media/base/audio_renderer_mixer.h

   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                      const base::Closure& error_cb);
  31   void RemoveMixerInput(AudioConverter::InputCallback* input);
  32
  33   void set_pause_delay_for_testing(base::TimeDelta delay) {
  34     pause_delay_ = delay;
  35   }
  36
  37  private:
  38   // AudioRendererSink::RenderCallback implementation.
  39   virtual int Render(AudioBus* audio_bus,
  40                      int audio_delay_milliseconds) OVERRIDE;
  41   virtual void OnRenderError() OVERRIDE;
  42
  43   // Output sink for this mixer.
  44   scoped_refptr<AudioRendererSink> audio_sink_;
  45
  46   // Set of mixer inputs to be mixed by this mixer.  Access is thread-safe
  47   // through |mixer_inputs_lock_|.
  48   typedef std::map<AudioConverter::InputCallback*, base::Closure>
  49       AudioRendererMixerInputSet;
  50   AudioRendererMixerInputSet mixer_inputs_;
  51   base::Lock mixer_inputs_lock_;
  52
  53   // Handles mixing and resampling between input and output parameters.
  54   AudioConverter audio_converter_;
  55
  56   // Handles physical stream pause when no inputs are playing.  For latency
  57   // reasons we don't want to immediately pause the physical stream.
  58   base::TimeDelta pause_delay_;
  59   base::TimeTicks last_play_time_;
  60   bool playing_;
  61
  62   DISALLOW_COPY_AND_ASSIGN(AudioRendererMixer);
  63 };
  64
  65 }  // namespace media
  66
  67 #endif  // MEDIA_BASE_AUDIO_RENDERER_MIXER_H_