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 // Creates an audio output stream based on the PulseAudio asynchronous API; 6 // specifically using the pa_threaded_mainloop model. 7 // 8 // If the stream is successfully opened, Close() must be called before the 9 // stream is deleted as Close() is responsible for ensuring resource cleanup 10 // occurs. 11 // 12 // This object is designed so that all AudioOutputStream methods will be called 13 // on the same thread that created the object. 14 // 15 // WARNING: This object blocks on internal PulseAudio calls in Open() while 16 // waiting for PulseAudio's context structure to be ready. It also blocks in 17 // inside PulseAudio in Start() and repeated during playback, waiting for 18 // PulseAudio write callbacks to occur. 19 20 #ifndef MEDIA_AUDIO_PULSE_PULSE_OUTPUT_H_ 21 #define MEDIA_AUDIO_PULSE_PULSE_OUTPUT_H_ 22 23 #include "base/memory/scoped_ptr.h" 24 #include "media/audio/audio_io.h" 25 #include "media/audio/audio_parameters.h" 26 27 struct pa_context; 28 struct pa_operation; 29 struct pa_stream; 30 struct pa_threaded_mainloop; 31 32 namespace media { 33 class AudioManagerBase; 34 35 class PulseAudioOutputStream : public AudioOutputStream { 36 public: 37 PulseAudioOutputStream(const AudioParameters& params, 38 AudioManagerBase* manager); 39 40 virtual ~PulseAudioOutputStream(); 41 42 // Implementation of AudioOutputStream. 43 virtual bool Open() OVERRIDE; 44 virtual void Close() OVERRIDE; 45 virtual void Start(AudioSourceCallback* callback) OVERRIDE; 46 virtual void Stop() OVERRIDE; 47 virtual void SetVolume(double volume) OVERRIDE; 48 virtual void GetVolume(double* volume) OVERRIDE; 49 50 private: 51 // Called by PulseAudio when |pa_stream_| change state. If an unexpected 52 // failure state change happens and |source_callback_| is set 53 // this method will forward the error via OnError(). 54 static void StreamNotifyCallback(pa_stream* s, void* p_this); 55 56 // Called by PulseAudio when it needs more audio data. 57 static void StreamRequestCallback(pa_stream* s, size_t len, void* p_this); 58 59 // Fulfill a write request from the write request callback. Outputs silence 60 // if the request could not be fulfilled. 61 void FulfillWriteRequest(size_t requested_bytes); 62 63 // Close() helper function to free internal structs. 64 void Reset(); 65 66 // AudioParameters from the constructor. 67 const AudioParameters params_; 68 69 // Audio manager that created us. Used to report that we've closed. 70 AudioManagerBase* manager_; 71 72 // PulseAudio API structs. 73 pa_context* pa_context_; 74 pa_threaded_mainloop* pa_mainloop_; 75 pa_stream* pa_stream_; 76 77 // Float representation of volume from 0.0 to 1.0. 78 float volume_; 79 80 // Callback to audio data source. Must only be modified while holding a lock 81 // on |pa_mainloop_| via pa_threaded_mainloop_lock(). 82 AudioSourceCallback* source_callback_; 83 84 // Container for retrieving data from AudioSourceCallback::OnMoreData(). 85 scoped_ptr<AudioBus> audio_bus_; 86 87 DISALLOW_COPY_AND_ASSIGN(PulseAudioOutputStream); 88 }; 89 90 } // namespace media 91 92 #endif // MEDIA_AUDIO_PULSE_PULSE_OUTPUT_H_ 93
