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 28namespace base { 29class SingleThreadTaskRunner; 30} 31 32namespace media { 33 34class AudioOutputProxy; 35 36class MEDIA_EXPORT AudioOutputDispatcher 37 : public base::RefCountedThreadSafe<AudioOutputDispatcher> { 38 public: 39 AudioOutputDispatcher(AudioManager* audio_manager, 40 const AudioParameters& params, 41 const std::string& device_id); 42 43 // Called by AudioOutputProxy to open the stream. 44 // Returns false, if it fails to open it. 45 virtual bool OpenStream() = 0; 46 47 // Called by AudioOutputProxy when the stream is started. 48 // Uses |callback| to get source data and report errors, if any. 49 // Does *not* take ownership of this callback. 50 // Returns true if started successfully, false otherwise. 51 virtual bool StartStream(AudioOutputStream::AudioSourceCallback* callback, 52 AudioOutputProxy* stream_proxy) = 0; 53 54 // Called by AudioOutputProxy when the stream is stopped. 55 // Ownership of the |stream_proxy| is passed to the dispatcher. 56 virtual void StopStream(AudioOutputProxy* stream_proxy) = 0; 57 58 // Called by AudioOutputProxy when the volume is set. 59 virtual void StreamVolumeSet(AudioOutputProxy* stream_proxy, 60 double volume) = 0; 61 62 // Called by AudioOutputProxy when the stream is closed. 63 virtual void CloseStream(AudioOutputProxy* stream_proxy) = 0; 64 65 // Called on the audio thread when the AudioManager is shutting down. 66 virtual void Shutdown() = 0; 67 68 const std::string& device_id() const { return device_id_; } 69 70 protected: 71 friend class base::RefCountedThreadSafe<AudioOutputDispatcher>; 72 virtual ~AudioOutputDispatcher(); 73 74 // A no-reference-held pointer (we don't want circular references) back to the 75 // AudioManager that owns this object. 76 AudioManager* audio_manager_; 77 const scoped_refptr<base::SingleThreadTaskRunner> task_runner_; 78 const AudioParameters params_; 79 std::string device_id_; 80 81 private: 82 DISALLOW_COPY_AND_ASSIGN(AudioOutputDispatcher); 83}; 84 85} // namespace media 86 87#endif // MEDIA_AUDIO_AUDIO_OUTPUT_DISPATCHER_H_ 88