root/media/formats/mp4/box_definitions.cc

DEFINITIONS

1. BoxType
2. Parse
3. BoxType
4. Parse
5. BoxType
6. Parse
7. sample_count
8. BoxType
9. Parse
10. BoxType
11. Parse
12. version
13. BoxType
14. Parse
15. default_iv_size
16. BoxType
17. Parse
18. BoxType
19. Parse
20. BoxType
21. Parse
22. next_track_id
23. BoxType
24. Parse
25. height
26. BoxType
27. Parse
28. BoxType
29. Parse
30. BoxType
31. Parse
32. BoxType
33. Parse
34. BoxType
35. Parse
36. BoxType
37. Parse
38. BoxType
39. Parse
40. length_size
41. BoxType
42. Parse
43. v_spacing
44. BoxType
45. Parse
46. height
47. BoxType
48. Parse
49. IsFormatValid
50. BoxType
51. Parse
52. samplerate
53. BoxType
54. Parse
55. duration
56. BoxType
57. Parse
58. BoxType
59. Parse
60. BoxType
61. Parse
62. BoxType
63. Parse
64. BoxType
65. Parse
66. default_sample_flags
67. BoxType
68. Parse
69. BoxType
70. Parse
71. BoxType
72. Parse
73. BoxType
74. Parse
75. BoxType
76. Parse
77. has_default_sample_flags
78. BoxType
79. Parse
80. data_offset
81. BoxType
82. Parse
83. BoxType
84. Parse
85. BoxType
86. Parse
87. BoxType
88. Parse
89. sample_depends_on

// Copyright 2014 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include "media/formats/mp4/box_definitions.h"

#include "base/logging.h"
#include "media/formats/mp4/es_descriptor.h"
#include "media/formats/mp4/rcheck.h"

namespace media {
namespace mp4 {

FileType::FileType() {}
FileType::~FileType() {}
FourCC FileType::BoxType() const { return FOURCC_FTYP; }

bool FileType::Parse(BoxReader* reader) {
  RCHECK(reader->ReadFourCC(&major_brand) && reader->Read4(&minor_version));
  size_t num_brands = (reader->size() - reader->pos()) / sizeof(FourCC);
  return reader->SkipBytes(sizeof(FourCC) * num_brands);  // compatible_brands
}

ProtectionSystemSpecificHeader::ProtectionSystemSpecificHeader() {}
ProtectionSystemSpecificHeader::~ProtectionSystemSpecificHeader() {}
FourCC ProtectionSystemSpecificHeader::BoxType() const { return FOURCC_PSSH; }

bool ProtectionSystemSpecificHeader::Parse(BoxReader* reader) {
  // Validate the box's contents and hang on to the system ID.
  uint32 size;
  RCHECK(reader->ReadFullBoxHeader() &&
         reader->ReadVec(&system_id, 16) &&
         reader->Read4(&size) &&
         reader->HasBytes(size));

  // Copy the entire box, including the header, for passing to EME as initData.
  DCHECK(raw_box.empty());
  raw_box.assign(reader->data(), reader->data() + reader->size());
  return true;
}

SampleAuxiliaryInformationOffset::SampleAuxiliaryInformationOffset() {}
SampleAuxiliaryInformationOffset::~SampleAuxiliaryInformationOffset() {}
FourCC SampleAuxiliaryInformationOffset::BoxType() const { return FOURCC_SAIO; }

bool SampleAuxiliaryInformationOffset::Parse(BoxReader* reader) {
  RCHECK(reader->ReadFullBoxHeader());
  if (reader->flags() & 1)
    RCHECK(reader->SkipBytes(8));

  uint32 count;
  RCHECK(reader->Read4(&count) &&
         reader->HasBytes(count * (reader->version() == 1 ? 8 : 4)));
  offsets.resize(count);

  for (uint32 i = 0; i < count; i++) {
    if (reader->version() == 1) {
      RCHECK(reader->Read8(&offsets[i]));
    } else {
      RCHECK(reader->Read4Into8(&offsets[i]));
    }
  }
  return true;
}

SampleAuxiliaryInformationSize::SampleAuxiliaryInformationSize()
  : default_sample_info_size(0), sample_count(0) {
}
SampleAuxiliaryInformationSize::~SampleAuxiliaryInformationSize() {}
FourCC SampleAuxiliaryInformationSize::BoxType() const { return FOURCC_SAIZ; }

bool SampleAuxiliaryInformationSize::Parse(BoxReader* reader) {
  RCHECK(reader->ReadFullBoxHeader());
  if (reader->flags() & 1)
    RCHECK(reader->SkipBytes(8));

  RCHECK(reader->Read1(&default_sample_info_size) &&
         reader->Read4(&sample_count));
  if (default_sample_info_size == 0)
    return reader->ReadVec(&sample_info_sizes, sample_count);
  return true;
}

OriginalFormat::OriginalFormat() : format(FOURCC_NULL) {}
OriginalFormat::~OriginalFormat() {}
FourCC OriginalFormat::BoxType() const { return FOURCC_FRMA; }

bool OriginalFormat::Parse(BoxReader* reader) {
  return reader->ReadFourCC(&format);
}

SchemeType::SchemeType() : type(FOURCC_NULL), version(0) {}
SchemeType::~SchemeType() {}
FourCC SchemeType::BoxType() const { return FOURCC_SCHM; }

bool SchemeType::Parse(BoxReader* reader) {
  RCHECK(reader->ReadFullBoxHeader() &&
         reader->ReadFourCC(&type) &&
         reader->Read4(&version));
  return true;
}

TrackEncryption::TrackEncryption()
  : is_encrypted(false), default_iv_size(0) {
}
TrackEncryption::~TrackEncryption() {}
FourCC TrackEncryption::BoxType() const { return FOURCC_TENC; }

bool TrackEncryption::Parse(BoxReader* reader) {
  uint8 flag;
  RCHECK(reader->ReadFullBoxHeader() &&
         reader->SkipBytes(2) &&
         reader->Read1(&flag) &&
         reader->Read1(&default_iv_size) &&
         reader->ReadVec(&default_kid, 16));
  is_encrypted = (flag != 0);
  if (is_encrypted) {
    RCHECK(default_iv_size == 8 || default_iv_size == 16);
  } else {
    RCHECK(default_iv_size == 0);
  }
  return true;
}

SchemeInfo::SchemeInfo() {}
SchemeInfo::~SchemeInfo() {}
FourCC SchemeInfo::BoxType() const { return FOURCC_SCHI; }

bool SchemeInfo::Parse(BoxReader* reader) {
  return reader->ScanChildren() && reader->ReadChild(&track_encryption);
}

ProtectionSchemeInfo::ProtectionSchemeInfo() {}
ProtectionSchemeInfo::~ProtectionSchemeInfo() {}
FourCC ProtectionSchemeInfo::BoxType() const { return FOURCC_SINF; }

bool ProtectionSchemeInfo::Parse(BoxReader* reader) {
  RCHECK(reader->ScanChildren() &&
         reader->ReadChild(&format) &&
         reader->ReadChild(&type));
  if (type.type == FOURCC_CENC)
    RCHECK(reader->ReadChild(&info));
  // Other protection schemes are silently ignored. Since the protection scheme
  // type can't be determined until this box is opened, we return 'true' for
  // non-CENC protection scheme types. It is the parent box's responsibility to
  // ensure that this scheme type is a supported one.
  return true;
}

MovieHeader::MovieHeader()
    : creation_time(0),
      modification_time(0),
      timescale(0),
      duration(0),
      rate(-1),
      volume(-1),
      next_track_id(0) {}
MovieHeader::~MovieHeader() {}
FourCC MovieHeader::BoxType() const { return FOURCC_MVHD; }

bool MovieHeader::Parse(BoxReader* reader) {
  RCHECK(reader->ReadFullBoxHeader());

  if (reader->version() == 1) {
    RCHECK(reader->Read8(&creation_time) &&
           reader->Read8(&modification_time) &&
           reader->Read4(&timescale) &&
           reader->Read8(&duration));
  } else {
    RCHECK(reader->Read4Into8(&creation_time) &&
           reader->Read4Into8(&modification_time) &&
           reader->Read4(&timescale) &&
           reader->Read4Into8(&duration));
  }

  RCHECK(reader->Read4s(&rate) &&
         reader->Read2s(&volume) &&
         reader->SkipBytes(10) &&  // reserved
         reader->SkipBytes(36) &&  // matrix
         reader->SkipBytes(24) &&  // predefined zero
         reader->Read4(&next_track_id));
  return true;
}

TrackHeader::TrackHeader()
    : creation_time(0),
      modification_time(0),
      track_id(0),
      duration(0),
      layer(-1),
      alternate_group(-1),
      volume(-1),
      width(0),
      height(0) {}
TrackHeader::~TrackHeader() {}
FourCC TrackHeader::BoxType() const { return FOURCC_TKHD; }

bool TrackHeader::Parse(BoxReader* reader) {
  RCHECK(reader->ReadFullBoxHeader());
  if (reader->version() == 1) {
    RCHECK(reader->Read8(&creation_time) &&
           reader->Read8(&modification_time) &&
           reader->Read4(&track_id) &&
           reader->SkipBytes(4) &&    // reserved
           reader->Read8(&duration));
  } else {
    RCHECK(reader->Read4Into8(&creation_time) &&
           reader->Read4Into8(&modification_time) &&
           reader->Read4(&track_id) &&
           reader->SkipBytes(4) &&   // reserved
           reader->Read4Into8(&duration));
  }

  RCHECK(reader->SkipBytes(8) &&  // reserved
         reader->Read2s(&layer) &&
         reader->Read2s(&alternate_group) &&
         reader->Read2s(&volume) &&
         reader->SkipBytes(2) &&  // reserved
         reader->SkipBytes(36) &&  // matrix
         reader->Read4(&width) &&
         reader->Read4(&height));
  width >>= 16;
  height >>= 16;
  return true;
}

SampleDescription::SampleDescription() : type(kInvalid) {}
SampleDescription::~SampleDescription() {}
FourCC SampleDescription::BoxType() const { return FOURCC_STSD; }

bool SampleDescription::Parse(BoxReader* reader) {
  uint32 count;
  RCHECK(reader->SkipBytes(4) &&
         reader->Read4(&count));
  video_entries.clear();
  audio_entries.clear();

  // Note: this value is preset before scanning begins. See comments in the
  // Parse(Media*) function.
  if (type == kVideo) {
    RCHECK(reader->ReadAllChildren(&video_entries));
  } else if (type == kAudio) {
    RCHECK(reader->ReadAllChildren(&audio_entries));
  }
  return true;
}

SyncSample::SyncSample() : is_present(false) {}
SyncSample::~SyncSample() {}
FourCC SyncSample::BoxType() const { return FOURCC_STSS; }

bool SyncSample::Parse(BoxReader* reader) {
  uint32 entry_count;
  RCHECK(reader->ReadFullBoxHeader() &&
         reader->Read4(&entry_count));

  is_present = true;

  if (entry_count == 0)
    return true;

  // Skip over the entries since we don't actually care about
  // them right now. In most fragmented files with an stss, there
  // aren't any entries anyways because the random access point info
  // is signalled in the fragments.
  int64 skip_size = 4 * entry_count;
  if (skip_size > INT_MAX)
    return false;

  RCHECK(reader->SkipBytes(skip_size));

  return true;
}

SampleTable::SampleTable() {}
SampleTable::~SampleTable() {}
FourCC SampleTable::BoxType() const { return FOURCC_STBL; }

bool SampleTable::Parse(BoxReader* reader) {
  return reader->ScanChildren() &&
      reader->ReadChild(&description) &&
      reader->MaybeReadChild(&sync_sample);
}

EditList::EditList() {}
EditList::~EditList() {}
FourCC EditList::BoxType() const { return FOURCC_ELST; }

bool EditList::Parse(BoxReader* reader) {
  uint32 count;
  RCHECK(reader->ReadFullBoxHeader() && reader->Read4(&count));

  if (reader->version() == 1) {
    RCHECK(reader->HasBytes(count * 20));
  } else {
    RCHECK(reader->HasBytes(count * 12));
  }
  edits.resize(count);

  for (std::vector<EditListEntry>::iterator edit = edits.begin();
       edit != edits.end(); ++edit) {
    if (reader->version() == 1) {
      RCHECK(reader->Read8(&edit->segment_duration) &&
             reader->Read8s(&edit->media_time));
    } else {
      RCHECK(reader->Read4Into8(&edit->segment_duration) &&
             reader->Read4sInto8s(&edit->media_time));
    }
    RCHECK(reader->Read2s(&edit->media_rate_integer) &&
           reader->Read2s(&edit->media_rate_fraction));
  }
  return true;
}

Edit::Edit() {}
Edit::~Edit() {}
FourCC Edit::BoxType() const { return FOURCC_EDTS; }

bool Edit::Parse(BoxReader* reader) {
  return reader->ScanChildren() && reader->ReadChild(&list);
}

HandlerReference::HandlerReference() : type(kInvalid) {}
HandlerReference::~HandlerReference() {}
FourCC HandlerReference::BoxType() const { return FOURCC_HDLR; }

bool HandlerReference::Parse(BoxReader* reader) {
  FourCC hdlr_type;
  RCHECK(reader->SkipBytes(8) && reader->ReadFourCC(&hdlr_type));
  // Note: remaining fields in box ignored
  if (hdlr_type == FOURCC_VIDE) {
    type = kVideo;
  } else if (hdlr_type == FOURCC_SOUN) {
    type = kAudio;
  } else {
    type = kInvalid;
  }
  return true;
}

AVCDecoderConfigurationRecord::AVCDecoderConfigurationRecord()
    : version(0),
      profile_indication(0),
      profile_compatibility(0),
      avc_level(0),
      length_size(0) {}

AVCDecoderConfigurationRecord::~AVCDecoderConfigurationRecord() {}
FourCC AVCDecoderConfigurationRecord::BoxType() const { return FOURCC_AVCC; }

bool AVCDecoderConfigurationRecord::Parse(BoxReader* reader) {
  RCHECK(reader->Read1(&version) && version == 1 &&
         reader->Read1(&profile_indication) &&
         reader->Read1(&profile_compatibility) &&
         reader->Read1(&avc_level));

  uint8 length_size_minus_one;
  RCHECK(reader->Read1(&length_size_minus_one) &&
         (length_size_minus_one & 0xfc) == 0xfc);
  length_size = (length_size_minus_one & 0x3) + 1;

  uint8 num_sps;
  RCHECK(reader->Read1(&num_sps) && (num_sps & 0xe0) == 0xe0);
  num_sps &= 0x1f;

  sps_list.resize(num_sps);
  for (int i = 0; i < num_sps; i++) {
    uint16 sps_length;
    RCHECK(reader->Read2(&sps_length) &&
           reader->ReadVec(&sps_list[i], sps_length));
  }

  uint8 num_pps;
  RCHECK(reader->Read1(&num_pps));

  pps_list.resize(num_pps);
  for (int i = 0; i < num_pps; i++) {
    uint16 pps_length;
    RCHECK(reader->Read2(&pps_length) &&
           reader->ReadVec(&pps_list[i], pps_length));
  }

  return true;
}

PixelAspectRatioBox::PixelAspectRatioBox() : h_spacing(1), v_spacing(1) {}
PixelAspectRatioBox::~PixelAspectRatioBox() {}
FourCC PixelAspectRatioBox::BoxType() const { return FOURCC_PASP; }

bool PixelAspectRatioBox::Parse(BoxReader* reader) {
  RCHECK(reader->Read4(&h_spacing) &&
         reader->Read4(&v_spacing));
  return true;
}

VideoSampleEntry::VideoSampleEntry()
    : format(FOURCC_NULL),
      data_reference_index(0),
      width(0),
      height(0) {}

VideoSampleEntry::~VideoSampleEntry() {}
FourCC VideoSampleEntry::BoxType() const {
  DCHECK(false) << "VideoSampleEntry should be parsed according to the "
                << "handler type recovered in its Media ancestor.";
  return FOURCC_NULL;
}

bool VideoSampleEntry::Parse(BoxReader* reader) {
  format = reader->type();
  RCHECK(reader->SkipBytes(6) &&
         reader->Read2(&data_reference_index) &&
         reader->SkipBytes(16) &&
         reader->Read2(&width) &&
         reader->Read2(&height) &&
         reader->SkipBytes(50));

  RCHECK(reader->ScanChildren() &&
         reader->MaybeReadChild(&pixel_aspect));

  if (format == FOURCC_ENCV) {
    // Continue scanning until a recognized protection scheme is found, or until
    // we run out of protection schemes.
    while (sinf.type.type != FOURCC_CENC) {
      if (!reader->ReadChild(&sinf))
        return false;
    }
  }

  if (IsFormatValid())
    RCHECK(reader->ReadChild(&avcc));

  return true;
}

bool VideoSampleEntry::IsFormatValid() const {
  return format == FOURCC_AVC1 || format == FOURCC_AVC3 ||
      (format == FOURCC_ENCV && (sinf.format.format == FOURCC_AVC1 ||
                                 sinf.format.format == FOURCC_AVC3));
}

ElementaryStreamDescriptor::ElementaryStreamDescriptor()
    : object_type(kForbidden) {}

ElementaryStreamDescriptor::~ElementaryStreamDescriptor() {}

FourCC ElementaryStreamDescriptor::BoxType() const {
  return FOURCC_ESDS;
}

bool ElementaryStreamDescriptor::Parse(BoxReader* reader) {
  std::vector<uint8> data;
  ESDescriptor es_desc;

  RCHECK(reader->ReadFullBoxHeader());
  RCHECK(reader->ReadVec(&data, reader->size() - reader->pos()));
  RCHECK(es_desc.Parse(data));

  object_type = es_desc.object_type();

  RCHECK(aac.Parse(es_desc.decoder_specific_info()));

  return true;
}

AudioSampleEntry::AudioSampleEntry()
    : format(FOURCC_NULL),
      data_reference_index(0),
      channelcount(0),
      samplesize(0),
      samplerate(0) {}

AudioSampleEntry::~AudioSampleEntry() {}

FourCC AudioSampleEntry::BoxType() const {
  DCHECK(false) << "AudioSampleEntry should be parsed according to the "
                << "handler type recovered in its Media ancestor.";
  return FOURCC_NULL;
}

bool AudioSampleEntry::Parse(BoxReader* reader) {
  format = reader->type();
  RCHECK(reader->SkipBytes(6) &&
         reader->Read2(&data_reference_index) &&
         reader->SkipBytes(8) &&
         reader->Read2(&channelcount) &&
         reader->Read2(&samplesize) &&
         reader->SkipBytes(4) &&
         reader->Read4(&samplerate));
  // Convert from 16.16 fixed point to integer
  samplerate >>= 16;

  RCHECK(reader->ScanChildren());
  if (format == FOURCC_ENCA) {
    // Continue scanning until a recognized protection scheme is found, or until
    // we run out of protection schemes.
    while (sinf.type.type != FOURCC_CENC) {
      if (!reader->ReadChild(&sinf))
        return false;
    }
  }

  // ESDS is not valid in case of EAC3.
  RCHECK(reader->MaybeReadChild(&esds));
  return true;
}

MediaHeader::MediaHeader()
    : creation_time(0),
      modification_time(0),
      timescale(0),
      duration(0) {}
MediaHeader::~MediaHeader() {}
FourCC MediaHeader::BoxType() const { return FOURCC_MDHD; }

bool MediaHeader::Parse(BoxReader* reader) {
  RCHECK(reader->ReadFullBoxHeader());

  if (reader->version() == 1) {
    RCHECK(reader->Read8(&creation_time) &&
           reader->Read8(&modification_time) &&
           reader->Read4(&timescale) &&
           reader->Read8(&duration));
  } else {
    RCHECK(reader->Read4Into8(&creation_time) &&
           reader->Read4Into8(&modification_time) &&
           reader->Read4(&timescale) &&
           reader->Read4Into8(&duration));
  }
  // Skip language information
  return reader->SkipBytes(4);
}

MediaInformation::MediaInformation() {}
MediaInformation::~MediaInformation() {}
FourCC MediaInformation::BoxType() const { return FOURCC_MINF; }

bool MediaInformation::Parse(BoxReader* reader) {
  return reader->ScanChildren() &&
         reader->ReadChild(&sample_table);
}

Media::Media() {}
Media::~Media() {}
FourCC Media::BoxType() const { return FOURCC_MDIA; }

bool Media::Parse(BoxReader* reader) {
  RCHECK(reader->ScanChildren() &&
         reader->ReadChild(&header) &&
         reader->ReadChild(&handler));

  // Maddeningly, the HandlerReference box specifies how to parse the
  // SampleDescription box, making the latter the only box (of those that we
  // support) which cannot be parsed correctly on its own (or even with
  // information from its strict ancestor tree). We thus copy the handler type
  // to the sample description box *before* parsing it to provide this
  // information while parsing.
  information.sample_table.description.type = handler.type;
  RCHECK(reader->ReadChild(&information));
  return true;
}

Track::Track() {}
Track::~Track() {}
FourCC Track::BoxType() const { return FOURCC_TRAK; }

bool Track::Parse(BoxReader* reader) {
  RCHECK(reader->ScanChildren() &&
         reader->ReadChild(&header) &&
         reader->ReadChild(&media) &&
         reader->MaybeReadChild(&edit));
  return true;
}

MovieExtendsHeader::MovieExtendsHeader() : fragment_duration(0) {}
MovieExtendsHeader::~MovieExtendsHeader() {}
FourCC MovieExtendsHeader::BoxType() const { return FOURCC_MEHD; }

bool MovieExtendsHeader::Parse(BoxReader* reader) {
  RCHECK(reader->ReadFullBoxHeader());
  if (reader->version() == 1) {
    RCHECK(reader->Read8(&fragment_duration));
  } else {
    RCHECK(reader->Read4Into8(&fragment_duration));
  }
  return true;
}

TrackExtends::TrackExtends()
    : track_id(0),
      default_sample_description_index(0),
      default_sample_duration(0),
      default_sample_size(0),
      default_sample_flags(0) {}
TrackExtends::~TrackExtends() {}
FourCC TrackExtends::BoxType() const { return FOURCC_TREX; }

bool TrackExtends::Parse(BoxReader* reader) {
  RCHECK(reader->ReadFullBoxHeader() &&
         reader->Read4(&track_id) &&
         reader->Read4(&default_sample_description_index) &&
         reader->Read4(&default_sample_duration) &&
         reader->Read4(&default_sample_size) &&
         reader->Read4(&default_sample_flags));
  return true;
}

MovieExtends::MovieExtends() {}
MovieExtends::~MovieExtends() {}
FourCC MovieExtends::BoxType() const { return FOURCC_MVEX; }

bool MovieExtends::Parse(BoxReader* reader) {
  header.fragment_duration = 0;
  return reader->ScanChildren() &&
         reader->MaybeReadChild(&header) &&
         reader->ReadChildren(&tracks);
}

Movie::Movie() : fragmented(false) {}
Movie::~Movie() {}
FourCC Movie::BoxType() const { return FOURCC_MOOV; }

bool Movie::Parse(BoxReader* reader) {
  return reader->ScanChildren() &&
         reader->ReadChild(&header) &&
         reader->ReadChildren(&tracks) &&
         // Media Source specific: 'mvex' required
         reader->ReadChild(&extends) &&
         reader->MaybeReadChildren(&pssh);
}

TrackFragmentDecodeTime::TrackFragmentDecodeTime() : decode_time(0) {}
TrackFragmentDecodeTime::~TrackFragmentDecodeTime() {}
FourCC TrackFragmentDecodeTime::BoxType() const { return FOURCC_TFDT; }

bool TrackFragmentDecodeTime::Parse(BoxReader* reader) {
  RCHECK(reader->ReadFullBoxHeader());
  if (reader->version() == 1)
    return reader->Read8(&decode_time);
  else
    return reader->Read4Into8(&decode_time);
}

MovieFragmentHeader::MovieFragmentHeader() : sequence_number(0) {}
MovieFragmentHeader::~MovieFragmentHeader() {}
FourCC MovieFragmentHeader::BoxType() const { return FOURCC_MFHD; }

bool MovieFragmentHeader::Parse(BoxReader* reader) {
  return reader->SkipBytes(4) && reader->Read4(&sequence_number);
}

TrackFragmentHeader::TrackFragmentHeader()
    : track_id(0),
      sample_description_index(0),
      default_sample_duration(0),
      default_sample_size(0),
      default_sample_flags(0),
      has_default_sample_flags(false) {}

TrackFragmentHeader::~TrackFragmentHeader() {}
FourCC TrackFragmentHeader::BoxType() const { return FOURCC_TFHD; }

bool TrackFragmentHeader::Parse(BoxReader* reader) {
  RCHECK(reader->ReadFullBoxHeader() && reader->Read4(&track_id));

  // Media Source specific: reject tracks that set 'base-data-offset-present'.
  // Although the Media Source requires that 'default-base-is-moof' (14496-12
  // Amendment 2) be set, we omit this check as many otherwise-valid files in
  // the wild don't set it.
  //
  //  RCHECK((flags & 0x020000) && !(flags & 0x1));
  RCHECK(!(reader->flags() & 0x1));

  if (reader->flags() & 0x2) {
    RCHECK(reader->Read4(&sample_description_index));
  } else {
    sample_description_index = 0;
  }

  if (reader->flags() & 0x8) {
    RCHECK(reader->Read4(&default_sample_duration));
  } else {
    default_sample_duration = 0;
  }

  if (reader->flags() & 0x10) {
    RCHECK(reader->Read4(&default_sample_size));
  } else {
    default_sample_size = 0;
  }

  if (reader->flags() & 0x20) {
    RCHECK(reader->Read4(&default_sample_flags));
    has_default_sample_flags = true;
  } else {
    has_default_sample_flags = false;
  }

  return true;
}

TrackFragmentRun::TrackFragmentRun()
    : sample_count(0), data_offset(0) {}
TrackFragmentRun::~TrackFragmentRun() {}
FourCC TrackFragmentRun::BoxType() const { return FOURCC_TRUN; }

bool TrackFragmentRun::Parse(BoxReader* reader) {
  RCHECK(reader->ReadFullBoxHeader() &&
         reader->Read4(&sample_count));
  const uint32 flags = reader->flags();

  bool data_offset_present = (flags & 0x1) != 0;
  bool first_sample_flags_present = (flags & 0x4) != 0;
  bool sample_duration_present = (flags & 0x100) != 0;
  bool sample_size_present = (flags & 0x200) != 0;
  bool sample_flags_present = (flags & 0x400) != 0;
  bool sample_composition_time_offsets_present = (flags & 0x800) != 0;

  if (data_offset_present) {
    RCHECK(reader->Read4(&data_offset));
  } else {
    data_offset = 0;
  }

  uint32 first_sample_flags;
  if (first_sample_flags_present)
    RCHECK(reader->Read4(&first_sample_flags));

  int fields = sample_duration_present + sample_size_present +
      sample_flags_present + sample_composition_time_offsets_present;
  RCHECK(reader->HasBytes(fields * sample_count));

  if (sample_duration_present)
    sample_durations.resize(sample_count);
  if (sample_size_present)
    sample_sizes.resize(sample_count);
  if (sample_flags_present)
    sample_flags.resize(sample_count);
  if (sample_composition_time_offsets_present)
    sample_composition_time_offsets.resize(sample_count);

  for (uint32 i = 0; i < sample_count; ++i) {
    if (sample_duration_present)
      RCHECK(reader->Read4(&sample_durations[i]));
    if (sample_size_present)
      RCHECK(reader->Read4(&sample_sizes[i]));
    if (sample_flags_present)
      RCHECK(reader->Read4(&sample_flags[i]));
    if (sample_composition_time_offsets_present)
      RCHECK(reader->Read4s(&sample_composition_time_offsets[i]));
  }

  if (first_sample_flags_present) {
    if (sample_flags.size() == 0) {
      sample_flags.push_back(first_sample_flags);
    } else {
      sample_flags[0] = first_sample_flags;
    }
  }
  return true;
}

TrackFragment::TrackFragment() {}
TrackFragment::~TrackFragment() {}
FourCC TrackFragment::BoxType() const { return FOURCC_TRAF; }

bool TrackFragment::Parse(BoxReader* reader) {
  return reader->ScanChildren() &&
         reader->ReadChild(&header) &&
         // Media Source specific: 'tfdt' required
         reader->ReadChild(&decode_time) &&
         reader->MaybeReadChildren(&runs) &&
         reader->MaybeReadChild(&auxiliary_offset) &&
         reader->MaybeReadChild(&auxiliary_size) &&
         reader->MaybeReadChild(&sdtp);
}

MovieFragment::MovieFragment() {}
MovieFragment::~MovieFragment() {}
FourCC MovieFragment::BoxType() const { return FOURCC_MOOF; }

bool MovieFragment::Parse(BoxReader* reader) {
  RCHECK(reader->ScanChildren() &&
         reader->ReadChild(&header) &&
         reader->ReadChildren(&tracks) &&
         reader->MaybeReadChildren(&pssh));
  return true;
}

IndependentAndDisposableSamples::IndependentAndDisposableSamples() {}
IndependentAndDisposableSamples::~IndependentAndDisposableSamples() {}
FourCC IndependentAndDisposableSamples::BoxType() const { return FOURCC_SDTP; }

bool IndependentAndDisposableSamples::Parse(BoxReader* reader) {
  RCHECK(reader->ReadFullBoxHeader());
  RCHECK(reader->version() == 0);
  RCHECK(reader->flags() == 0);

  int sample_count = reader->size() - reader->pos();
  sample_depends_on_.resize(sample_count);
  for (int i = 0; i < sample_count; ++i) {
    uint8 sample_info;
    RCHECK(reader->Read1(&sample_info));

    sample_depends_on_[i] =
        static_cast<SampleDependsOn>((sample_info >> 4) & 0x3);

    RCHECK(sample_depends_on_[i] != kSampleDependsOnReserved);
  }

  return true;
}

SampleDependsOn IndependentAndDisposableSamples::sample_depends_on(
    size_t i) const {
  if (i >= sample_depends_on_.size())
    return kSampleDependsOnUnknown;

  return sample_depends_on_[i];
}

}  // namespace mp4
}  // namespace media