1 files changed, 73 insertions, 0 deletions
diff --git a/media/cast/test/audio_utility.cc b/media/cast/test/audio_utility.cc
new file mode 100644
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+++ b/media/cast/test/audio_utility.cc
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+// Copyright 2013 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "media/cast/test/audio_utility.h"
+
+#include "base/time/time.h"
+#include "media/base/audio_bus.h"
+#include "media/cast/cast_config.h"
+
+namespace media {
+namespace cast {
+
+TestAudioBusFactory::TestAudioBusFactory(int num_channels,
+                                         int sample_rate,
+                                         float sine_wave_frequency,
+                                         float volume)
+    : num_channels_(num_channels),
+      sample_rate_(sample_rate),
+      volume_(volume),
+      source_(num_channels, sine_wave_frequency, sample_rate) {
+  CHECK_LT(0, num_channels);
+  CHECK_LT(0, sample_rate);
+  CHECK_LE(0.0f, volume_);
+  CHECK_LE(volume_, 1.0f);
+}
+
+TestAudioBusFactory::~TestAudioBusFactory() {}
+
+scoped_ptr<AudioBus> TestAudioBusFactory::NextAudioBus(
+    const base::TimeDelta& duration) {
+  const int num_samples = static_cast<int>(
+      (sample_rate_ * duration) / base::TimeDelta::FromSeconds(1));
+  scoped_ptr<AudioBus> bus(AudioBus::Create(num_channels_, num_samples));
+  source_.OnMoreData(bus.get(), AudioBuffersState());
+  bus->Scale(volume_);
+  return bus.Pass();
+}
+
+scoped_ptr<PcmAudioFrame> ToPcmAudioFrame(const AudioBus& audio_bus,
+                                          int sample_rate) {
+  scoped_ptr<PcmAudioFrame> audio_frame(new PcmAudioFrame());
+  audio_frame->channels = audio_bus.channels();
+  audio_frame->frequency = sample_rate;
+  audio_frame->samples.resize(audio_bus.channels() * audio_bus.frames());
+  audio_bus.ToInterleaved(
+      audio_bus.frames(), sizeof(audio_frame->samples.front()),
+      &audio_frame->samples.front());
+  return audio_frame.Pass();
+}
+
+int CountZeroCrossings(const std::vector<int16>& samples) {
+  // The sample values must pass beyond |kAmplitudeThreshold| on the opposite
+  // side of zero before a crossing will be counted.
+  const int kAmplitudeThreshold = 1000;  // Approx. 3% of max amplitude.
+
+  int count = 0;
+  std::vector<int16>::const_iterator i = samples.begin();
+  int16 last = 0;
+  for (; i != samples.end() && abs(last) < kAmplitudeThreshold; ++i)
+    last = *i;
+  for (; i != samples.end(); ++i) {
+    if (abs(*i) >= kAmplitudeThreshold &&
+        (last < 0) != (*i < 0)) {
+      ++count;
+      last = *i;
+    }
+  }
+  return count;
+}
+
+}  // namespace cast
+}  // namespace media