Fix encrypted AAC in BMFF by adding subsample info.

AAC audio is sent to the Source Buffer in ADTS format, which requires
adding a header to each media sample. Encrypted subsample information
was not being adjusted to compensate for the extra clear bytes.

TEST=Manual, pending audio decryption support in decoder
BUG=132351


Review URL: https://chromiumcodereview.appspot.com/10886022

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@153854 0039d316-1c4b-4281-b951-d872f2087c98

4 files changed, 43 insertions, 17 deletions

diff --git a/media/mp4/aac.cc b/media/mp4/aac.cc
index 2804d6b..2982687 100644
--- a/media/mp4/aac.cc
+++ b/media/mp4/aac.cc
@@ -156,7 +156,7 @@ ChannelLayout AAC::channel_layout() const {
 }
 
 bool AAC::ConvertEsdsToADTS(std::vector<uint8>* buffer) const {
-  size_t size = buffer->size() + 7;
+  size_t size = buffer->size() + kADTSHeaderSize;
 
   DCHECK(profile_ >= 1 && profile_ <= 4 && frequency_index_ != 0xf &&
          channel_config_ <= 7);
@@ -167,7 +167,7 @@ bool AAC::ConvertEsdsToADTS(std::vector<uint8>* buffer) const {
 
   std::vector<uint8>& adts = *buffer;
 
-  adts.insert(buffer->begin(), 7, 0);
+  adts.insert(buffer->begin(), kADTSHeaderSize, 0);
   adts[0] = 0xff;
   adts[1] = 0xf1;
   adts[2] = ((profile_ - 1) << 6) + (frequency_index_ << 2) +
diff --git a/media/mp4/aac.h b/media/mp4/aac.h
index 73464ee..e12b6a4 100644
--- a/media/mp4/aac.h
+++ b/media/mp4/aac.h
@@ -46,6 +46,9 @@ class MEDIA_EXPORT AAC {
   // unchanged.
   bool ConvertEsdsToADTS(std::vector<uint8>* buffer) const;
 
+  // Size in bytes of the ADTS header added by ConvertEsdsToADTS().
+  static const size_t kADTSHeaderSize = 7;
+
  private:
   bool SkipDecoderGASpecificConfig(BitReader* bit_reader) const;
   bool SkipErrorSpecificConfig() const;
diff --git a/media/mp4/mp4_stream_parser.cc b/media/mp4/mp4_stream_parser.cc
index b025b7a..b8f6331 100644
--- a/media/mp4/mp4_stream_parser.cc
+++ b/media/mp4/mp4_stream_parser.cc
@@ -309,6 +309,25 @@ bool MP4StreamParser::PrepareAVCBuffer(
   return true;
 }
 
+bool MP4StreamParser::PrepareAACBuffer(
+    const AAC& aac_config, std::vector<uint8>* frame_buf,
+    std::vector<SubsampleEntry>* subsamples) const {
+  // Append an ADTS header to every audio sample.
+  RCHECK(aac_config.ConvertEsdsToADTS(frame_buf));
+
+  // As above, adjust subsample information to account for the headers. AAC is
+  // not required to use subsample encryption, so we may need to add an entry.
+  if (subsamples->empty()) {
+    SubsampleEntry entry;
+    entry.clear_bytes = AAC::kADTSHeaderSize;
+    entry.cypher_bytes = frame_buf->size() - AAC::kADTSHeaderSize;
+    subsamples->push_back(entry);
+  } else {
+    (*subsamples)[0].clear_bytes += AAC::kADTSHeaderSize;
+  }
+  return true;
+}
+
 bool MP4StreamParser::EnqueueSample(BufferQueue* audio_buffers,
                                     BufferQueue* video_buffers,
                                     bool* err) {
@@ -366,39 +385,40 @@ bool MP4StreamParser::EnqueueSample(BufferQueue* audio_buffers,
   if (buf_size < runs_->sample_size()) return false;
 
   scoped_ptr<DecryptConfig> decrypt_config;
-  if (runs_->is_encrypted())
+  std::vector<SubsampleEntry> subsamples;
+  if (runs_->is_encrypted()) {
     decrypt_config = runs_->GetDecryptConfig();
+    subsamples = decrypt_config->subsamples();
+  }
 
   std::vector<uint8> frame_buf(buf, buf + runs_->sample_size());
   if (video) {
-    std::vector<SubsampleEntry> subsamples;
-    if (decrypt_config.get())
-      subsamples = decrypt_config->subsamples();
     if (!PrepareAVCBuffer(runs_->video_description().avcc,
                           &frame_buf, &subsamples)) {
       DLOG(ERROR) << "Failed to prepare AVC sample for decode";
       *err = true;
       return false;
     }
-    if (!subsamples.empty()) {
-      decrypt_config.reset(new DecryptConfig(
-          decrypt_config->key_id(),
-          decrypt_config->iv(),
-          decrypt_config->checksum(),
-          decrypt_config->data_offset(),
-          subsamples));
-    }
   }
 
   if (audio) {
-    const AAC& aac = runs_->audio_description().esds.aac;
-    if (!aac.ConvertEsdsToADTS(&frame_buf)) {
-      DLOG(ERROR) << "Failed to convert ESDS to ADTS";
+    if (!PrepareAACBuffer(runs_->audio_description().esds.aac,
+                          &frame_buf, &subsamples)) {
+      DLOG(ERROR) << "Failed to prepare AAC sample for decode";
       *err = true;
       return false;
     }
   }
 
+  if (decrypt_config.get() != NULL && !subsamples.empty()) {
+    decrypt_config.reset(new DecryptConfig(
+        decrypt_config->key_id(),
+        decrypt_config->iv(),
+        decrypt_config->checksum(),
+        decrypt_config->data_offset(),
+        subsamples));
+  }
+
   scoped_refptr<StreamParserBuffer> stream_buf =
     StreamParserBuffer::CopyFrom(&frame_buf[0], frame_buf.size(),
                                  runs_->is_keyframe());
diff --git a/media/mp4/mp4_stream_parser.h b/media/mp4/mp4_stream_parser.h
index 9710fd2..4c8df36 100644
--- a/media/mp4/mp4_stream_parser.h
+++ b/media/mp4/mp4_stream_parser.h
@@ -64,6 +64,9 @@ class MEDIA_EXPORT MP4StreamParser : public StreamParser {
   bool PrepareAVCBuffer(const AVCDecoderConfigurationRecord& avc_config,
                         std::vector<uint8>* frame_buf,
                         std::vector<SubsampleEntry>* subsamples) const;
+  bool PrepareAACBuffer(const AAC& aac_config,
+                        std::vector<uint8>* frame_buf,
+                        std::vector<SubsampleEntry>* subsamples) const;
   bool EnqueueSample(BufferQueue* audio_buffers,
                      BufferQueue* video_buffers,
                      bool* err);