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/callback_forward.h"
   9 #include "base/memory/ref_counted.h"
  10 #include "media/base/media_export.h"
  11
  12 namespace base {
  13 class SingleThreadTaskRunner;
  14 }
  15
  16 namespace media {
  17 class AudioBus;
  18 class AudioParameters;
  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   // |worker_task_runner| is the task runner on which the ReadCB provided to
  25   // Start() will be executed on.  This may or may not be the be for the same
  26   // thread that invokes the Start/Stop methods.
  27   // |params| is used to determine the frequency of callbacks.
  28   FakeAudioConsumer(
  29       const scoped_refptr<base::SingleThreadTaskRunner>& worker_task_runner,
  30       const AudioParameters& params);
  31   ~FakeAudioConsumer();
  32
  33   // Start executing |read_cb| at a regular intervals.  Stop() must be called by
  34   // the same thread before destroying FakeAudioConsumer.
  35   typedef base::Callback<void(AudioBus* audio_bus)> ReadCB;
  36   void Start(const ReadCB& read_cb);
  37
  38   // Stop executing the ReadCB provided to Start().  Blocks until the worker
  39   // loop is not inside a ReadCB invocation.  Safe to call multiple times.  Must
  40   // be called on the same thread that called Start().
  41   void Stop();
  42
  43  private:
  44   // All state and implementation is kept within this ref-counted class because
  45   // cancellation of posted tasks must happen on the worker thread some time
  46   // after the call to Stop() (on the main thread) returns.
  47   class Worker;
  48   const scoped_refptr<Worker> worker_;
  49
  50   DISALLOW_COPY_AND_ASSIGN(FakeAudioConsumer);
  51 };
  52
  53 }  // namespace media
  54
  55 #endif  // MEDIA_AUDIO_FAKE_AUDIO_CONSUMER_H_