Add AudioBufferStream.

media/base/audio_decoder.h

 // Copyright (c) 2012 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.
 
 #ifndef MEDIA_BASE_AUDIO_DECODER_H_
 #define MEDIA_BASE_AUDIO_DECODER_H_
 
 #include "base/callback.h"
 #include "base/memory/ref_counted.h"
+#include "media/base/audio_decoder_config.h"
 #include "media/base/channel_layout.h"
+#include "media/base/decoder_buffer.h"
+#include "media/base/media_export.h"
 #include "media/base/pipeline_status.h"
-#include "media/base/media_export.h"
 
 namespace media {
 
 class AudioBuffer;
 class DemuxerStream;
 
 class MEDIA_EXPORT AudioDecoder {
  public:
-  // Status codes for read operations.
+  // Status codes for decode operations.
+  // TODO(rileya): Now that both AudioDecoder and VideoDecoder Status enums
+  // match, break them into a decoder_status.h.
   enum Status {
-    kOk,
-    kAborted,
-    kDecodeError,
+    kOk,  // We're all good.
+    kAborted,  // We aborted as a result of Stop() or Reset().
+    kNotEnoughData,  // Not enough data to produce a video frame.
+    kDecodeError,  // A decoding error occurred.
+    kDecryptError  // Decrypting error happened.
   };
 
   AudioDecoder();
   virtual ~AudioDecoder();
 
   // Initializes an AudioDecoder with the given DemuxerStream, executing the
   // callback upon completion.
   // statistics_cb is used to update global pipeline statistics.
-  virtual void Initialize(DemuxerStream* stream,
-                          const PipelineStatusCB& status_cb,
-                          const StatisticsCB& statistics_cb) = 0;
+  virtual void Initialize(const AudioDecoderConfig& config,
+                          const PipelineStatusCB& status_cb) = 0;
 
   // Requests samples to be decoded and returned via the provided callback.
-  // Only one read may be in flight at any given time.
+  // Only one decode may be in flight at any given time.
   //
   // Implementations guarantee that the callback will not be called from within
   // this method.
   //
   // Non-NULL sample buffer pointers will contain decoded audio data or may
   // indicate the end of the stream. A NULL buffer pointer indicates an aborted
-  // Read(). This can happen if the DemuxerStream gets flushed and doesn't have
-  // any more data to return.
+  // Decode().
   typedef base::Callback<void(Status, const scoped_refptr<AudioBuffer>&)>
-      ReadCB;
-  virtual void Read(const ReadCB& read_cb) = 0;
+      DecodeCB;
+  virtual void Decode(const scoped_refptr<DecoderBuffer>& buffer,
+                      const DecodeCB& decode_cb) = 0;
+
+  // Some AudioDecoders will queue up multiple AudioBuffers from a single
+  // DecoderBuffer, if we have any such queued buffers this will return the next
+  // one. Otherwise we return a NULL AudioBuffer.
+  virtual scoped_refptr<AudioBuffer> GetDecodeOutput();
 
   // Resets decoder state, dropping any queued encoded data.
   virtual void Reset(const base::Closure& closure) = 0;
 
   // Stops decoder, fires any pending callbacks and sets the decoder to an
   // uninitialized state. An AudioDecoder cannot be re-initialized after it has
   // been stopped.
   // Note that if Initialize() has been called, Stop() must be called and
   // complete before deleting the decoder.
   virtual void Stop(const base::Closure& closure) = 0;
 
   // Returns various information about the decoded audio format.
   virtual int bits_per_channel() = 0;
   virtual ChannelLayout channel_layout() = 0;
   virtual int samples_per_second() = 0;
 
  private:
   DISALLOW_COPY_AND_ASSIGN(AudioDecoder);
 };
 
 }  // namespace media
 
 #endif  // MEDIA_BASE_AUDIO_DECODER_H_