media/audio/simple_sources.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 #ifndef MEDIA_AUDIO_SIMPLE_SOURCES_H_
   6 #define MEDIA_AUDIO_SIMPLE_SOURCES_H_
   7
   8 #include "base/synchronization/lock.h"
   9 #include "media/audio/audio_io.h"
  10 #include "media/base/seekable_buffer.h"
  11
  12 namespace media {
  13
  14 // An audio source that produces a pure sinusoidal tone.
  15 class MEDIA_EXPORT SineWaveAudioSource
  16     : public AudioOutputStream::AudioSourceCallback {
  17  public:
  18   // |channels| is the number of audio channels, |freq| is the frequency in
  19   // hertz and it has to be less than half of the sampling frequency
  20   // |sample_freq| or else you will get aliasing.
  21   SineWaveAudioSource(int channels, double freq, double sample_freq);
  22   virtual ~SineWaveAudioSource() {}
  23
  24   // Return up to |cap| samples of data via OnMoreData().  Use Reset() to
  25   // allow more data to be served.
  26   void CapSamples(int cap);
  27   void Reset();
  28
  29   // Implementation of AudioSourceCallback.
  30   virtual int OnMoreData(AudioBus* audio_bus,
  31                          AudioBuffersState audio_buffers) OVERRIDE;
  32   virtual int OnMoreIOData(AudioBus* source,
  33                            AudioBus* dest,
  34                            AudioBuffersState audio_buffers) OVERRIDE;
  35   virtual void OnError(AudioOutputStream* stream) OVERRIDE;
  36
  37   // The number of OnMoreData()+OnMoreIOData() and OnError() calls respectively.
  38   int callbacks() { return callbacks_; }
  39   int errors() { return errors_; }
  40
  41  protected:
  42   int channels_;
  43   double f_;
  44   int time_state_;
  45   int cap_;
  46   int callbacks_;
  47   int errors_;
  48   base::Lock time_lock_;
  49 };
  50
  51 }  // namespace media
  52
  53 #endif  // MEDIA_AUDIO_SIMPLE_SOURCES_H_