libavcodec/flacdec.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 libavcodec/flacdec.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 #include "libavutil/crc.h"
  39 #include "avcodec.h"
  40 #include "internal.h"
  41 #include "bitstream.h"
  42 #include "bytestream.h"
  43 #include "golomb.h"
  44 #include "flac.h"
  45 #include "flacdata.h"
  46
  47 #undef NDEBUG
  48 #include <assert.h>
  49
  50 typedef struct FLACContext {
  51     FLACSTREAMINFO
  52
  53     AVCodecContext *avctx;                  ///< parent AVCodecContext
  54     GetBitContext gb;                       ///< GetBitContext initialized to start at the current frame
  55
  56     int blocksize;                          ///< number of samples in the current frame
  57     int curr_bps;                           ///< bps for current subframe, adjusted for channel correlation and wasted bits
  58     int sample_shift;                       ///< shift required to make output samples 16-bit or 32-bit
  59     int is32;                               ///< flag to indicate if output should be 32-bit instead of 16-bit
  60     int ch_mode;                            ///< channel decorrelation type in the current frame
  61     int got_streaminfo;                     ///< indicates if the STREAMINFO has been read
  62
  63     int32_t *decoded[FLAC_MAX_CHANNELS];    ///< decoded samples
  64     uint8_t *bitstream;
  65     unsigned int bitstream_size;
  66     unsigned int bitstream_index;
  67     unsigned int allocated_bitstream_size;
  68 } FLACContext;
  69
  70 static const int sample_size_table[] =
  71 { 0, 8, 12, 0, 16, 20, 24, 0 };
  72
  73 static int64_t get_utf8(GetBitContext *gb)
  74 {
  75     int64_t val;
  76     GET_UTF8(val, get_bits(gb, 8), return -1;)
  77     return val;
  78 }
  79
  80 static void allocate_buffers(FLACContext *s);
  81
  82 int ff_flac_is_extradata_valid(AVCodecContext *avctx,
  83                                enum FLACExtradataFormat *format,
  84                                uint8_t **streaminfo_start)
  85 {
  86     if (!avctx->extradata || avctx->extradata_size < FLAC_STREAMINFO_SIZE) {
  87         av_log(avctx, AV_LOG_ERROR, "extradata NULL or too small.\n");
  88         return 0;
  89     }
  90     if (AV_RL32(avctx->extradata) != MKTAG('f','L','a','C')) {
  91         /* extradata contains STREAMINFO only */
  92         if (avctx->extradata_size != FLAC_STREAMINFO_SIZE) {
  93             av_log(avctx, AV_LOG_WARNING, "extradata contains %d bytes too many.\n",
  94                    FLAC_STREAMINFO_SIZE-avctx->extradata_size);
  95         }
  96         *format = FLAC_EXTRADATA_FORMAT_STREAMINFO;
  97         *streaminfo_start = avctx->extradata;
  98     } else {
  99         if (avctx->extradata_size < 8+FLAC_STREAMINFO_SIZE) {
 100             av_log(avctx, AV_LOG_ERROR, "extradata too small.\n");
 101             return 0;
 102         }
 103         *format = FLAC_EXTRADATA_FORMAT_FULL_HEADER;
 104         *streaminfo_start = &avctx->extradata[8];
 105     }
 106     return 1;
 107 }
 108
 109 static av_cold int flac_decode_init(AVCodecContext *avctx)
 110 {
 111     enum FLACExtradataFormat format;
 112     uint8_t *streaminfo;
 113     FLACContext *s = avctx->priv_data;
 114     s->avctx = avctx;
 115
 116     avctx->sample_fmt = SAMPLE_FMT_S16;
 117
 118     /* for now, the raw FLAC header is allowed to be passed to the decoder as
 119        frame data instead of extradata. */
 120     if (!avctx->extradata)
 121         return 0;
 122
 123     if (!ff_flac_is_extradata_valid(avctx, &format, &streaminfo))
 124         return -1;
 125
 126     /* initialize based on the demuxer-supplied streamdata header */
 127     ff_flac_parse_streaminfo(avctx, (FLACStreaminfo *)s, streaminfo);
 128     allocate_buffers(s);
 129     s->got_streaminfo = 1;
 130
 131     return 0;
 132 }
 133
 134 static void dump_headers(AVCodecContext *avctx, FLACStreaminfo *s)
 135 {
 136     av_log(avctx, AV_LOG_DEBUG, "  Max Blocksize: %d\n", s->max_blocksize);
 137     av_log(avctx, AV_LOG_DEBUG, "  Max Framesize: %d\n", s->max_framesize);
 138     av_log(avctx, AV_LOG_DEBUG, "  Samplerate: %d\n", s->samplerate);
 139     av_log(avctx, AV_LOG_DEBUG, "  Channels: %d\n", s->channels);
 140     av_log(avctx, AV_LOG_DEBUG, "  Bits: %d\n", s->bps);
 141 }
 142
 143 static void allocate_buffers(FLACContext *s)
 144 {
 145     int i;
 146
 147     assert(s->max_blocksize);
 148
 149     if (s->max_framesize == 0 && s->max_blocksize) {
 150         s->max_framesize = ff_flac_get_max_frame_size(s->max_blocksize,
 151                                                       s->channels, s->bps);
 152     }
 153
 154     for (i = 0; i < s->channels; i++) {
 155         s->decoded[i] = av_realloc(s->decoded[i],
 156                                    sizeof(int32_t)*s->max_blocksize);
 157     }
 158
 159     if (s->allocated_bitstream_size < s->max_framesize)
 160         s->bitstream= av_fast_realloc(s->bitstream,
 161                                       &s->allocated_bitstream_size,
 162                                       s->max_framesize);
 163 }
 164
 165 void ff_flac_parse_streaminfo(AVCodecContext *avctx, struct FLACStreaminfo *s,
 166                               const uint8_t *buffer)
 167 {
 168     GetBitContext gb;
 169     init_get_bits(&gb, buffer, FLAC_STREAMINFO_SIZE*8);
 170
 171     skip_bits(&gb, 16); /* skip min blocksize */
 172     s->max_blocksize = get_bits(&gb, 16);
 173     if (s->max_blocksize < FLAC_MIN_BLOCKSIZE) {
 174         av_log(avctx, AV_LOG_WARNING, "invalid max blocksize: %d\n",
 175                s->max_blocksize);
 176         s->max_blocksize = 16;
 177     }
 178
 179     skip_bits(&gb, 24); /* skip min frame size */
 180     s->max_framesize = get_bits_long(&gb, 24);
 181
 182     s->samplerate = get_bits_long(&gb, 20);
 183     s->channels = get_bits(&gb, 3) + 1;
 184     s->bps = get_bits(&gb, 5) + 1;
 185
 186     avctx->channels = s->channels;
 187     avctx->sample_rate = s->samplerate;
 188     avctx->bits_per_raw_sample = s->bps;
 189     if (s->bps > 16)
 190         avctx->sample_fmt = SAMPLE_FMT_S32;
 191     else
 192         avctx->sample_fmt = SAMPLE_FMT_S16;
 193
 194     s->samples  = get_bits_long(&gb, 32) << 4;
 195     s->samples |= get_bits(&gb, 4);
 196
 197     skip_bits_long(&gb, 64); /* md5 sum */
 198     skip_bits_long(&gb, 64); /* md5 sum */
 199
 200     dump_headers(avctx, s);
 201 }
 202
 203 void ff_flac_parse_block_header(const uint8_t *block_header,
 204                                 int *last, int *type, int *size)
 205 {
 206     int tmp = bytestream_get_byte(&block_header);
 207     if (last)
 208         *last = tmp & 0x80;
 209     if (type)
 210         *type = tmp & 0x7F;
 211     if (size)
 212         *size = bytestream_get_be24(&block_header);
 213 }
 214
 215 /**
 216  * Parse the STREAMINFO from an inline header.
 217  * @param s the flac decoding context
 218  * @param buf input buffer, starting with the "fLaC" marker
 219  * @param buf_size buffer size
 220  * @return non-zero if metadata is invalid
 221  */
 222 static int parse_streaminfo(FLACContext *s, const uint8_t *buf, int buf_size)
 223 {
 224     int metadata_type, metadata_size;
 225
 226     if (buf_size < FLAC_STREAMINFO_SIZE+8) {
 227         /* need more data */
 228         return 0;
 229     }
 230     ff_flac_parse_block_header(&buf[4], NULL, &metadata_type, &metadata_size);
 231     if (metadata_type != FLAC_METADATA_TYPE_STREAMINFO ||
 232         metadata_size != FLAC_STREAMINFO_SIZE) {
 233         return AVERROR_INVALIDDATA;
 234     }
 235     ff_flac_parse_streaminfo(s->avctx, (FLACStreaminfo *)s, &buf[8]);
 236     allocate_buffers(s);
 237     s->got_streaminfo = 1;
 238
 239     return 0;
 240 }
 241
 242 /**
 243  * Determine the size of an inline header.
 244  * @param buf input buffer, starting with the "fLaC" marker
 245  * @param buf_size buffer size
 246  * @return number of bytes in the header, or 0 if more data is needed
 247  */
 248 static int get_metadata_size(const uint8_t *buf, int buf_size)
 249 {
 250     int metadata_last, metadata_size;
 251     const uint8_t *buf_end = buf + buf_size;
 252
 253     buf += 4;
 254     do {
 255         ff_flac_parse_block_header(buf, &metadata_last, NULL, &metadata_size);
 256         buf += 4;
 257         if (buf + metadata_size > buf_end) {
 258             /* need more data in order to read the complete header */
 259             return 0;
 260         }
 261         buf += metadata_size;
 262     } while (!metadata_last);
 263
 264     return buf_size - (buf_end - buf);
 265 }
 266
 267 static int decode_residuals(FLACContext *s, int channel, int pred_order)
 268 {
 269     int i, tmp, partition, method_type, rice_order;
 270     int sample = 0, samples;
 271
 272     method_type = get_bits(&s->gb, 2);
 273     if (method_type > 1) {
 274         av_log(s->avctx, AV_LOG_ERROR, "illegal residual coding method %d\n",
 275                method_type);
 276         return -1;
 277     }
 278
 279     rice_order = get_bits(&s->gb, 4);
 280
 281     samples= s->blocksize >> rice_order;
 282     if (pred_order > samples) {
 283         av_log(s->avctx, AV_LOG_ERROR, "invalid predictor order: %i > %i\n",
 284                pred_order, samples);
 285         return -1;
 286     }
 287
 288     sample=
 289     i= pred_order;
 290     for (partition = 0; partition < (1 << rice_order); partition++) {
 291         tmp = get_bits(&s->gb, method_type == 0 ? 4 : 5);
 292         if (tmp == (method_type == 0 ? 15 : 31)) {
 293             tmp = get_bits(&s->gb, 5);
 294             for (; i < samples; i++, sample++)
 295                 s->decoded[channel][sample] = get_sbits_long(&s->gb, tmp);
 296         } else {
 297             for (; i < samples; i++, sample++) {
 298                 s->decoded[channel][sample] = get_sr_golomb_flac(&s->gb, tmp, INT_MAX, 0);
 299             }
 300         }
 301         i= 0;
 302     }
 303
 304     return 0;
 305 }
 306
 307 static int decode_subframe_fixed(FLACContext *s, int channel, int pred_order)
 308 {
 309     const int blocksize = s->blocksize;
 310     int32_t *decoded = s->decoded[channel];
 311     int av_uninit(a), av_uninit(b), av_uninit(c), av_uninit(d), i;
 312
 313     /* warm up samples */
 314     for (i = 0; i < pred_order; i++) {
 315         decoded[i] = get_sbits_long(&s->gb, s->curr_bps);
 316     }
 317
 318     if (decode_residuals(s, channel, pred_order) < 0)
 319         return -1;
 320
 321     if (pred_order > 0)
 322         a = decoded[pred_order-1];
 323     if (pred_order > 1)
 324         b = a - decoded[pred_order-2];
 325     if (pred_order > 2)
 326         c = b - decoded[pred_order-2] + decoded[pred_order-3];
 327     if (pred_order > 3)
 328         d = c - decoded[pred_order-2] + 2*decoded[pred_order-3] - decoded[pred_order-4];
 329
 330     switch (pred_order) {
 331     case 0:
 332         break;
 333     case 1:
 334         for (i = pred_order; i < blocksize; i++)
 335             decoded[i] = a += decoded[i];
 336         break;
 337     case 2:
 338         for (i = pred_order; i < blocksize; i++)
 339             decoded[i] = a += b += decoded[i];
 340         break;
 341     case 3:
 342         for (i = pred_order; i < blocksize; i++)
 343             decoded[i] = a += b += c += decoded[i];
 344         break;
 345     case 4:
 346         for (i = pred_order; i < blocksize; i++)
 347             decoded[i] = a += b += c += d += decoded[i];
 348         break;
 349     default:
 350         av_log(s->avctx, AV_LOG_ERROR, "illegal pred order %d\n", pred_order);
 351         return -1;
 352     }
 353
 354     return 0;
 355 }
 356
 357 static int decode_subframe_lpc(FLACContext *s, int channel, int pred_order)
 358 {
 359     int i, j;
 360     int coeff_prec, qlevel;
 361     int coeffs[pred_order];
 362     int32_t *decoded = s->decoded[channel];
 363
 364     /* warm up samples */
 365     for (i = 0; i < pred_order; i++) {
 366         decoded[i] = get_sbits_long(&s->gb, s->curr_bps);
 367     }
 368
 369     coeff_prec = get_bits(&s->gb, 4) + 1;
 370     if (coeff_prec == 16) {
 371         av_log(s->avctx, AV_LOG_ERROR, "invalid coeff precision\n");
 372         return -1;
 373     }
 374     qlevel = get_sbits(&s->gb, 5);
 375     if (qlevel < 0) {
 376         av_log(s->avctx, AV_LOG_ERROR, "qlevel %d not supported, maybe buggy stream\n",
 377                qlevel);
 378         return -1;
 379     }
 380
 381     for (i = 0; i < pred_order; i++) {
 382         coeffs[i] = get_sbits(&s->gb, coeff_prec);
 383     }
 384
 385     if (decode_residuals(s, channel, pred_order) < 0)
 386         return -1;
 387
 388     if (s->bps > 16) {
 389         int64_t sum;
 390         for (i = pred_order; i < s->blocksize; i++) {
 391             sum = 0;
 392             for (j = 0; j < pred_order; j++)
 393                 sum += (int64_t)coeffs[j] * decoded[i-j-1];
 394             decoded[i] += sum >> qlevel;
 395         }
 396     } else {
 397         for (i = pred_order; i < s->blocksize-1; i += 2) {
 398             int c;
 399             int d = decoded[i-pred_order];
 400             int s0 = 0, s1 = 0;
 401             for (j = pred_order-1; j > 0; j--) {
 402                 c = coeffs[j];
 403                 s0 += c*d;
 404                 d = decoded[i-j];
 405                 s1 += c*d;
 406             }
 407             c = coeffs[0];
 408             s0 += c*d;
 409             d = decoded[i] += s0 >> qlevel;
 410             s1 += c*d;
 411             decoded[i+1] += s1 >> qlevel;
 412         }
 413         if (i < s->blocksize) {
 414             int sum = 0;
 415             for (j = 0; j < pred_order; j++)
 416                 sum += coeffs[j] * decoded[i-j-1];
 417             decoded[i] += sum >> qlevel;
 418         }
 419     }
 420
 421     return 0;
 422 }
 423
 424 static inline int decode_subframe(FLACContext *s, int channel)
 425 {
 426     int type, wasted = 0;
 427     int i, tmp;
 428
 429     s->curr_bps = s->bps;
 430     if (channel == 0) {
 431         if (s->ch_mode == FLAC_CHMODE_RIGHT_SIDE)
 432             s->curr_bps++;
 433     } else {
 434         if (s->ch_mode == FLAC_CHMODE_LEFT_SIDE || s->ch_mode == FLAC_CHMODE_MID_SIDE)
 435             s->curr_bps++;
 436     }
 437
 438     if (get_bits1(&s->gb)) {
 439         av_log(s->avctx, AV_LOG_ERROR, "invalid subframe padding\n");
 440         return -1;
 441     }
 442     type = get_bits(&s->gb, 6);
 443
 444     if (get_bits1(&s->gb)) {
 445         wasted = 1;
 446         while (!get_bits1(&s->gb))
 447             wasted++;
 448         s->curr_bps -= wasted;
 449     }
 450     if (s->curr_bps > 32) {
 451         ff_log_missing_feature(s->avctx, "decorrelated bit depth > 32", 0);
 452         return -1;
 453     }
 454
 455 //FIXME use av_log2 for types
 456     if (type == 0) {
 457         tmp = get_sbits_long(&s->gb, s->curr_bps);
 458         for (i = 0; i < s->blocksize; i++)
 459             s->decoded[channel][i] = tmp;
 460     } else if (type == 1) {
 461         for (i = 0; i < s->blocksize; i++)
 462             s->decoded[channel][i] = get_sbits_long(&s->gb, s->curr_bps);
 463     } else if ((type >= 8) && (type <= 12)) {
 464         if (decode_subframe_fixed(s, channel, type & ~0x8) < 0)
 465             return -1;
 466     } else if (type >= 32) {
 467         if (decode_subframe_lpc(s, channel, (type & ~0x20)+1) < 0)
 468             return -1;
 469     } else {
 470         av_log(s->avctx, AV_LOG_ERROR, "invalid coding type\n");
 471         return -1;
 472     }
 473
 474     if (wasted) {
 475         int i;
 476         for (i = 0; i < s->blocksize; i++)
 477             s->decoded[channel][i] <<= wasted;
 478     }
 479
 480     return 0;
 481 }
 482
 483 static int decode_frame(FLACContext *s, int alloc_data_size)
 484 {
 485     int blocksize_code, sample_rate_code, sample_size_code, i, crc8;
 486     int ch_mode, bps, blocksize, samplerate;
 487     GetBitContext *gb = &s->gb;
 488
 489     blocksize_code = get_bits(gb, 4);
 490
 491     sample_rate_code = get_bits(gb, 4);
 492
 493     ch_mode = get_bits(gb, 4); /* channel assignment */
 494     if (ch_mode < FLAC_MAX_CHANNELS && s->channels == ch_mode+1) {
 495         ch_mode = FLAC_CHMODE_INDEPENDENT;
 496     } else if (ch_mode > FLAC_CHMODE_MID_SIDE || s->channels != 2) {
 497         av_log(s->avctx, AV_LOG_ERROR, "unsupported channel assignment %d (channels=%d)\n",
 498                ch_mode, s->channels);
 499         return -1;
 500     }
 501
 502     sample_size_code = get_bits(gb, 3);
 503     if (sample_size_code == 0)
 504         bps= s->bps;
 505     else if ((sample_size_code != 3) && (sample_size_code != 7))
 506         bps = sample_size_table[sample_size_code];
 507     else {
 508         av_log(s->avctx, AV_LOG_ERROR, "invalid sample size code (%d)\n",
 509                sample_size_code);
 510         return -1;
 511     }
 512     if (bps > 16) {
 513         s->avctx->sample_fmt = SAMPLE_FMT_S32;
 514         s->sample_shift = 32 - bps;
 515         s->is32 = 1;
 516     } else {
 517         s->avctx->sample_fmt = SAMPLE_FMT_S16;
 518         s->sample_shift = 16 - bps;
 519         s->is32 = 0;
 520     }
 521     s->bps = s->avctx->bits_per_raw_sample = bps;
 522
 523     if (get_bits1(gb)) {
 524         av_log(s->avctx, AV_LOG_ERROR, "broken stream, invalid padding\n");
 525         return -1;
 526     }
 527
 528     if (get_utf8(gb) < 0) {
 529         av_log(s->avctx, AV_LOG_ERROR, "utf8 fscked\n");
 530         return -1;
 531     }
 532
 533     if (blocksize_code == 0) {
 534         av_log(s->avctx, AV_LOG_ERROR, "reserved blocksize code: 0\n");
 535         return -1;
 536     } else if (blocksize_code == 6)
 537         blocksize = get_bits(gb, 8)+1;
 538     else if (blocksize_code == 7)
 539         blocksize = get_bits(gb, 16)+1;
 540     else
 541         blocksize = ff_flac_blocksize_table[blocksize_code];
 542
 543     if (blocksize > s->max_blocksize) {
 544         av_log(s->avctx, AV_LOG_ERROR, "blocksize %d > %d\n", blocksize,
 545                s->max_blocksize);
 546         return -1;
 547     }
 548
 549     if (blocksize * s->channels * (s->is32 ? 4 : 2) > alloc_data_size)
 550         return -1;
 551
 552     if (sample_rate_code == 0)
 553         samplerate= s->samplerate;
 554     else if (sample_rate_code < 12)
 555         samplerate = ff_flac_sample_rate_table[sample_rate_code];
 556     else if (sample_rate_code == 12)
 557         samplerate = get_bits(gb, 8) * 1000;
 558     else if (sample_rate_code == 13)
 559         samplerate = get_bits(gb, 16);
 560     else if (sample_rate_code == 14)
 561         samplerate = get_bits(gb, 16) * 10;
 562     else {
 563         av_log(s->avctx, AV_LOG_ERROR, "illegal sample rate code %d\n",
 564                sample_rate_code);
 565         return -1;
 566     }
 567
 568     skip_bits(gb, 8);
 569     crc8 = av_crc(av_crc_get_table(AV_CRC_8_ATM), 0,
 570                   gb->buffer, get_bits_count(gb)/8);
 571     if (crc8) {
 572         av_log(s->avctx, AV_LOG_ERROR, "header crc mismatch crc=%2X\n", crc8);
 573         return -1;
 574     }
 575
 576     s->blocksize    = blocksize;
 577     s->samplerate   = samplerate;
 578     s->bps          = bps;
 579     s->ch_mode      = ch_mode;
 580
 581 //    dump_headers(s->avctx, (FLACStreaminfo *)s);
 582
 583     /* subframes */
 584     for (i = 0; i < s->channels; i++) {
 585         if (decode_subframe(s, i) < 0)
 586             return -1;
 587     }
 588
 589     align_get_bits(gb);
 590
 591     /* frame footer */
 592     skip_bits(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 i, j = 0, input_buf_size = 0, bytes_read = 0;
 603     int16_t *samples_16 = data;
 604     int32_t *samples_32 = data;
 605     int alloc_data_size= *data_size;
 606
 607     *data_size=0;
 608
 609     if (s->max_framesize == 0) {
 610         s->max_framesize= FFMAX(4, buf_size); // should hopefully be enough for the first header
 611         s->bitstream= av_fast_realloc(s->bitstream, &s->allocated_bitstream_size, s->max_framesize);
 612     }
 613
 614     if (1 && s->max_framesize) { //FIXME truncated
 615         if (s->bitstream_size < 4 || AV_RL32(s->bitstream) != MKTAG('f','L','a','C'))
 616             buf_size= FFMIN(buf_size, s->max_framesize - FFMIN(s->bitstream_size, s->max_framesize));
 617         input_buf_size= buf_size;
 618
 619         if (s->bitstream_size + buf_size < buf_size || s->bitstream_index + s->bitstream_size + buf_size < s->bitstream_index)
 620             return -1;
 621
 622         if (s->allocated_bitstream_size < s->bitstream_size + buf_size)
 623             s->bitstream= av_fast_realloc(s->bitstream, &s->allocated_bitstream_size, s->bitstream_size + buf_size);
 624
 625         if (s->bitstream_index + s->bitstream_size + buf_size > s->allocated_bitstream_size) {
 626             memmove(s->bitstream, &s->bitstream[s->bitstream_index],
 627                     s->bitstream_size);
 628             s->bitstream_index=0;
 629         }
 630         memcpy(&s->bitstream[s->bitstream_index + s->bitstream_size],
 631                buf, buf_size);
 632         buf= &s->bitstream[s->bitstream_index];
 633         buf_size += s->bitstream_size;
 634         s->bitstream_size= buf_size;
 635
 636         if (buf_size < s->max_framesize && input_buf_size) {
 637             return input_buf_size;
 638         }
 639     }
 640
 641     /* check that there is at least the smallest decodable amount of data.
 642        this amount corresponds to the smallest valid FLAC frame possible.
 643        FF F8 69 02 00 00 9A 00 00 34 46 */
 644     if (buf_size < 11)
 645         goto end;
 646
 647     /* check for inline header */
 648     if (AV_RB32(buf) == MKBETAG('f','L','a','C')) {
 649         if (!s->got_streaminfo && parse_streaminfo(s, buf, buf_size)) {
 650             av_log(s->avctx, AV_LOG_ERROR, "invalid header\n");
 651             return -1;
 652         }
 653         bytes_read = get_metadata_size(buf, buf_size);
 654         goto end;
 655     }
 656
 657     /* check for frame sync code and resync stream if necessary */
 658     if ((AV_RB16(buf) & 0xFFFE) != 0xFFF8) {
 659         const uint8_t *buf_end = buf + buf_size;
 660         av_log(s->avctx, AV_LOG_ERROR, "FRAME HEADER not here\n");
 661         while (buf+2 < buf_end && (AV_RB16(buf) & 0xFFFE) != 0xFFF8)
 662             buf++;
 663         bytes_read = buf_size - (buf_end - buf);
 664         goto end; // we may not have enough bits left to decode a frame, so try next time
 665     }
 666
 667     /* decode frame */
 668     init_get_bits(&s->gb, buf, buf_size*8);
 669     skip_bits(&s->gb, 16);
 670     if (decode_frame(s, alloc_data_size) < 0) {
 671         av_log(s->avctx, AV_LOG_ERROR, "decode_frame() failed\n");
 672         s->bitstream_size=0;
 673         s->bitstream_index=0;
 674         return -1;
 675     }
 676     *data_size = s->blocksize * s->channels * (s->is32 ? 4 : 2);
 677     bytes_read = (get_bits_count(&s->gb)+7)/8;
 678
 679 #define DECORRELATE(left, right)\
 680             assert(s->channels == 2);\
 681             for (i = 0; i < s->blocksize; i++) {\
 682                 int a= s->decoded[0][i];\
 683                 int b= s->decoded[1][i];\
 684                 if (s->is32) {\
 685                     *samples_32++ = (left)  << s->sample_shift;\
 686                     *samples_32++ = (right) << s->sample_shift;\
 687                 } else {\
 688                     *samples_16++ = (left)  << s->sample_shift;\
 689                     *samples_16++ = (right) << s->sample_shift;\
 690                 }\
 691             }\
 692             break;
 693
 694     switch (s->ch_mode) {
 695     case FLAC_CHMODE_INDEPENDENT:
 696         for (j = 0; j < s->blocksize; j++) {
 697             for (i = 0; i < s->channels; i++) {
 698                 if (s->is32)
 699                     *samples_32++ = s->decoded[i][j] << s->sample_shift;
 700                 else
 701                     *samples_16++ = s->decoded[i][j] << s->sample_shift;
 702             }
 703         }
 704         break;
 705     case FLAC_CHMODE_LEFT_SIDE:
 706         DECORRELATE(a,a-b)
 707     case FLAC_CHMODE_RIGHT_SIDE:
 708         DECORRELATE(a+b,b)
 709     case FLAC_CHMODE_MID_SIDE:
 710         DECORRELATE( (a-=b>>1) + b, a)
 711     }
 712
 713 end:
 714     if (bytes_read > buf_size) {
 715         av_log(s->avctx, AV_LOG_ERROR, "overread: %d\n", bytes_read - buf_size);
 716         s->bitstream_size=0;
 717         s->bitstream_index=0;
 718         return -1;
 719     }
 720
 721     if (s->bitstream_size) {
 722         s->bitstream_index += bytes_read;
 723         s->bitstream_size  -= bytes_read;
 724         return input_buf_size;
 725     } else
 726         return bytes_read;
 727 }
 728
 729 static av_cold int flac_decode_close(AVCodecContext *avctx)
 730 {
 731     FLACContext *s = avctx->priv_data;
 732     int i;
 733
 734     for (i = 0; i < s->channels; i++) {
 735         av_freep(&s->decoded[i]);
 736     }
 737     av_freep(&s->bitstream);
 738
 739     return 0;
 740 }
 741
 742 static void flac_flush(AVCodecContext *avctx)
 743 {
 744     FLACContext *s = avctx->priv_data;
 745
 746     s->bitstream_size=
 747     s->bitstream_index= 0;
 748 }
 749
 750 AVCodec flac_decoder = {
 751     "flac",
 752     CODEC_TYPE_AUDIO,
 753     CODEC_ID_FLAC,
 754     sizeof(FLACContext),
 755     flac_decode_init,
 756     NULL,
 757     flac_decode_close,
 758     flac_decode_frame,
 759     CODEC_CAP_DELAY,
 760     .flush= flac_flush,
 761     .long_name= NULL_IF_CONFIG_SMALL("FLAC (Free Lossless Audio Codec)"),
 762 };