Merge AudioRendererImpl and AudioRendererBase; add NullAudioSink

This CL removes AudioRendererImpl and replaces it with AudioRendererBase.
NullAudioRenderer is also removed and replaced with NullAudioSink.
Also, a subtle bug is fixed in AudioRendererBase to allow for smooth
video playback when running Chrome with the --disable-audio flag.

BUG=119549,116645
TEST=media_unittests, playing video on Chrome/content_shell with and without --disable-audio flag should look identical


Review URL: http://codereview.chromium.org/9826023

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@131089 0039d316-1c4b-4281-b951-d872f2087c98

1 files changed, 65 insertions, 0 deletions

diff --git a/media/audio/null_audio_sink.h b/media/audio/null_audio_sink.h
new file mode 100644
index 0000000..32245eb
--- /dev/null
+++ b/media/audio/null_audio_sink.h
@@ -0,0 +1,65 @@
+// 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_FILTERS_NULL_AUDIO_RENDERER_H_
+#define MEDIA_FILTERS_NULL_AUDIO_RENDERER_H_
+
+// NullAudioSink effectively uses an extra thread to "throw away" the
+// audio data at a rate resembling normal playback speed.  It's just like
+// decoding to /dev/null!
+//
+// NullAudioSink can also be used in situations where the client has no
+// audio device or we haven't written an audio implementation for a particular
+// platform yet.
+
+#include <vector>
+
+#include "base/threading/thread.h"
+#include "media/base/audio_renderer_sink.h"
+
+namespace media {
+
+class MEDIA_EXPORT NullAudioSink
+    : NON_EXPORTED_BASE(public AudioRendererSink) {
+ public:
+  NullAudioSink();
+  virtual ~NullAudioSink();
+
+  // AudioRendererSink implementation.
+  virtual void Initialize(const AudioParameters& params,
+                          RenderCallback* callback) OVERRIDE;
+  virtual void Start() OVERRIDE;
+  virtual void Stop() OVERRIDE;
+  virtual void Pause(bool flush) OVERRIDE;
+  virtual void Play() OVERRIDE;
+  virtual void SetPlaybackRate(float rate) OVERRIDE;
+  virtual bool SetVolume(double volume) OVERRIDE;
+  virtual void GetVolume(double* volume) OVERRIDE;
+
+ private:
+  // Audio thread task that periodically calls FillBuffer() to consume
+  // audio data.
+  void FillBufferTask();
+
+  void SetPlaying(bool is_playing);
+
+  // A buffer passed to FillBuffer to advance playback.
+  std::vector<float*> audio_data_;
+
+  AudioParameters params_;
+  bool initialized_;
+  float playback_rate_;
+  bool playing_;
+  RenderCallback* callback_;
+
+  // Separate thread used to throw away data.
+  base::Thread thread_;
+  base::Lock lock_;
+
+  DISALLOW_COPY_AND_ASSIGN(NullAudioSink);
+};
+
+}  // namespace media
+
+#endif  // MEDIA_FILTERS_NULL_AUDIO_RENDERER_H_