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      1 // Copyright 2013 The Chromium Authors. All rights reserved.
      2 // Use of this source code is governed by a BSD-style license that can be
      3 // found in the LICENSE file.
      4 
      5 #ifndef MEDIA_BLINK_WEBAUDIOSOURCEPROVIDER_IMPL_H_
      6 #define MEDIA_BLINK_WEBAUDIOSOURCEPROVIDER_IMPL_H_
      7 
      8 #include "base/callback.h"
      9 #include "base/memory/weak_ptr.h"
     10 #include "base/synchronization/lock.h"
     11 #include "media/base/audio_renderer_sink.h"
     12 #include "media/base/media_export.h"
     13 #include "third_party/WebKit/public/platform/WebAudioSourceProvider.h"
     14 #include "third_party/WebKit/public/platform/WebVector.h"
     15 
     16 namespace blink {
     17 class WebAudioSourceProviderClient;
     18 }
     19 
     20 namespace media {
     21 
     22 // WebAudioSourceProviderImpl provides a bridge between classes:
     23 //     blink::WebAudioSourceProvider <---> AudioRendererSink
     24 //
     25 // WebAudioSourceProviderImpl wraps an existing audio sink that is used unless
     26 // WebKit has set a client via setClient(). While a client is set WebKit will
     27 // periodically call provideInput() to render a certain number of audio
     28 // sample-frames using the sink's RenderCallback to get the data.
     29 //
     30 // All calls are protected by a lock.
     31 class MEDIA_EXPORT WebAudioSourceProviderImpl
     32     : NON_EXPORTED_BASE(public blink::WebAudioSourceProvider),
     33       NON_EXPORTED_BASE(public AudioRendererSink) {
     34  public:
     35   explicit WebAudioSourceProviderImpl(
     36       const scoped_refptr<AudioRendererSink>& sink);
     37 
     38   // blink::WebAudioSourceProvider implementation.
     39   virtual void setClient(blink::WebAudioSourceProviderClient* client);
     40   virtual void provideInput(const blink::WebVector<float*>& audio_data,
     41                             size_t number_of_frames);
     42 
     43   // AudioRendererSink implementation.
     44   virtual void Start() OVERRIDE;
     45   virtual void Stop() OVERRIDE;
     46   virtual void Play() OVERRIDE;
     47   virtual void Pause() OVERRIDE;
     48   virtual bool SetVolume(double volume) OVERRIDE;
     49   virtual void Initialize(const AudioParameters& params,
     50                           RenderCallback* renderer) OVERRIDE;
     51 
     52  protected:
     53   virtual ~WebAudioSourceProviderImpl();
     54 
     55  private:
     56   // Calls setFormat() on |client_| from the Blink renderer thread.
     57   void OnSetFormat();
     58 
     59   // Closure that posts a task to call OnSetFormat() on the renderer thread.
     60   base::Closure set_format_cb_;
     61 
     62   // Set to true when Initialize() is called.
     63   int channels_;
     64   int sample_rate_;
     65   double volume_;
     66 
     67   // Tracks the current playback state.
     68   enum PlaybackState { kStopped, kStarted, kPlaying };
     69   PlaybackState state_;
     70 
     71   // Where audio comes from.
     72   AudioRendererSink::RenderCallback* renderer_;
     73 
     74   // When set via setClient() it overrides |sink_| for consuming audio.
     75   blink::WebAudioSourceProviderClient* client_;
     76 
     77   // Where audio ends up unless overridden by |client_|.
     78   base::Lock sink_lock_;
     79   scoped_refptr<AudioRendererSink> sink_;
     80   scoped_ptr<AudioBus> bus_wrapper_;
     81 
     82   // NOTE: Weak pointers must be invalidated before all other member variables.
     83   base::WeakPtrFactory<WebAudioSourceProviderImpl> weak_factory_;
     84 
     85   DISALLOW_IMPLICIT_CONSTRUCTORS(WebAudioSourceProviderImpl);
     86 };
     87 
     88 }  // namespace media
     89 
     90 #endif  // MEDIA_BLINK_WEBAUDIOSOURCEPROVIDER_IMPL_H_
     91