text: // 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.
  //
  // AudioRendererHost serves audio related requests from AudioRenderer which
  // lives inside the render process and provide access to audio hardware.
  //
  // This class is owned by BrowserRenderProcessHost, and instantiated on UI
  // thread, but all other operations and method calls happen on IO thread, so we
  // need to be extra careful about the lifetime of this object. AudioManager is a
  // singleton and created in IO thread, audio output streams are also created in
  // the IO thread, so we need to destroy them also in IO thread. After this class
  // is created, a task of OnInitialized() is posted on IO thread in which
  // singleton of AudioManager is created.
  //
  // Here's an example of a typical IPC dialog for audio:
  //
  //   Renderer                     AudioRendererHost
  //      |                               |
  //      |         CreateStream >        |
  //      |     < NotifyStreamCreated     |
  //      |                               |
  //      |          PlayStream >         |
  //      |  < NotifyStreamStateChanged   | kAudioStreamPlaying
  //      |                               |
  //      |         PauseStream >         |
  //      |  < NotifyStreamStateChanged   | kAudioStreamPaused
  //      |                               |
  //      |          PlayStream >         |
  //      |  < NotifyStreamStateChanged   | kAudioStreamPlaying
  //      |             ...               |
  //      |         CloseStream >         |
  //      v                               v
  
  // A SyncSocket pair is used to signal buffer readiness between processes.
  
  #ifndef CONTENT_BROWSER_RENDERER_HOST_MEDIA_AUDIO_RENDERER_HOST_H_
  #define CONTENT_BROWSER_RENDERER_HOST_MEDIA_AUDIO_RENDERER_HOST_H_
  
  #include <map>
  
  #include "base/gtest_prod_util.h"
  #include "base/memory/ref_counted.h"
  #include "base/memory/scoped_ptr.h"
  #include "base/process/process.h"
  #include "base/sequenced_task_runner_helpers.h"
  #include "content/common/content_export.h"
  #include "content/public/browser/browser_message_filter.h"
  #include "content/public/browser/browser_thread.h"
  #include "content/public/browser/render_view_host.h"
  #include "media/audio/audio_io.h"
  #include "media/audio/audio_output_controller.h"
  #include "media/audio/simple_sources.h"
  
  namespace media {
  class AudioManager;
  class AudioParameters;
  }
  
  namespace content {
  
  class AudioMirroringManager;
  class MediaInternals;
  class MediaStreamManager;
  class ResourceContext;
  
  class CONTENT_EXPORT AudioRendererHost : public BrowserMessageFilter {
   public:
    // Called from UI thread from the owner of this object.
    AudioRendererHost(int render_process_id,
                      media::AudioManager* audio_manager,
                      AudioMirroringManager* mirroring_manager,
                      MediaInternals* media_internals,
                      MediaStreamManager* media_stream_manager);
  
    // Calls |callback| with the list of AudioOutputControllers for this object.
    void GetOutputControllers(
        int render_view_id,
        const RenderViewHost::GetAudioOutputControllersCallback& callback) const;
  
    // BrowserMessageFilter implementation.
    virtual void OnChannelClosing() OVERRIDE;
    virtual void OnDestruct() const OVERRIDE;
    virtual bool OnMessageReceived(const IPC::Message& message,
                                   bool* message_was_ok) OVERRIDE;
  
   private:
    friend class AudioRendererHostTest;
    friend class BrowserThread;
    friend class base::DeleteHelper<AudioRendererHost>;
    friend class MockAudioRendererHost;
    friend class TestAudioRendererHost;
    FRIEND_TEST_ALL_PREFIXES(AudioRendererHostTest, CreateMockStream);
    FRIEND_TEST_ALL_PREFIXES(AudioRendererHostTest, MockStreamDataConversation);
  
    class AudioEntry;
    typedef std::map<int, AudioEntry*> AudioEntryMap;
  
    virtual ~AudioRendererHost();
  
    // Methods called on IO thread ----------------------------------------------
  
    // Audio related IPC message handlers.
  
    // Creates an audio output stream with the specified format whose data is
    // produced by an entity in the render view referenced by |render_view_id|.
    // |session_id| is used for unified IO to find out which input device to be
    // opened for the stream. For clients that do not use unified IO,
    // |session_id| will be ignored.
    // Upon success/failure, the peer is notified via the NotifyStreamCreated
    // message.
    void OnCreateStream(int stream_id,
                        int render_view_id,
                        int session_id,
                        const media::AudioParameters& params);
  
    // Play the audio stream referenced by |stream_id|.
    void OnPlayStream(int stream_id);
  
    // Pause the audio stream referenced by |stream_id|.
    void OnPauseStream(int stream_id);
  
    // Close the audio stream referenced by |stream_id|.
    void OnCloseStream(int stream_id);
  
    // Set the volume of the audio stream referenced by |stream_id|.
    void OnSetVolume(int stream_id, double volume);
  
    // Complete the process of creating an audio stream. This will set up the
    // shared memory or shared socket in low latency mode and send the
    // NotifyStreamCreated message to the peer.
    void DoCompleteCreation(int stream_id);
  
    RenderViewHost::AudioOutputControllerList DoGetOutputControllers(
        int render_view_id) const;
  
    // Propagate measured power level of the audio signal to MediaObserver.
    void DoNotifyAudioPowerLevel(int stream_id, float power_dbfs, bool clipped);
  
    // Send an error message to the renderer.
    void SendErrorMessage(int stream_id);
  
    // Delete an audio entry, notifying observers first.  This is called by
    // AudioOutputController after it has closed.
    void DeleteEntry(scoped_ptr<AudioEntry> entry);
  
    // Send an error message to the renderer, then close the stream.
    void ReportErrorAndClose(int stream_id);
  
    // A helper method to look up a AudioEntry identified by |stream_id|.
    // Returns NULL if not found.
    AudioEntry* LookupById(int stream_id);
  
    // ID of the RenderProcessHost that owns this instance.
    const int render_process_id_;
  
    media::AudioManager* const audio_manager_;
    AudioMirroringManager* const mirroring_manager_;
    MediaInternals* const media_internals_;
  
    // Used to access to AudioInputDeviceManager.
    MediaStreamManager* media_stream_manager_;
  
    // A map of stream IDs to audio sources.
    AudioEntryMap audio_entries_;
  
    DISALLOW_COPY_AND_ASSIGN(AudioRendererHost);
  };
  
  }  // namespace content
  
  #endif  // CONTENT_BROWSER_RENDERER_HOST_MEDIA_AUDIO_RENDERER_HOST_H_
  