1 // Copyright (c) 2012 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 // AudioOutputDispatcher is a single-threaded base class that dispatches 6 // creation and deletion of audio output streams. AudioOutputProxy objects use 7 // this class to allocate and recycle actual audio output streams. When playback 8 // is started, the proxy calls StartStream() to get an output stream that it 9 // uses to play audio. When playback is stopped, the proxy returns the stream 10 // back to the dispatcher by calling StopStream(). 11 // 12 // AudioManagerBase creates one specialization of AudioOutputDispatcher on the 13 // audio thread for each possible set of audio parameters. I.e streams with 14 // different parameters are managed independently. The AudioOutputDispatcher 15 // instance is then deleted on the audio thread when the AudioManager shuts 16 // down. 17 18 #ifndef MEDIA_AUDIO_AUDIO_OUTPUT_DISPATCHER_H_ 19 #define MEDIA_AUDIO_AUDIO_OUTPUT_DISPATCHER_H_ 20 21 #include "base/basictypes.h" 22 #include "base/memory/ref_counted.h" 23 #include "base/timer/timer.h" 24 #include "media/audio/audio_io.h" 25 #include "media/audio/audio_manager.h" 26 #include "media/audio/audio_parameters.h" 27 28 namespace base { 29 class MessageLoopProxy; 30 } 31 32 namespace media { 33 34 class AudioOutputProxy; 35 36 class MEDIA_EXPORT AudioOutputDispatcher 37 : public base::RefCountedThreadSafe<AudioOutputDispatcher> { 38 public: 39 AudioOutputDispatcher(AudioManager* audio_manager, 40 const AudioParameters& params, 41 const std::string& output_device_id, 42 const std::string& input_device_id); 43 44 // Called by AudioOutputProxy to open the stream. 45 // Returns false, if it fails to open it. 46 virtual bool OpenStream() = 0; 47 48 // Called by AudioOutputProxy when the stream is started. 49 // Uses |callback| to get source data and report errors, if any. 50 // Does *not* take ownership of this callback. 51 // Returns true if started successfully, false otherwise. 52 virtual bool StartStream(AudioOutputStream::AudioSourceCallback* callback, 53 AudioOutputProxy* stream_proxy) = 0; 54 55 // Called by AudioOutputProxy when the stream is stopped. 56 // Ownership of the |stream_proxy| is passed to the dispatcher. 57 virtual void StopStream(AudioOutputProxy* stream_proxy) = 0; 58 59 // Called by AudioOutputProxy when the volume is set. 60 virtual void StreamVolumeSet(AudioOutputProxy* stream_proxy, 61 double volume) = 0; 62 63 // Called by AudioOutputProxy when the stream is closed. 64 virtual void CloseStream(AudioOutputProxy* stream_proxy) = 0; 65 66 // Called on the audio thread when the AudioManager is shutting down. 67 virtual void Shutdown() = 0; 68 69 // Called by the AudioManager to restart streams when a wedge is detected. A 70 // wedge means the OS failed to request any audio after StartStream(). When a 71 // wedge is detected all streams across all dispatchers must be closed. After 72 // all streams are closed, streams are restarted. See http://crbug.com/160920 73 virtual void CloseStreamsForWedgeFix() = 0; 74 virtual void RestartStreamsForWedgeFix() = 0; 75 76 // Accessor to the input device id used by unified IO. 77 const std::string& input_device_id() const { return input_device_id_; } 78 79 protected: 80 friend class base::RefCountedThreadSafe<AudioOutputDispatcher>; 81 virtual ~AudioOutputDispatcher(); 82 83 // A no-reference-held pointer (we don't want circular references) back to the 84 // AudioManager that owns this object. 85 AudioManager* audio_manager_; 86 const scoped_refptr<base::MessageLoopProxy> message_loop_; 87 const AudioParameters params_; 88 std::string output_device_id_; 89 const std::string input_device_id_; 90 91 private: 92 DISALLOW_COPY_AND_ASSIGN(AudioOutputDispatcher); 93 }; 94 95 } // namespace media 96 97 #endif // MEDIA_AUDIO_AUDIO_OUTPUT_DISPATCHER_H_ 98
