quicktime/trak.c

   1 #include "funcprotos.h"
   2 #include "quicktime.h"
   3
   4
   5
   6
   7 int quicktime_trak_init(quicktime_trak_t *trak)
   8 {
   9         quicktime_tkhd_init(&(trak->tkhd));
  10         quicktime_edts_init(&(trak->edts));
  11         quicktime_mdia_init(&(trak->mdia));
  12         return 0;
  13 }
  14
  15 int quicktime_trak_init_video(quicktime_t *file,
  16                                                         quicktime_trak_t *trak,
  17                                                         int frame_w,
  18                                                         int frame_h,
  19                                                         float frame_rate,
  20                                                         char *compressor)
  21 {
  22
  23         quicktime_tkhd_init_video(file,
  24                 &(trak->tkhd),
  25                 frame_w,
  26                 frame_h);
  27         quicktime_mdia_init_video(file,
  28                 &(trak->mdia),
  29                 frame_w,
  30                 frame_h,
  31                 frame_rate,
  32                 compressor);
  33         quicktime_edts_init_table(&(trak->edts));
  34
  35         return 0;
  36 }
  37
  38 int quicktime_trak_init_audio(quicktime_t *file,
  39                                                         quicktime_trak_t *trak,
  40                                                         int channels,
  41                                                         int sample_rate,
  42                                                         int bits,
  43                                                         char *compressor)
  44 {
  45         quicktime_mdia_init_audio(file, &(trak->mdia),
  46                 channels,
  47                 sample_rate,
  48                 bits,
  49                 compressor);
  50         quicktime_edts_init_table(&(trak->edts));
  51         return 0;
  52 }
  53
  54 int quicktime_trak_delete(quicktime_trak_t *trak)
  55 {
  56         quicktime_mdia_delete(&(trak->mdia));
  57         quicktime_edts_delete(&(trak->edts));
  58         quicktime_tkhd_delete(&(trak->tkhd));
  59         return 0;
  60 }
  61
  62
  63 int quicktime_trak_dump(quicktime_trak_t *trak)
  64 {
  65         printf(" track\n");
  66         quicktime_tkhd_dump(&(trak->tkhd));
  67         quicktime_edts_dump(&(trak->edts));
  68         quicktime_mdia_dump(&(trak->mdia));
  69
  70         return 0;
  71 }
  72
  73 // Used when reading a file
  74 quicktime_trak_t* quicktime_add_trak(quicktime_t *file)
  75 {
  76         quicktime_moov_t *moov = &(file->moov);
  77         if(moov->total_tracks < MAXTRACKS)
  78         {
  79                 moov->trak[moov->total_tracks] = calloc(1, sizeof(quicktime_trak_t));
  80                 quicktime_trak_init(moov->trak[moov->total_tracks]);
  81                 moov->total_tracks++;
  82         }
  83         return moov->trak[moov->total_tracks - 1];
  84 }
  85
  86 int quicktime_delete_trak(quicktime_moov_t *moov)
  87 {
  88         if(moov->total_tracks)
  89         {
  90                 moov->total_tracks--;
  91                 quicktime_trak_delete(moov->trak[moov->total_tracks]);
  92                 free(moov->trak[moov->total_tracks]);
  93         }
  94         return 0;
  95 }
  96
  97
  98 int quicktime_read_trak(quicktime_t *file, quicktime_trak_t *trak, quicktime_atom_t *trak_atom)
  99 {
 100         quicktime_atom_t leaf_atom;
 101
 102         do
 103         {
 104                 quicktime_atom_read_header(file, &leaf_atom);
 105
 106 //printf("quicktime_read_trak %llx %llx\n", quicktime_position(file), quicktime_ftell(file));
 107 /* mandatory */
 108                 if(quicktime_atom_is(&leaf_atom, "tkhd"))
 109                         { quicktime_read_tkhd(file, &(trak->tkhd)); }
 110                 else
 111                 if(quicktime_atom_is(&leaf_atom, "mdia"))
 112                         { quicktime_read_mdia(file, &(trak->mdia), &leaf_atom); }
 113                 else
 114 /* optional */
 115                 if(quicktime_atom_is(&leaf_atom, "clip"))
 116                         { quicktime_atom_skip(file, &leaf_atom); }
 117                 else
 118                 if(quicktime_atom_is(&leaf_atom, "matt"))
 119                         { quicktime_atom_skip(file, &leaf_atom); }
 120                 else
 121                 if(quicktime_atom_is(&leaf_atom, "edts"))
 122                         { quicktime_read_edts(file, &(trak->edts), &leaf_atom); }
 123                 else
 124                 if(quicktime_atom_is(&leaf_atom, "load"))
 125                         { quicktime_atom_skip(file, &leaf_atom); }
 126                 else
 127                 if(quicktime_atom_is(&leaf_atom, "tref"))
 128                         { quicktime_atom_skip(file, &leaf_atom); }
 129                 else
 130                 if(quicktime_atom_is(&leaf_atom, "imap"))
 131                         { quicktime_atom_skip(file, &leaf_atom); }
 132                 else
 133                 if(quicktime_atom_is(&leaf_atom, "udta"))
 134                         { quicktime_atom_skip(file, &leaf_atom); }
 135                 else
 136                         quicktime_atom_skip(file, &leaf_atom);
 137 //printf("quicktime_read_trak %llx %llx\n", quicktime_position(file), leaf_atom.end);
 138         }while(quicktime_position(file) < trak_atom->end);
 139
 140         return 0;
 141 }
 142
 143 int quicktime_write_trak(quicktime_t *file,
 144         quicktime_trak_t *trak,
 145         long moov_time_scale)
 146 {
 147         long duration;
 148         long timescale;
 149         quicktime_atom_t atom;
 150         quicktime_atom_write_header(file, &atom, "trak");
 151         quicktime_trak_duration(trak, &duration, &timescale);
 152
 153 /*printf("quicktime_write_trak duration %d\n", duration); */
 154 /* get duration in movie's units */
 155         trak->tkhd.duration = (long)((float)duration / timescale * moov_time_scale);
 156         trak->mdia.mdhd.duration = duration;
 157         trak->mdia.mdhd.time_scale = timescale;
 158
 159         quicktime_write_tkhd(file, &(trak->tkhd));
 160         quicktime_write_edts(file, &(trak->edts), trak->tkhd.duration);
 161         quicktime_write_mdia(file, &(trak->mdia));
 162
 163         quicktime_atom_write_footer(file, &atom);
 164
 165         return 0;
 166 }
 167
 168 int64_t quicktime_track_end(quicktime_trak_t *trak)
 169 {
 170 /* get the byte endpoint of the track in the file */
 171         int64_t size = 0;
 172         int64_t chunk, chunk_offset, chunk_samples, sample;
 173         quicktime_stsz_t *stsz = &(trak->mdia.minf.stbl.stsz);
 174         quicktime_stsz_table_t *table = stsz->table;
 175         quicktime_stsc_t *stsc = &(trak->mdia.minf.stbl.stsc);
 176         quicktime_stco_t *stco;
 177
 178 /* get the last chunk offset */
 179 /* the chunk offsets contain the HEADER_LENGTH themselves */
 180         stco = &(trak->mdia.minf.stbl.stco);
 181         chunk = stco->total_entries;
 182         size = chunk_offset = stco->table[chunk - 1].offset;
 183
 184 /* get the number of samples in the last chunk */
 185         chunk_samples = stsc->table[stsc->total_entries - 1].samples;
 186
 187 /* get the size of last samples */
 188         if(stsz->sample_size)
 189         {
 190 /* assume audio so calculate the sample size */
 191                 size += chunk_samples * stsz->sample_size
 192                         * trak->mdia.minf.stbl.stsd.table[0].channels
 193                         * trak->mdia.minf.stbl.stsd.table[0].sample_size / 8;
 194         }
 195         else
 196         {
 197 /* assume video */
 198                 for(sample = stsz->total_entries - chunk_samples;
 199                         sample < stsz->total_entries; sample++)
 200                 {
 201                         size += stsz->table[sample].size;
 202                 }
 203         }
 204
 205         return size;
 206 }
 207
 208 long quicktime_track_samples(quicktime_t *file, quicktime_trak_t *trak)
 209 {
 210 /*printf("file->rd %d file->wr %d\n", file->rd, file->wr); */
 211         if(file->wr)
 212         {
 213 /* get the sample count when creating a new file */
 214                 quicktime_stsc_table_t *table = trak->mdia.minf.stbl.stsc.table;
 215                 long total_entries = trak->mdia.minf.stbl.stsc.total_entries;
 216                 long chunk = trak->mdia.minf.stbl.stco.total_entries;
 217                 long sample;
 218
 219                 if(chunk)
 220                 {
 221                         sample = quicktime_sample_of_chunk(trak, chunk);
 222                         sample += table[total_entries - 1].samples;
 223                 }
 224                 else
 225                         sample = 0;
 226
 227                 return sample;
 228         }
 229         else
 230         {
 231 /* get the sample count when reading only */
 232                 quicktime_stts_t *stts = &(trak->mdia.minf.stbl.stts);
 233                 int64_t total = 0;
 234                 int i;
 235
 236                 if(trak->mdia.minf.is_audio)
 237                 {
 238
 239 // Get total sample duration
 240                         for(i = 0; i < stts->total_entries; i++)
 241                         {
 242                                 total += stts->table[i].sample_count *
 243                                         stts->table[i].sample_duration;
 244                         }
 245
 246                         return total;
 247                 }
 248                 else
 249                 if(trak->mdia.minf.is_video)
 250                 {
 251 /* Get total number of samples */
 252                         for(i = 0; i < stts->total_entries; i++)
 253                         {
 254                                 total += stts->table[i].sample_count;
 255                         }
 256                         return total;
 257                 }
 258                 return total;
 259         }
 260 }
 261
 262 long quicktime_sample_of_chunk(quicktime_trak_t *trak, long chunk)
 263 {
 264         quicktime_stsc_table_t *table = trak->mdia.minf.stbl.stsc.table;
 265         long total_entries = trak->mdia.minf.stbl.stsc.total_entries;
 266         long chunk1entry, chunk2entry;
 267         long chunk1, chunk2, chunks, total = 0;
 268
 269         for(chunk1entry = total_entries - 1, chunk2entry = total_entries;
 270                 chunk1entry >= 0;
 271                 chunk1entry--, chunk2entry--)
 272         {
 273                 chunk1 = table[chunk1entry].chunk;
 274
 275                 if(chunk > chunk1)
 276                 {
 277                         if(chunk2entry < total_entries)
 278                         {
 279                                 chunk2 = table[chunk2entry].chunk;
 280
 281                                 if(chunk < chunk2) chunk2 = chunk;
 282                         }
 283                         else
 284                                 chunk2 = chunk;
 285
 286                         chunks = chunk2 - chunk1;
 287
 288                         total += chunks * table[chunk1entry].samples;
 289                 }
 290         }
 291
 292         return total;
 293 }
 294
 295 // For AVI
 296 int quicktime_avg_chunk_samples(quicktime_t *file, quicktime_trak_t *trak)
 297 {
 298         int i, chunk = trak->mdia.minf.stbl.stco.total_entries - 1;
 299         long total_samples;
 300
 301         if(chunk >= 0)
 302         {
 303                 total_samples = quicktime_sample_of_chunk(trak, chunk);
 304                 return total_samples / (chunk + 1);
 305         }
 306         else
 307         {
 308                 total_samples = quicktime_track_samples(file, trak);
 309                 return total_samples;
 310         }
 311 }
 312
 313 int quicktime_chunk_of_sample(int64_t *chunk_sample,
 314         int64_t *chunk,
 315         quicktime_trak_t *trak,
 316         long sample)
 317 {
 318         quicktime_stsc_table_t *table = trak->mdia.minf.stbl.stsc.table;
 319         long total_entries = trak->mdia.minf.stbl.stsc.total_entries;
 320         long chunk2entry;
 321         long chunk1, chunk2, chunk1samples, range_samples, total = 0;
 322
 323         chunk1 = 1;
 324         chunk1samples = 0;
 325         chunk2entry = 0;
 326
 327         if(!total_entries)
 328         {
 329                 *chunk_sample = 0;
 330                 *chunk = 0;
 331                 return 0;
 332         }
 333
 334         do
 335         {
 336                 chunk2 = table[chunk2entry].chunk;
 337                 *chunk = chunk2 - chunk1;
 338                 range_samples = *chunk * chunk1samples;
 339
 340                 if(sample < total + range_samples) break;
 341
 342                 chunk1samples = table[chunk2entry].samples;
 343                 chunk1 = chunk2;
 344
 345                 if(chunk2entry < total_entries)
 346                 {
 347                         chunk2entry++;
 348                         total += range_samples;
 349                 }
 350         }while(chunk2entry < total_entries);
 351
 352         if(chunk1samples)
 353                 *chunk = (sample - total) / chunk1samples + chunk1;
 354         else
 355                 *chunk = 1;
 356
 357         *chunk_sample = total + (*chunk - chunk1) * chunk1samples;
 358         return 0;
 359 }
 360
 361 int64_t quicktime_chunk_to_offset(quicktime_t *file, quicktime_trak_t *trak, long chunk)
 362 {
 363         quicktime_stco_table_t *table = trak->mdia.minf.stbl.stco.table;
 364         int64_t result = 0;
 365
 366         if(trak->mdia.minf.stbl.stco.total_entries &&
 367                 chunk > trak->mdia.minf.stbl.stco.total_entries)
 368                 result = table[trak->mdia.minf.stbl.stco.total_entries - 1].offset;
 369         else
 370         if(trak->mdia.minf.stbl.stco.total_entries)
 371                 result = table[chunk - 1].offset;
 372         else
 373                 result = HEADER_LENGTH * 2;
 374
 375 // Skip chunk header for AVI.  Skip it here instead of in read_chunk because some
 376 // codecs can't use read_chunk
 377         if(file->use_avi)
 378         {
 379 //printf("quicktime_chunk_to_offset 1 %llx %llx\n", result, file->mdat.atom.start);
 380                 result += 8 + file->mdat.atom.start;
 381         }
 382         return result;
 383 }
 384
 385 long quicktime_offset_to_chunk(int64_t *chunk_offset,
 386         quicktime_trak_t *trak,
 387         int64_t offset)
 388 {
 389         quicktime_stco_table_t *table = trak->mdia.minf.stbl.stco.table;
 390         int i;
 391
 392         for(i = trak->mdia.minf.stbl.stco.total_entries - 1; i >= 0; i--)
 393         {
 394                 if(table[i].offset <= offset)
 395                 {
 396                         *chunk_offset = table[i].offset;
 397                         return i + 1;
 398                 }
 399         }
 400         *chunk_offset = HEADER_LENGTH * 2;
 401         return 1;
 402 }
 403
 404 int quicktime_chunk_bytes(quicktime_t *file,
 405         int64_t *chunk_offset,
 406         int chunk,
 407         quicktime_trak_t *trak)
 408 {
 409         int result;
 410         *chunk_offset = quicktime_chunk_to_offset(file, trak, chunk);
 411         quicktime_set_position(file, *chunk_offset - 4);
 412         result = quicktime_read_int32_le(file);
 413         return result;
 414 }
 415
 416 int64_t quicktime_sample_range_size(quicktime_trak_t *trak,
 417         long chunk_sample,
 418         long sample)
 419 {
 420         quicktime_stsz_table_t *table = trak->mdia.minf.stbl.stsz.table;
 421         int64_t i, total;
 422
 423         if(trak->mdia.minf.stbl.stsz.sample_size)
 424         {
 425 /* assume audio */
 426                 return quicktime_samples_to_bytes(trak, sample - chunk_sample);
 427         }
 428         else
 429         {
 430 /* video or vbr audio */
 431                 for(i = chunk_sample, total = 0;
 432                         i < sample && i < trak->mdia.minf.stbl.stsz.total_entries;
 433                         i++)
 434                 {
 435                         total += trak->mdia.minf.stbl.stsz.table[i].size;
 436                 }
 437         }
 438         return total;
 439 }
 440
 441 int64_t quicktime_sample_to_offset(quicktime_t *file,
 442         quicktime_trak_t *trak,
 443         long sample)
 444 {
 445         int64_t chunk, chunk_sample, chunk_offset1, chunk_offset2;
 446
 447         quicktime_chunk_of_sample(&chunk_sample, &chunk, trak, sample);
 448         chunk_offset1 = quicktime_chunk_to_offset(file, trak, chunk);
 449         chunk_offset2 = chunk_offset1 +
 450                 quicktime_sample_range_size(trak, chunk_sample, sample);
 451         return chunk_offset2;
 452 }
 453
 454 long quicktime_offset_to_sample(quicktime_trak_t *trak, int64_t offset)
 455 {
 456         int64_t chunk_offset;
 457         int64_t chunk = quicktime_offset_to_chunk(&chunk_offset, trak, offset);
 458         int64_t chunk_sample = quicktime_sample_of_chunk(trak, chunk);
 459         int64_t sample, sample_offset;
 460         quicktime_stsz_table_t *table = trak->mdia.minf.stbl.stsz.table;
 461         int64_t total_samples = trak->mdia.minf.stbl.stsz.total_entries;
 462
 463         if(trak->mdia.minf.stbl.stsz.sample_size)
 464         {
 465                 sample = chunk_sample + (offset - chunk_offset) /
 466                         trak->mdia.minf.stbl.stsz.sample_size;
 467         }
 468         else
 469         for(sample = chunk_sample, sample_offset = chunk_offset;
 470                 sample_offset < offset && sample < total_samples; )
 471         {
 472                 sample_offset += table[sample].size;
 473                 if(sample_offset < offset) sample++;
 474         }
 475
 476         return sample;
 477 }
 478
 479 void quicktime_write_chunk_header(quicktime_t *file,
 480         quicktime_trak_t *trak,
 481         quicktime_atom_t *chunk)
 482 {
 483         if(file->use_avi)
 484         {
 485 /* Get tag from first riff strl */
 486                 quicktime_riff_t *first_riff = file->riff[0];
 487                 quicktime_hdrl_t *hdrl = &first_riff->hdrl;
 488                 quicktime_strl_t *strl = hdrl->strl[trak->tkhd.track_id - 1];
 489                 char *tag = strl->tag;
 490
 491 /* Create new RIFF object at 1 Gig mark */
 492                 quicktime_riff_t *riff = file->riff[file->total_riffs - 1];
 493                 if(quicktime_position(file) - riff->atom.start > 0x40000000)
 494                 {
 495                         quicktime_finalize_riff(file, riff);
 496                         quicktime_init_riff(file);
 497                 }
 498
 499
 500
 501 /* Write AVI header */
 502                 quicktime_atom_write_header(file, chunk, tag);
 503         }
 504         else
 505         {
 506                 chunk->start = quicktime_position(file);
 507         }
 508 }
 509
 510 void quicktime_write_chunk_footer(quicktime_t *file,
 511         quicktime_trak_t *trak,
 512         int current_chunk,
 513         quicktime_atom_t *chunk,
 514         int samples)
 515 {
 516         int64_t offset = chunk->start;
 517         int sample_size = quicktime_position(file) - offset;
 518
 519
 520 // Write AVI footer
 521         if(file->use_avi)
 522         {
 523                 quicktime_atom_write_footer(file, chunk);
 524
 525 // Save version 1 index entry for first RIFF only
 526                 if(file->total_riffs < 2)
 527                 {
 528                         quicktime_update_idx1table(file,
 529                                 trak,
 530                                 offset,
 531                                 sample_size);
 532                 }
 533
 534 // Save partial index entry
 535                 quicktime_update_ixtable(file,
 536                         trak,
 537                         offset,
 538                         sample_size);
 539         }
 540
 541         if(offset + sample_size > file->mdat.atom.size)
 542                 file->mdat.atom.size = offset + sample_size;
 543
 544         quicktime_update_stco(&(trak->mdia.minf.stbl.stco),
 545                 current_chunk,
 546                 offset);
 547
 548         if(trak->mdia.minf.is_video)
 549                 quicktime_update_stsz(&(trak->mdia.minf.stbl.stsz),
 550                 current_chunk - 1,
 551                 sample_size);
 552
 553         quicktime_update_stsc(&(trak->mdia.minf.stbl.stsc),
 554                 current_chunk,
 555                 samples);
 556 }
 557
 558 int quicktime_write_vbr_frame(quicktime_t *file,
 559         int track,
 560         char *data,
 561         int data_size,
 562         int samples)
 563 {
 564         quicktime_audio_map_t *track_map = &(file->atracks[track]);
 565         quicktime_trak_t *trak = track_map->track;
 566         quicktime_atom_t chunk_atom;
 567         int result = 0;
 568
 569
 570         quicktime_write_chunk_header(file, trak, &chunk_atom);
 571         result = !quicktime_write_data(file, data, data_size);
 572         int64_t offset = chunk_atom.start;
 573
 574 // AVI case
 575         if(file->use_avi)
 576         {
 577                 quicktime_atom_write_footer(file, &chunk_atom);
 578 // Save version 1 index entry for first RIFF only
 579                 if(file->total_riffs < 2)
 580                 {
 581                         quicktime_update_idx1table(file,
 582                                 trak,
 583                                 offset,
 584                                 data_size);
 585                 }
 586
 587 // Save version 2 index entry
 588                 quicktime_update_ixtable(file,
 589                         trak,
 590                         offset,
 591                         data_size);
 592         }
 593
 594 // Update MDAT size
 595         if(offset + data_size > file->mdat.atom.size)
 596                 file->mdat.atom.size = offset + data_size;
 597
 598 // Update time to sample table
 599         quicktime_stts_append_audio(file,
 600                 &(trak->mdia.minf.stbl.stts),
 601                 samples);
 602
 603         int64_t total_chunks = quicktime_stts_total_samples(file,
 604                 &(trak->mdia.minf.stbl.stts));
 605         quicktime_update_stco(&(trak->mdia.minf.stbl.stco),
 606                 total_chunks,
 607                 offset);
 608         quicktime_update_stsc(&(trak->mdia.minf.stbl.stsc),
 609                 total_chunks,
 610                 1);
 611         quicktime_update_stsz(&(trak->mdia.minf.stbl.stsz),
 612                 total_chunks - 1,
 613                 data_size);
 614
 615
 616         return result;
 617 }
 618
 619
 620 /*
 621  * int quicktime_update_tables(quicktime_t *file,
 622  *                                                      quicktime_trak_t *trak,
 623  *                                                      int64_t offset,
 624  *                                                      int64_t chunk,
 625  *                                                      int64_t sample,
 626  *                                                      int64_t samples,
 627  *                                                      int64_t sample_size)
 628  * {
 629  * //if(file->use_avi)
 630  * printf("quicktime_update_tables: replaced by quicktime_write_chunk_header and quicktime_write_chunk_footer\n");
 631  *
 632  *      if(offset + sample_size > file->mdat.atom.size)
 633  *              file->mdat.atom.size = offset + sample_size;
 634  *
 635  *      quicktime_update_stco(&(trak->mdia.minf.stbl.stco), chunk, offset);
 636  *
 637  *      if(trak->mdia.minf.is_video)
 638  *              quicktime_update_stsz(&(trak->mdia.minf.stbl.stsz), sample, sample_size);
 639  *
 640  *
 641  *      quicktime_update_stsc(&(trak->mdia.minf.stbl.stsc), chunk, samples);
 642  *      return 0;
 643  * }
 644  */
 645
 646
 647 /**
 648  * This is used for writing the header
 649  **/
 650 int quicktime_trak_duration(quicktime_trak_t *trak,
 651         long *duration,
 652         long *timescale)
 653 {
 654         quicktime_stts_t *stts = &(trak->mdia.minf.stbl.stts);
 655         int i;
 656         *duration = 0;
 657
 658         for(i = 0; i < stts->total_entries; i++)
 659         {
 660                 *duration += stts->table[i].sample_duration *
 661                         stts->table[i].sample_count;
 662         }
 663
 664         *timescale = trak->mdia.mdhd.time_scale;
 665         return 0;
 666 }
 667
 668 int quicktime_trak_fix_counts(quicktime_t *file, quicktime_trak_t *trak)
 669 {
 670         long samples = quicktime_track_samples(file, trak);
 671
 672         if(!trak->mdia.minf.stbl.stts.is_vbr)
 673         {
 674                 trak->mdia.minf.stbl.stts.table[0].sample_count = samples;
 675
 676                 if(!trak->mdia.minf.stbl.stsz.total_entries)
 677                 {
 678                         trak->mdia.minf.stbl.stsz.sample_size = 1;
 679                         trak->mdia.minf.stbl.stsz.total_entries = samples;
 680                 }
 681         }
 682         return 0;
 683 }
 684
 685 long quicktime_chunk_samples(quicktime_trak_t *trak, long chunk)
 686 {
 687         long result, current_chunk;
 688         quicktime_stsc_t *stsc = &(trak->mdia.minf.stbl.stsc);
 689         long i = stsc->total_entries - 1;
 690
 691         do
 692         {
 693                 current_chunk = stsc->table[i].chunk;
 694                 result = stsc->table[i].samples;
 695                 i--;
 696         }while(i >= 0 && current_chunk > chunk);
 697
 698         return result;
 699 }
 700
 701 int quicktime_trak_shift_offsets(quicktime_trak_t *trak, int64_t offset)
 702 {
 703         quicktime_stco_t *stco = &(trak->mdia.minf.stbl.stco);
 704         int i;
 705
 706         for(i = 0; i < stco->total_entries; i++)
 707         {
 708                 stco->table[i].offset += offset;
 709         }
 710         return 0;
 711 }
 712
 713 char* quicktime_compressor(quicktime_trak_t *track)
 714 {
 715         return track->mdia.minf.stbl.stsd.table[0].format;
 716 }
 717
 718
 719 int quicktime_sample_duration(quicktime_trak_t *trak)
 720 {
 721         quicktime_stts_t *stts = &trak->mdia.minf.stbl.stts;
 722         int i;
 723         int max_count = 0;
 724         int result = 1;
 725         for(i = 0; i < stts->total_entries; i++)
 726         {
 727                 quicktime_stts_table_t *table = &stts->table[i];
 728                 if(table->sample_count > max_count)
 729                 {
 730                         max_count = table->sample_count;
 731                         result = table->sample_duration;
 732                 }
 733         }
 734         return result;
 735 }
 736
 737