media/cast/test/audio_utility.h

   1 // Copyright 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_CAST_TEST_AUDIO_UTILITY_H_
   6 #define MEDIA_CAST_TEST_AUDIO_UTILITY_H_
   7
   8 #include "media/audio/simple_sources.h"
   9
  10 namespace base {
  11 class TimeDelta;
  12 }
  13
  14 namespace media {
  15 class AudioBus;
  16 }
  17
  18 namespace media {
  19 namespace cast {
  20
  21 struct PcmAudioFrame;
  22
  23 // Produces AudioBuses of varying duration where each successive output contains
  24 // the continuation of a single sine wave.
  25 class TestAudioBusFactory {
  26  public:
  27   TestAudioBusFactory(int num_channels, int sample_rate,
  28                       float sine_wave_frequency, float volume);
  29   ~TestAudioBusFactory();
  30
  31   // Creates a new AudioBus of the given |duration|, filled with the next batch
  32   // of sine wave samples.
  33   scoped_ptr<AudioBus> NextAudioBus(const base::TimeDelta& duration);
  34
  35   // A reasonable test tone.
  36   static const int kMiddleANoteFreq = 440;
  37
  38  private:
  39   const int num_channels_;
  40   const int sample_rate_;
  41   const float volume_;
  42   SineWaveAudioSource source_;
  43
  44   DISALLOW_COPY_AND_ASSIGN(TestAudioBusFactory);
  45 };
  46
  47 // Convenience function to convert an |audio_bus| to its equivalent
  48 // PcmAudioFrame.
  49 // TODO(miu): Remove this once all code has migrated to use AudioBus.  See
  50 // comment in media/cast/cast_config.h.
  51 scoped_ptr<PcmAudioFrame> ToPcmAudioFrame(const AudioBus& audio_bus,
  52                                           int sample_rate);
  53
  54 // Assuming |samples| contains a single-frequency sine wave (and maybe some
  55 // low-amplitude noise), count the number of times the sine wave crosses
  56 // zero.
  57 int CountZeroCrossings(const std::vector<int16>& samples);
  58
  59 }  // namespace cast
  60 }  // namespace media
  61
  62 #endif  // MEDIA_CAST_TEST_AUDIO_UTILITY_H_