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      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_view_id| refers to the RenderView containing the entity
     49   // rendering the audio.  |source_render_frame_id| refers to the RenderFrame
     50   // containing the entity rendering the audio.  Caller must ensure
     51   // AudioRendererMixerManager outlives the returned input.
     52   media::AudioRendererMixerInput* CreateInput(int source_render_view_id,
     53                                               int source_render_frame_id);
     54 
     55   // Returns a mixer instance based on AudioParameters; an existing one if one
     56   // with the provided AudioParameters exists or a new one if not.
     57   media::AudioRendererMixer* GetMixer(int source_render_view_id,
     58                                       int source_render_frame_id,
     59                                       const media::AudioParameters& params);
     60 
     61   // Remove a mixer instance given a mixer if the only other reference is held
     62   // by AudioRendererMixerManager.  Every AudioRendererMixer owner must call
     63   // this method when it's done with a mixer.
     64   void RemoveMixer(int source_render_view_id,
     65                    const media::AudioParameters& params);
     66 
     67  private:
     68   friend class AudioRendererMixerManagerTest;
     69 
     70   // Define a key so that only those AudioRendererMixerInputs from the same
     71   // RenderView and with the same AudioParameters can be mixed together.  The
     72   // first value is the RenderViewId.
     73   typedef std::pair<int, media::AudioParameters> MixerKey;
     74 
     75   // Custom compare operator for the AudioRendererMixerMap.  Allows reuse of
     76   // mixers where only irrelevant keys mismatch; e.g., effects, bits per sample.
     77   struct MixerKeyCompare {
     78     bool operator()(const MixerKey& a, const MixerKey& b) const {
     79       if (a.first != b.first)
     80         return a.first < b.first;
     81       if (a.second.sample_rate() != b.second.sample_rate())
     82         return a.second.sample_rate() < b.second.sample_rate();
     83       if (a.second.channels() != b.second.channels())
     84         return a.second.channels() < b.second.channels();
     85 
     86       // Ignore effects(), bits_per_sample(), format(), and frames_per_buffer(),
     87       // these parameters do not affect mixer reuse.  All AudioRendererMixer
     88       // units disable FIFO, so frames_per_buffer() can be safely ignored.
     89       return a.second.channel_layout() < b.second.channel_layout();
     90     }
     91   };
     92 
     93   // Map of MixerKey to <AudioRendererMixer, Count>.  Count allows
     94   // AudioRendererMixerManager to keep track explicitly (v.s. RefCounted which
     95   // is implicit) of the number of outstanding AudioRendererMixers.
     96   struct AudioRendererMixerReference {
     97     media::AudioRendererMixer* mixer;
     98     int ref_count;
     99   };
    100   typedef std::map<MixerKey, AudioRendererMixerReference, MixerKeyCompare>
    101       AudioRendererMixerMap;
    102 
    103   // Overrides the AudioRendererSink implementation for unit testing.
    104   void SetAudioRendererSinkForTesting(media::AudioRendererSink* sink);
    105 
    106   // Active mixers.
    107   AudioRendererMixerMap mixers_;
    108   base::Lock mixers_lock_;
    109 
    110   // Audio hardware configuration.  Used to construct output AudioParameters for
    111   // each AudioRendererMixer instance.
    112   media::AudioHardwareConfig* const hardware_config_;
    113 
    114   media::AudioRendererSink* sink_for_testing_;
    115 
    116   DISALLOW_COPY_AND_ASSIGN(AudioRendererMixerManager);
    117 };
    118 
    119 }  // namespace content
    120 
    121 #endif  // CONTENT_RENDERER_MEDIA_AUDIO_RENDERER_MIXER_MANAGER_H_
    122