media/formats/mp4/track_run_iterator.cc

   1 // Copyright 2014 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #include "media/formats/mp4/track_run_iterator.h"
   6
   7 #include <algorithm>
   8
   9 #include "media/base/buffers.h"
  10 #include "media/formats/mp4/rcheck.h"
  11 #include "media/formats/mp4/sample_to_group_iterator.h"
  12
  13 namespace media {
  14 namespace mp4 {
  15
  16 struct SampleInfo {
  17   int size;
  18   int duration;
  19   int cts_offset;
  20   bool is_keyframe;
  21   bool is_random_access_point;
  22   uint32 cenc_group_description_index;
  23 };
  24
  25 struct TrackRunInfo {
  26   uint32 track_id;
  27   std::vector<SampleInfo> samples;
  28   int64 timescale;
  29   int64 start_dts;
  30   int64 sample_start_offset;
  31
  32   bool is_audio;
  33   const AudioSampleEntry* audio_description;
  34   const VideoSampleEntry* video_description;
  35
  36   int64 aux_info_start_offset;  // Only valid if aux_info_total_size > 0.
  37   int aux_info_default_size;
  38   std::vector<uint8> aux_info_sizes;  // Populated if default_size == 0.
  39   int aux_info_total_size;
  40
  41   std::vector<CencSampleEncryptionInfoEntry> sample_encryption_info;
  42
  43   TrackRunInfo();
  44   ~TrackRunInfo();
  45 };
  46
  47 TrackRunInfo::TrackRunInfo()
  48     : track_id(0),
  49       timescale(-1),
  50       start_dts(-1),
  51       sample_start_offset(-1),
  52       is_audio(false),
  53       aux_info_start_offset(-1),
  54       aux_info_default_size(-1),
  55       aux_info_total_size(-1) {
  56 }
  57 TrackRunInfo::~TrackRunInfo() {}
  58
  59 base::TimeDelta TimeDeltaFromRational(int64 numer, int64 denom) {
  60   // To avoid overflow, split the following calculation:
  61   // (numer * base::Time::kMicrosecondsPerSecond) / denom
  62   // into:
  63   //  (numer / denom) * base::Time::kMicrosecondsPerSecond +
  64   // ((numer % denom) * base::Time::kMicrosecondsPerSecond) / denom
  65   int64 a = numer / denom;
  66   DCHECK_LE((a > 0 ? a : -a), kint64max / base::Time::kMicrosecondsPerSecond);
  67   int64 timea_in_us = a * base::Time::kMicrosecondsPerSecond;
  68
  69   int64 b = numer % denom;
  70   DCHECK_LE((b > 0 ? b : -b), kint64max / base::Time::kMicrosecondsPerSecond);
  71   int64 timeb_in_us = (b * base::Time::kMicrosecondsPerSecond) / denom;
  72
  73   DCHECK((timeb_in_us < 0) || (timea_in_us <= kint64max - timeb_in_us));
  74   DCHECK((timeb_in_us > 0) || (timea_in_us >= kint64min - timeb_in_us));
  75   return base::TimeDelta::FromMicroseconds(timea_in_us + timeb_in_us);
  76 }
  77
  78 DecodeTimestamp DecodeTimestampFromRational(int64 numer, int64 denom) {
  79   return DecodeTimestamp::FromPresentationTime(
  80       TimeDeltaFromRational(numer, denom));
  81 }
  82
  83 TrackRunIterator::TrackRunIterator(const Movie* moov,
  84                                    const LogCB& log_cb)
  85     : moov_(moov), log_cb_(log_cb), sample_offset_(0) {
  86   CHECK(moov);
  87 }
  88
  89 TrackRunIterator::~TrackRunIterator() {}
  90
  91 static bool PopulateSampleInfo(const TrackExtends& trex,
  92                                const TrackFragmentHeader& tfhd,
  93                                const TrackFragmentRun& trun,
  94                                const int64 edit_list_offset,
  95                                const uint32 i,
  96                                SampleInfo* sample_info,
  97                                const SampleDependsOn sdtp_sample_depends_on,
  98                                const LogCB& log_cb) {
  99   if (i < trun.sample_sizes.size()) {
 100     sample_info->size = trun.sample_sizes[i];
 101   } else if (tfhd.default_sample_size > 0) {
 102     sample_info->size = tfhd.default_sample_size;
 103   } else {
 104     sample_info->size = trex.default_sample_size;
 105   }
 106
 107   if (i < trun.sample_durations.size()) {
 108     sample_info->duration = trun.sample_durations[i];
 109   } else if (tfhd.default_sample_duration > 0) {
 110     sample_info->duration = tfhd.default_sample_duration;
 111   } else {
 112     sample_info->duration = trex.default_sample_duration;
 113   }
 114
 115   if (i < trun.sample_composition_time_offsets.size()) {
 116     sample_info->cts_offset = trun.sample_composition_time_offsets[i];
 117   } else {
 118     sample_info->cts_offset = 0;
 119   }
 120   sample_info->cts_offset += edit_list_offset;
 121
 122   uint32 flags;
 123   if (i < trun.sample_flags.size()) {
 124     flags = trun.sample_flags[i];
 125   } else if (tfhd.has_default_sample_flags) {
 126     flags = tfhd.default_sample_flags;
 127   } else {
 128     flags = trex.default_sample_flags;
 129   }
 130
 131   SampleDependsOn sample_depends_on =
 132       static_cast<SampleDependsOn>((flags >> 24) & 0x3);
 133
 134   if (sample_depends_on == kSampleDependsOnUnknown)
 135     sample_depends_on = sdtp_sample_depends_on;
 136
 137   // ISO/IEC 14496-12  Section 8.8.3.1 : The negation of |sample_is_sync_sample|
 138   // provides the same information as the sync sample table [8.6.2]. When
 139   // |sample_is_sync_sample| is true for a sample, it is the same as if the
 140   // sample were not in a movie fragment and marked with an entry in the sync
 141   // sample table (or, if all samples are sync samples, the sync sample table
 142   // were absent).
 143   bool sample_is_sync_sample = !(flags & kSampleIsNonSyncSample);
 144   sample_info->is_random_access_point = sample_is_sync_sample;
 145
 146   switch (sample_depends_on) {
 147     case kSampleDependsOnUnknown:
 148       sample_info->is_keyframe = sample_is_sync_sample;
 149       break;
 150
 151     case kSampleDependsOnOthers:
 152       sample_info->is_keyframe = false;
 153       break;
 154
 155     case kSampleDependsOnNoOther:
 156       sample_info->is_keyframe = true;
 157       break;
 158
 159     case kSampleDependsOnReserved:
 160       MEDIA_LOG(log_cb) << "Reserved value used in sample dependency info.";
 161       return false;
 162   }
 163   return true;
 164 }
 165
 166 // In well-structured encrypted media, each track run will be immediately
 167 // preceded by its auxiliary information; this is the only optimal storage
 168 // pattern in terms of minimum number of bytes from a serial stream needed to
 169 // begin playback. It also allows us to optimize caching on memory-constrained
 170 // architectures, because we can cache the relatively small auxiliary
 171 // information for an entire run and then discard data from the input stream,
 172 // instead of retaining the entire 'mdat' box.
 173 //
 174 // We optimize for this situation (with no loss of generality) by sorting track
 175 // runs during iteration in order of their first data offset (either sample data
 176 // or auxiliary data).
 177 class CompareMinTrackRunDataOffset {
 178  public:
 179   bool operator()(const TrackRunInfo& a, const TrackRunInfo& b) {
 180     int64 a_aux = a.aux_info_total_size ? a.aux_info_start_offset : kint64max;
 181     int64 b_aux = b.aux_info_total_size ? b.aux_info_start_offset : kint64max;
 182
 183     int64 a_lesser = std::min(a_aux, a.sample_start_offset);
 184     int64 a_greater = std::max(a_aux, a.sample_start_offset);
 185     int64 b_lesser = std::min(b_aux, b.sample_start_offset);
 186     int64 b_greater = std::max(b_aux, b.sample_start_offset);
 187
 188     if (a_lesser == b_lesser) return a_greater < b_greater;
 189     return a_lesser < b_lesser;
 190   }
 191 };
 192
 193 bool TrackRunIterator::Init(const MovieFragment& moof) {
 194   runs_.clear();
 195
 196   for (size_t i = 0; i < moof.tracks.size(); i++) {
 197     const TrackFragment& traf = moof.tracks[i];
 198
 199     const Track* trak = NULL;
 200     for (size_t t = 0; t < moov_->tracks.size(); t++) {
 201       if (moov_->tracks[t].header.track_id == traf.header.track_id)
 202         trak = &moov_->tracks[t];
 203     }
 204     RCHECK(trak);
 205
 206     const TrackExtends* trex = NULL;
 207     for (size_t t = 0; t < moov_->extends.tracks.size(); t++) {
 208       if (moov_->extends.tracks[t].track_id == traf.header.track_id)
 209         trex = &moov_->extends.tracks[t];
 210     }
 211     RCHECK(trex);
 212
 213     const SampleDescription& stsd =
 214         trak->media.information.sample_table.description;
 215     if (stsd.type != kAudio && stsd.type != kVideo) {
 216       DVLOG(1) << "Skipping unhandled track type";
 217       continue;
 218     }
 219     size_t desc_idx = traf.header.sample_description_index;
 220     if (!desc_idx) desc_idx = trex->default_sample_description_index;
 221     RCHECK(desc_idx > 0);  // Descriptions are one-indexed in the file
 222     desc_idx -= 1;
 223
 224     // Process edit list to remove CTS offset introduced in the presence of
 225     // B-frames (those that contain a single edit with a nonnegative media
 226     // time). Other uses of edit lists are not supported, as they are
 227     // both uncommon and better served by higher-level protocols.
 228     int64 edit_list_offset = 0;
 229     const std::vector<EditListEntry>& edits = trak->edit.list.edits;
 230     if (!edits.empty()) {
 231       if (edits.size() > 1)
 232         DVLOG(1) << "Multi-entry edit box detected; some components ignored.";
 233
 234       if (edits[0].media_time < 0) {
 235         DVLOG(1) << "Empty edit list entry ignored.";
 236       } else {
 237         edit_list_offset = -edits[0].media_time;
 238       }
 239     }
 240
 241     SampleToGroupIterator sample_to_group_itr(traf.sample_to_group);
 242     bool is_sample_to_group_valid = sample_to_group_itr.IsValid();
 243
 244     int64 run_start_dts = traf.decode_time.decode_time;
 245     int sample_count_sum = 0;
 246     for (size_t j = 0; j < traf.runs.size(); j++) {
 247       const TrackFragmentRun& trun = traf.runs[j];
 248       TrackRunInfo tri;
 249       tri.track_id = traf.header.track_id;
 250       tri.timescale = trak->media.header.timescale;
 251       tri.start_dts = run_start_dts;
 252       tri.sample_start_offset = trun.data_offset;
 253       tri.sample_encryption_info = traf.sample_group_description.entries;
 254
 255       tri.is_audio = (stsd.type == kAudio);
 256       if (tri.is_audio) {
 257         RCHECK(!stsd.audio_entries.empty());
 258         if (desc_idx > stsd.audio_entries.size())
 259           desc_idx = 0;
 260         tri.audio_description = &stsd.audio_entries[desc_idx];
 261       } else {
 262         RCHECK(!stsd.video_entries.empty());
 263         if (desc_idx > stsd.video_entries.size())
 264           desc_idx = 0;
 265         tri.video_description = &stsd.video_entries[desc_idx];
 266       }
 267
 268       // Collect information from the auxiliary_offset entry with the same index
 269       // in the 'saiz' container as the current run's index in the 'trun'
 270       // container, if it is present.
 271       if (traf.auxiliary_offset.offsets.size() > j) {
 272         // There should be an auxiliary info entry corresponding to each sample
 273         // in the auxiliary offset entry's corresponding track run.
 274         RCHECK(traf.auxiliary_size.sample_count >=
 275                sample_count_sum + trun.sample_count);
 276         tri.aux_info_start_offset = traf.auxiliary_offset.offsets[j];
 277         tri.aux_info_default_size =
 278             traf.auxiliary_size.default_sample_info_size;
 279         if (tri.aux_info_default_size == 0) {
 280           const std::vector<uint8>& sizes =
 281               traf.auxiliary_size.sample_info_sizes;
 282           tri.aux_info_sizes.insert(tri.aux_info_sizes.begin(),
 283               sizes.begin() + sample_count_sum,
 284               sizes.begin() + sample_count_sum + trun.sample_count);
 285         }
 286
 287         // If the default info size is positive, find the total size of the aux
 288         // info block from it, otherwise sum over the individual sizes of each
 289         // aux info entry in the aux_offset entry.
 290         if (tri.aux_info_default_size) {
 291           tri.aux_info_total_size =
 292               tri.aux_info_default_size * trun.sample_count;
 293         } else {
 294           tri.aux_info_total_size = 0;
 295           for (size_t k = 0; k < trun.sample_count; k++) {
 296             tri.aux_info_total_size += tri.aux_info_sizes[k];
 297           }
 298         }
 299       } else {
 300         tri.aux_info_start_offset = -1;
 301         tri.aux_info_total_size = 0;
 302       }
 303
 304       tri.samples.resize(trun.sample_count);
 305       for (size_t k = 0; k < trun.sample_count; k++) {
 306         if (!PopulateSampleInfo(*trex, traf.header, trun, edit_list_offset,
 307                                 k, &tri.samples[k],
 308                                 traf.sdtp.sample_depends_on(k),
 309                                 log_cb_)) {
 310           return false;
 311         }
 312
 313         run_start_dts += tri.samples[k].duration;
 314
 315         if (!is_sample_to_group_valid) {
 316           // Set group description index to 0 to read encryption information
 317           // from TrackEncryption Box.
 318           tri.samples[k].cenc_group_description_index = 0;
 319           continue;
 320         }
 321
 322         // ISO-14496-12 Section 8.9.2.3 and 8.9.4 : group description index
 323         // (1) ranges from 1 to the number of sample group entries in the track
 324         // level SampleGroupDescription Box, or (2) takes the value 0 to
 325         // indicate that this sample is a member of no group, in this case, the
 326         // sample is associated with the default values specified in
 327         // TrackEncryption Box, or (3) starts at 0x10001, i.e. the index value
 328         // 1, with the value 1 in the top 16 bits, to reference fragment-local
 329         // SampleGroupDescription Box.
 330         // Case (1) is not supported currently. We might not need it either as
 331         // the same functionality can be better achieved using (2).
 332         uint32 index = sample_to_group_itr.group_description_index();
 333         if (index >= SampleToGroupEntry::kFragmentGroupDescriptionIndexBase) {
 334           index -= SampleToGroupEntry::kFragmentGroupDescriptionIndexBase;
 335           RCHECK(index != 0 && index <= tri.sample_encryption_info.size());
 336         } else if (index != 0) {
 337           NOTIMPLEMENTED() << "'sgpd' box in 'moov' is not supported.";
 338           return false;
 339         }
 340         tri.samples[k].cenc_group_description_index = index;
 341         is_sample_to_group_valid = sample_to_group_itr.Advance();
 342       }
 343       runs_.push_back(tri);
 344       sample_count_sum += trun.sample_count;
 345     }
 346
 347     // We should have iterated through all samples in SampleToGroup Box.
 348     RCHECK(!sample_to_group_itr.IsValid());
 349   }
 350
 351   std::sort(runs_.begin(), runs_.end(), CompareMinTrackRunDataOffset());
 352   run_itr_ = runs_.begin();
 353   ResetRun();
 354   return true;
 355 }
 356
 357 void TrackRunIterator::AdvanceRun() {
 358   ++run_itr_;
 359   ResetRun();
 360 }
 361
 362 void TrackRunIterator::ResetRun() {
 363   if (!IsRunValid()) return;
 364   sample_dts_ = run_itr_->start_dts;
 365   sample_offset_ = run_itr_->sample_start_offset;
 366   sample_itr_ = run_itr_->samples.begin();
 367   cenc_info_.clear();
 368 }
 369
 370 void TrackRunIterator::AdvanceSample() {
 371   DCHECK(IsSampleValid());
 372   sample_dts_ += sample_itr_->duration;
 373   sample_offset_ += sample_itr_->size;
 374   ++sample_itr_;
 375 }
 376
 377 // This implementation only indicates a need for caching if CENC auxiliary
 378 // info is available in the stream.
 379 bool TrackRunIterator::AuxInfoNeedsToBeCached() {
 380   DCHECK(IsRunValid());
 381   return aux_info_size() > 0 && cenc_info_.size() == 0;
 382 }
 383
 384 // This implementation currently only caches CENC auxiliary info.
 385 bool TrackRunIterator::CacheAuxInfo(const uint8* buf, int buf_size) {
 386   RCHECK(AuxInfoNeedsToBeCached() && buf_size >= aux_info_size());
 387
 388   cenc_info_.resize(run_itr_->samples.size());
 389   int64 pos = 0;
 390   for (size_t i = 0; i < run_itr_->samples.size(); i++) {
 391     int info_size = run_itr_->aux_info_default_size;
 392     if (!info_size)
 393       info_size = run_itr_->aux_info_sizes[i];
 394
 395     if (IsSampleEncrypted(i)) {
 396       BufferReader reader(buf + pos, info_size);
 397       RCHECK(cenc_info_[i].Parse(GetIvSize(i), &reader));
 398     }
 399     pos += info_size;
 400   }
 401
 402   return true;
 403 }
 404
 405 bool TrackRunIterator::IsRunValid() const {
 406   return run_itr_ != runs_.end();
 407 }
 408
 409 bool TrackRunIterator::IsSampleValid() const {
 410   return IsRunValid() && (sample_itr_ != run_itr_->samples.end());
 411 }
 412
 413 // Because tracks are in sorted order and auxiliary information is cached when
 414 // returning samples, it is guaranteed that no data will be required before the
 415 // lesser of the minimum data offset of this track and the next in sequence.
 416 // (The stronger condition - that no data is required before the minimum data
 417 // offset of this track alone - is not guaranteed, because the BMFF spec does
 418 // not have any inter-run ordering restrictions.)
 419 int64 TrackRunIterator::GetMaxClearOffset() {
 420   int64 offset = kint64max;
 421
 422   if (IsSampleValid()) {
 423     offset = std::min(offset, sample_offset_);
 424     if (AuxInfoNeedsToBeCached())
 425       offset = std::min(offset, aux_info_offset());
 426   }
 427   if (run_itr_ != runs_.end()) {
 428     std::vector<TrackRunInfo>::const_iterator next_run = run_itr_ + 1;
 429     if (next_run != runs_.end()) {
 430       offset = std::min(offset, next_run->sample_start_offset);
 431       if (next_run->aux_info_total_size)
 432         offset = std::min(offset, next_run->aux_info_start_offset);
 433     }
 434   }
 435   if (offset == kint64max) return 0;
 436   return offset;
 437 }
 438
 439 uint32 TrackRunIterator::track_id() const {
 440   DCHECK(IsRunValid());
 441   return run_itr_->track_id;
 442 }
 443
 444 bool TrackRunIterator::is_encrypted() const {
 445   DCHECK(IsSampleValid());
 446   return IsSampleEncrypted(sample_itr_ - run_itr_->samples.begin());
 447 }
 448
 449 int64 TrackRunIterator::aux_info_offset() const {
 450   return run_itr_->aux_info_start_offset;
 451 }
 452
 453 int TrackRunIterator::aux_info_size() const {
 454   return run_itr_->aux_info_total_size;
 455 }
 456
 457 bool TrackRunIterator::is_audio() const {
 458   DCHECK(IsRunValid());
 459   return run_itr_->is_audio;
 460 }
 461
 462 const AudioSampleEntry& TrackRunIterator::audio_description() const {
 463   DCHECK(is_audio());
 464   DCHECK(run_itr_->audio_description);
 465   return *run_itr_->audio_description;
 466 }
 467
 468 const VideoSampleEntry& TrackRunIterator::video_description() const {
 469   DCHECK(!is_audio());
 470   DCHECK(run_itr_->video_description);
 471   return *run_itr_->video_description;
 472 }
 473
 474 int64 TrackRunIterator::sample_offset() const {
 475   DCHECK(IsSampleValid());
 476   return sample_offset_;
 477 }
 478
 479 int TrackRunIterator::sample_size() const {
 480   DCHECK(IsSampleValid());
 481   return sample_itr_->size;
 482 }
 483
 484 DecodeTimestamp TrackRunIterator::dts() const {
 485   DCHECK(IsSampleValid());
 486   return DecodeTimestampFromRational(sample_dts_, run_itr_->timescale);
 487 }
 488
 489 base::TimeDelta TrackRunIterator::cts() const {
 490   DCHECK(IsSampleValid());
 491   return TimeDeltaFromRational(sample_dts_ + sample_itr_->cts_offset,
 492                                run_itr_->timescale);
 493 }
 494
 495 base::TimeDelta TrackRunIterator::duration() const {
 496   DCHECK(IsSampleValid());
 497   return TimeDeltaFromRational(sample_itr_->duration, run_itr_->timescale);
 498 }
 499
 500 bool TrackRunIterator::is_keyframe() const {
 501   DCHECK(IsSampleValid());
 502   return sample_itr_->is_keyframe;
 503 }
 504
 505 bool TrackRunIterator::is_random_access_point() const {
 506   DCHECK(IsSampleValid());
 507   return sample_itr_->is_random_access_point;
 508 }
 509
 510 const TrackEncryption& TrackRunIterator::track_encryption() const {
 511   if (is_audio())
 512     return audio_description().sinf.info.track_encryption;
 513   return video_description().sinf.info.track_encryption;
 514 }
 515
 516 scoped_ptr<DecryptConfig> TrackRunIterator::GetDecryptConfig() {
 517   DCHECK(is_encrypted());
 518
 519   if (cenc_info_.empty()) {
 520     DCHECK_EQ(0, aux_info_size());
 521     MEDIA_LOG(log_cb_) << "Aux Info is not available.";
 522     return scoped_ptr<DecryptConfig>();
 523   }
 524
 525   size_t sample_idx = sample_itr_ - run_itr_->samples.begin();
 526   DCHECK_LT(sample_idx, cenc_info_.size());
 527   const FrameCENCInfo& cenc_info = cenc_info_[sample_idx];
 528
 529   size_t total_size = 0;
 530   if (!cenc_info.subsamples.empty() &&
 531       (!cenc_info.GetTotalSizeOfSubsamples(&total_size) ||
 532        total_size != static_cast<size_t>(sample_size()))) {
 533     MEDIA_LOG(log_cb_) << "Incorrect CENC subsample size.";
 534     return scoped_ptr<DecryptConfig>();
 535   }
 536
 537   const std::vector<uint8>& kid = GetKeyId(sample_idx);
 538   return scoped_ptr<DecryptConfig>(new DecryptConfig(
 539       std::string(reinterpret_cast<const char*>(&kid[0]), kid.size()),
 540       std::string(reinterpret_cast<const char*>(cenc_info.iv),
 541                   arraysize(cenc_info.iv)),
 542       cenc_info.subsamples));
 543 }
 544
 545 uint32 TrackRunIterator::GetGroupDescriptionIndex(uint32 sample_index) const {
 546   DCHECK(IsRunValid());
 547   DCHECK_LT(sample_index, run_itr_->samples.size());
 548   return run_itr_->samples[sample_index].cenc_group_description_index;
 549 }
 550
 551 const CencSampleEncryptionInfoEntry&
 552 TrackRunIterator::GetSampleEncryptionInfoEntry(
 553     uint32 group_description_index) const {
 554   DCHECK(IsRunValid());
 555   DCHECK_NE(group_description_index, 0u);
 556   DCHECK_LE(group_description_index, run_itr_->sample_encryption_info.size());
 557   // |group_description_index| is 1-based. Subtract by 1 to index the vector.
 558   return run_itr_->sample_encryption_info[group_description_index - 1];
 559 }
 560
 561 bool TrackRunIterator::IsSampleEncrypted(size_t sample_index) const {
 562   uint32 index = GetGroupDescriptionIndex(sample_index);
 563   return (index == 0) ? track_encryption().is_encrypted
 564                       : GetSampleEncryptionInfoEntry(index).is_encrypted;
 565 }
 566
 567 const std::vector<uint8>& TrackRunIterator::GetKeyId(
 568     size_t sample_index) const {
 569   uint32 index = GetGroupDescriptionIndex(sample_index);
 570   return (index == 0) ? track_encryption().default_kid
 571                       : GetSampleEncryptionInfoEntry(index).key_id;
 572 }
 573
 574 uint8 TrackRunIterator::GetIvSize(size_t sample_index) const {
 575   uint32 index = GetGroupDescriptionIndex(sample_index);
 576   return (index == 0) ? track_encryption().default_iv_size
 577                       : GetSampleEncryptionInfoEntry(index).iv_size;
 578 }
 579
 580 }  // namespace mp4
 581 }  // namespace media