simple_sources.h revision 2a99a7e74a7f215066514fe81d2bfa6639d9eddd 
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
12namespace media {
13
14// An audio source that produces a pure sinusoidal tone.
15class 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_
54