Support parsing of sgpd and sbgp boxes

media/formats/mp4/box_definitions.cc

 // 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"
 
@@ skipping 742 matching lines @@
   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;
 }
 
+SampleToGroup::SampleToGroup() : grouping_type(0), grouping_type_parameter(0) {}
+SampleToGroup::~SampleToGroup() {}
+FourCC SampleToGroup::BoxType() const { return FOURCC_SBGP; }
+
+bool SampleToGroup::Parse(BoxReader* reader) {
+  RCHECK(reader->ReadFullBoxHeader() &&
+         reader->Read4(&grouping_type));
+
+  if (reader->version() == 1)
+    RCHECK(reader->Read4(&grouping_type_parameter));
+
+  if (grouping_type != FOURCC_SEIG) {
+    DLOG(WARNING) << "SampleToGroup box with grouping_type '" << grouping_type
+                  << "' is not supported.";
+    return true;
+  }
+
+  uint32 count;
+  RCHECK(reader->Read4(&count));
+  entries.resize(count);
+  for (uint32 i = 0; i < count; ++i) {
+    RCHECK(reader->Read4(&entries[i].sample_count) &&
+           reader->Read4(&entries[i].group_description_index));
+  }
+  return true;
+}
+
+CencSampleEncryptionInfoEntry::CencSampleEncryptionInfoEntry()
+    : is_encrypted(false), iv_size(0) {}
+CencSampleEncryptionInfoEntry::~CencSampleEncryptionInfoEntry() {}
+
+SampleGroupDescription::SampleGroupDescription() : grouping_type(0) {}
+SampleGroupDescription::~SampleGroupDescription() {}
+FourCC SampleGroupDescription::BoxType() const { return FOURCC_SGPD; }
+
+bool SampleGroupDescription::Parse(BoxReader* reader) {
+  RCHECK(reader->ReadFullBoxHeader() &&
+         reader->Read4(&grouping_type));
+
+  if (grouping_type != FOURCC_SEIG) {
+    DLOG(WARNING) << "SampleGroupDescription box with grouping_type '"
+                  << grouping_type << "' is not supported.";
+    return true;
+  }
+
+  const uint8 version = reader->version();
+
+  const size_t kKeyIdSize = 16;
+  const size_t kEntrySize = sizeof(uint32) + kKeyIdSize;
+  uint32 default_length = 0;
+  if (version == 1) {
+      RCHECK(reader->Read4(&default_length));
+      RCHECK(default_length == 0 || default_length == kEntrySize);
+  }
+
+  uint32 count;
+  RCHECK(reader->Read4(&count));
+  entries.resize(count);
+  for (uint32 i = 0; i < count; ++i) {
+    if (version == 1) {
+      if (default_length == 0) {
+        uint32 description_length = 0;
+        RCHECK(reader->Read4(&description_length));
+        RCHECK(description_length == kEntrySize);
+      }
+    }
+
+    uint8 flag;
+    RCHECK(reader->SkipBytes(2) &&  // reserved.
+           reader->Read1(&flag) &&
+           reader->Read1(&entries[i].iv_size) &&
+           reader->ReadVec(&entries[i].key_id, kKeyIdSize));
+
+    entries[i].is_encrypted = (flag != 0);
+    if (entries[i].is_encrypted) {
+      RCHECK(entries[i].iv_size == 8 || entries[i].iv_size == 16);
+    } else {
+      RCHECK(entries[i].iv_size == 0);
+    }
+  }
+  return true;
+}
+
 TrackFragment::TrackFragment() {}
 TrackFragment::~TrackFragment() {}
 FourCC TrackFragment::BoxType() const { return FOURCC_TRAF; }
 
 bool TrackFragment::Parse(BoxReader* reader) {
-  return reader->ScanChildren() &&
+  RCHECK(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);
+         reader->MaybeReadChild(&sdtp));
+
+  // Continue reading until SEIG is found, or until run out of child boxes.
+  while (sample_group_description.grouping_type != FOURCC_SEIG &&
+         reader->HasChild(&sample_group_description)) {
+    RCHECK(reader->ReadChild(&sample_group_description));
+  }
+  while (sample_to_group.grouping_type != FOURCC_SEIG &&
+         reader->HasChild(&sample_to_group)) {
+    RCHECK(reader->ReadChild(&sample_to_group));
+  }

[xhwang, 2014/05/01 19:11:28]

Why can't we use MaybeReadChild? Is it because there could be multiple sbgp or
sgpd boxes with other grouping types? It may worth some comments to explain why.

[kqyang, 2014/05/01 20:26:35]

Yes, MaybeReadChild does not tell us whether it reads successfully or it returns
true because there are no more child boxes.

Added more comments explaining it.

+  return true;
 }
 
 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) &&
@@ skipping 28 matching lines @@
 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