Home | History | Annotate | Download | only in audio 
      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 // AudioOutputDispatcherImpl is an implementation of AudioOutputDispatcher.
      6 //
      7 // To avoid opening and closing audio devices more frequently than necessary,
      8 // each dispatcher has a pool of inactive physical streams. A stream is closed
      9 // only if it hasn't been used for a certain period of time (specified via the
     10 // constructor).
     11 //
     12 
     13 #ifndef MEDIA_AUDIO_AUDIO_OUTPUT_DISPATCHER_IMPL_H_
     14 #define MEDIA_AUDIO_AUDIO_OUTPUT_DISPATCHER_IMPL_H_
     15 
     16 #include <list>
     17 #include <map>
     18 
     19 #include "base/basictypes.h"
     20 #include "base/memory/ref_counted.h"
     21 #include "base/memory/weak_ptr.h"
     22 #include "base/timer/timer.h"
     23 #include "media/audio/audio_io.h"
     24 #include "media/audio/audio_manager.h"
     25 #include "media/audio/audio_output_dispatcher.h"
     26 #include "media/audio/audio_parameters.h"
     27 
     28 namespace media {
     29 
     30 class AudioOutputProxy;
     31 
     32 class MEDIA_EXPORT AudioOutputDispatcherImpl : public AudioOutputDispatcher {
     33  public:
     34   // |close_delay_ms| specifies delay after the stream is paused until
     35   // the audio device is closed.
     36   AudioOutputDispatcherImpl(AudioManager* audio_manager,
     37                             const AudioParameters& params,
     38                             const std::string& input_device_id,
     39                             const base::TimeDelta& close_delay);
     40 
     41   // Opens a new physical stream if there are no pending streams in
     42   // |idle_streams_|.  Do not call Close() or Stop() if this method fails.
     43   virtual bool OpenStream() OVERRIDE;
     44 
     45   // If there are pending streams in |idle_streams_| then it reuses one of
     46   // them, otherwise creates a new one.
     47   virtual bool StartStream(AudioOutputStream::AudioSourceCallback* callback,
     48                            AudioOutputProxy* stream_proxy) OVERRIDE;
     49 
     50   // Holds the physical stream temporarily in |pausing_streams_| and then
     51   // |stream| is  added to the pool of pending streams (i.e. |idle_streams_|).
     52   virtual void StopStream(AudioOutputProxy* stream_proxy) OVERRIDE;
     53 
     54   virtual void StreamVolumeSet(AudioOutputProxy* stream_proxy,
     55                                double volume) OVERRIDE;
     56 
     57   virtual void CloseStream(AudioOutputProxy* stream_proxy) OVERRIDE;
     58 
     59   virtual void Shutdown() OVERRIDE;
     60 
     61  private:
     62   typedef std::map<AudioOutputProxy*, AudioOutputStream*> AudioStreamMap;
     63   friend class base::RefCountedThreadSafe<AudioOutputDispatcherImpl>;
     64   virtual ~AudioOutputDispatcherImpl();
     65 
     66   friend class AudioOutputProxyTest;
     67 
     68   // Creates a new physical output stream, opens it and pushes to
     69   // |idle_streams_|.  Returns false if the stream couldn't be created or
     70   // opened.
     71   bool CreateAndOpenStream();
     72 
     73   // A task scheduled by StartStream(). Opens a new stream and puts
     74   // it in |idle_streams_|.
     75   void OpenTask();
     76 
     77   // Before a stream is reused, it should sit idle for a bit.  This task is
     78   // called once that time has elapsed.
     79   void StopStreamTask();
     80 
     81   // Called by |close_timer_|. Closes all pending streams.
     82   void ClosePendingStreams();
     83 
     84   base::TimeDelta pause_delay_;
     85   size_t paused_proxies_;
     86   typedef std::list<AudioOutputStream*> AudioOutputStreamList;
     87   AudioOutputStreamList idle_streams_;
     88   AudioOutputStreamList pausing_streams_;
     89 
     90   // Used to post delayed tasks to ourselves that we cancel inside Shutdown().
     91   base::WeakPtrFactory<AudioOutputDispatcherImpl> weak_this_;
     92   base::DelayTimer<AudioOutputDispatcherImpl> close_timer_;
     93 
     94   AudioStreamMap proxy_to_physical_map_;
     95 
     96   DISALLOW_COPY_AND_ASSIGN(AudioOutputDispatcherImpl);
     97 };
     98 
     99 }  // namespace media
    100 
    101 #endif  // MEDIA_AUDIO_AUDIO_OUTPUT_DISPATCHER_IMPL_H_
    102