libavcodec/flac.c

   1 /*
   2  * FLAC (Free Lossless Audio Codec) decoder
   3  * Copyright (c) 2003 Alex Beregszaszi
   4  *
   5  * This file is part of FFmpeg.
   6  *
   7  * FFmpeg is free software; you can redistribute it and/or
   8  * modify it under the terms of the GNU Lesser General Public
   9  * License as published by the Free Software Foundation; either
  10  * version 2.1 of the License, or (at your option) any later version.
  11  *
  12  * FFmpeg is distributed in the hope that it will be useful,
  13  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  15  * Lesser General Public License for more details.
  16  *
  17  * You should have received a copy of the GNU Lesser General Public
  18  * License along with FFmpeg; if not, write to the Free Software
  19  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  20  */
  21
  22 /**
  23  * @file flac.c
  24  * FLAC (Free Lossless Audio Codec) decoder
  25  * @author Alex Beregszaszi
  26  *
  27  * For more information on the FLAC format, visit:
  28  *  http://flac.sourceforge.net/
  29  *
  30  * This decoder can be used in 1 of 2 ways: Either raw FLAC data can be fed
  31  * through, starting from the initial 'fLaC' signature; or by passing the
  32  * 34-byte streaminfo structure through avctx->extradata[_size] followed
  33  * by data starting with the 0xFFF8 marker.
  34  */
  35
  36 #include <limits.h>
  37
  38 #define ALT_BITSTREAM_READER
  39 #include "libavutil/crc.h"
  40 #include "avcodec.h"
  41 #include "bitstream.h"
  42 #include "golomb.h"
  43 #include "flac.h"
  44
  45 #undef NDEBUG
  46 #include <assert.h>
  47
  48 #define MAX_CHANNELS 8
  49 #define MAX_BLOCKSIZE 65535
  50 #define FLAC_STREAMINFO_SIZE 34
  51
  52 enum decorrelation_type {
  53     INDEPENDENT,
  54     LEFT_SIDE,
  55     RIGHT_SIDE,
  56     MID_SIDE,
  57 };
  58
  59 typedef struct FLACContext {
  60     FLACSTREAMINFO
  61
  62     AVCodecContext *avctx;
  63     GetBitContext gb;
  64
  65     int blocksize/*, last_blocksize*/;
  66     int curr_bps;
  67     enum decorrelation_type decorrelation;
  68
  69     int32_t *decoded[MAX_CHANNELS];
  70     uint8_t *bitstream;
  71     int bitstream_size;
  72     int bitstream_index;
  73     unsigned int allocated_bitstream_size;
  74 } FLACContext;
  75
  76 #define METADATA_TYPE_STREAMINFO 0
  77
  78 static int sample_rate_table[] =
  79 { 0, 0, 0, 0,
  80   8000, 16000, 22050, 24000, 32000, 44100, 48000, 96000,
  81   0, 0, 0, 0 };
  82
  83 static int sample_size_table[] =
  84 { 0, 8, 12, 0, 16, 20, 24, 0 };
  85
  86 static int blocksize_table[] = {
  87      0,    192, 576<<0, 576<<1, 576<<2, 576<<3,      0,      0,
  88 256<<0, 256<<1, 256<<2, 256<<3, 256<<4, 256<<5, 256<<6, 256<<7
  89 };
  90
  91 static int64_t get_utf8(GetBitContext *gb){
  92     int64_t val;
  93     GET_UTF8(val, get_bits(gb, 8), return -1;)
  94     return val;
  95 }
  96
  97 static void allocate_buffers(FLACContext *s);
  98 static int metadata_parse(FLACContext *s);
  99
 100 static av_cold int flac_decode_init(AVCodecContext * avctx)
 101 {
 102     FLACContext *s = avctx->priv_data;
 103     s->avctx = avctx;
 104
 105     if (avctx->extradata_size > 4) {
 106         /* initialize based on the demuxer-supplied streamdata header */
 107         if (avctx->extradata_size == FLAC_STREAMINFO_SIZE) {
 108             ff_flac_parse_streaminfo(avctx, (FLACStreaminfo *)s, avctx->extradata);
 109             allocate_buffers(s);
 110         } else {
 111             init_get_bits(&s->gb, avctx->extradata, avctx->extradata_size*8);
 112             metadata_parse(s);
 113         }
 114     }
 115
 116     return 0;
 117 }
 118
 119 static void dump_headers(AVCodecContext *avctx, FLACStreaminfo *s)
 120 {
 121     av_log(avctx, AV_LOG_DEBUG, "  Blocksize: %d .. %d\n", s->min_blocksize, s->max_blocksize);
 122     av_log(avctx, AV_LOG_DEBUG, "  Max Framesize: %d\n", s->max_framesize);
 123     av_log(avctx, AV_LOG_DEBUG, "  Samplerate: %d\n", s->samplerate);
 124     av_log(avctx, AV_LOG_DEBUG, "  Channels: %d\n", s->channels);
 125     av_log(avctx, AV_LOG_DEBUG, "  Bits: %d\n", s->bps);
 126 }
 127
 128 static void allocate_buffers(FLACContext *s){
 129     int i;
 130
 131     assert(s->max_blocksize);
 132
 133     if(s->max_framesize == 0 && s->max_blocksize){
 134         s->max_framesize= (s->channels * s->bps * s->max_blocksize + 7)/ 8; //FIXME header overhead
 135     }
 136
 137     for (i = 0; i < s->channels; i++)
 138     {
 139         s->decoded[i] = av_realloc(s->decoded[i], sizeof(int32_t)*s->max_blocksize);
 140     }
 141
 142     s->bitstream= av_fast_realloc(s->bitstream, &s->allocated_bitstream_size, s->max_framesize);
 143 }
 144
 145 void ff_flac_parse_streaminfo(AVCodecContext *avctx, struct FLACStreaminfo *s,
 146                               const uint8_t *buffer)
 147 {
 148     GetBitContext gb;
 149     init_get_bits(&gb, buffer, FLAC_STREAMINFO_SIZE*8);
 150
 151     /* mandatory streaminfo */
 152     s->min_blocksize = get_bits(&gb, 16);
 153     s->max_blocksize = get_bits(&gb, 16);
 154
 155     skip_bits(&gb, 24); /* skip min frame size */
 156     s->max_framesize = get_bits_long(&gb, 24);
 157
 158     s->samplerate = get_bits_long(&gb, 20);
 159     s->channels = get_bits(&gb, 3) + 1;
 160     s->bps = get_bits(&gb, 5) + 1;
 161
 162     avctx->channels = s->channels;
 163     avctx->sample_rate = s->samplerate;
 164
 165     skip_bits(&gb, 36); /* total num of samples */
 166
 167     skip_bits(&gb, 64); /* md5 sum */
 168     skip_bits(&gb, 64); /* md5 sum */
 169
 170     dump_headers(avctx, s);
 171 }
 172
 173 /**
 174  * Parse a list of metadata blocks. This list of blocks must begin with
 175  * the fLaC marker.
 176  * @param s the flac decoding context containing the gb bit reader used to
 177  *          parse metadata
 178  * @return 1 if some metadata was read, 0 if no fLaC marker was found
 179  */
 180 static int metadata_parse(FLACContext *s)
 181 {
 182     int i, metadata_last, metadata_type, metadata_size, streaminfo_updated=0;
 183
 184     if (show_bits_long(&s->gb, 32) == MKBETAG('f','L','a','C')) {
 185         skip_bits(&s->gb, 32);
 186
 187         av_log(s->avctx, AV_LOG_DEBUG, "STREAM HEADER\n");
 188         do {
 189             metadata_last = get_bits1(&s->gb);
 190             metadata_type = get_bits(&s->gb, 7);
 191             metadata_size = get_bits_long(&s->gb, 24);
 192
 193             av_log(s->avctx, AV_LOG_DEBUG,
 194                    " metadata block: flag = %d, type = %d, size = %d\n",
 195                    metadata_last, metadata_type, metadata_size);
 196             if (metadata_size) {
 197                 switch (metadata_type) {
 198                 case METADATA_TYPE_STREAMINFO:
 199                     ff_flac_parse_streaminfo(s->avctx, (FLACStreaminfo *)s, s->gb.buffer+get_bits_count(&s->gb)/8);
 200                     streaminfo_updated = 1;
 201
 202                 default:
 203                     for (i=0; i<metadata_size; i++)
 204                         skip_bits(&s->gb, 8);
 205                 }
 206             }
 207         } while (!metadata_last);
 208
 209         if (streaminfo_updated)
 210             allocate_buffers(s);
 211         return 1;
 212     }
 213     return 0;
 214 }
 215
 216 static int decode_residuals(FLACContext *s, int channel, int pred_order)
 217 {
 218     int i, tmp, partition, method_type, rice_order;
 219     int sample = 0, samples;
 220
 221     method_type = get_bits(&s->gb, 2);
 222     if (method_type > 1){
 223         av_log(s->avctx, AV_LOG_DEBUG, "illegal residual coding method %d\n", method_type);
 224         return -1;
 225     }
 226
 227     rice_order = get_bits(&s->gb, 4);
 228
 229     samples= s->blocksize >> rice_order;
 230     if (pred_order > samples) {
 231         av_log(s->avctx, AV_LOG_ERROR, "invalid predictor order: %i > %i\n", pred_order, samples);
 232         return -1;
 233     }
 234
 235     sample=
 236     i= pred_order;
 237     for (partition = 0; partition < (1 << rice_order); partition++)
 238     {
 239         tmp = get_bits(&s->gb, method_type == 0 ? 4 : 5);
 240         if (tmp == (method_type == 0 ? 15 : 31))
 241         {
 242             av_log(s->avctx, AV_LOG_DEBUG, "fixed len partition\n");
 243             tmp = get_bits(&s->gb, 5);
 244             for (; i < samples; i++, sample++)
 245                 s->decoded[channel][sample] = get_sbits(&s->gb, tmp);
 246         }
 247         else
 248         {
 249 //            av_log(s->avctx, AV_LOG_DEBUG, "rice coded partition k=%d\n", tmp);
 250             for (; i < samples; i++, sample++){
 251                 s->decoded[channel][sample] = get_sr_golomb_flac(&s->gb, tmp, INT_MAX, 0);
 252             }
 253         }
 254         i= 0;
 255     }
 256
 257 //    av_log(s->avctx, AV_LOG_DEBUG, "partitions: %d, samples: %d\n", 1 << rice_order, sample);
 258
 259     return 0;
 260 }
 261
 262 static int decode_subframe_fixed(FLACContext *s, int channel, int pred_order)
 263 {
 264     const int blocksize = s->blocksize;
 265     int32_t *decoded = s->decoded[channel];
 266     int a, b, c, d, i;
 267
 268 //    av_log(s->avctx, AV_LOG_DEBUG, "  SUBFRAME FIXED\n");
 269
 270     /* warm up samples */
 271 //    av_log(s->avctx, AV_LOG_DEBUG, "   warm up samples: %d\n", pred_order);
 272
 273     for (i = 0; i < pred_order; i++)
 274     {
 275         decoded[i] = get_sbits(&s->gb, s->curr_bps);
 276 //        av_log(s->avctx, AV_LOG_DEBUG, "    %d: %d\n", i, s->decoded[channel][i]);
 277     }
 278
 279     if (decode_residuals(s, channel, pred_order) < 0)
 280         return -1;
 281
 282     if(pred_order > 0)
 283         a = decoded[pred_order-1];
 284     if(pred_order > 1)
 285         b = a - decoded[pred_order-2];
 286     if(pred_order > 2)
 287         c = b - decoded[pred_order-2] + decoded[pred_order-3];
 288     if(pred_order > 3)
 289         d = c - decoded[pred_order-2] + 2*decoded[pred_order-3] - decoded[pred_order-4];
 290
 291     switch(pred_order)
 292     {
 293         case 0:
 294             break;
 295         case 1:
 296             for (i = pred_order; i < blocksize; i++)
 297                 decoded[i] = a += decoded[i];
 298             break;
 299         case 2:
 300             for (i = pred_order; i < blocksize; i++)
 301                 decoded[i] = a += b += decoded[i];
 302             break;
 303         case 3:
 304             for (i = pred_order; i < blocksize; i++)
 305                 decoded[i] = a += b += c += decoded[i];
 306             break;
 307         case 4:
 308             for (i = pred_order; i < blocksize; i++)
 309                 decoded[i] = a += b += c += d += decoded[i];
 310             break;
 311         default:
 312             av_log(s->avctx, AV_LOG_ERROR, "illegal pred order %d\n", pred_order);
 313             return -1;
 314     }
 315
 316     return 0;
 317 }
 318
 319 static int decode_subframe_lpc(FLACContext *s, int channel, int pred_order)
 320 {
 321     int i, j;
 322     int coeff_prec, qlevel;
 323     int coeffs[pred_order];
 324     int32_t *decoded = s->decoded[channel];
 325
 326 //    av_log(s->avctx, AV_LOG_DEBUG, "  SUBFRAME LPC\n");
 327
 328     /* warm up samples */
 329 //    av_log(s->avctx, AV_LOG_DEBUG, "   warm up samples: %d\n", pred_order);
 330
 331     for (i = 0; i < pred_order; i++)
 332     {
 333         decoded[i] = get_sbits(&s->gb, s->curr_bps);
 334 //        av_log(s->avctx, AV_LOG_DEBUG, "    %d: %d\n", i, decoded[i]);
 335     }
 336
 337     coeff_prec = get_bits(&s->gb, 4) + 1;
 338     if (coeff_prec == 16)
 339     {
 340         av_log(s->avctx, AV_LOG_DEBUG, "invalid coeff precision\n");
 341         return -1;
 342     }
 343 //    av_log(s->avctx, AV_LOG_DEBUG, "   qlp coeff prec: %d\n", coeff_prec);
 344     qlevel = get_sbits(&s->gb, 5);
 345 //    av_log(s->avctx, AV_LOG_DEBUG, "   quant level: %d\n", qlevel);
 346     if(qlevel < 0){
 347         av_log(s->avctx, AV_LOG_DEBUG, "qlevel %d not supported, maybe buggy stream\n", qlevel);
 348         return -1;
 349     }
 350
 351     for (i = 0; i < pred_order; i++)
 352     {
 353         coeffs[i] = get_sbits(&s->gb, coeff_prec);
 354 //        av_log(s->avctx, AV_LOG_DEBUG, "    %d: %d\n", i, coeffs[i]);
 355     }
 356
 357     if (decode_residuals(s, channel, pred_order) < 0)
 358         return -1;
 359
 360     if (s->bps > 16) {
 361         int64_t sum;
 362         for (i = pred_order; i < s->blocksize; i++)
 363         {
 364             sum = 0;
 365             for (j = 0; j < pred_order; j++)
 366                 sum += (int64_t)coeffs[j] * decoded[i-j-1];
 367             decoded[i] += sum >> qlevel;
 368         }
 369     } else {
 370         for (i = pred_order; i < s->blocksize-1; i += 2)
 371         {
 372             int c;
 373             int d = decoded[i-pred_order];
 374             int s0 = 0, s1 = 0;
 375             for (j = pred_order-1; j > 0; j--)
 376             {
 377                 c = coeffs[j];
 378                 s0 += c*d;
 379                 d = decoded[i-j];
 380                 s1 += c*d;
 381             }
 382             c = coeffs[0];
 383             s0 += c*d;
 384             d = decoded[i] += s0 >> qlevel;
 385             s1 += c*d;
 386             decoded[i+1] += s1 >> qlevel;
 387         }
 388         if (i < s->blocksize)
 389         {
 390             int sum = 0;
 391             for (j = 0; j < pred_order; j++)
 392                 sum += coeffs[j] * decoded[i-j-1];
 393             decoded[i] += sum >> qlevel;
 394         }
 395     }
 396
 397     return 0;
 398 }
 399
 400 static inline int decode_subframe(FLACContext *s, int channel)
 401 {
 402     int type, wasted = 0;
 403     int i, tmp;
 404
 405     s->curr_bps = s->bps;
 406     if(channel == 0){
 407         if(s->decorrelation == RIGHT_SIDE)
 408             s->curr_bps++;
 409     }else{
 410         if(s->decorrelation == LEFT_SIDE || s->decorrelation == MID_SIDE)
 411             s->curr_bps++;
 412     }
 413
 414     if (get_bits1(&s->gb))
 415     {
 416         av_log(s->avctx, AV_LOG_ERROR, "invalid subframe padding\n");
 417         return -1;
 418     }
 419     type = get_bits(&s->gb, 6);
 420 //    wasted = get_bits1(&s->gb);
 421
 422 //    if (wasted)
 423 //    {
 424 //        while (!get_bits1(&s->gb))
 425 //            wasted++;
 426 //        if (wasted)
 427 //            wasted++;
 428 //        s->curr_bps -= wasted;
 429 //    }
 430 #if 0
 431     wasted= 16 - av_log2(show_bits(&s->gb, 17));
 432     skip_bits(&s->gb, wasted+1);
 433     s->curr_bps -= wasted;
 434 #else
 435     if (get_bits1(&s->gb))
 436     {
 437         wasted = 1;
 438         while (!get_bits1(&s->gb))
 439             wasted++;
 440         s->curr_bps -= wasted;
 441         av_log(s->avctx, AV_LOG_DEBUG, "%d wasted bits\n", wasted);
 442     }
 443 #endif
 444 //FIXME use av_log2 for types
 445     if (type == 0)
 446     {
 447         av_log(s->avctx, AV_LOG_DEBUG, "coding type: constant\n");
 448         tmp = get_sbits(&s->gb, s->curr_bps);
 449         for (i = 0; i < s->blocksize; i++)
 450             s->decoded[channel][i] = tmp;
 451     }
 452     else if (type == 1)
 453     {
 454         av_log(s->avctx, AV_LOG_DEBUG, "coding type: verbatim\n");
 455         for (i = 0; i < s->blocksize; i++)
 456             s->decoded[channel][i] = get_sbits(&s->gb, s->curr_bps);
 457     }
 458     else if ((type >= 8) && (type <= 12))
 459     {
 460 //        av_log(s->avctx, AV_LOG_DEBUG, "coding type: fixed\n");
 461         if (decode_subframe_fixed(s, channel, type & ~0x8) < 0)
 462             return -1;
 463     }
 464     else if (type >= 32)
 465     {
 466 //        av_log(s->avctx, AV_LOG_DEBUG, "coding type: lpc\n");
 467         if (decode_subframe_lpc(s, channel, (type & ~0x20)+1) < 0)
 468             return -1;
 469     }
 470     else
 471     {
 472         av_log(s->avctx, AV_LOG_ERROR, "invalid coding type\n");
 473         return -1;
 474     }
 475
 476     if (wasted)
 477     {
 478         int i;
 479         for (i = 0; i < s->blocksize; i++)
 480             s->decoded[channel][i] <<= wasted;
 481     }
 482
 483     return 0;
 484 }
 485
 486 static int decode_frame(FLACContext *s, int alloc_data_size)
 487 {
 488     int blocksize_code, sample_rate_code, sample_size_code, assignment, i, crc8;
 489     int decorrelation, bps, blocksize, samplerate;
 490
 491     blocksize_code = get_bits(&s->gb, 4);
 492
 493     sample_rate_code = get_bits(&s->gb, 4);
 494
 495     assignment = get_bits(&s->gb, 4); /* channel assignment */
 496     if (assignment < 8 && s->channels == assignment+1)
 497         decorrelation = INDEPENDENT;
 498     else if (assignment >=8 && assignment < 11 && s->channels == 2)
 499         decorrelation = LEFT_SIDE + assignment - 8;
 500     else
 501     {
 502         av_log(s->avctx, AV_LOG_ERROR, "unsupported channel assignment %d (channels=%d)\n", assignment, s->channels);
 503         return -1;
 504     }
 505
 506     sample_size_code = get_bits(&s->gb, 3);
 507     if(sample_size_code == 0)
 508         bps= s->bps;
 509     else if((sample_size_code != 3) && (sample_size_code != 7))
 510         bps = sample_size_table[sample_size_code];
 511     else
 512     {
 513         av_log(s->avctx, AV_LOG_ERROR, "invalid sample size code (%d)\n", sample_size_code);
 514         return -1;
 515     }
 516
 517     if (get_bits1(&s->gb))
 518     {
 519         av_log(s->avctx, AV_LOG_ERROR, "broken stream, invalid padding\n");
 520         return -1;
 521     }
 522
 523     if(get_utf8(&s->gb) < 0){
 524         av_log(s->avctx, AV_LOG_ERROR, "utf8 fscked\n");
 525         return -1;
 526     }
 527 #if 0
 528     if (/*((blocksize_code == 6) || (blocksize_code == 7)) &&*/
 529         (s->min_blocksize != s->max_blocksize)){
 530     }else{
 531     }
 532 #endif
 533
 534     if (blocksize_code == 0)
 535         blocksize = s->min_blocksize;
 536     else if (blocksize_code == 6)
 537         blocksize = get_bits(&s->gb, 8)+1;
 538     else if (blocksize_code == 7)
 539         blocksize = get_bits(&s->gb, 16)+1;
 540     else
 541         blocksize = blocksize_table[blocksize_code];
 542
 543     if(blocksize > s->max_blocksize){
 544         av_log(s->avctx, AV_LOG_ERROR, "blocksize %d > %d\n", blocksize, s->max_blocksize);
 545         return -1;
 546     }
 547
 548     if(blocksize * s->channels * sizeof(int16_t) > alloc_data_size)
 549         return -1;
 550
 551     if (sample_rate_code == 0){
 552         samplerate= s->samplerate;
 553     }else if ((sample_rate_code > 3) && (sample_rate_code < 12))
 554         samplerate = sample_rate_table[sample_rate_code];
 555     else if (sample_rate_code == 12)
 556         samplerate = get_bits(&s->gb, 8) * 1000;
 557     else if (sample_rate_code == 13)
 558         samplerate = get_bits(&s->gb, 16);
 559     else if (sample_rate_code == 14)
 560         samplerate = get_bits(&s->gb, 16) * 10;
 561     else{
 562         av_log(s->avctx, AV_LOG_ERROR, "illegal sample rate code %d\n", sample_rate_code);
 563         return -1;
 564     }
 565
 566     skip_bits(&s->gb, 8);
 567     crc8 = av_crc(av_crc_get_table(AV_CRC_8_ATM), 0,
 568                   s->gb.buffer, get_bits_count(&s->gb)/8);
 569     if(crc8){
 570         av_log(s->avctx, AV_LOG_ERROR, "header crc mismatch crc=%2X\n", crc8);
 571         return -1;
 572     }
 573
 574     s->blocksize    = blocksize;
 575     s->samplerate   = samplerate;
 576     s->bps          = bps;
 577     s->decorrelation= decorrelation;
 578
 579 //    dump_headers(s->avctx, (FLACStreaminfo *)s);
 580
 581     /* subframes */
 582     for (i = 0; i < s->channels; i++)
 583     {
 584 //        av_log(s->avctx, AV_LOG_DEBUG, "decoded: %x residual: %x\n", s->decoded[i], s->residual[i]);
 585         if (decode_subframe(s, i) < 0)
 586             return -1;
 587     }
 588
 589     align_get_bits(&s->gb);
 590
 591     /* frame footer */
 592     skip_bits(&s->gb, 16); /* data crc */
 593
 594     return 0;
 595 }
 596
 597 static int flac_decode_frame(AVCodecContext *avctx,
 598                             void *data, int *data_size,
 599                             const uint8_t *buf, int buf_size)
 600 {
 601     FLACContext *s = avctx->priv_data;
 602     int tmp = 0, i, j = 0, input_buf_size = 0;
 603     int16_t *samples = data;
 604     int alloc_data_size= *data_size;
 605
 606     *data_size=0;
 607
 608     if(s->max_framesize == 0){
 609         s->max_framesize= 65536; // should hopefully be enough for the first header
 610         s->bitstream= av_fast_realloc(s->bitstream, &s->allocated_bitstream_size, s->max_framesize);
 611     }
 612
 613     if(1 && s->max_framesize){//FIXME truncated
 614             buf_size= FFMAX(FFMIN(buf_size, s->max_framesize - s->bitstream_size), 0);
 615             input_buf_size= buf_size;
 616
 617             if(s->bitstream_index + s->bitstream_size + buf_size > s->allocated_bitstream_size){
 618 //                printf("memmove\n");
 619                 memmove(s->bitstream, &s->bitstream[s->bitstream_index], s->bitstream_size);
 620                 s->bitstream_index=0;
 621             }
 622             memcpy(&s->bitstream[s->bitstream_index + s->bitstream_size], buf, buf_size);
 623             buf= &s->bitstream[s->bitstream_index];
 624             buf_size += s->bitstream_size;
 625             s->bitstream_size= buf_size;
 626
 627             if(buf_size < s->max_framesize){
 628 //                printf("wanna more data ...\n");
 629                 return input_buf_size;
 630             }
 631     }
 632
 633     init_get_bits(&s->gb, buf, buf_size*8);
 634
 635     if (!metadata_parse(s))
 636     {
 637         tmp = show_bits(&s->gb, 16);
 638         if((tmp & 0xFFFE) != 0xFFF8){
 639             av_log(s->avctx, AV_LOG_ERROR, "FRAME HEADER not here\n");
 640             while(get_bits_count(&s->gb)/8+2 < buf_size && (show_bits(&s->gb, 16) & 0xFFFE) != 0xFFF8)
 641                 skip_bits(&s->gb, 8);
 642             goto end; // we may not have enough bits left to decode a frame, so try next time
 643         }
 644         skip_bits(&s->gb, 16);
 645         if (decode_frame(s, alloc_data_size) < 0){
 646             av_log(s->avctx, AV_LOG_ERROR, "decode_frame() failed\n");
 647             s->bitstream_size=0;
 648             s->bitstream_index=0;
 649             return -1;
 650         }
 651     }
 652
 653
 654 #if 0
 655     /* fix the channel order here */
 656     if (s->order == MID_SIDE)
 657     {
 658         short *left = samples;
 659         short *right = samples + s->blocksize;
 660         for (i = 0; i < s->blocksize; i += 2)
 661         {
 662             uint32_t x = s->decoded[0][i];
 663             uint32_t y = s->decoded[0][i+1];
 664
 665             right[i] = x - (y / 2);
 666             left[i] = right[i] + y;
 667         }
 668         *data_size = 2 * s->blocksize;
 669     }
 670     else
 671     {
 672     for (i = 0; i < s->channels; i++)
 673     {
 674         switch(s->order)
 675         {
 676             case INDEPENDENT:
 677                 for (j = 0; j < s->blocksize; j++)
 678                     samples[(s->blocksize*i)+j] = s->decoded[i][j];
 679                 break;
 680             case LEFT_SIDE:
 681             case RIGHT_SIDE:
 682                 if (i == 0)
 683                     for (j = 0; j < s->blocksize; j++)
 684                         samples[(s->blocksize*i)+j] = s->decoded[0][j];
 685                 else
 686                     for (j = 0; j < s->blocksize; j++)
 687                         samples[(s->blocksize*i)+j] = s->decoded[0][j] - s->decoded[i][j];
 688                 break;
 689 //            case MID_SIDE:
 690 //                av_log(s->avctx, AV_LOG_DEBUG, "mid-side unsupported\n");
 691         }
 692         *data_size += s->blocksize;
 693     }
 694     }
 695 #else
 696 #define DECORRELATE(left, right)\
 697             assert(s->channels == 2);\
 698             for (i = 0; i < s->blocksize; i++)\
 699             {\
 700                 int a= s->decoded[0][i];\
 701                 int b= s->decoded[1][i];\
 702                 *samples++ = ((left)  << (24 - s->bps)) >> 8;\
 703                 *samples++ = ((right) << (24 - s->bps)) >> 8;\
 704             }\
 705             break;
 706
 707     switch(s->decorrelation)
 708     {
 709         case INDEPENDENT:
 710             for (j = 0; j < s->blocksize; j++)
 711             {
 712                 for (i = 0; i < s->channels; i++)
 713                     *samples++ = (s->decoded[i][j] << (24 - s->bps)) >> 8;
 714             }
 715             break;
 716         case LEFT_SIDE:
 717             DECORRELATE(a,a-b)
 718         case RIGHT_SIDE:
 719             DECORRELATE(a+b,b)
 720         case MID_SIDE:
 721             DECORRELATE( (a-=b>>1) + b, a)
 722     }
 723 #endif
 724
 725     *data_size = (int8_t *)samples - (int8_t *)data;
 726 //    av_log(s->avctx, AV_LOG_DEBUG, "data size: %d\n", *data_size);
 727
 728 //    s->last_blocksize = s->blocksize;
 729 end:
 730     i= (get_bits_count(&s->gb)+7)/8;
 731     if(i > buf_size){
 732         av_log(s->avctx, AV_LOG_ERROR, "overread: %d\n", i - buf_size);
 733         s->bitstream_size=0;
 734         s->bitstream_index=0;
 735         return -1;
 736     }
 737
 738     if(s->bitstream_size){
 739         s->bitstream_index += i;
 740         s->bitstream_size  -= i;
 741         return input_buf_size;
 742     }else
 743         return i;
 744 }
 745
 746 static av_cold int flac_decode_close(AVCodecContext *avctx)
 747 {
 748     FLACContext *s = avctx->priv_data;
 749     int i;
 750
 751     for (i = 0; i < s->channels; i++)
 752     {
 753         av_freep(&s->decoded[i]);
 754     }
 755     av_freep(&s->bitstream);
 756
 757     return 0;
 758 }
 759
 760 static void flac_flush(AVCodecContext *avctx){
 761     FLACContext *s = avctx->priv_data;
 762
 763     s->bitstream_size=
 764     s->bitstream_index= 0;
 765 }
 766
 767 AVCodec flac_decoder = {
 768     "flac",
 769     CODEC_TYPE_AUDIO,
 770     CODEC_ID_FLAC,
 771     sizeof(FLACContext),
 772     flac_decode_init,
 773     NULL,
 774     flac_decode_close,
 775     flac_decode_frame,
 776     .flush= flac_flush,
 777     .long_name= "FLAC (Free Lossless Audio Codec)"
 778 };