANNELS];
  67     uint8_t *bitstream;
  68     int bitstream_size;
  69     int bitstream_index;
  70     unsigned int allocated_bitstream_size;
  71 } FLACContext;
  72
  73 #define METADATA_TYPE_STREAMINFO 0
  74
  75 static int sample_rate_table[] =
  76 { 0, 0, 0, 0,
  77   8000, 16000, 22050, 24000, 32000, 44100, 48000, 96000,
  78   0, 0, 0, 0 };
  79
  80 static int sample_size_table[] =
  81 { 0, 8, 12, 0, 16, 20, 24, 0 };
  82
  83 static int blocksize_table[] = {
  84      0,    192, 576<<0, 576<<1, 576<<2, 576<<3,      0,      0,
  85 256<<0, 256<<1, 256<<2, 256<<3, 256<<4, 256<<5, 256<<6, 256<<7
  86 };
  87
  88 static int64_t get_utf8(GetBitContext *gb)
  89 {
  90     uint64_t val;
  91     int ones=0, bytes;
  92
  93     while(get_bits1(gb))
  94         ones++;
  95
  96     if     (ones==0) bytes=0;
  97     else if(ones==1) return -1;
  98     else             bytes= ones - 1;
  99
 100     val= get_bits(gb, 7-ones);
 101     while(bytes--){
 102         const int tmp = get_bits(gb, 8);
 103
 104         if((tmp>>6) != 2)
 105             return -1;
 106         val<<=6;
 107         val|= tmp&0x3F;
 108     }
 109     return val;
 110 }
 111
 112 #if 0
 113 static int skip_utf8(GetBitContext *gb)
 114 {
 115     int ones=0, bytes;
 116
 117     while(get_bits1(gb))
 118         ones++;
 119
 120     if     (ones==0) bytes=0;
 121     else if(ones==1) return -1;
 122     else             bytes= ones - 1;
 123
 124     skip_bits(gb, 7-ones);
 125     while(bytes--){
 126         const int tmp = get_bits(gb, 8);
 127
 128         if((tmp>>6) != 2)
 129             return -1;
 130     }
 131     return 0;
 132 }
 133 #endif
 134
 135 static void metadata_streaminfo(FLACContext *s);
 136 static void dump_headers(FLACContext *s);
 137
 138 static int flac_decode_init(AVCodecContext * avctx)
 139 {
 140     FLACContext *s = avctx->priv_data;
 141     s->avctx = avctx;
 142
 143     /* initialize based on the demuxer-supplied streamdata header */
 144     if (avctx->extradata_size == FLAC_STREAMINFO_SIZE) {
 145         init_get_bits(&s->gb, avctx->extradata, avctx->extradata_size*8);
 146         metadata_streaminfo(s);
 147         dump_headers(s);
 148     }
 149
 150     return 0;
 151 }
 152
 153 static void dump_headers(FLACContext *s)
 154 {
 155     av_log(s->avctx, AV_LOG_DEBUG, "  Blocksize: %d .. %d (%d)\n", s->min_blocksize, s->max_blocksize, s->blocksize);
 156     av_log(s->avctx, AV_LOG_DEBUG, "  Framesize: %d .. %d\n", s->min_framesize, s->max_framesize);
 157     av_log(s->avctx, AV_LOG_DEBUG, "  Samplerate: %d\n", s->samplerate);
 158     av_log(s->avctx, AV_LOG_DEBUG, "  Channels: %d\n", s->channels);
 159     av_log(s->avctx, AV_LOG_DEBUG, "  Bits: %d\n", s->bps);
 160 }
 161
 162 static void allocate_buffers(FLACContext *s){
 163     int i;
 164
 165     assert(s->max_blocksize);
 166
 167     if(s->max_framesize == 0 && s->max_blocksize){
 168         s->max_framesize= (s->channels * s->bps * s->max_blocksize + 7)/ 8; //FIXME header overhead
 169     }
 170
 171     for (i = 0; i < s->channels; i++)
 172     {
 173         s->decoded[i] = av_realloc(s->decoded[i], sizeof(int32_t)*s->max_blocksize);
 174     }
 175
 176     s->bitstream= av_fast_realloc(s->bitstream, &s->allocated_bitstream_size, s->max_framesize);
 177 }
 178
 179 static void metadata_streaminfo(FLACContext *s)
 180 {
 181     /* mandatory streaminfo */
 182     s->min_blocksize = get_bits(&s->gb, 16);
 183     s->max_blocksize = get_bits(&s->gb, 16);
 184
 185     s->min_framesize = get_bits_long(&s->gb, 24);
 186     s->max_framesize = get_bits_long(&s->gb, 24);
 187
 188     s->samplerate = get_bits_long(&s->gb, 20);
 189     s->channels = get_bits(&s->gb, 3) + 1;
 190     s->bps = get_bits(&s->gb, 5) + 1;
 191
 192     s->avctx->channels = s->channels;
 193     s->avctx->sample_rate = s->samplerate;
 194
 195     skip_bits(&s->gb, 36); /* total num of samples */
 196
 197     skip_bits(&s->gb, 64); /* md5 sum */
 198     skip_bits(&s->gb, 64); /* md5 sum */
 199
 200     allocate_buffers(s);
 201 }
 202
 203 static int decode_residuals(FLACContext *s, int channel, int pred_order)
 204 {
 205     int i, tmp, partition, method_type, rice_order;
 206     int sample = 0, samples;
 207
 208     method_type = get_bits(&s->gb, 2);
 209     if (method_type != 0){
 210         av_log(s->avctx, AV_LOG_DEBUG, "illegal residual coding method %d\n", method_type);
 211         return -1;
 212     }
 213
 214     rice_order = get_bits(&s->gb, 4);
 215
 216     samples= s->blocksize >> rice_order;
 217
 218     sample=
 219     i= pred_order;
 220     for (partition = 0; partition < (1 << rice_order); partition++)
 221     {
 222         tmp = get_bits(&s->gb, 4);
 223         if (tmp == 15)
 224         {
 225             av_log(s->avctx, AV_LOG_DEBUG, "fixed len partition\n");
 226             tmp = get_bits(&s->gb, 5);
 227             for (; i < samples; i++, sample++)
 228                 s->decoded[channel][sample] = get_sbits(&s->gb, tmp);
 229         }
 230         else
 231         {
 232 //            av_log(s->avctx, AV_LOG_DEBUG, "rice coded partition k=%d\n", tmp);
 233             for (; i < samples; i++, sample++){
 234                 s->decoded[channel][sample] = get_sr_golomb_flac(&s->gb, tmp, INT_MAX, 0);
 235             }
 236         }
 237         i= 0;
 238     }
 239
 240 //    av_log(s->avctx, AV_LOG_DEBUG, "partitions: %d, samples: %d\n", 1 << rice_order, sample);
 241
 242     return 0;
 243 }
 244
 245 static int decode_subframe_fixed(FLACContext *s, int channel, int pred_order)
 246 {
 247     int i;
 248
 249 //    av_log(s->avctx, AV_LOG_DEBUG, "  SUBFRAME FIXED\n");
 250
 251     /* warm up samples */
 252 //    av_log(s->avctx, AV_LOG_DEBUG, "   warm up samples: %d\n", pred_order);
 253
 254     for (i = 0; i < pred_order; i++)
 255     {
 256         s->decoded[channel][i] = get_sbits(&s->gb, s->curr_bps);
 257 //        av_log(s->avctx, AV_LOG_DEBUG, "    %d: %d\n", i, s->decoded[channel][i]);
 258     }
 259
 260     if (decode_residuals(s, channel, pred_order) < 0)
 261         return -1;
 262
 263     switch(pred_order)
 264     {
 265         case 0:
 266             break;
 267         case 1:
 268             for (i = pred_order; i < s->blocksize; i++)
 269                 s->decoded[channel][i] +=   s->decoded[channel][i-1];
 270             break;
 271         case 2:
 272             for (i = pred_order; i < s->blocksize; i++)
 273                 s->decoded[channel][i] += 2*s->decoded[channel][i-1]
 274                                           - s->decoded[channel][i-2];
 275             break;
 276         case 3:
 277             for (i = pred_order; i < s->blocksize; i++)
 278                 s->decoded[channel][i] += 3*s->decoded[channel][i-1]
 279                                         - 3*s->decoded[channel][i-2]
 280                                         +   s->decoded[channel][i-3];
 281             break;
 282         case 4:
 283             for (i = pred_order; i < s->blocksize; i++)
 284                 s->decoded[channel][i] += 4*s->decoded[channel][i-1]
 285                                         - 6*s->decoded[channel][i-2]
 286                                         + 4*s->decoded[channel][i-3]
 287                                         -   s->decoded[channel][i-4];
 288             break;
 289         default:
 290             av_log(s->avctx, AV_LOG_ERROR, "illegal pred order %d\n", pred_order);
 291             return -1;
 292     }
 293
 294     return 0;
 295 }
 296
 297 static int decode_subframe_lpc(FLACContext *s, int channel, int pred_order)
 298 {
 299     int sum, i, j;
 300     int coeff_prec, qlevel;
 301     int coeffs[pred_order];
 302
 303 //    av_log(s->avctx, AV_LOG_DEBUG, "  SUBFRAME LPC\n");
 304
 305     /* warm up samples */
 306 //    av_log(s->avctx, AV_LOG_DEBUG, "   warm up samples: %d\n", pred_order);
 307
 308     for (i = 0; i < pred_order; i++)
 309     {
 310         s->decoded[channel][i] = get_sbits(&s->gb, s->curr_bps);
 311 //        av_log(s->avctx, AV_LOG_DEBUG, "    %d: %d\n", i, s->decoded[channel][i]);
 312     }
 313
 314     coeff_prec = get_bits(&s->gb, 4) + 1;
 315     if (coeff_prec == 16)
 316     {
 317         av_log(s->avctx, AV_LOG_DEBUG, "invalid coeff precision\n");
 318         return -1;
 319     }
 320 //    av_log(s->avctx, AV_LOG_DEBUG, "   qlp coeff prec: %d\n", coeff_prec);
 321     qlevel = get_sbits(&s->gb, 5);
 322 //    av_log(s->avctx, AV_LOG_DEBUG, "   quant level: %d\n", qlevel);
 323     if(qlevel < 0){
 324         av_log(s->avctx, AV_LOG_DEBUG, "qlevel %d not supported, maybe buggy stream\n", qlevel);
 325         return -1;
 326     }
 327
 328     for (i = 0; i < pred_order; i++)
 329     {
 330         coeffs[i] = get_sbits(&s->gb, coeff_prec);
 331 //        av_log(s->avctx, AV_LOG_DEBUG, "    %d: %d\n", i, coeffs[i]);
 332     }
 333
 334     if (decode_residuals(s, channel, pred_order) < 0)
 335         return -1;
 336
 337     for (i = pred_order; i < s->blocksize; i++)
 338     {
 339         sum = 0;
 340         for (j = 0; j < pred_order; j++)
 341             sum += coeffs[j] * s->decoded[channel][i-j-1];
 342         s->decoded[channel][i] += sum >> qlevel;
 343     }
 344
 345     return 0;
 346 }
 347
 348 static inline int decode_subframe(FLACContext *s, int channel)
 349 {
 350     int type, wasted = 0;
 351     int i, tmp;
 352
 353     s->curr_bps = s->bps;
 354     if(channel == 0){
 355         if(s->decorrelation == RIGHT_SIDE)
 356             s->curr_bps++;
 357     }else{
 358         if(s->decorrelation == LEFT_SIDE || s->decorrelation == MID_SIDE)
 359             s->curr_bps++;
 360     }
 361
 362     if (get_bits1(&s->gb))
 363     {
 364         av_log(s->avctx, AV_LOG_ERROR, "invalid subframe padding\n");
 365         return -1;
 366     }
 367     type = get_bits(&s->gb, 6);
 368 //    wasted = get_bits1(&s->gb);
 369
 370 //    if (wasted)
 371 //    {
 372 //        while (!get_bits1(&s->gb))
 373 //            wasted++;
 374 //        if (wasted)
 375 //            wasted++;
 376 //        s->curr_bps -= wasted;
 377 //    }
 378 #if 0
 379     wasted= 16 - av_log2(show_bits(&s->gb, 17));
 380     skip_bits(&s->gb, wasted+1);
 381     s->curr_bps -= wasted;
 382 #else
 383     if (get_bits1(&s->gb))
 384     {
 385         wasted = 1;
 386         while (!get_bits1(&s->gb))
 387             wasted++;
 388         s->curr_bps -= wasted;
 389         av_log(s->avctx, AV_LOG_DEBUG, "%d wasted bits\n", wasted);
 390     }
 391 #endif
 392 //FIXME use av_log2 for types
 393     if (type == 0)
 394     {
 395         av_log(s->avctx, AV_LOG_DEBUG, "coding type: constant\n");
 396         tmp = get_sbits(&s->gb, s->curr_bps);
 397         for (i = 0; i < s->blocksize; i++)
 398             s->decoded[channel][i] = tmp;
 399     }
 400     else if (type == 1)
 401     {
 402         av_log(s->avctx, AV_LOG_DEBUG, "coding type: verbatim\n");
 403         for (i = 0; i < s->blocksize; i++)
 404             s->decoded[channel][i] = get_sbits(&s->gb, s->curr_bps);
 405     }
 406     else if ((type >= 8) && (type <= 12))
 407     {
 408 //        av_log(s->avctx, AV_LOG_DEBUG, "coding type: fixed\n");
 409         if (decode_subframe_fixed(s, channel, type & ~0x8) < 0)
 410             return -1;
 411     }
 412     else if (type >= 32)
 413     {
 414 //        av_log(s->avctx, AV_LOG_DEBUG, "coding type: lpc\n");
 415         if (decode_subframe_lpc(s, channel, (type & ~0x20)+1) < 0)
 416             return -1;
 417     }
 418     else
 419     {
 420         av_log(s->avctx, AV_LOG_ERROR, "invalid coding type\n");
 421         return -1;
 422     }
 423
 424     if (wasted)
 425     {
 426         int i;
 427         for (i = 0; i < s->blocksize; i++)
 428             s->decoded[channel][i] <<= wasted;
 429     }
 430
 431     return 0;
 432 }
 433
 434 static int decode_frame(FLACContext *s)
 435 {
 436     int blocksize_code, sample_rate_code, sample_size_code, assignment, i, crc8;
 437     int decorrelation, bps, blocksize, samplerate;
 438
 439     blocksize_code = get_bits(&s->gb, 4);
 440
 441     sample_rate_code = get_bits(&s->gb, 4);
 442
 443     assignment = get_bits(&s->gb, 4); /* channel assignment */
 444     if (assignment < 8 && s->channels == assignment+1)
 445         decorrelation = INDEPENDENT;
 446     else if (assignment >=8 && assignment < 11 && s->channels == 2)
 447         decorrelation = LEFT_SIDE + assignment - 8;
 448     else
 449     {
 450         av_log(s->avctx, AV_LOG_ERROR, "unsupported channel assignment %d (channels=%d)\n", assignment, s->channels);
 451         return -1;
 452     }
 453
 454     sample_size_code = get_bits(&s->gb, 3);
 455     if(sample_size_code == 0)
 456         bps= s->bps;
 457     else if((sample_size_code != 3) && (sample_size_code != 7))
 458         bps = sample_size_table[sample_size_code];
 459     else
 460     {
 461         av_log(s->avctx, AV_LOG_ERROR, "invalid sample size code (%d)\n", sample_size_code);
 462         return -1;
 463     }
 464
 465     if (get_bits1(&s->gb))
 466     {
 467         av_log(s->avctx, AV_LOG_ERROR, "broken stream, invalid padding\n");
 468         return -1;
 469     }
 470
 471     if(get_utf8(&s->gb) < 0){
 472         av_log(s->avctx, AV_LOG_ERROR, "utf8 fscked\n");
 473         return -1;
 474     }
 475 #if 0
 476     if (/*((blocksize_code == 6) || (blocksize_code == 7)) &&*/
 477         (s->min_blocksize != s->max_blocksize)){
 478     }else{
 479     }
 480 #endif
 481
 482     if (blocksize_code == 0)
 483         blocksize = s->min_blocksize;
 484     else if (blocksize_code == 6)
 485         blocksize = get_bits(&s->gb, 8)+1;
 486     else if (blocksize_code == 7)
 487         blocksize = get_bits(&s->gb, 16)+1;
 488     else
 489         blocksize = blocksize_table[blocksize_code];
 490
 491     if(blocksize > s->max_blocksize){
 492         av_log(s->avctx, AV_LOG_ERROR, "blocksize %d > %d\n", blocksize, s->max_blocksize);
 493         return -1;
 494     }
 495
 496     if (sample_rate_code == 0){
 497         samplerate= s->samplerate;
 498     }else if ((sample_rate_code > 3) && (sample_rate_code < 12))
 499         samplerate = sample_rate_table[sample_rate_code];
 500     else if (sample_rate_code == 12)
 501         samplerate = get_bits(&s->gb, 8) * 1000;
 502     else if (sample_rate_code == 13)
 503         samplerate = get_bits(&s->gb, 16);
 504     else if (sample_rate_code == 14)
 505         samplerate = get_bits(&s->gb, 16) * 10;
 506     else{
 507         av_log(s->avctx, AV_LOG_ERROR, "illegal sample rate code %d\n", sample_rate_code);
 508         return -1;
 509     }
 510
 511     skip_bits(&s->gb, 8);
 512     crc8= av_crc(av_crc07, 0, s->gb.buffer, get_bits_count(&s->gb)/8);
 513     if(crc8){
 514         av_log(s->avctx, AV_LOG_ERROR, "header crc mismatch crc=%2X\n", crc8);
 515         return -1;
 516     }
 517
 518     s->blocksize    = blocksize;
 519     s->samplerate   = samplerate;
 520     s->bps          = bps;
 521     s->decorrelation= decorrelation;
 522
 523 //    dump_headers(s);
 524
 525     /* subframes */
 526     for (i = 0; i < s->channels; i++)
 527     {
 528 //        av_log(s->avctx, AV_LOG_DEBUG, "decoded: %x residual: %x\n", s->decoded[i], s->residual[i]);
 529         if (decode_subframe(s, i) < 0)
 530             return -1;
 531     }
 532
 533     align_get_bits(&s->gb);
 534
 535     /* frame footer */
 536     skip_bits(&s->gb, 16); /* data crc */
 537
 538     return 0;
 539 }
 540
 541 static int flac_decode_frame(AVCodecContext *avctx,
 542                             void *data, int *data_size,
 543                             uint8_t *buf, int buf_size)
 544 {
 545     FLACContext *s = avctx->priv_data;
 546     int metadata_last, metadata_type, metadata_size;
 547     int tmp = 0, i, j = 0, input_buf_size = 0;
 548     int16_t *samples = data;
 549
 550     if(s->max_framesize == 0){
 551         s->max_framesize= 65536; // should hopefully be enough for the first header
 552         s->bitstream= av_fast_realloc(s->bitstream, &s->allocated_bitstream_size, s->max_framesize);
 553     }
 554
 555     if(1 && s->max_framesize){//FIXME truncated
 556             buf_size= FFMAX(FFMIN(buf_size, s->max_framesize - s->bitstream_size), 0);
 557             input_buf_size= buf_size;
 558
 559             if(s->bitstream_index + s->bitstream_size + buf_size > s->allocated_bitstream_size){
 560 //                printf("memmove\n");
 561                 memmove(s->bitstream, &s->bitstream[s->bitstream_index], s->bitstream_size);
 562                 s->bitstream_index=0;
 563             }
 564             memcpy(&s->bitstream[s->bitstream_index + s->bitstream_size], buf, buf_size);
 565             buf= &s->bitstream[s->bitstream_index];
 566             buf_size += s->bitstream_size;
 567             s->bitstream_size= buf_size;
 568
 569             if(buf_size < s->max_framesize){
 570 //                printf("wanna more data ...\n");
 571                 return input_buf_size;
 572             }
 573     }
 574
 575     init_get_bits(&s->gb, buf, buf_size*8);
 576
 577     /* fLaC signature (be) */
 578     if (show_bits_long(&s->gb, 32) == bswap_32(ff_get_fourcc("fLaC")))
 579     {
 580         skip_bits(&s->gb, 32);
 581
 582         av_log(s->avctx, AV_LOG_DEBUG, "STREAM HEADER\n");
 583         do {
 584             metadata_last = get_bits(&s->gb, 1);
 585             metadata_type = get_bits(&s->gb, 7);
 586             metadata_size = get_bits_long(&s->gb, 24);
 587
 588             av_log(s->avctx, AV_LOG_DEBUG, " metadata block: flag = %d, type = %d, size = %d\n",
 589                 metadata_last, metadata_type,
 590                 metadata_size);
 591             if(metadata_size){
 592                 switch(metadata_type)
 593                 {
 594                 case METADATA_TYPE_STREAMINFO:{
 595                     metadata_streaminfo(s);
 596
 597                     /* Buffer might have been reallocated, reinit bitreader */
 598                     if(buf != &s->bitstream[s->bitstream_index])
 599                     {
 600                         int bits_count = get_bits_count(&s->gb);
 601                         buf= &s->bitstream[s->bitstream_index];
 602                         init_get_bits(&s->gb, buf, buf_size*8);
 603                         skip_bits(&s->gb, bits_count);
 604                     }
 605
 606                     dump_headers(s);
 607                     break;}
 608                 default:
 609                     for(i=0; i<metadata_size; i++)
 610                         skip_bits(&s->gb, 8);
 611                 }
 612             }
 613         } while(!metadata_last);
 614     }
 615     else
 616     {
 617
 618         tmp = show_bits(&s->gb, 16);
 619         if(tmp != 0xFFF8){
 620             av_log(s->avctx, AV_LOG_ERROR, "FRAME HEADER not here\n");
 621             while(get_bits_count(&s->gb)/8+2 < buf_size && show_bits(&s->gb, 16) != 0xFFF8)
 622                 skip_bits(&s->gb, 8);
 623             goto end; // we may not have enough bits left to decode a frame, so try next time
 624         }
 625         skip_bits(&s->gb, 16);
 626         if (decode_frame(s) < 0){
 627             av_log(s->avctx, AV_LOG_ERROR, "decode_frame() failed\n");
 628             s->bitstream_size=0;
 629             s->bitstream_index=0;
 630             return -1;
 631         }
 632     }
 633
 634
 635 #if 0
 636     /* fix the channel order here */
 637     if (s->order == MID_SIDE)
 638     {
 639         short *left = samples;
 640         short *right = samples + s->blocksize;
 641         for (i = 0; i < s->blocksize; i += 2)
 642         {
 643             uint32_t x = s->decoded[0][i];
 644             uint32_t y = s->decoded[0][i+1];
 645
 646             right[i] = x - (y / 2);
 647             left[i] = right[i] + y;
 648         }
 649         *data_size = 2 * s->blocksize;
 650     }
 651     else
 652     {
 653     for (i = 0; i < s->channels; i++)
 654     {
 655         switch(s->order)
 656         {
 657             case INDEPENDENT:
 658                 for (j = 0; j < s->blocksize; j++)
 659                     samples[(s->blocksize*i)+j] = s->decoded[i][j];
 660                 break;
 661             case LEFT_SIDE:
 662             case RIGHT_SIDE:
 663                 if (i == 0)
 664                     for (j = 0; j < s->blocksize; j++)
 665                         samples[(s->blocksize*i)+j] = s->decoded[0][j];
 666                 else
 667                     for (j = 0; j < s->blocksize; j++)
 668                         samples[(s->blocksize*i)+j] = s->decoded[0][j] - s->decoded[i][j];
 669                 break;
 670 //            case MID_SIDE:
 671 //                av_log(s->avctx, AV_LOG_DEBUG, "mid-side unsupported\n");
 672         }
 673         *data_size += s->blocksize;
 674     }
 675     }
 676 #else
 677     switch(s->decorrelation)
 678     {
 679         case INDEPENDENT:
 680             for (j = 0; j < s->blocksize; j++)
 681             {
 682                 for (i = 0; i < s->channels; i++)
 683                     *(samples++) = s->decoded[i][j];
 684             }
 685             break;
 686         case LEFT_SIDE:
 687             assert(s->channels == 2);
 688             for (i = 0; i < s->blocksize; i++)
 689             {
 690                 *(samples++) = s->decoded[0][i];
 691                 *(samples++) = s->decoded[0][i] - s->decoded[1][i];
 692             }
 693             break;
 694         case RIGHT_SIDE:
 695             assert(s->channels == 2);
 696             for (i = 0; i < s->blocksize; i++)
 697             {
 698                 *(samples++) = s->decoded[0][i] + s->decoded[1][i];
 699                 *(samples++) = s->decoded[1][i];
 700             }
 701             break;
 702         case MID_SIDE:
 703             assert(s->channels == 2);
 704             for (i = 0; i < s->blocksize; i++)
 705             {
 706                 int mid, side;
 707                 mid = s->decoded[0][i];
 708                 side = s->decoded[1][i];
 709
 710 #if 1 //needs to be checked but IMHO it should be binary identical
 711                 mid -= side>>1;
 712                 *(samples++) = mid + side;
 713                 *(samples++) = mid;
 714 #else
 715
 716                 mid <<= 1;
 717                 if (side & 1)
 718                     mid++;
 719                 *(samples++) = (mid + side) >> 1;
 720                 *(samples++) = (mid - side) >> 1;
 721 #endif
 722             }
 723             break;
 724     }
 725 #endif
 726
 727     *data_size = (int8_t *)samples - (int8_t *)data;
 728 //    av_log(s->avctx, AV_LOG_DEBUG, "data size: %d\n", *data_size);
 729
 730 //    s->last_blocksize = s->blocksize;
 731 end:
 732     i= (get_bits_count(&s->gb)+7)/8;;
 733     if(i > buf_size){
 734         av_log(s->avctx, AV_LOG_ERROR, "overread: %d\n", i - buf_size);
 735         s->bitstream_size=0;
 736         s->bitstream_index=0;
 737         return -1;
 738     }
 739
 740     if(s->bitstream_size){
 741         s->bitstream_index += i;
 742         s->bitstream_size  -= i;
 743         return input_buf_size;
 744     }else
 745         return i;
 746 }
 747
 748 static int flac_decode_close(AVCodecContext *avctx)
 749 {
 750     FLACContext *s = avctx->priv_data;
 751     int i;
 752
 753     for (i = 0; i < s->channels; i++)
 754     {
 755         av_freep(&s->decoded[i]);
 756     }
 757     av_freep(&s->bitstream);
 758
 759     return 0;
 760 }
 761
 762 static void flac_flush(AVCodecContext *avctx){
 763     FLACContext *s = avctx->priv_data;
 764
 765     s->bitstream_size=
 766     s->bitstream_index= 0;
 767 }
 768
 769 AVCodec flac_decoder = {
 770     "flac",
 771     CODEC_TYPE_AUDIO,
 772     CODEC_ID_FLAC,
 773     sizeof(FLACContext),
 774     flac_decode_init,
 775     NULL,
 776     flac_decode_close,
 777     flac_decode_frame,
 778     .flush= flac_flush,
 779 };