media/audio/audio_output_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 // AudioOutputMixer is a class that implements browser-side audio mixer.
   6 // AudioOutputMixer implements both AudioOutputDispatcher and
   7 // AudioSourceCallback interfaces.
   8
   9 #ifndef MEDIA_AUDIO_AUDIO_OUTPUT_MIXER_H_
  10 #define MEDIA_AUDIO_AUDIO_OUTPUT_MIXER_H_
  11
  12 #include <map>
  13
  14 #include "base/basictypes.h"
  15 #include "base/memory/ref_counted.h"
  16 #include "base/memory/scoped_ptr.h"
  17 #include "base/memory/weak_ptr.h"
  18 #include "base/synchronization/lock.h"
  19 #include "base/timer.h"
  20 #include "media/audio/audio_io.h"
  21 #include "media/audio/audio_manager.h"
  22 #include "media/audio/audio_output_dispatcher.h"
  23 #include "media/audio/audio_parameters.h"
  24
  25 namespace media {
  26
  27 class MEDIA_EXPORT AudioOutputMixer
  28     : public AudioOutputDispatcher,
  29       public AudioOutputStream::AudioSourceCallback {
  30  public:
  31   AudioOutputMixer(AudioManager* audio_manager,
  32                    const AudioParameters& params,
  33                    const base::TimeDelta& close_delay);
  34
  35   // AudioOutputDispatcher interface.
  36   virtual bool OpenStream() OVERRIDE;
  37   virtual bool StartStream(AudioOutputStream::AudioSourceCallback* callback,
  38                            AudioOutputProxy* stream_proxy) OVERRIDE;
  39   virtual void StopStream(AudioOutputProxy* stream_proxy) OVERRIDE;
  40   virtual void StreamVolumeSet(AudioOutputProxy* stream_proxy,
  41                                double volume) OVERRIDE;
  42   virtual void CloseStream(AudioOutputProxy* stream_proxy) OVERRIDE;
  43   virtual void Shutdown() OVERRIDE;
  44
  45   // AudioSourceCallback interface.
  46   virtual uint32 OnMoreData(uint8* dest,
  47                             uint32 max_size,
  48                             AudioBuffersState buffers_state) OVERRIDE;
  49   virtual void OnError(AudioOutputStream* stream, int code) OVERRIDE;
  50   virtual void WaitTillDataReady() OVERRIDE;
  51
  52  private:
  53   friend class base::RefCountedThreadSafe<AudioOutputMixer>;
  54   virtual ~AudioOutputMixer();
  55
  56   // Called by |close_timer_|. Closes physical stream.
  57   void ClosePhysicalStream();
  58
  59   // The |lock_| must be acquired whenever we modify |proxies_| in the audio
  60   // manager thread or accessing it in the hardware audio thread. Read in the
  61   // audio manager thread is safe.
  62   base::Lock lock_;
  63
  64   // List of audio output proxies currently being played.
  65   // For every proxy we store aux structure containing data necessary for
  66   // mixing.
  67   struct ProxyData {
  68     AudioOutputStream::AudioSourceCallback* audio_source_callback;
  69     double volume;
  70     int pending_bytes;
  71   };
  72   typedef std::map<AudioOutputProxy*, ProxyData> ProxyMap;
  73   ProxyMap proxies_;
  74
  75   // Physical stream for this mixer.
  76   scoped_ptr<AudioOutputStream> physical_stream_;
  77
  78   // Temporary buffer used when mixing. Allocated in the constructor
  79   // to avoid constant allocation/deallocation in the callback.
  80   scoped_array<uint8> mixer_data_;
  81
  82   // Used to post delayed tasks to ourselves that we cancel inside Shutdown().
  83   base::WeakPtrFactory<AudioOutputMixer> weak_this_;
  84   base::DelayTimer<AudioOutputMixer> close_timer_;
  85
  86   // Size of data in all in-flight buffers.
  87   int pending_bytes_;
  88
  89   DISALLOW_COPY_AND_ASSIGN(AudioOutputMixer);
  90 };
  91
  92 }  // namespace media
  93
  94 #endif  // MEDIA_AUDIO_AUDIO_OUTPUT_MIXER_H_