Add AudioBufferStream.

media/filters/decoder_stream.cc

Index: media/filters/decoder_stream.cc
diff --git a/media/filters/decoder_stream.cc b/media/filters/decoder_stream.cc
index ebda8c00594cc948e3fb528e85b4c1ee2f05d1ff..37711bdcee08fdb52dc740ed1272192115972c9d 100644
--- a/media/filters/decoder_stream.cc
+++ b/media/filters/decoder_stream.cc
@@ -10,6 +10,7 @@
 #include "base/location.h"
 #include "base/logging.h"
 #include "base/single_thread_task_runner.h"
+#include "media/base/audio_decoder.h"
 #include "media/base/bind_to_current_loop.h"
 #include "media/base/decoder_buffer.h"
 #include "media/base/demuxer_stream.h"
@@ -28,6 +29,11 @@ const char* GetTraceString<DemuxerStream::VIDEO>() {
   return "DecoderStream<VIDEO>::Decode";
 }
 
+template <>
+const char* GetTraceString<DemuxerStream::AUDIO>() {
+  return "DecoderStream<AUDIO>::Decode";
+}
+
 template <DemuxerStream::Type StreamType>
 DecoderStream<StreamType>::DecoderStream(
     const scoped_refptr<base::SingleThreadTaskRunner>& task_runner,
@@ -65,7 +71,6 @@ void DecoderStream<StreamType>::Initialize(DemuxerStream* stream,
   // TODO(xhwang): DecoderSelector only needs a config to select a decoder.
   decoder_selector_->SelectDecoder(
       stream,
-      StatisticsCB(),
       base::Bind(&DecoderStream<StreamType>::OnDecoderSelected,
                  weak_factory_.GetWeakPtr()));
 }
@@ -95,7 +100,8 @@ void DecoderStream<StreamType>::Read(const ReadCB& read_cb) {
     return;
   }
 
-  ReadFromDemuxerStream();
+  if (!SendQueuedOutput())
+    ReadFromDemuxerStream();
 }
 
 template <DemuxerStream::Type StreamType>
@@ -185,6 +191,12 @@ bool DecoderStream<StreamType>::CanReadWithoutStalling() const {
   return decoder_->CanReadWithoutStalling();
 }
 
+template <>
+bool DecoderStream<DemuxerStream::AUDIO>::CanReadWithoutStalling() const {
+  DCHECK(task_runner_->BelongsToCurrentThread());
+  return true;
+}
+
 template <DemuxerStream::Type StreamType>
 void DecoderStream<StreamType>::OnDecoderSelected(
     scoped_ptr<Decoder> selected_decoder,
@@ -319,6 +331,7 @@ void DecoderStream<StreamType>::OnDecodeOutputReady(
     return;
   }
 
+  DCHECK(output);
   SatisfyRead(OK, output);
 }
 
@@ -336,6 +349,21 @@ void DecoderStream<StreamType>::ReadFromDemuxerStream() {
 }
 
 template <DemuxerStream::Type StreamType>
+bool DecoderStream<StreamType>::SendQueuedOutput() {
+  return false;
+}
+
+template <>
+bool DecoderStream<DemuxerStream::AUDIO>::SendQueuedOutput() {

[xhwang, 2014/02/27 19:52:28]

The name "SendQueuedOutput" is a bit odd. How about adding GetDecodeOutput() to
both AudioDecoder and VideoDecoder, and having VideoDecoder::GetDecodeOutput()
always return NULL, then we don't need this specialization here.

+  AudioDecoder::Status status;
+  if (scoped_refptr<AudioBuffer> buffer = decoder_->GetAudioBuffer(&status)) {
+    OnDecodeOutputReady(0, status, buffer);

[xhwang, 2014/02/27 19:52:28]

since the first parameter is always 0, how about calling SatisfyRead() directly?

+    return true;
+  }
+  return false;
+}
+
+template <DemuxerStream::Type StreamType>
 void DecoderStream<StreamType>::OnBufferReady(
     DemuxerStream::Status status,
     const scoped_refptr<DecoderBuffer>& buffer) {
@@ -387,12 +415,10 @@ void DecoderStream<StreamType>::ReinitializeDecoder() {
   DCHECK(task_runner_->BelongsToCurrentThread());
   DCHECK_EQ(state_, STATE_FLUSHING_DECODER) << state_;
 
-  // TODO(rileya): Specialize this for audio, or, better yet, change
-  // DemuxerStream config getters to be templated.
-  DCHECK(stream_->video_decoder_config().IsValidConfig());
+  DCHECK(StreamTraits::GetDecoderConfig(*stream_).IsValidConfig());
   state_ = STATE_REINITIALIZING_DECODER;
   decoder_->Initialize(
-      stream_->video_decoder_config(),
+      StreamTraits::GetDecoderConfig(*stream_),
       base::Bind(&DecoderStream<StreamType>::OnDecoderReinitialized,
                  weak_factory_.GetWeakPtr()));
 }
@@ -492,4 +518,5 @@ void DecoderStream<StreamType>::OnDecoderStopped() {
 }
 
 template class DecoderStream<DemuxerStream::VIDEO>;
+template class DecoderStream<DemuxerStream::AUDIO>;
 }  // namespace media