media/audio/fake_audio_consumer.h

   1 // Copyright (c) 2013 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_AUDIO_FAKE_AUDIO_CONSUMER_H_
   6 #define MEDIA_AUDIO_FAKE_AUDIO_CONSUMER_H_
   7
   8 #include "base/cancelable_callback.h"
   9 #include "base/memory/scoped_ptr.h"
  10 #include "base/time.h"
  11 #include "media/audio/audio_parameters.h"
  12
  13 namespace base {
  14 class MessageLoopProxy;
  15 }
  16
  17 namespace media {
  18 class AudioBus;
  19
  20 // A fake audio consumer.  Using a provided message loop, FakeAudioConsumer will
  21 // simulate a real time consumer of audio data.
  22 class MEDIA_EXPORT FakeAudioConsumer {
  23  public:
  24   // |message_loop| is the loop on which the ReadCB provided to Start() will be
  25   // executed on.  |params| is used to determine the frequency of callbacks.
  26   FakeAudioConsumer(const scoped_refptr<base::MessageLoopProxy>& message_loop,
  27                     const AudioParameters& params);
  28   ~FakeAudioConsumer();
  29
  30   // Start executing |read_cb| at a regular interval.  Must be called on the
  31   // message loop provided during construction.  Stop() must be called before
  32   // destroying FakeAudioConsumer.
  33   typedef base::Callback<void(AudioBus* audio_bus)> ReadCB;
  34   void Start(const ReadCB& read_cb);
  35
  36   // Stop executing the ReadCB provided to Start().  Cancels any outstanding
  37   // callbacks.  Safe to call multiple times.  Must be called on the message
  38   // loop provided during construction.
  39   void Stop();
  40
  41  private:
  42   // Task that regularly calls |read_cb_| according to the playback rate as
  43   // determined by the audio parameters given during construction.  Runs on
  44   // |message_loop_|.
  45   void DoRead();
  46
  47   scoped_refptr<base::MessageLoopProxy> message_loop_;
  48   ReadCB read_cb_;
  49   scoped_ptr<AudioBus> audio_bus_;
  50   base::TimeDelta buffer_duration_;
  51   base::Time next_read_time_;
  52
  53   // Used to post delayed tasks to the AudioThread that we can cancel.
  54   base::CancelableClosure read_task_cb_;
  55
  56   DISALLOW_COPY_AND_ASSIGN(FakeAudioConsumer);
  57 };
  58
  59 }  // namespace media
  60
  61 #endif  // MEDIA_AUDIO_FAKE_AUDIO_CONSUMER_H_