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 #ifndef MEDIA_BASE_AUDIO_RENDERER_MIXER_H_ 6 #define MEDIA_BASE_AUDIO_RENDERER_MIXER_H_ 7 8 #include <map> 9 10 #include "base/synchronization/lock.h" 11 #include "base/time/time.h" 12 #include "media/base/audio_converter.h" 13 #include "media/base/audio_renderer_sink.h" 14 15 namespace media { 16 17 // Mixes a set of AudioConverter::InputCallbacks into a single output stream 18 // which is funneled into a single shared AudioRendererSink; saving a bundle 19 // on renderer side resources. 20 class MEDIA_EXPORT AudioRendererMixer 21 : NON_EXPORTED_BASE(public AudioRendererSink::RenderCallback) { 22 public: 23 AudioRendererMixer(const AudioParameters& input_params, 24 const AudioParameters& output_params, 25 const scoped_refptr<AudioRendererSink>& sink); 26 virtual ~AudioRendererMixer(); 27 28 // Add or remove a mixer input from mixing; called by AudioRendererMixerInput. 29 void AddMixerInput(AudioConverter::InputCallback* input); 30 void RemoveMixerInput(AudioConverter::InputCallback* input); 31 32 // Since errors may occur even when no inputs are playing, an error callback 33 // must be registered separately from adding a mixer input. The same callback 34 // must be given to both the functions. 35 void AddErrorCallback(const base::Closure& error_cb); 36 void RemoveErrorCallback(const base::Closure& error_cb); 37 38 void set_pause_delay_for_testing(base::TimeDelta delay) { 39 pause_delay_ = delay; 40 } 41 42 private: 43 // AudioRendererSink::RenderCallback implementation. 44 virtual int Render(AudioBus* audio_bus, 45 int audio_delay_milliseconds) OVERRIDE; 46 virtual void OnRenderError() OVERRIDE; 47 48 // Output sink for this mixer. 49 scoped_refptr<AudioRendererSink> audio_sink_; 50 51 // ---------------[ All variables below protected by |lock_| ]--------------- 52 base::Lock lock_; 53 54 // List of error callbacks used by this mixer. 55 typedef std::list<base::Closure> ErrorCallbackList; 56 ErrorCallbackList error_callbacks_; 57 58 // Handles mixing and resampling between input and output parameters. 59 AudioConverter audio_converter_; 60 61 // Handles physical stream pause when no inputs are playing. For latency 62 // reasons we don't want to immediately pause the physical stream. 63 base::TimeDelta pause_delay_; 64 base::TimeTicks last_play_time_; 65 bool playing_; 66 67 DISALLOW_COPY_AND_ASSIGN(AudioRendererMixer); 68 }; 69 70 } // namespace media 71 72 #endif // MEDIA_BASE_AUDIO_RENDERER_MIXER_H_ 73
