Add support for AudioRollRecoveryEntry

This is part of the effort to support Opus in iso-bmff #83.

Changes in this CL:
- Add support for multiple SampleGroupDescription and SampleToGroup
  boxes in TrackFragment box;
- Add support for SampleGroupDescription and SampleToGroup boxes
  in SampleTable box;
- Add support for AudioRollRecoveryEntry in Sample Group and 'roll'
  sample grouping type;
- Also fix a bug that default length was not set correctly in
  SampleGroupDescription when constant iv is used.

Change-Id: I7e31386ea6cd17a8ee5e1dca4c1a90937d51368f

packager/media/base/fourccs.h

@@ -82,6 +82,7 @@ enum FourCC : uint32_t {
   FOURCC_pdin = 0x7064696e,
   FOURCC_prft = 0x70726674,
   FOURCC_pssh = 0x70737368,
+  FOURCC_roll = 0x726f6c6c,
   FOURCC_saio = 0x7361696f,
   FOURCC_saiz = 0x7361697a,
   FOURCC_sbgp = 0x73626770,

packager/media/formats/mp4/box_definitions.cc

@@ -921,6 +921,187 @@ uint32_t SyncSample::ComputeSizeInternal() {
          sizeof(uint32_t) * sample_number.size();
 }
 
+CencSampleEncryptionInfoEntry::CencSampleEncryptionInfoEntry()
+    : is_protected(0),
+      per_sample_iv_size(0),
+      crypt_byte_block(0),
+      skip_byte_block(0) {}
+CencSampleEncryptionInfoEntry::~CencSampleEncryptionInfoEntry() {};
+
+bool CencSampleEncryptionInfoEntry::ReadWrite(BoxBuffer* buffer) {
+  if (!buffer->Reading()) {
+    if (key_id.size() != kCencKeyIdSize) {
+      LOG(WARNING) << "CENC defines key id length of " << kCencKeyIdSize
+                   << " bytes; got " << key_id.size()
+                   << ". Resized accordingly.";
+      key_id.resize(kCencKeyIdSize);
+    }
+    RCHECK(crypt_byte_block < 16 && skip_byte_block < 16);
+  }
+
+  RCHECK(buffer->IgnoreBytes(1));  // reserved.
+
+  uint8_t pattern = crypt_byte_block << 4 | skip_byte_block;
+  RCHECK(buffer->ReadWriteUInt8(&pattern));
+  crypt_byte_block = pattern >> 4;
+  skip_byte_block = pattern & 0x0F;
+
+  RCHECK(buffer->ReadWriteUInt8(&is_protected) &&
+         buffer->ReadWriteUInt8(&per_sample_iv_size) &&
+         buffer->ReadWriteVector(&key_id, kCencKeyIdSize));
+
+  if (is_protected == 1) {
+    if (per_sample_iv_size == 0) {  // For constant iv.
+      uint8_t constant_iv_size = constant_iv.size();
+      RCHECK(buffer->ReadWriteUInt8(&constant_iv_size));
+      RCHECK(constant_iv_size == 8 || constant_iv_size == 16);
+      RCHECK(buffer->ReadWriteVector(&constant_iv, constant_iv_size));
+    } else {
+      RCHECK(per_sample_iv_size == 8 || per_sample_iv_size == 16);
+      DCHECK(constant_iv.empty());
+    }
+  } else {
+    // Expect |is_protected| to be 0, i.e. not protected. Other values of
+    // |is_protected| is not supported.
+    RCHECK(is_protected == 0);
+    RCHECK(per_sample_iv_size == 0);
+  }
+  return true;
+}
+
+uint32_t CencSampleEncryptionInfoEntry::ComputeSize() const {
+  return sizeof(uint32_t) + kCencKeyIdSize +
+         (constant_iv.empty() ? 0 : (sizeof(uint8_t) + constant_iv.size()));
+}
+
+AudioRollRecoveryEntry::AudioRollRecoveryEntry(): roll_distance(0) {}
+AudioRollRecoveryEntry::~AudioRollRecoveryEntry() {}
+
+bool AudioRollRecoveryEntry::ReadWrite(BoxBuffer* buffer) {
+  RCHECK(buffer->ReadWriteInt16(&roll_distance));
+  return true;
+}
+
+uint32_t AudioRollRecoveryEntry::ComputeSize() const {
+  return sizeof(roll_distance);
+}
+
+SampleGroupDescription::SampleGroupDescription() : grouping_type(0) {}
+SampleGroupDescription::~SampleGroupDescription() {}
+FourCC SampleGroupDescription::BoxType() const { return FOURCC_sgpd; }
+
+bool SampleGroupDescription::ReadWriteInternal(BoxBuffer* buffer) {
+  RCHECK(ReadWriteHeaderInternal(buffer) &&
+         buffer->ReadWriteUInt32(&grouping_type));
+
+  switch (grouping_type) {
+    case FOURCC_seig:
+      return ReadWriteEntries(buffer, &cenc_sample_encryption_info_entries);
+    case FOURCC_roll:
+      return ReadWriteEntries(buffer, &audio_roll_recovery_entries);
+    default:
+      DCHECK(buffer->Reading());
+      DLOG(WARNING) << "Sample group '" << grouping_type
+                    << "' is not supported.";
+      return true;
+  }
+}
+
+template <typename T>
+bool SampleGroupDescription::ReadWriteEntries(BoxBuffer* buffer,
+                                              std::vector<T>* entries) {
+  uint32_t default_length = 0;
+  if (!buffer->Reading()) {
+    DCHECK(!entries->empty());
+    default_length = (*entries)[0].ComputeSize();
+    DCHECK_NE(default_length, 0u);
+  }
+  if (version == 1)
+    RCHECK(buffer->ReadWriteUInt32(&default_length));
+  if (version >= 2) {
+    NOTIMPLEMENTED() << "Unsupported SampleGroupDescriptionBox 'sgpd' version "
+                     << static_cast<int>(version);
+    return false;
+  }
+
+  uint32_t count = entries->size();
+  RCHECK(buffer->ReadWriteUInt32(&count));
+  RCHECK(count != 0);
+  entries->resize(count);
+
+  for (T& entry : *entries) {
+    if (version == 1) {
+      uint32_t description_length = default_length;
+      if (buffer->Reading() && default_length == 0)
+        RCHECK(buffer->ReadWriteUInt32(&description_length));
+      RCHECK(entry.ReadWrite(buffer));
+      RCHECK(entry.ComputeSize() == description_length);
+    } else {
+      RCHECK(entry.ReadWrite(buffer));
+    }
+  }
+  return true;
+}
+
+uint32_t SampleGroupDescription::ComputeSizeInternal() {
+  // Version 0 is obsoleted, so always generate version 1 box.
+  version = 1;
+  size_t entries_size = 0;
+  switch (grouping_type) {
+    case FOURCC_seig:
+      for (const auto& entry : cenc_sample_encryption_info_entries)
+        entries_size += entry.ComputeSize();
+      break;
+    case FOURCC_roll:
+      for (const auto& entry : audio_roll_recovery_entries)
+        entries_size += entry.ComputeSize();
+      break;
+  }
+  // This box is optional. Skip it if it is not used.
+  if (entries_size == 0)
+    return 0;
+  return HeaderSize() + sizeof(grouping_type) +
+         (version == 1 ? sizeof(uint32_t) : 0) + sizeof(uint32_t) +
+         entries_size;
+}
+
+SampleToGroup::SampleToGroup() : grouping_type(0), grouping_type_parameter(0) {}
+SampleToGroup::~SampleToGroup() {}
+FourCC SampleToGroup::BoxType() const { return FOURCC_sbgp; }
+
+bool SampleToGroup::ReadWriteInternal(BoxBuffer* buffer) {
+  RCHECK(ReadWriteHeaderInternal(buffer) &&
+         buffer->ReadWriteUInt32(&grouping_type));
+  if (version == 1)
+    RCHECK(buffer->ReadWriteUInt32(&grouping_type_parameter));
+
+  if (grouping_type != FOURCC_seig && grouping_type != FOURCC_roll) {
+    DCHECK(buffer->Reading());
+    DLOG(WARNING) << "Sample group "
+                  << FourCCToString(static_cast<FourCC>(grouping_type))
+                  << " is not supported.";
+    return true;
+  }
+
+  uint32_t count = entries.size();
+  RCHECK(buffer->ReadWriteUInt32(&count));
+  entries.resize(count);
+  for (uint32_t i = 0; i < count; ++i) {
+    RCHECK(buffer->ReadWriteUInt32(&entries[i].sample_count) &&
+           buffer->ReadWriteUInt32(&entries[i].group_description_index));
+  }
+  return true;
+}
+
+uint32_t SampleToGroup::ComputeSizeInternal() {
+  // This box is optional. Skip it if it is not used.
+  if (entries.empty())
+    return 0;
+  return HeaderSize() + sizeof(grouping_type) +
+         (version == 1 ? sizeof(grouping_type_parameter) : 0) +
+         sizeof(uint32_t) + entries.size() * sizeof(entries[0]);
+}
+
 SampleTable::SampleTable() {}
 SampleTable::~SampleTable() {}
 FourCC SampleTable::BoxType() const { return FOURCC_stbl; }
@@ -961,15 +1142,30 @@ bool SampleTable::ReadWriteInternal(BoxBuffer* buffer) {
            buffer->ReadWriteChild(&chunk_large_offset));
   }
   RCHECK(buffer->TryReadWriteChild(&sync_sample));
+  if (buffer->Reading()) {
+    RCHECK(buffer->reader()->TryReadChildren(&sample_group_descriptions) &&
+           buffer->reader()->TryReadChildren(&sample_to_groups));
+  } else {
+    for (auto& sample_group_description : sample_group_descriptions)
+      RCHECK(buffer->ReadWriteChild(&sample_group_description));
+    for (auto& sample_to_group : sample_to_groups)
+      RCHECK(buffer->ReadWriteChild(&sample_to_group));
+  }
   return true;
 }
 
 uint32_t SampleTable::ComputeSizeInternal() {
-  return HeaderSize() + description.ComputeSize() +
+  uint32_t box_size =
-         decoding_time_to_sample.ComputeSize() +
+      HeaderSize() + description.ComputeSize() +
-         composition_time_to_sample.ComputeSize() +
+      decoding_time_to_sample.ComputeSize() +
-         sample_to_chunk.ComputeSize() + sample_size.ComputeSize() +
+      composition_time_to_sample.ComputeSize() + sample_to_chunk.ComputeSize() +
-         chunk_large_offset.ComputeSize() + sync_sample.ComputeSize();
+      sample_size.ComputeSize() + chunk_large_offset.ComputeSize() +
+      sync_sample.ComputeSize();
+  for (auto& sample_group_description : sample_group_descriptions)
+    box_size += sample_group_description.ComputeSize();
+  for (auto& sample_to_group : sample_to_groups)
+    box_size += sample_to_group.ComputeSize();
+  return box_size;
 }
 
 EditList::EditList() {}
@@ -2199,152 +2395,6 @@ uint32_t TrackFragmentRun::ComputeSizeInternal() {
   return box_size;
 }
 
-SampleToGroup::SampleToGroup() : grouping_type(0), grouping_type_parameter(0) {}
-SampleToGroup::~SampleToGroup() {}
-FourCC SampleToGroup::BoxType() const { return FOURCC_sbgp; }
-
-bool SampleToGroup::ReadWriteInternal(BoxBuffer* buffer) {
-  RCHECK(ReadWriteHeaderInternal(buffer) &&
-         buffer->ReadWriteUInt32(&grouping_type));
-  if (version == 1)
-    RCHECK(buffer->ReadWriteUInt32(&grouping_type_parameter));
-
-  if (grouping_type != FOURCC_seig) {
-    DCHECK(buffer->Reading());
-    DLOG(WARNING) << "Sample group "
-                  << FourCCToString(static_cast<FourCC>(grouping_type))
-                  << " is not supported.";
-    return true;
-  }
-
-  uint32_t count = entries.size();
-  RCHECK(buffer->ReadWriteUInt32(&count));
-  entries.resize(count);
-  for (uint32_t i = 0; i < count; ++i) {
-    RCHECK(buffer->ReadWriteUInt32(&entries[i].sample_count) &&
-           buffer->ReadWriteUInt32(&entries[i].group_description_index));
-  }
-  return true;
-}
-
-uint32_t SampleToGroup::ComputeSizeInternal() {
-  // This box is optional. Skip it if it is not used.
-  if (entries.empty())
-    return 0;
-  return HeaderSize() + sizeof(grouping_type) +
-         (version == 1 ? sizeof(grouping_type_parameter) : 0) +
-         sizeof(uint32_t) + entries.size() * sizeof(entries[0]);
-}
-
-CencSampleEncryptionInfoEntry::CencSampleEncryptionInfoEntry()
-    : is_protected(0),
-      per_sample_iv_size(0),
-      crypt_byte_block(0),
-      skip_byte_block(0) {}
-CencSampleEncryptionInfoEntry::~CencSampleEncryptionInfoEntry() {};
-
-SampleGroupDescription::SampleGroupDescription() : grouping_type(0) {}
-SampleGroupDescription::~SampleGroupDescription() {}
-FourCC SampleGroupDescription::BoxType() const { return FOURCC_sgpd; }
-
-bool SampleGroupDescription::ReadWriteInternal(BoxBuffer* buffer) {
-  RCHECK(ReadWriteHeaderInternal(buffer) &&
-         buffer->ReadWriteUInt32(&grouping_type));
-
-  if (grouping_type != FOURCC_seig) {
-    DCHECK(buffer->Reading());
-    DLOG(WARNING) << "Sample group '" << grouping_type << "' is not supported.";
-    return true;
-  }
-
-  const size_t kEntrySize = sizeof(uint32_t) + kCencKeyIdSize;
-  uint32_t default_length = 0;
-  if (version == 1) {
-    if (buffer->Reading()) {
-      RCHECK(buffer->ReadWriteUInt32(&default_length));
-      RCHECK(default_length == 0 || default_length >= kEntrySize);
-    } else {
-      default_length = kEntrySize;
-      RCHECK(buffer->ReadWriteUInt32(&default_length));
-    }
-  }
-
-  uint32_t count = entries.size();
-  RCHECK(buffer->ReadWriteUInt32(&count));
-  entries.resize(count);
-  for (uint32_t i = 0; i < count; ++i) {
-    if (version == 1) {
-      if (buffer->Reading() && default_length == 0) {
-        uint32_t description_length = 0;
-        RCHECK(buffer->ReadWriteUInt32(&description_length));
-        RCHECK(description_length >= kEntrySize);
-      }
-    }
-
-    if (!buffer->Reading()) {
-      if (entries[i].key_id.size() != kCencKeyIdSize) {
-        LOG(WARNING) << "CENC defines key id length of " << kCencKeyIdSize
-                     << " bytes; got " << entries[i].key_id.size()
-                     << ". Resized accordingly.";
-        entries[i].key_id.resize(kCencKeyIdSize);
-      }
-      RCHECK(entries[i].crypt_byte_block < 16 &&
-             entries[i].skip_byte_block < 16);
-    }
-
-    RCHECK(buffer->IgnoreBytes(1));  // reserved.
-
-    uint8_t pattern =
-        entries[i].crypt_byte_block << 4 | entries[i].skip_byte_block;
-    RCHECK(buffer->ReadWriteUInt8(&pattern));
-    entries[i].crypt_byte_block = pattern >> 4;
-    entries[i].skip_byte_block = pattern & 0x0F;
-
-    RCHECK(buffer->ReadWriteUInt8(&entries[i].is_protected) &&
-           buffer->ReadWriteUInt8(&entries[i].per_sample_iv_size) &&
-           buffer->ReadWriteVector(&entries[i].key_id, kCencKeyIdSize));
-
-    if (entries[i].is_protected == 1) {
-      if (entries[i].per_sample_iv_size == 0) {  // For constant iv.
-        uint8_t constant_iv_size = entries[i].constant_iv.size();
-        RCHECK(buffer->ReadWriteUInt8(&constant_iv_size));
-        RCHECK(constant_iv_size == 8 || constant_iv_size == 16);
-        RCHECK(
-            buffer->ReadWriteVector(&entries[i].constant_iv, constant_iv_size));
-      } else {
-        RCHECK(entries[i].per_sample_iv_size == 8 ||
-               entries[i].per_sample_iv_size == 16);
-        RCHECK(entries[i].constant_iv.empty());
-      }
-    } else {
-      // Expect |is_protected| to be 0, i.e. not protected. Other values of
-      // |is_protected| is not supported.
-      RCHECK(entries[i].is_protected == 0);
-      RCHECK(entries[i].per_sample_iv_size == 0);
-    }
-
-  }
-  return true;
-}
-
-uint32_t SampleGroupDescription::ComputeSizeInternal() {
-  // Version 0 is obsoleted, so always generate version 1 box.
-  version = 1;
-  // This box is optional. Skip it if it is not used.
-  if (entries.empty())
-    return 0;
-  size_t entries_size = 0;
-  for (const auto& entry : entries) {
-    entries_size += sizeof(uint32_t) + kCencKeyIdSize +
-                    (entry.constant_iv.empty()
-                         ? 0
-                         : (sizeof(uint8_t) + entry.constant_iv.size()));
-  }
-  return HeaderSize() + sizeof(grouping_type) +
-         (version == 1 ? sizeof(uint32_t) : 0) + sizeof(uint32_t) +
-         entries_size;
-}
-
 TrackFragment::TrackFragment() : decode_time_absent(false) {}
 TrackFragment::~TrackFragment() {}
 FourCC TrackFragment::BoxType() const { return FOURCC_traf; }
@@ -2358,27 +2408,18 @@ bool TrackFragment::ReadWriteInternal(BoxBuffer* buffer) {
     decode_time_absent = !buffer->reader()->ChildExist(&decode_time);
     if (!decode_time_absent)
       RCHECK(buffer->ReadWriteChild(&decode_time));
-    RCHECK(buffer->reader()->TryReadChildren(&runs));
+    RCHECK(buffer->reader()->TryReadChildren(&runs) &&
-
+           buffer->reader()->TryReadChildren(&sample_group_descriptions) &&
-    // There could be multiple SampleGroupDescription and SampleToGroup boxes
+           buffer->reader()->TryReadChildren(&sample_to_groups));
-    // with different grouping types. For common encryption, the relevant
-    // grouping type is 'seig'. Continue reading until 'seig' is found, or
-    // until running out of child boxes.
-    while (sample_to_group.grouping_type != FOURCC_seig &&
-           buffer->reader()->ChildExist(&sample_to_group)) {
-      RCHECK(buffer->reader()->ReadChild(&sample_to_group));
-    }
-    while (sample_group_description.grouping_type != FOURCC_seig &&
-           buffer->reader()->ChildExist(&sample_group_description)) {
-      RCHECK(buffer->reader()->ReadChild(&sample_group_description));
-    }
   } else {
     if (!decode_time_absent)
       RCHECK(buffer->ReadWriteChild(&decode_time));
     for (uint32_t i = 0; i < runs.size(); ++i)
       RCHECK(buffer->ReadWriteChild(&runs[i]));
-    RCHECK(buffer->TryReadWriteChild(&sample_to_group) &&
+    for (uint32_t i = 0; i < sample_to_groups.size(); ++i)
-           buffer->TryReadWriteChild(&sample_group_description));
+      RCHECK(buffer->ReadWriteChild(&sample_to_groups[i]));
+    for (uint32_t i = 0; i < sample_group_descriptions.size(); ++i)
+      RCHECK(buffer->ReadWriteChild(&sample_group_descriptions[i]));
   }
   return buffer->TryReadWriteChild(&auxiliary_size) &&
          buffer->TryReadWriteChild(&auxiliary_offset) &&
@@ -2388,11 +2429,14 @@ bool TrackFragment::ReadWriteInternal(BoxBuffer* buffer) {
 uint32_t TrackFragment::ComputeSizeInternal() {
   uint32_t box_size =
       HeaderSize() + header.ComputeSize() + decode_time.ComputeSize() +
-      sample_to_group.ComputeSize() + sample_group_description.ComputeSize() +
       auxiliary_size.ComputeSize() + auxiliary_offset.ComputeSize() +
       sample_encryption.ComputeSize();
   for (uint32_t i = 0; i < runs.size(); ++i)
     box_size += runs[i].ComputeSize();
+  for (uint32_t i = 0; i < sample_group_descriptions.size(); ++i)
+    box_size += sample_group_descriptions[i].ComputeSize();
+  for (uint32_t i = 0; i < sample_to_groups.size(); ++i)
+    box_size += sample_to_groups[i].ComputeSize();
   return box_size;
 }
 

packager/media/formats/mp4/box_definitions.h

@@ -468,6 +468,67 @@ struct SyncSample : FullBox {
   std::vector<uint32_t> sample_number;
 };
 
+struct CencSampleEncryptionInfoEntry {
+  CencSampleEncryptionInfoEntry();
+  ~CencSampleEncryptionInfoEntry();
+
+  bool ReadWrite(BoxBuffer* buffer);
+  uint32_t ComputeSize() const;
+
+  uint8_t is_protected;
+  uint8_t per_sample_iv_size;
+  std::vector<uint8_t> key_id;
+
+  // For pattern-based encryption.
+  uint8_t crypt_byte_block;
+  uint8_t skip_byte_block;
+
+  // Present only if |is_protected == 1 && per_sample_iv_size == 0|.
+  std::vector<uint8_t> constant_iv;
+};
+
+struct AudioRollRecoveryEntry {
+  AudioRollRecoveryEntry();
+  ~AudioRollRecoveryEntry();
+
+  bool ReadWrite(BoxBuffer* buffer);
+  uint32_t ComputeSize() const;
+
+  int16_t roll_distance;
+};
+
+struct SampleGroupDescription : FullBox {
+  DECLARE_BOX_METHODS(SampleGroupDescription);
+
+  template <typename T>
+  bool ReadWriteEntries(BoxBuffer* buffer, std::vector<T>* entries);
+
+  uint32_t grouping_type;
+  // Only present if grouping_type == 'seig'.
+  std::vector<CencSampleEncryptionInfoEntry>
+      cenc_sample_encryption_info_entries;
+  // Only present if grouping_type == 'roll'.
+  std::vector<AudioRollRecoveryEntry> audio_roll_recovery_entries;
+};
+
+struct SampleToGroupEntry {
+  enum GroupDescriptionIndexBase {
+    kTrackGroupDescriptionIndexBase = 0,
+    kTrackFragmentGroupDescriptionIndexBase = 0x10000,
+  };
+
+  uint32_t sample_count;
+  uint32_t group_description_index;
+};
+
+struct SampleToGroup : FullBox {
+  DECLARE_BOX_METHODS(SampleToGroup);
+
+  uint32_t grouping_type;
+  uint32_t grouping_type_parameter;  // Version 1 only.
+  std::vector<SampleToGroupEntry> entries;
+};
+
 struct SampleTable : Box {
   DECLARE_BOX_METHODS(SampleTable);
 
@@ -481,6 +542,8 @@ struct SampleTable : Box {
   // ChunkLargeOffset.
   ChunkLargeOffset chunk_large_offset;
   SyncSample sync_sample;
+  std::vector<SampleGroupDescription> sample_group_descriptions;
+  std::vector<SampleToGroup> sample_to_groups;
 };
 
 struct MediaHeader : FullBox {
@@ -654,47 +717,6 @@ struct TrackFragmentRun : FullBox {
   std::vector<int64_t> sample_composition_time_offsets;
 };
 
-struct SampleToGroupEntry {
-  enum GroupDescriptionIndexBase {
-    kTrackGroupDescriptionIndexBase = 0,
-    kTrackFragmentGroupDescriptionIndexBase = 0x10000,
-  };
-
-  uint32_t sample_count;
-  uint32_t group_description_index;
-};
-
-struct SampleToGroup : FullBox {
-  DECLARE_BOX_METHODS(SampleToGroup);
-
-  uint32_t grouping_type;
-  uint32_t grouping_type_parameter;  // Version 1 only.
-  std::vector<SampleToGroupEntry> entries;
-};
-
-struct CencSampleEncryptionInfoEntry {
-  CencSampleEncryptionInfoEntry();
-  ~CencSampleEncryptionInfoEntry();
-
-  uint8_t is_protected;
-  uint8_t per_sample_iv_size;
-  std::vector<uint8_t> key_id;
-
-  // For pattern-based encryption.
-  uint8_t crypt_byte_block;
-  uint8_t skip_byte_block;
-
-  // Present only if |is_protected == 1 && per_sample_iv_size == 0|.
-  std::vector<uint8_t> constant_iv;
-};
-
-struct SampleGroupDescription : FullBox {
-  DECLARE_BOX_METHODS(SampleGroupDescription);
-
-  uint32_t grouping_type;
-  std::vector<CencSampleEncryptionInfoEntry> entries;
-};
-
 struct TrackFragment : Box {
   DECLARE_BOX_METHODS(TrackFragment);
 
@@ -702,8 +724,8 @@ struct TrackFragment : Box {
   std::vector<TrackFragmentRun> runs;
   bool decode_time_absent;
   TrackFragmentDecodeTime decode_time;
-  SampleToGroup sample_to_group;
+  std::vector<SampleGroupDescription> sample_group_descriptions;
-  SampleGroupDescription sample_group_description;
+  std::vector<SampleToGroup> sample_to_groups;
   SampleAuxiliaryInformationSize auxiliary_size;
   SampleAuxiliaryInformationOffset auxiliary_offset;
   SampleEncryption sample_encryption;

packager/media/formats/mp4/box_definitions_comparison.h

@@ -156,6 +156,42 @@ inline bool operator==(const SyncSample& lhs, const SyncSample& rhs) {
   return lhs.sample_number == rhs.sample_number;
 }
 
+inline bool operator==(const CencSampleEncryptionInfoEntry& lhs,
+                       const CencSampleEncryptionInfoEntry& rhs) {
+  return lhs.is_protected == rhs.is_protected &&
+         lhs.per_sample_iv_size == rhs.per_sample_iv_size &&
+         lhs.key_id == rhs.key_id &&
+         lhs.crypt_byte_block == rhs.crypt_byte_block &&
+         lhs.skip_byte_block == rhs.skip_byte_block &&
+         lhs.constant_iv == rhs.constant_iv;
+}
+
+inline bool operator==(const AudioRollRecoveryEntry& lhs,
+                       const AudioRollRecoveryEntry& rhs) {
+  return lhs.roll_distance == rhs.roll_distance;
+}
+
+inline bool operator==(const SampleGroupDescription& lhs,
+                       const SampleGroupDescription& rhs) {
+  return lhs.grouping_type == rhs.grouping_type &&
+         lhs.cenc_sample_encryption_info_entries ==
+             rhs.cenc_sample_encryption_info_entries &&
+         lhs.audio_roll_recovery_entries == rhs.audio_roll_recovery_entries;
+}
+
+inline bool operator==(const SampleToGroupEntry& lhs,
+                       const SampleToGroupEntry& rhs) {
+  return lhs.sample_count == rhs.sample_count &&
+         lhs.group_description_index == rhs.group_description_index;
+}
+
+inline bool operator==(const SampleToGroup& lhs,
+                       const SampleToGroup& rhs) {
+  return lhs.grouping_type == rhs.grouping_type &&
+         lhs.grouping_type_parameter == rhs.grouping_type_parameter &&
+         lhs.entries == rhs.entries;
+}
+
 inline bool operator==(const SampleTable& lhs, const SampleTable& rhs) {
   return lhs.description == rhs.description &&
          lhs.decoding_time_to_sample == rhs.decoding_time_to_sample &&
@@ -163,7 +199,9 @@ inline bool operator==(const SampleTable& lhs, const SampleTable& rhs) {
          lhs.sample_to_chunk == rhs.sample_to_chunk &&
          lhs.sample_size == rhs.sample_size &&
          lhs.chunk_large_offset == rhs.chunk_large_offset &&
-         lhs.sync_sample == rhs.sync_sample;
+         lhs.sync_sample == rhs.sync_sample &&
+         lhs.sample_group_descriptions == rhs.sample_group_descriptions &&
+         lhs.sample_to_groups == rhs.sample_to_groups;
 }
 
 inline bool operator==(const EditListEntry& lhs, const EditListEntry& rhs) {
@@ -385,35 +423,6 @@ inline bool operator==(const TrackFragmentRun& lhs,
              rhs.sample_composition_time_offsets;
 }
 
-inline bool operator==(const SampleToGroupEntry& lhs,
-                       const SampleToGroupEntry& rhs) {
-  return lhs.sample_count == rhs.sample_count &&
-         lhs.group_description_index == rhs.group_description_index;
-}
-
-inline bool operator==(const SampleToGroup& lhs,
-                       const SampleToGroup& rhs) {
-  return lhs.grouping_type == rhs.grouping_type &&
-         lhs.grouping_type_parameter == rhs.grouping_type_parameter &&
-         lhs.entries == rhs.entries;
-}
-
-inline bool operator==(const CencSampleEncryptionInfoEntry& lhs,
-                       const CencSampleEncryptionInfoEntry& rhs) {
-  return lhs.is_protected == rhs.is_protected &&
-         lhs.per_sample_iv_size == rhs.per_sample_iv_size &&
-         lhs.key_id == rhs.key_id &&
-         lhs.crypt_byte_block == rhs.crypt_byte_block &&
-         lhs.skip_byte_block == rhs.skip_byte_block &&
-         lhs.constant_iv == rhs.constant_iv;
-}
-
-inline bool operator==(const SampleGroupDescription& lhs,
-                       const SampleGroupDescription& rhs) {
-  return lhs.grouping_type == rhs.grouping_type &&
-         lhs.entries == rhs.entries;
-}
-
 inline bool operator==(const TrackFragment& lhs, const TrackFragment& rhs) {
   return lhs.header == rhs.header && lhs.runs == rhs.runs &&
          lhs.decode_time == rhs.decode_time &&

packager/media/formats/mp4/box_definitions_unittest.cc

@@ -567,6 +567,45 @@ class BoxDefinitionsTestGeneral : public testing::Test {
 
   void Modify(SyncSample* stss) { stss->sample_number.pop_back(); }
 
+  void Fill(SampleGroupDescription* sgpd) {
+    sgpd->grouping_type = FOURCC_seig;
+    sgpd->cenc_sample_encryption_info_entries.resize(2);
+    sgpd->cenc_sample_encryption_info_entries[0].is_protected = 1;
+    sgpd->cenc_sample_encryption_info_entries[0].per_sample_iv_size = 8;
+    sgpd->cenc_sample_encryption_info_entries[0].key_id.assign(
+        kData16Bytes, kData16Bytes + arraysize(kData16Bytes));
+    sgpd->cenc_sample_encryption_info_entries[0].crypt_byte_block = 3;
+    sgpd->cenc_sample_encryption_info_entries[0].skip_byte_block = 7;
+    sgpd->cenc_sample_encryption_info_entries[1].is_protected = 0;
+    sgpd->cenc_sample_encryption_info_entries[1].per_sample_iv_size = 0;
+    sgpd->cenc_sample_encryption_info_entries[1].key_id.resize(16);
+    sgpd->version = 1;
+  }
+
+  void Modify(SampleGroupDescription* sgpd) {
+    sgpd->cenc_sample_encryption_info_entries.resize(1);
+    sgpd->cenc_sample_encryption_info_entries[0].is_protected = 1;
+    sgpd->cenc_sample_encryption_info_entries[0].per_sample_iv_size = 0;
+    sgpd->cenc_sample_encryption_info_entries[0].constant_iv.assign(
+        kData16Bytes, kData16Bytes + arraysize(kData16Bytes));
+    sgpd->cenc_sample_encryption_info_entries[0].key_id.resize(16);
+  }
+
+  void Fill(SampleToGroup* sbgp) {
+    sbgp->grouping_type = FOURCC_seig;
+    sbgp->entries.resize(2);
+    sbgp->entries[0].sample_count = 3;
+    sbgp->entries[0].group_description_index = 0x10002;
+    sbgp->entries[1].sample_count = 1212;
+    sbgp->entries[1].group_description_index = 0x10001;
+  }
+
+  void Modify(SampleToGroup* sbgp) {
+    sbgp->entries.resize(1);
+    sbgp->entries[0].sample_count = 5;
+    sbgp->entries[0].group_description_index = 0x10001;
+  }
+
   void Fill(SampleTable* stbl) {
     Fill(&stbl->description);
     Fill(&stbl->decoding_time_to_sample);
@@ -575,11 +614,17 @@ class BoxDefinitionsTestGeneral : public testing::Test {
     Fill(&stbl->sample_size);
     Fill(&stbl->chunk_large_offset);
     Fill(&stbl->sync_sample);
+    stbl->sample_group_descriptions.resize(1);
+    Fill(&stbl->sample_group_descriptions[0]);
+    stbl->sample_to_groups.resize(1);
+    Fill(&stbl->sample_to_groups[0]);
   }
 
   void Modify(SampleTable* stbl) {
     Modify(&stbl->chunk_large_offset);
     Modify(&stbl->sync_sample);
+    stbl->sample_group_descriptions.clear();
+    stbl->sample_to_groups.clear();
   }
 
   void Fill(MediaHeader* mdhd) {
@@ -768,47 +813,6 @@ class BoxDefinitionsTestGeneral : public testing::Test {
     trun->version = 0;
   }
 
-  void Fill(SampleToGroup* sbgp) {
-    sbgp->grouping_type = FOURCC_seig;
-    sbgp->entries.resize(2);
-    sbgp->entries[0].sample_count = 3;
-    sbgp->entries[0].group_description_index = 0x10002;
-    sbgp->entries[1].sample_count = 1212;
-    sbgp->entries[1].group_description_index = 0x10001;
-  }
-
-  void Modify(SampleToGroup* sbgp) {
-    sbgp->entries.resize(1);
-    sbgp->entries[0].sample_count = 5;
-    sbgp->entries[0].group_description_index = 0x10001;
-  }
-
-  void Fill(SampleGroupDescription* sgpd) {
-    sgpd->grouping_type = FOURCC_seig;
-    sgpd->entries.resize(3);
-    sgpd->entries[0].is_protected = 1;
-    sgpd->entries[0].per_sample_iv_size = 8;
-    sgpd->entries[0].key_id.assign(kData16Bytes,
-                                   kData16Bytes + arraysize(kData16Bytes));
-    sgpd->entries[0].crypt_byte_block = 3;
-    sgpd->entries[0].skip_byte_block = 7;
-    sgpd->entries[1].is_protected = 0;
-    sgpd->entries[1].per_sample_iv_size = 0;
-    sgpd->entries[1].key_id.resize(16);
-    sgpd->entries[2].is_protected = 1;
-    sgpd->entries[2].per_sample_iv_size = 0;
-    sgpd->entries[2].constant_iv.assign(kData16Bytes,
-                                        kData16Bytes + arraysize(kData16Bytes));
-    sgpd->entries[2].key_id.resize(16);
-    sgpd->version = 1;
-  }
-
-  void Modify(SampleGroupDescription* sgpd) {
-    sgpd->entries.resize(1);
-    sgpd->entries[0].key_id[4] = 88;
-    sgpd->version = 1;
-  }
-
   void Fill(TrackFragment* traf) {
     Fill(&traf->header);
     traf->runs.resize(1);
@@ -821,8 +825,19 @@ class BoxDefinitionsTestGeneral : public testing::Test {
   void Modify(TrackFragment* traf) {
     Modify(&traf->header);
     Modify(&traf->decode_time);
-    Fill(&traf->sample_to_group);
+
-    Fill(&traf->sample_group_description);
+    traf->sample_group_descriptions.resize(2);
+    Fill(&traf->sample_group_descriptions[0]);
+    traf->sample_group_descriptions[1].grouping_type = FOURCC_roll;
+    traf->sample_group_descriptions[1].audio_roll_recovery_entries.resize(1);
+    traf->sample_group_descriptions[1]
+        .audio_roll_recovery_entries[0]
+        .roll_distance = -10;
+
+    traf->sample_to_groups.resize(2);
+    Fill(&traf->sample_to_groups[0]);
+    Modify(&traf->sample_to_groups[1]);
+    traf->sample_to_groups[1].grouping_type = FOURCC_roll;
   }
 
   void Fill(MovieFragment* moof) {
@@ -951,10 +966,10 @@ class BoxDefinitionsTestGeneral : public testing::Test {
   bool IsOptional(const WebVTTSourceLabelBox* box) { return true; }
   bool IsOptional(const CompositionTimeToSample* box) { return true; }
   bool IsOptional(const SyncSample* box) { return true; }
+  bool IsOptional(const SampleGroupDescription* box) { return true; }
+  bool IsOptional(const SampleToGroup* box) { return true; }
   bool IsOptional(const MovieExtendsHeader* box) { return true; }
   bool IsOptional(const MovieExtends* box) { return true; }
-  bool IsOptional(const SampleToGroup* box) { return true; }
-  bool IsOptional(const SampleGroupDescription* box) { return true; }
   bool IsOptional(const CueSourceIDBox* box) { return true; }
   bool IsOptional(const CueIDBox* box) { return true; }
   bool IsOptional(const CueTimeBox* box) { return true; }
@@ -1006,6 +1021,8 @@ typedef testing::Types<FileType,
                        ChunkLargeOffset,
                        ChunkOffset,
                        SyncSample,
+                       SampleGroupDescription,
+                       SampleToGroup,
                        SampleTable>
     Boxes;
 typedef testing::Types<MediaHeader,
@@ -1029,8 +1046,6 @@ typedef testing::Types<MediaHeader,
                        TrackFragment,
                        MovieFragment,
                        SegmentIndex,
-                       SampleToGroup,
-                       SampleGroupDescription,
                        CueSourceIDBox,
                        CueTimeBox,
                        CueIDBox,

packager/media/formats/mp4/encrypting_fragmenter.cc

@@ -67,7 +67,7 @@ EncryptingFragmenter::EncryptingFragmenter(
     FourCC protection_scheme,
     uint8_t crypt_byte_block,
     uint8_t skip_byte_block)
-    : Fragmenter(traf),
+    : Fragmenter(info, traf),
       info_(info),
       encryption_key_(encryption_key.Pass()),
       nalu_length_size_(GetNaluLengthSize(*info)),

packager/media/formats/mp4/encrypting_fragmenter.h

@@ -26,6 +26,7 @@ namespace mp4 {
 /// EncryptingFragmenter generates MP4 fragments with sample encrypted.
 class EncryptingFragmenter : public Fragmenter {
  public:
+  /// @param info contains stream information.
   /// @param traf points to a TrackFragment box.
   /// @param encryption_key contains the encryption parameters.
   /// @param clear_time specifies clear lead duration in units of the current

packager/media/formats/mp4/fragmenter.cc

@@ -9,6 +9,7 @@
 #include <limits>
 
 #include "packager/media/base/buffer_writer.h"
+#include "packager/media/base/audio_stream_info.h"
 #include "packager/media/base/media_sample.h"
 #include "packager/media/formats/mp4/box_definitions.h"
 
@@ -18,10 +19,18 @@ namespace mp4 {
 
 namespace {
 const int64_t kInvalidTime = std::numeric_limits<int64_t>::max();
+
+uint64_t GetSeekPreroll(const StreamInfo& stream_info) {
+  if (stream_info.stream_type() != kStreamAudio) return 0;
+  const AudioStreamInfo& audio_stream_info =
+      static_cast<const AudioStreamInfo&>(stream_info);
+  return audio_stream_info.seek_preroll_ns();
+}
 }  // namespace
 
-Fragmenter::Fragmenter(TrackFragment* traf)
+Fragmenter::Fragmenter(scoped_refptr<StreamInfo> info, TrackFragment* traf)
     : traf_(traf),
+      seek_preroll_(GetSeekPreroll(*info)),
       fragment_initialized_(false),
       fragment_finalized_(false),
       fragment_duration_(0),
@@ -80,6 +89,8 @@ Status Fragmenter::InitializeFragment(int64_t first_sample_dts) {
   traf_->runs.clear();
   traf_->runs.resize(1);
   traf_->runs[0].flags = TrackFragmentRun::kDataOffsetPresentMask;
+  traf_->sample_group_descriptions.clear();
+  traf_->sample_to_groups.clear();
   traf_->header.sample_description_index = 1;  // 1-based.
   traf_->header.flags = TrackFragmentHeader::kDefaultBaseIsMoofMask |
                         TrackFragmentHeader::kSampleDescriptionIndexPresentMask;
@@ -113,6 +124,35 @@ void Fragmenter::FinalizeFragment() {
     traf_->runs[0].flags |= TrackFragmentRun::kSampleFlagsPresentMask;
   }
 
+  // Add SampleToGroup boxes. A SampleToGroup box with grouping type of 'roll'
+  // needs to be added if there is seek preroll, referencing sample group
+  // description in track level; Also need to add SampleToGroup boxes
+  // correponding to every SampleGroupDescription boxes, referencing sample
+  // group description in fragment level.
+  DCHECK_EQ(traf_->sample_to_groups.size(), 0u);
+  if (seek_preroll_ > 0) {
+    traf_->sample_to_groups.resize(traf_->sample_to_groups.size() + 1);
+    SampleToGroup& sample_to_group = traf_->sample_to_groups.back();
+    sample_to_group.grouping_type = FOURCC_roll;
+
+    sample_to_group.entries.resize(1);
+    SampleToGroupEntry& sample_to_group_entry = sample_to_group.entries.back();
+    sample_to_group_entry.sample_count = traf_->runs[0].sample_count;
+    sample_to_group_entry.group_description_index =
+        SampleToGroupEntry::kTrackGroupDescriptionIndexBase + 1;
+  }
+  for (const auto& sample_group_description : traf_->sample_group_descriptions) {
+    traf_->sample_to_groups.resize(traf_->sample_to_groups.size() + 1);
+    SampleToGroup& sample_to_group = traf_->sample_to_groups.back();
+    sample_to_group.grouping_type = sample_group_description.grouping_type;
+
+    sample_to_group.entries.resize(1);
+    SampleToGroupEntry& sample_to_group_entry = sample_to_group.entries.back();
+    sample_to_group_entry.sample_count = traf_->runs[0].sample_count;
+    sample_to_group_entry.group_description_index =
+        SampleToGroupEntry::kTrackFragmentGroupDescriptionIndexBase + 1;
+  }
+
   fragment_finalized_ = true;
   fragment_initialized_ = false;
 }

packager/media/formats/mp4/fragmenter.h

@@ -19,6 +19,7 @@ namespace media {
 
 class BufferWriter;
 class MediaSample;
+class StreamInfo;
 
 namespace mp4 {
 
@@ -29,8 +30,9 @@ struct TrackFragment;
 /// box and corresponding 'mdat' box.
 class Fragmenter {
  public:
+  /// @param info contains stream information.
   /// @param traf points to a TrackFragment box.
-  Fragmenter(TrackFragment* traf);
+  Fragmenter(scoped_refptr<StreamInfo> info, TrackFragment* traf);
 
   virtual ~Fragmenter();
 
@@ -74,6 +76,7 @@ class Fragmenter {
   bool StartsWithSAP();
 
   TrackFragment* traf_;
+  uint64_t seek_preroll_;
   bool fragment_initialized_;
   bool fragment_finalized_;
   uint64_t fragment_duration_;

packager/media/formats/mp4/key_rotation_fragmenter.cc

@@ -107,9 +107,15 @@ Status KeyRotationFragmenter::PrepareFragmentForEncryption(
   // i.e. there is at most one key for the fragment. So there should be only
   // one entry in SampleGroupDescription box and one entry in SampleToGroup box.
   // Fill in SampleGroupDescription box information.
-  traf()->sample_group_description.grouping_type = FOURCC_seig;
+  traf()->sample_group_descriptions.resize(
-  traf()->sample_group_description.entries.resize(1);
+      traf()->sample_group_descriptions.size() + 1);
-  auto& sample_group_entry = traf()->sample_group_description.entries[0];
+  SampleGroupDescription& sample_group_description =
+      traf()->sample_group_descriptions.back();
+  sample_group_description.grouping_type = FOURCC_seig;
+
+  sample_group_description.cenc_sample_encryption_info_entries.resize(1);
+  CencSampleEncryptionInfoEntry& sample_group_entry =
+      sample_group_description.cenc_sample_encryption_info_entries.back();
   sample_group_entry.is_protected = 1;
   if (protection_scheme() == FOURCC_cbcs) {
     // For 'cbcs' scheme, Constant IVs SHALL be used.
@@ -122,23 +128,9 @@ Status KeyRotationFragmenter::PrepareFragmentForEncryption(
   sample_group_entry.skip_byte_block = skip_byte_block();
   sample_group_entry.key_id = encryption_key()->key_id;
 
-  // Fill in SampleToGroup box information.
-  traf()->sample_to_group.grouping_type = FOURCC_seig;
-  traf()->sample_to_group.entries.resize(1);
-  // sample_count is adjusted in |FinalizeFragment| later.
-  traf()->sample_to_group.entries[0].group_description_index =
-      SampleToGroupEntry::kTrackFragmentGroupDescriptionIndexBase + 1;
-
   return Status::OK;
 }
 
-void KeyRotationFragmenter::FinalizeFragmentForEncryption() {
-  EncryptingFragmenter::FinalizeFragmentForEncryption();
-  DCHECK_EQ(1u, traf()->sample_to_group.entries.size());
-  traf()->sample_to_group.entries[0].sample_count =
-      traf()->auxiliary_size.sample_count;
-}
-
 }  // namespace mp4
 }  // namespace media
 }  // namespace edash_packager

packager/media/formats/mp4/key_rotation_fragmenter.h

@@ -23,6 +23,7 @@ struct MovieFragment;
 class KeyRotationFragmenter : public EncryptingFragmenter {
  public:
   /// @param moof points to a MovieFragment box.
+  /// @param info contains stream information.
   /// @param traf points to a TrackFragment box.
   /// @param encryption_key_source points to the source which generates
   ///        encryption keys.
@@ -57,7 +58,6 @@ class KeyRotationFragmenter : public EncryptingFragmenter {
   /// @name Fragmenter implementation overrides.
   /// @{
   Status PrepareFragmentForEncryption(bool enable_encryption) override;
-  void FinalizeFragmentForEncryption() override;
   /// @}
 
  private:

packager/media/formats/mp4/mp4_media_parser.cc

@@ -440,6 +440,34 @@ bool MP4MediaParser::ParseMoov(BoxReader* reader) {
           return false;
       }
 
+      // Extract possible seek preroll.
+      uint64_t seek_preroll_ns = 0;
+      for (const auto& sample_group_description :
+           track->media.information.sample_table.sample_group_descriptions) {
+        if (sample_group_description.grouping_type != FOURCC_roll)
+          continue;
+        const auto& audio_roll_recovery_entries =
+            sample_group_description.audio_roll_recovery_entries;
+        if (audio_roll_recovery_entries.size() != 1) {
+          LOG(WARNING) << "Unexpected number of entries in "
+                          "SampleGroupDescription table with grouping type "
+                          "'roll'.";
+          break;
+        }
+        const int16_t roll_distance_in_samples =
+            audio_roll_recovery_entries[0].roll_distance;
+        if (roll_distance_in_samples < 0) {
+          RCHECK(sampling_frequency != 0);
+          seek_preroll_ns = kNanosecondsPerSecond *
+                            (-roll_distance_in_samples) / sampling_frequency;
+        } else {
+          LOG(WARNING)
+              << "Roll distance is supposed to be negative, but seeing "
+              << roll_distance_in_samples;
+        }
+        break;
+      }
+
       const bool is_encrypted =
           entry.sinf.info.track_encryption.default_is_protected == 1;
       DVLOG(1) << "is_audio_track_encrypted_: " << is_encrypted;
@@ -453,7 +481,7 @@ bool MP4MediaParser::ParseMoov(BoxReader* reader) {
           entry.samplesize,
           num_channels,
           sampling_frequency,
-          0 /* seek preroll */,
+          seek_preroll_ns,
           codec_delay_ns,
           max_bitrate,
           avg_bitrate,

packager/media/formats/mp4/mp4_muxer.cc

@@ -287,10 +287,41 @@ void MP4Muxer::GenerateAudioTrak(const AudioStreamInfo* audio_info,
   audio.channelcount = audio_info->num_channels();
   audio.samplesize = audio_info->sample_bits();
   audio.samplerate = audio_info->sampling_frequency();
-  SampleDescription& sample_description =
+  SampleTable& sample_table = trak->media.information.sample_table;
-      trak->media.information.sample_table.description;
+  SampleDescription& sample_description = sample_table.description;
   sample_description.type = kAudio;
   sample_description.audio_entries.push_back(audio);
+
+  // Opus requires at least one sample group description box and at least one
+  // sample to group box with grouping type 'roll' within sample table box.
+  if (audio_info->codec() == kCodecOpus) {
+    sample_table.sample_group_descriptions.resize(1);
+    SampleGroupDescription& sample_group_description =
+        sample_table.sample_group_descriptions.back();
+    sample_group_description.grouping_type = FOURCC_roll;
+    sample_group_description.audio_roll_recovery_entries.resize(1);
+    // The roll distance is expressed in sample units and always takes negative
+    // values.
+    const uint64_t kNanosecondsPerSecond = 1000000000ull;
+    sample_group_description.audio_roll_recovery_entries[0].roll_distance =
+        -(audio_info->seek_preroll_ns() * audio.samplerate +
+          kNanosecondsPerSecond / 2) /
+        kNanosecondsPerSecond;
+
+    sample_table.sample_to_groups.resize(1);
+    SampleToGroup& sample_to_group = sample_table.sample_to_groups.back();
+    sample_to_group.grouping_type = FOURCC_roll;
+
+    sample_to_group.entries.resize(1);
+    SampleToGroupEntry& sample_to_group_entry = sample_to_group.entries.back();
+    // All samples are in track fragments.
+    sample_to_group_entry.sample_count = 0;
+    sample_to_group_entry.group_description_index =
+        SampleToGroupEntry::kTrackGroupDescriptionIndexBase + 1;
+  } else if (audio_info->seek_preroll_ns() != 0) {
+    LOG(WARNING) << "Unexpected seek preroll for codec " << audio_info->codec();
+    return;
+  }
 }
 
 bool MP4Muxer::GetInitRangeStartAndEnd(uint32_t* start, uint32_t* end) {

packager/media/formats/mp4/segmenter.cc

@@ -170,7 +170,7 @@ Status Segmenter::Initialize(const std::vector<MediaStream*>& streams,
         sidx_->reference_id = i + 1;
     }
     if (!encryption_key_source) {
-      fragmenters_[i] = new Fragmenter(&moof_->tracks[i]);
+      fragmenters_[i] = new Fragmenter(streams[i]->info(), &moof_->tracks[i]);
       continue;
     }