media/formats/mp4/mp4_stream_parser.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/mp4_stream_parser.h"
   6
   7 #include "base/callback_helpers.h"
   8 #include "base/logging.h"
   9 #include "base/time/time.h"
  10 #include "media/base/audio_decoder_config.h"
  11 #include "media/base/stream_parser_buffer.h"
  12 #include "media/base/text_track_config.h"
  13 #include "media/base/video_decoder_config.h"
  14 #include "media/base/video_util.h"
  15 #include "media/formats/mp4/box_definitions.h"
  16 #include "media/formats/mp4/box_reader.h"
  17 #include "media/formats/mp4/es_descriptor.h"
  18 #include "media/formats/mp4/rcheck.h"
  19 #include "media/formats/mpeg/adts_constants.h"
  20
  21 namespace media {
  22 namespace mp4 {
  23
  24 MP4StreamParser::MP4StreamParser(const std::set<int>& audio_object_types,
  25                                  bool has_sbr)
  26     : state_(kWaitingForInit),
  27       moof_head_(0),
  28       mdat_tail_(0),
  29       highest_end_offset_(0),
  30       has_audio_(false),
  31       has_video_(false),
  32       audio_track_id_(0),
  33       video_track_id_(0),
  34       audio_object_types_(audio_object_types),
  35       has_sbr_(has_sbr),
  36       is_audio_track_encrypted_(false),
  37       is_video_track_encrypted_(false),
  38       num_top_level_box_skipped_(0) {
  39 }
  40
  41 MP4StreamParser::~MP4StreamParser() {}
  42
  43 void MP4StreamParser::Init(
  44     const InitCB& init_cb,
  45     const NewConfigCB& config_cb,
  46     const NewBuffersCB& new_buffers_cb,
  47     bool /* ignore_text_tracks */,
  48     const EncryptedMediaInitDataCB& encrypted_media_init_data_cb,
  49     const NewMediaSegmentCB& new_segment_cb,
  50     const base::Closure& end_of_segment_cb,
  51     const LogCB& log_cb) {
  52   DCHECK_EQ(state_, kWaitingForInit);
  53   DCHECK(init_cb_.is_null());
  54   DCHECK(!init_cb.is_null());
  55   DCHECK(!config_cb.is_null());
  56   DCHECK(!new_buffers_cb.is_null());
  57   DCHECK(!encrypted_media_init_data_cb.is_null());
  58   DCHECK(!end_of_segment_cb.is_null());
  59
  60   ChangeState(kParsingBoxes);
  61   init_cb_ = init_cb;
  62   config_cb_ = config_cb;
  63   new_buffers_cb_ = new_buffers_cb;
  64   encrypted_media_init_data_cb_ = encrypted_media_init_data_cb;
  65   new_segment_cb_ = new_segment_cb;
  66   end_of_segment_cb_ = end_of_segment_cb;
  67   log_cb_ = log_cb;
  68 }
  69
  70 void MP4StreamParser::Reset() {
  71   queue_.Reset();
  72   runs_.reset();
  73   moof_head_ = 0;
  74   mdat_tail_ = 0;
  75 }
  76
  77 void MP4StreamParser::Flush() {
  78   DCHECK_NE(state_, kWaitingForInit);
  79   Reset();
  80   ChangeState(kParsingBoxes);
  81 }
  82
  83 bool MP4StreamParser::Parse(const uint8* buf, int size) {
  84   DCHECK_NE(state_, kWaitingForInit);
  85
  86   if (state_ == kError)
  87     return false;
  88
  89   queue_.Push(buf, size);
  90
  91   BufferQueue audio_buffers;
  92   BufferQueue video_buffers;
  93
  94   bool result = false;
  95   bool err = false;
  96
  97   do {
  98     switch (state_) {
  99       case kWaitingForInit:
 100       case kError:
 101         NOTREACHED();
 102         return false;
 103
 104       case kParsingBoxes:
 105         result = ParseBox(&err);
 106         break;
 107
 108       case kWaitingForSampleData:
 109         result = HaveEnoughDataToEnqueueSamples();
 110         if (result)
 111           ChangeState(kEmittingSamples);
 112         break;
 113
 114       case kEmittingSamples:
 115         result = EnqueueSample(&audio_buffers, &video_buffers, &err);
 116         if (result) {
 117           int64 max_clear = runs_->GetMaxClearOffset() + moof_head_;
 118           err = !ReadAndDiscardMDATsUntil(max_clear);
 119         }
 120         break;
 121     }
 122   } while (result && !err);
 123
 124   if (!err)
 125     err = !SendAndFlushSamples(&audio_buffers, &video_buffers);
 126
 127   if (err) {
 128     DLOG(ERROR) << "Error while parsing MP4";
 129     moov_.reset();
 130     Reset();
 131     ChangeState(kError);
 132     return false;
 133   }
 134
 135   return true;
 136 }
 137
 138 bool MP4StreamParser::ParseBox(bool* err) {
 139   const uint8* buf;
 140   int size;
 141   queue_.Peek(&buf, &size);
 142   if (!size) return false;
 143
 144   scoped_ptr<BoxReader> reader(
 145       BoxReader::ReadTopLevelBox(buf, size, log_cb_, err));
 146   if (reader.get() == NULL) return false;
 147
 148   if (reader->type() == FOURCC_MOOV) {
 149     *err = !ParseMoov(reader.get());
 150   } else if (reader->type() == FOURCC_MOOF) {
 151     moof_head_ = queue_.head();
 152     *err = !ParseMoof(reader.get());
 153
 154     // Set up first mdat offset for ReadMDATsUntil().
 155     mdat_tail_ = queue_.head() + reader->size();
 156
 157     // Return early to avoid evicting 'moof' data from queue. Auxiliary info may
 158     // be located anywhere in the file, including inside the 'moof' itself.
 159     // (Since 'default-base-is-moof' is mandated, no data references can come
 160     // before the head of the 'moof', so keeping this box around is sufficient.)
 161     return !(*err);
 162   } else {
 163     const int kMaxNumLogsForSkippingTopLevelBox = 5;
 164
 165     // TODO(wolenetz): Do not log when skipping ftyp, since strict MSE would
 166     // require ftyp. See http://crbug.com/499077
 167     LIMITED_MEDIA_LOG(DEBUG, log_cb_, num_top_level_box_skipped_,
 168                       kMaxNumLogsForSkippingTopLevelBox)
 169         << "Skipping unrecognized top-level box: "
 170         << FourCCToString(reader->type());
 171   }
 172
 173   queue_.Pop(reader->size());
 174   return !(*err);
 175 }
 176
 177
 178 bool MP4StreamParser::ParseMoov(BoxReader* reader) {
 179   moov_.reset(new Movie);
 180   RCHECK(moov_->Parse(reader));
 181   runs_.reset();
 182
 183   has_audio_ = false;
 184   has_video_ = false;
 185
 186   AudioDecoderConfig audio_config;
 187   VideoDecoderConfig video_config;
 188
 189   for (std::vector<Track>::const_iterator track = moov_->tracks.begin();
 190        track != moov_->tracks.end(); ++track) {
 191     // TODO(strobe): Only the first audio and video track present in a file are
 192     // used. (Track selection is better accomplished via Source IDs, though, so
 193     // adding support for track selection within a stream is low-priority.)
 194     const SampleDescription& samp_descr =
 195         track->media.information.sample_table.description;
 196
 197     // TODO(strobe): When codec reconfigurations are supported, detect and send
 198     // a codec reconfiguration for fragments using a sample description index
 199     // different from the previous one
 200     size_t desc_idx = 0;
 201     for (size_t t = 0; t < moov_->extends.tracks.size(); t++) {
 202       const TrackExtends& trex = moov_->extends.tracks[t];
 203       if (trex.track_id == track->header.track_id) {
 204         desc_idx = trex.default_sample_description_index;
 205         break;
 206       }
 207     }
 208     RCHECK(desc_idx > 0);
 209     desc_idx -= 1;  // BMFF descriptor index is one-based
 210
 211     if (track->media.handler.type == kAudio && !audio_config.IsValidConfig()) {
 212       RCHECK(!samp_descr.audio_entries.empty());
 213
 214       // It is not uncommon to find otherwise-valid files with incorrect sample
 215       // description indices, so we fail gracefully in that case.
 216       if (desc_idx >= samp_descr.audio_entries.size())
 217         desc_idx = 0;
 218       const AudioSampleEntry& entry = samp_descr.audio_entries[desc_idx];
 219       const AAC& aac = entry.esds.aac;
 220
 221       if (!(entry.format == FOURCC_MP4A ||
 222             (entry.format == FOURCC_ENCA &&
 223              entry.sinf.format.format == FOURCC_MP4A))) {
 224         MEDIA_LOG(ERROR, log_cb_) << "Unsupported audio format 0x" << std::hex
 225                                   << entry.format << " in stsd box.";
 226         return false;
 227       }
 228
 229       uint8 audio_type = entry.esds.object_type;
 230       DVLOG(1) << "audio_type " << std::hex << static_cast<int>(audio_type);
 231       if (audio_object_types_.find(audio_type) == audio_object_types_.end()) {
 232         MEDIA_LOG(ERROR, log_cb_) << "audio object type 0x" << std::hex
 233                                   << audio_type
 234                                   << " does not match what is specified in the"
 235                                   << " mimetype.";
 236         return false;
 237       }
 238
 239       AudioCodec codec = kUnknownAudioCodec;
 240       ChannelLayout channel_layout = CHANNEL_LAYOUT_NONE;
 241       int sample_per_second = 0;
 242       std::vector<uint8> extra_data;
 243       // Check if it is MPEG4 AAC defined in ISO 14496 Part 3 or
 244       // supported MPEG2 AAC varients.
 245       if (ESDescriptor::IsAAC(audio_type)) {
 246         codec = kCodecAAC;
 247         channel_layout = aac.GetChannelLayout(has_sbr_);
 248         sample_per_second = aac.GetOutputSamplesPerSecond(has_sbr_);
 249 #if defined(OS_ANDROID)
 250         extra_data = aac.codec_specific_data();
 251 #endif
 252       } else {
 253         MEDIA_LOG(ERROR, log_cb_) << "Unsupported audio object type 0x"
 254                                   << std::hex << audio_type << " in esds.";
 255         return false;
 256       }
 257
 258       SampleFormat sample_format;
 259       if (entry.samplesize == 8) {
 260         sample_format = kSampleFormatU8;
 261       } else if (entry.samplesize == 16) {
 262         sample_format = kSampleFormatS16;
 263       } else if (entry.samplesize == 32) {
 264         sample_format = kSampleFormatS32;
 265       } else {
 266         LOG(ERROR) << "Unsupported sample size.";
 267         return false;
 268       }
 269
 270       is_audio_track_encrypted_ = entry.sinf.info.track_encryption.is_encrypted;
 271       DVLOG(1) << "is_audio_track_encrypted_: " << is_audio_track_encrypted_;
 272       audio_config.Initialize(
 273           codec, sample_format, channel_layout, sample_per_second,
 274           extra_data.size() ? &extra_data[0] : NULL, extra_data.size(),
 275           is_audio_track_encrypted_, false, base::TimeDelta(),
 276           0);
 277       has_audio_ = true;
 278       audio_track_id_ = track->header.track_id;
 279     }
 280     if (track->media.handler.type == kVideo && !video_config.IsValidConfig()) {
 281       RCHECK(!samp_descr.video_entries.empty());
 282       if (desc_idx >= samp_descr.video_entries.size())
 283         desc_idx = 0;
 284       const VideoSampleEntry& entry = samp_descr.video_entries[desc_idx];
 285
 286       if (!entry.IsFormatValid()) {
 287         MEDIA_LOG(ERROR, log_cb_) << "Unsupported video format 0x" << std::hex
 288                                   << entry.format << " in stsd box.";
 289         return false;
 290       }
 291
 292       // TODO(strobe): Recover correct crop box
 293       gfx::Size coded_size(entry.width, entry.height);
 294       gfx::Rect visible_rect(coded_size);
 295       gfx::Size natural_size = GetNaturalSize(visible_rect.size(),
 296                                               entry.pixel_aspect.h_spacing,
 297                                               entry.pixel_aspect.v_spacing);
 298       is_video_track_encrypted_ = entry.sinf.info.track_encryption.is_encrypted;
 299       DVLOG(1) << "is_video_track_encrypted_: " << is_video_track_encrypted_;
 300       video_config.Initialize(kCodecH264, H264PROFILE_MAIN, VideoFrame::YV12,
 301                               VideoFrame::COLOR_SPACE_UNSPECIFIED, coded_size,
 302                               visible_rect, natural_size,
 303                               // No decoder-specific buffer needed for AVC;
 304                               // SPS/PPS are embedded in the video stream
 305                               NULL, 0, is_video_track_encrypted_, false);
 306       has_video_ = true;
 307       video_track_id_ = track->header.track_id;
 308     }
 309   }
 310
 311   RCHECK(config_cb_.Run(audio_config, video_config, TextTrackConfigMap()));
 312
 313   StreamParser::InitParameters params(kInfiniteDuration());
 314   if (moov_->extends.header.fragment_duration > 0) {
 315     params.duration = TimeDeltaFromRational(
 316         moov_->extends.header.fragment_duration, moov_->header.timescale);
 317     params.liveness = DemuxerStream::LIVENESS_RECORDED;
 318   } else if (moov_->header.duration > 0 &&
 319              moov_->header.duration != kuint64max) {
 320     params.duration =
 321         TimeDeltaFromRational(moov_->header.duration, moov_->header.timescale);
 322     params.liveness = DemuxerStream::LIVENESS_RECORDED;
 323   } else {
 324     // In ISO/IEC 14496-12:2005(E), 8.30.2: ".. If an MP4 file is created in
 325     // real-time, such as used in live streaming, it is not likely that the
 326     // fragment_duration is known in advance and this (mehd) box may be
 327     // omitted."
 328     // TODO(wolenetz): Investigate gating liveness detection on timeline_offset
 329     // when it's populated. See http://crbug.com/312699
 330     params.liveness = DemuxerStream::LIVENESS_LIVE;
 331   }
 332
 333   DVLOG(1) << "liveness: " << params.liveness;
 334
 335   if (!init_cb_.is_null())
 336     base::ResetAndReturn(&init_cb_).Run(params);
 337
 338   if (!moov_->pssh.empty())
 339     OnEncryptedMediaInitData(moov_->pssh);
 340
 341   return true;
 342 }
 343
 344 bool MP4StreamParser::ParseMoof(BoxReader* reader) {
 345   RCHECK(moov_.get());  // Must already have initialization segment
 346   MovieFragment moof;
 347   RCHECK(moof.Parse(reader));
 348   if (!runs_)
 349     runs_.reset(new TrackRunIterator(moov_.get(), log_cb_));
 350   RCHECK(runs_->Init(moof));
 351   RCHECK(ComputeHighestEndOffset(moof));
 352
 353   if (!moof.pssh.empty())
 354     OnEncryptedMediaInitData(moof.pssh);
 355
 356   new_segment_cb_.Run();
 357   ChangeState(kWaitingForSampleData);
 358   return true;
 359 }
 360
 361 void MP4StreamParser::OnEncryptedMediaInitData(
 362     const std::vector<ProtectionSystemSpecificHeader>& headers) {
 363   // TODO(strobe): ensure that the value of init_data (all PSSH headers
 364   // concatenated in arbitrary order) matches the EME spec.
 365   // See https://www.w3.org/Bugs/Public/show_bug.cgi?id=17673.
 366   size_t total_size = 0;
 367   for (size_t i = 0; i < headers.size(); i++)
 368     total_size += headers[i].raw_box.size();
 369
 370   std::vector<uint8> init_data(total_size);
 371   size_t pos = 0;
 372   for (size_t i = 0; i < headers.size(); i++) {
 373     memcpy(&init_data[pos], &headers[i].raw_box[0],
 374            headers[i].raw_box.size());
 375     pos += headers[i].raw_box.size();
 376   }
 377   encrypted_media_init_data_cb_.Run(EmeInitDataType::CENC, init_data);
 378 }
 379
 380 bool MP4StreamParser::PrepareAVCBuffer(
 381     const AVCDecoderConfigurationRecord& avc_config,
 382     std::vector<uint8>* frame_buf,
 383     std::vector<SubsampleEntry>* subsamples) const {
 384   // Convert the AVC NALU length fields to Annex B headers, as expected by
 385   // decoding libraries. Since this may enlarge the size of the buffer, we also
 386   // update the clear byte count for each subsample if encryption is used to
 387   // account for the difference in size between the length prefix and Annex B
 388   // start code.
 389   RCHECK(AVC::ConvertFrameToAnnexB(avc_config.length_size, frame_buf));
 390   if (!subsamples->empty()) {
 391     const int nalu_size_diff = 4 - avc_config.length_size;
 392     size_t expected_size = runs_->sample_size() +
 393         subsamples->size() * nalu_size_diff;
 394     RCHECK(frame_buf->size() == expected_size);
 395     for (size_t i = 0; i < subsamples->size(); i++)
 396       (*subsamples)[i].clear_bytes += nalu_size_diff;
 397   }
 398
 399   if (runs_->is_keyframe()) {
 400     // If this is a keyframe, we (re-)inject SPS and PPS headers at the start of
 401     // a frame. If subsample info is present, we also update the clear byte
 402     // count for that first subsample.
 403     RCHECK(AVC::InsertParamSetsAnnexB(avc_config, frame_buf, subsamples));
 404   }
 405
 406   DCHECK(AVC::IsValidAnnexB(*frame_buf, *subsamples));
 407   return true;
 408 }
 409
 410 bool MP4StreamParser::PrepareAACBuffer(
 411     const AAC& aac_config, std::vector<uint8>* frame_buf,
 412     std::vector<SubsampleEntry>* subsamples) const {
 413   // Append an ADTS header to every audio sample.
 414   RCHECK(aac_config.ConvertEsdsToADTS(frame_buf));
 415
 416   // As above, adjust subsample information to account for the headers. AAC is
 417   // not required to use subsample encryption, so we may need to add an entry.
 418   if (subsamples->empty()) {
 419     subsamples->push_back(SubsampleEntry(
 420         kADTSHeaderMinSize, frame_buf->size() - kADTSHeaderMinSize));
 421   } else {
 422     (*subsamples)[0].clear_bytes += kADTSHeaderMinSize;
 423   }
 424   return true;
 425 }
 426
 427 bool MP4StreamParser::EnqueueSample(BufferQueue* audio_buffers,
 428                                     BufferQueue* video_buffers,
 429                                     bool* err) {
 430   DCHECK_EQ(state_, kEmittingSamples);
 431
 432   if (!runs_->IsRunValid()) {
 433     // Flush any buffers we've gotten in this chunk so that buffers don't
 434     // cross NewSegment() calls
 435     *err = !SendAndFlushSamples(audio_buffers, video_buffers);
 436     if (*err)
 437       return false;
 438
 439     // Remain in kEmittingSamples state, discarding data, until the end of
 440     // the current 'mdat' box has been appended to the queue.
 441     if (!queue_.Trim(mdat_tail_))
 442       return false;
 443
 444     ChangeState(kParsingBoxes);
 445     end_of_segment_cb_.Run();
 446     return true;
 447   }
 448
 449   if (!runs_->IsSampleValid()) {
 450     runs_->AdvanceRun();
 451     return true;
 452   }
 453
 454   DCHECK(!(*err));
 455
 456   const uint8* buf;
 457   int buf_size;
 458   queue_.Peek(&buf, &buf_size);
 459   if (!buf_size) return false;
 460
 461   bool audio = has_audio_ && audio_track_id_ == runs_->track_id();
 462   bool video = has_video_ && video_track_id_ == runs_->track_id();
 463
 464   // Skip this entire track if it's not one we're interested in
 465   if (!audio && !video) {
 466     runs_->AdvanceRun();
 467     return true;
 468   }
 469
 470   // Attempt to cache the auxiliary information first. Aux info is usually
 471   // placed in a contiguous block before the sample data, rather than being
 472   // interleaved. If we didn't cache it, this would require that we retain the
 473   // start of the segment buffer while reading samples. Aux info is typically
 474   // quite small compared to sample data, so this pattern is useful on
 475   // memory-constrained devices where the source buffer consumes a substantial
 476   // portion of the total system memory.
 477   if (runs_->AuxInfoNeedsToBeCached()) {
 478     queue_.PeekAt(runs_->aux_info_offset() + moof_head_, &buf, &buf_size);
 479     if (buf_size < runs_->aux_info_size()) return false;
 480     *err = !runs_->CacheAuxInfo(buf, buf_size);
 481     return !*err;
 482   }
 483
 484   queue_.PeekAt(runs_->sample_offset() + moof_head_, &buf, &buf_size);
 485   if (buf_size < runs_->sample_size()) return false;
 486
 487   scoped_ptr<DecryptConfig> decrypt_config;
 488   std::vector<SubsampleEntry> subsamples;
 489   if (runs_->is_encrypted()) {
 490     decrypt_config = runs_->GetDecryptConfig();
 491     if (!decrypt_config) {
 492       *err = true;
 493       return false;
 494     }
 495     subsamples = decrypt_config->subsamples();
 496   }
 497
 498   std::vector<uint8> frame_buf(buf, buf + runs_->sample_size());
 499   if (video) {
 500     if (!PrepareAVCBuffer(runs_->video_description().avcc,
 501                           &frame_buf, &subsamples)) {
 502       MEDIA_LOG(ERROR, log_cb_) << "Failed to prepare AVC sample for decode";
 503       *err = true;
 504       return false;
 505     }
 506   }
 507
 508   if (audio) {
 509     if (ESDescriptor::IsAAC(runs_->audio_description().esds.object_type) &&
 510         !PrepareAACBuffer(runs_->audio_description().esds.aac,
 511                           &frame_buf, &subsamples)) {
 512       MEDIA_LOG(ERROR, log_cb_) << "Failed to prepare AAC sample for decode";
 513       *err = true;
 514       return false;
 515     }
 516   }
 517
 518   if (decrypt_config) {
 519     if (!subsamples.empty()) {
 520     // Create a new config with the updated subsamples.
 521     decrypt_config.reset(new DecryptConfig(
 522         decrypt_config->key_id(),
 523         decrypt_config->iv(),
 524         subsamples));
 525     }
 526     // else, use the existing config.
 527   } else if ((audio && is_audio_track_encrypted_) ||
 528              (video && is_video_track_encrypted_)) {
 529     // The media pipeline requires a DecryptConfig with an empty |iv|.
 530     // TODO(ddorwin): Refactor so we do not need a fake key ID ("1");
 531     decrypt_config.reset(
 532         new DecryptConfig("1", "", std::vector<SubsampleEntry>()));
 533   }
 534
 535   StreamParserBuffer::Type buffer_type = audio ? DemuxerStream::AUDIO :
 536       DemuxerStream::VIDEO;
 537
 538   // TODO(wolenetz/acolwell): Validate and use a common cross-parser TrackId
 539   // type and allow multiple tracks for same media type, if applicable. See
 540   // https://crbug.com/341581.
 541   //
 542   // NOTE: MPEG's "random access point" concept is equivalent to the
 543   // downstream code's "is keyframe" concept.
 544   scoped_refptr<StreamParserBuffer> stream_buf =
 545       StreamParserBuffer::CopyFrom(&frame_buf[0], frame_buf.size(),
 546                                    runs_->is_random_access_point(),
 547                                    buffer_type, 0);
 548
 549   if (decrypt_config)
 550     stream_buf->set_decrypt_config(decrypt_config.Pass());
 551
 552   stream_buf->set_duration(runs_->duration());
 553   stream_buf->set_timestamp(runs_->cts());
 554   stream_buf->SetDecodeTimestamp(runs_->dts());
 555
 556   DVLOG(3) << "Pushing frame: aud=" << audio
 557            << ", key=" << runs_->is_keyframe()
 558            << ", rap=" << runs_->is_random_access_point()
 559            << ", dur=" << runs_->duration().InMilliseconds()
 560            << ", dts=" << runs_->dts().InMilliseconds()
 561            << ", cts=" << runs_->cts().InMilliseconds()
 562            << ", size=" << runs_->sample_size();
 563
 564   if (audio) {
 565     audio_buffers->push_back(stream_buf);
 566   } else {
 567     video_buffers->push_back(stream_buf);
 568   }
 569
 570   runs_->AdvanceSample();
 571   return true;
 572 }
 573
 574 bool MP4StreamParser::SendAndFlushSamples(BufferQueue* audio_buffers,
 575                                           BufferQueue* video_buffers) {
 576   if (audio_buffers->empty() && video_buffers->empty())
 577     return true;
 578
 579   TextBufferQueueMap empty_text_map;
 580   bool success = new_buffers_cb_.Run(*audio_buffers,
 581                                      *video_buffers,
 582                                      empty_text_map);
 583   audio_buffers->clear();
 584   video_buffers->clear();
 585   return success;
 586 }
 587
 588 bool MP4StreamParser::ReadAndDiscardMDATsUntil(int64 max_clear_offset) {
 589   bool err = false;
 590   int64 upper_bound = std::min(max_clear_offset, queue_.tail());
 591   while (mdat_tail_ < upper_bound) {
 592     const uint8* buf = NULL;
 593     int size = 0;
 594     queue_.PeekAt(mdat_tail_, &buf, &size);
 595
 596     FourCC type;
 597     int box_sz;
 598     if (!BoxReader::StartTopLevelBox(buf, size, log_cb_,
 599                                      &type, &box_sz, &err))
 600       break;
 601
 602     if (type != FOURCC_MDAT) {
 603       MEDIA_LOG(DEBUG, log_cb_) << "Unexpected box type while parsing MDATs: "
 604                                 << FourCCToString(type);
 605     }
 606     mdat_tail_ += box_sz;
 607   }
 608   queue_.Trim(std::min(mdat_tail_, upper_bound));
 609   return !err;
 610 }
 611
 612 void MP4StreamParser::ChangeState(State new_state) {
 613   DVLOG(2) << "Changing state: " << new_state;
 614   state_ = new_state;
 615 }
 616
 617 bool MP4StreamParser::HaveEnoughDataToEnqueueSamples() {
 618   DCHECK_EQ(state_, kWaitingForSampleData);
 619   // For muxed content, make sure we have data up to |highest_end_offset_|
 620   // so we can ensure proper enqueuing behavior. Otherwise assume we have enough
 621   // data and allow per sample offset checks to meter sample enqueuing.
 622   // TODO(acolwell): Fix trun box handling so we don't have to special case
 623   // muxed content.
 624   return !(has_audio_ && has_video_ &&
 625            queue_.tail() < highest_end_offset_ + moof_head_);
 626 }
 627
 628 bool MP4StreamParser::ComputeHighestEndOffset(const MovieFragment& moof) {
 629   highest_end_offset_ = 0;
 630
 631   TrackRunIterator runs(moov_.get(), log_cb_);
 632   RCHECK(runs.Init(moof));
 633
 634   while (runs.IsRunValid()) {
 635     int64 aux_info_end_offset = runs.aux_info_offset() + runs.aux_info_size();
 636     if (aux_info_end_offset > highest_end_offset_)
 637       highest_end_offset_ = aux_info_end_offset;
 638
 639     while (runs.IsSampleValid()) {
 640       int64 sample_end_offset = runs.sample_offset() + runs.sample_size();
 641       if (sample_end_offset > highest_end_offset_)
 642         highest_end_offset_ = sample_end_offset;
 643
 644       runs.AdvanceSample();
 645     }
 646     runs.AdvanceRun();
 647   }
 648
 649   return true;
 650 }
 651
 652 }  // namespace mp4
 653 }  // namespace media