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 <string> 24 25 #include "base/memory/scoped_ptr.h" 26 #include "base/threading/thread_checker.h" 27 #include "media/audio/audio_io.h" 28 #include "media/audio/audio_parameters.h" 29 30 struct pa_context; 31 struct pa_operation; 32 struct pa_stream; 33 struct pa_threaded_mainloop; 34 35 namespace media { 36 class AudioManagerBase; 37 38 class PulseAudioOutputStream : public AudioOutputStream { 39 public: 40 PulseAudioOutputStream(const AudioParameters& params, 41 const std::string& device_id, 42 AudioManagerBase* manager); 43 44 virtual ~PulseAudioOutputStream(); 45 46 // Implementation of AudioOutputStream. 47 virtual bool Open() OVERRIDE; 48 virtual void Close() OVERRIDE; 49 virtual void Start(AudioSourceCallback* callback) OVERRIDE; 50 virtual void Stop() OVERRIDE; 51 virtual void SetVolume(double volume) OVERRIDE; 52 virtual void GetVolume(double* volume) OVERRIDE; 53 54 private: 55 // Called by PulseAudio when |pa_stream_| change state. If an unexpected 56 // failure state change happens and |source_callback_| is set 57 // this method will forward the error via OnError(). 58 static void StreamNotifyCallback(pa_stream* s, void* p_this); 59 60 // Called by PulseAudio when it needs more audio data. 61 static void StreamRequestCallback(pa_stream* s, size_t len, void* p_this); 62 63 // Fulfill a write request from the write request callback. Outputs silence 64 // if the request could not be fulfilled. 65 void FulfillWriteRequest(size_t requested_bytes); 66 67 // Close() helper function to free internal structs. 68 void Reset(); 69 70 // AudioParameters from the constructor. 71 const AudioParameters params_; 72 73 // The device ID for the device to open. 74 const std::string device_id_; 75 76 // Audio manager that created us. Used to report that we've closed. 77 AudioManagerBase* manager_; 78 79 // PulseAudio API structs. 80 pa_context* pa_context_; 81 pa_threaded_mainloop* pa_mainloop_; 82 pa_stream* pa_stream_; 83 84 // Float representation of volume from 0.0 to 1.0. 85 float volume_; 86 87 // Callback to audio data source. Must only be modified while holding a lock 88 // on |pa_mainloop_| via pa_threaded_mainloop_lock(). 89 AudioSourceCallback* source_callback_; 90 91 // Container for retrieving data from AudioSourceCallback::OnMoreData(). 92 scoped_ptr<AudioBus> audio_bus_; 93 94 base::ThreadChecker thread_checker_; 95 96 DISALLOW_COPY_AND_ASSIGN(PulseAudioOutputStream); 97 }; 98 99 } // namespace media 100 101 #endif // MEDIA_AUDIO_PULSE_PULSE_OUTPUT_H_ 102
