media/cast/test/audio_utility.cc

   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 #include "media/cast/test/audio_utility.h"
   6
   7 #include "base/time/time.h"
   8 #include "media/base/audio_bus.h"
   9 #include "media/cast/cast_config.h"
  10
  11 namespace media {
  12 namespace cast {
  13
  14 TestAudioBusFactory::TestAudioBusFactory(int num_channels,
  15                                          int sample_rate,
  16                                          float sine_wave_frequency,
  17                                          float volume)
  18     : num_channels_(num_channels),
  19       sample_rate_(sample_rate),
  20       volume_(volume),
  21       source_(num_channels, sine_wave_frequency, sample_rate) {
  22   CHECK_LT(0, num_channels);
  23   CHECK_LT(0, sample_rate);
  24   CHECK_LE(0.0f, volume_);
  25   CHECK_LE(volume_, 1.0f);
  26 }
  27
  28 TestAudioBusFactory::~TestAudioBusFactory() {}
  29
  30 scoped_ptr<AudioBus> TestAudioBusFactory::NextAudioBus(
  31     const base::TimeDelta& duration) {
  32   const int num_samples = static_cast<int>(
  33       (sample_rate_ * duration) / base::TimeDelta::FromSeconds(1));
  34   scoped_ptr<AudioBus> bus(AudioBus::Create(num_channels_, num_samples));
  35   source_.OnMoreData(bus.get(), AudioBuffersState());
  36   bus->Scale(volume_);
  37   return bus.Pass();
  38 }
  39
  40 scoped_ptr<PcmAudioFrame> ToPcmAudioFrame(const AudioBus& audio_bus,
  41                                           int sample_rate) {
  42   scoped_ptr<PcmAudioFrame> audio_frame(new PcmAudioFrame());
  43   audio_frame->channels = audio_bus.channels();
  44   audio_frame->frequency = sample_rate;
  45   audio_frame->samples.resize(audio_bus.channels() * audio_bus.frames());
  46   audio_bus.ToInterleaved(
  47       audio_bus.frames(), sizeof(audio_frame->samples.front()),
  48       &audio_frame->samples.front());
  49   return audio_frame.Pass();
  50 }
  51
  52 int CountZeroCrossings(const std::vector<int16>& samples) {
  53   // The sample values must pass beyond |kAmplitudeThreshold| on the opposite
  54   // side of zero before a crossing will be counted.
  55   const int kAmplitudeThreshold = 1000;  // Approx. 3% of max amplitude.
  56
  57   int count = 0;
  58   std::vector<int16>::const_iterator i = samples.begin();
  59   int16 last = 0;
  60   for (; i != samples.end() && abs(last) < kAmplitudeThreshold; ++i)
  61     last = *i;
  62   for (; i != samples.end(); ++i) {
  63     if (abs(*i) >= kAmplitudeThreshold &&
  64         (last < 0) != (*i < 0)) {
  65       ++count;
  66       last = *i;
  67     }
  68   }
  69   return count;
  70 }
  71
  72 }  // namespace cast
  73 }  // namespace media