Implemented AudioRendererImpl in renderer process using API

provided by RenderView for accessing audio device in the
browser using IPC, subclassing from media::AudioRendererBase
for buffer filling.

Review URL: http://codereview.chromium.org/28081

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@11392 0039d316-1c4b-4281-b951-d872f2087c98

1 files changed, 149 insertions, 14 deletions

diff --git a/chrome/renderer/media/audio_renderer_impl.h b/chrome/renderer/media/audio_renderer_impl.h
index 9d6b0b4..c0a8257 100644
--- a/chrome/renderer/media/audio_renderer_impl.h
+++ b/chrome/renderer/media/audio_renderer_impl.h
@@ -1,49 +1,184 @@
 // Copyright (c) 2009 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.
+//
+// Audio rendering unit utilizing audio output stream provided by browser
+// process through IPC.
+//
+// Relationship of classes.
+//
+//    AudioRendererHost            AudioRendererImpl
+//           ^                             ^
+//           |                             |
+//           v                 IPC         v
+//   ResourceMessageFilter <---------> RenderView
+//
+// Implementation of interface with audio device is in AudioRendererHost and
+// it provides services and entry points in ResourceMessageFilter, allowing
+// usage of IPC calls to interact with audio device. RenderView acts as a portal
+// for IPC calls and does no more than delegation.
+//
+// Transportation of audio buffer is done by using shared memory, after
+// OnCreateAudioStream is executed, OnCreated would be called along with a
+// SharedMemoryHandle upon successful creation of audio output stream in the
+// browser process. The same piece of shared memory would be used during the
+// lifetime of this unit.
+//
+// This class lives inside three threads during it's lifetime, namely:
+// 1. Render thread
+//    The thread within which this class is constructed and destroyed,
+//    interfacing with RenderView should only happen here.
+// 2. Pipeline thread
+//    Initialization of filter and proper stopping of filters happens here.
+//    Properties of this filter is also set in this thread.
+// 3. Audio decoder thread (If there's one.)
+//    Responsible for decoding audio data and gives raw PCM data to this object.
+//
+// Methods categorized according to the thread(s) they are running on.
+//
+// Render thread
+// +-- CreateFactory()
+// |     Helper method for construction this class.
+// |-- IsMetidFormatSupported()
+// |     Helper method to identify media formats accepted by this class for
+// |     construction.
+// |-- OnCreateAudioStream()
+// |     Calls RenderView::CreateAudioStream().
+// |-- OnStartAudioStream()
+// |     Calls RenderView::StartAudioStream().
+// |-- OnCloseAudioStream()
+// |     Calls RenderView::CloseAudioStream().
+// |-- OnSetAudioVolume()
+// |     Calls RenderView::SetAudioVolume().
+// |-- OnNotifyAudioPacketReady
+// |     Calls RenderView::NotifyAudioPacketReady().
+// |-- OnRequestPacket()
+// |     Called from RenderView when an audio packet requested is received
+// |     from browser process.
+// |-- OnStateChanged()
+// |     Called from RenderView upon state change of the audio output stream
+// |     in the browser process. Error of the output stream is reported here.
+// |-- OnCreated()
+// |     Called from RenderView upon successful creation of audio output stream
+// |     in the browser process, called along with a SharedMemoryHandle.
+// |-- OnVolume()
+// |     Called from RenderView about the volume of the audio output stream.
+// \-- ReleaseRendererResource()
+//       Release resources that live inside render thread.
+//
+// Pipeline thread
+// +-- AudioRendererImpl()
+// |     Constructor method.
+// |-- ~AudioRendererImpl()
+// |     Destructor method.
+// |-- SetPlaybackRate()
+// |     Given the playback rate information.
+// |-- GetMediaFormat()
+// |     Obtain the current media format of this unit.
+// |-- SetVolume()
+// |     Given the volume information.
+// |-- OnInitialize()
+// |     Called from AudioRendererBase for initialization event.
+// \-- OnStop()
+//       Called from AudioRendererBase for stop event.
+//
+// Audio decoder thread (If there's one.)
+// \-- OnAssignment()
+//       A raw PCM audio packet buffer is recevied here, this method is called
+//       from pipeline thread if audio decoder thread does not exist.
 
 #ifndef CHROME_RENDERER_MEDIA_AUDIO_RENDERER_IMPL_H_
 #define CHROME_RENDERER_MEDIA_AUDIO_RENDERER_IMPL_H_
 
 #include "base/shared_memory.h"
+#include "base/waitable_event.h"
 #include "media/audio/audio_output.h"
 #include "media/base/factory.h"
 #include "media/base/filters.h"
+#include "media/filters/audio_renderer_base.h"
 
 class WebMediaPlayerDelegateImpl;
 
-class AudioRendererImpl : public media::AudioRenderer {
+class AudioRendererImpl : public media::AudioRendererBase {
  public:
-  AudioRendererImpl(WebMediaPlayerDelegateImpl* delegate);
-
-  // media::MediaFilter implementation.
-  virtual void Stop();
-
-  // media::AudioRenderer implementation.
-  virtual bool Initialize(media::AudioDecoder* decoder);
-  virtual void SetVolume(float volume);
-
-  // Static method for creating factory for this object.
+  // Methods called on render thread ------------------------------------------
+  // Methods called during construction.
   static media::FilterFactory* CreateFactory(
       WebMediaPlayerDelegateImpl* delegate) {
     return new media::FilterFactoryImpl1<AudioRendererImpl,
                                          WebMediaPlayerDelegateImpl*>(delegate);
   }
-
-  // Answers question from the factory to see if we accept |format|.
   static bool IsMediaFormatSupported(const media::MediaFormat* format);
 
+  // Methods call from RenderView when audio related IPC messages are received
+  // from browser process.
   void OnRequestPacket();
   void OnStateChanged(AudioOutputStream::State state, int info);
   void OnCreated(base::SharedMemoryHandle handle, size_t length);
   void OnVolume(double left, double right);
 
+  // Release resources that lives in renderer thread, i.e. audio output streams.
+  void ReleaseRendererResources();
+
+  // Methods called on pipeline thread ----------------------------------------
+  // media::MediaFilter implementation.
+  virtual void SetPlaybackRate(float rate);
+  const media::MediaFormat* GetMediaFormat();
+
+  // media::AudioRenderer implementation.
+  virtual void SetVolume(float volume);
+
+  // AssignableBuffer<AudioRendererBase, BufferInterface> implementation.
+  virtual void OnAssignment(media::Buffer* buffer_in);
+
  protected:
-  virtual ~AudioRendererImpl();
+  // Methods called on audio renderer thread ----------------------------------
+  // These methods are called from AudioRendererBase.
+  virtual bool OnInitialize(const media::MediaFormat* media_format);
+  virtual void OnStop();
 
  private:
+  friend class media::FilterFactoryImpl1<AudioRendererImpl,
+                                         WebMediaPlayerDelegateImpl*>;
+
+  explicit AudioRendererImpl(WebMediaPlayerDelegateImpl* delegate);
+  virtual ~AudioRendererImpl();
+
+  // Methods call on render thread --------------------------------------------
+  // The following methods are tasks posted on the render thread that needs to
+  // be executed on that thread. They interact with WebMediaPlayerDelegateImpl
+  // and the containing RenderView, because method calls to RenderView must be
+  // executed on render thread.
+  void OnCreateAudioStream(AudioManager::Format format, int channels,
+                           int sample_rate, int bits_per_sample,
+                           size_t packet_size);
+  void OnStartAudioStream();
+  void OnCloseAudioStream();
+  void OnSetAudioVolume(double left, double right);
+  void OnNotifyAudioPacketReady();
+
   WebMediaPlayerDelegateImpl* delegate_;
 
+  // A map of media format information.
+  media::MediaFormat media_format_;
+
+  // ID of the stream created in the browser process.
+  int32 stream_id_;
+
+  // Memory shared by the browser process for audio buffer.
+  scoped_ptr<base::SharedMemory> shared_memory_;
+  size_t shared_memory_size_;
+
+  // Flag that tells whether we have any unfulfilled packet request.
+  bool packet_requested_;
+
+  // Message loop for the render thread, it's the message loop where this class
+  // is constructed.
+  MessageLoop* render_loop_;
+
+  // Event for releasing resources that live in render thread.
+  base::WaitableEvent resource_release_event_;
+
   DISALLOW_COPY_AND_ASSIGN(AudioRendererImpl);
 };