content/renderer/media/audio_renderer_mixer_manager.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 CONTENT_RENDERER_MEDIA_AUDIO_RENDERER_MIXER_MANAGER_H_
   6 #define CONTENT_RENDERER_MEDIA_AUDIO_RENDERER_MIXER_MANAGER_H_
   7
   8 #include <map>
   9 #include <utility>
  10
  11 #include "base/synchronization/lock.h"
  12 #include "content/common/content_export.h"
  13 #include "media/audio/audio_parameters.h"
  14
  15 namespace media {
  16 class AudioHardwareConfig;
  17 class AudioRendererMixer;
  18 class AudioRendererMixerInput;
  19 class AudioRendererSink;
  20 }
  21
  22 namespace content {
  23
  24 // Manages sharing of an AudioRendererMixer among AudioRendererMixerInputs based
  25 // on their AudioParameters configuration.  Inputs with the same AudioParameters
  26 // configuration will share a mixer while a new AudioRendererMixer will be
  27 // lazily created if one with the exact AudioParameters does not exist.
  28 //
  29 // There should only be one instance of AudioRendererMixerManager per render
  30 // thread.
  31 //
  32 // TODO(dalecurtis): Right now we require AudioParameters to be an exact match
  33 // when we should be able to ignore bits per channel since we're only dealing
  34 // with floats.  However, bits per channel is currently used to interleave the
  35 // audio data by AudioOutputDevice::AudioThreadCallback::Process for consumption
  36 // via the shared memory.  See http://crbug.com/114700.
  37 class CONTENT_EXPORT AudioRendererMixerManager {
  38  public:
  39   // Construct an instance using the given audio hardware configuration.  The
  40   // provided |hardware_config| is not owned by AudioRendererMixerManager and
  41   // must outlive it.
  42   explicit AudioRendererMixerManager(
  43       media::AudioHardwareConfig* hardware_config);
  44   ~AudioRendererMixerManager();
  45
  46   // Creates an AudioRendererMixerInput with the proper callbacks necessary to
  47   // retrieve an AudioRendererMixer instance from AudioRendererMixerManager.
  48   // |source_render_frame_id| refers to the RenderFrame containing the entity
  49   // rendering the audio.  Caller must ensure AudioRendererMixerManager outlives
  50   // the returned input.
  51   media::AudioRendererMixerInput* CreateInput(int source_render_frame_id);
  52
  53   // Returns a mixer instance based on AudioParameters; an existing one if one
  54   // with the provided AudioParameters exists or a new one if not.
  55   media::AudioRendererMixer* GetMixer(int source_render_frame_id,
  56                                       const media::AudioParameters& params);
  57
  58   // Remove a mixer instance given a mixer if the only other reference is held
  59   // by AudioRendererMixerManager.  Every AudioRendererMixer owner must call
  60   // this method when it's done with a mixer.
  61   void RemoveMixer(int source_render_frame_id,
  62                    const media::AudioParameters& params);
  63
  64  private:
  65   friend class AudioRendererMixerManagerTest;
  66
  67   // Define a key so that only those AudioRendererMixerInputs from the same
  68   // RenderView and with the same AudioParameters can be mixed together.  The
  69   // first value is the RenderViewId.
  70   typedef std::pair<int, media::AudioParameters> MixerKey;
  71
  72   // Custom compare operator for the AudioRendererMixerMap.  Allows reuse of
  73   // mixers where only irrelevant keys mismatch; e.g., effects, bits per sample.
  74   struct MixerKeyCompare {
  75     bool operator()(const MixerKey& a, const MixerKey& b) const {
  76       if (a.first != b.first)
  77         return a.first < b.first;
  78       if (a.second.sample_rate() != b.second.sample_rate())
  79         return a.second.sample_rate() < b.second.sample_rate();
  80       if (a.second.channels() != b.second.channels())
  81         return a.second.channels() < b.second.channels();
  82
  83       // Ignore effects(), bits_per_sample(), format(), and frames_per_buffer(),
  84       // these parameters do not affect mixer reuse.  All AudioRendererMixer
  85       // units disable FIFO, so frames_per_buffer() can be safely ignored.
  86       return a.second.channel_layout() < b.second.channel_layout();
  87     }
  88   };
  89
  90   // Map of MixerKey to <AudioRendererMixer, Count>.  Count allows
  91   // AudioRendererMixerManager to keep track explicitly (v.s. RefCounted which
  92   // is implicit) of the number of outstanding AudioRendererMixers.
  93   struct AudioRendererMixerReference {
  94     media::AudioRendererMixer* mixer;
  95     int ref_count;
  96   };
  97   typedef std::map<MixerKey, AudioRendererMixerReference, MixerKeyCompare>
  98       AudioRendererMixerMap;
  99
 100   // Overrides the AudioRendererSink implementation for unit testing.
 101   void SetAudioRendererSinkForTesting(media::AudioRendererSink* sink);
 102
 103   // Active mixers.
 104   AudioRendererMixerMap mixers_;
 105   base::Lock mixers_lock_;
 106
 107   // Audio hardware configuration.  Used to construct output AudioParameters for
 108   // each AudioRendererMixer instance.
 109   media::AudioHardwareConfig* const hardware_config_;
 110
 111   media::AudioRendererSink* sink_for_testing_;
 112
 113   DISALLOW_COPY_AND_ASSIGN(AudioRendererMixerManager);
 114 };
 115
 116 }  // namespace content
 117
 118 #endif  // CONTENT_RENDERER_MEDIA_AUDIO_RENDERER_MIXER_MANAGER_H_