Replace AudioSilenceDetector with an AudioPowerMonitor.

media/audio/audio_power_monitor_unittest.cc

+// Copyright (c) 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/audio/audio_power_monitor.h"
+
+#include <limits>
+
+#include "base/bind.h"
+#include "base/bind_helpers.h"
+#include "base/message_loop.h"
+#include "base/time/time.h"
+#include "media/base/audio_bus.h"
+#include "testing/gtest/include/gtest/gtest.h"
+
+namespace media {
+
+static const int kSampleRate = 48000;
+static const int kFramesPerBuffer = 128;
+
+static const int kTimeConstantMillis = 5;
+static const int kMeasurementPeriodMillis = 20;
+
+namespace {
+
+// Container for each parameterized test's data (input and expected results).
+class TestScenario {
+ public:
+  TestScenario(const float* data, int num_channels, int num_frames,
+               float expected_power, bool expected_clipped)
+      : expected_power_(expected_power), expected_clipped_(expected_clipped) {
+    CreatePopulatedBuffer(data, num_channels, num_frames);
+  }
+
+  // Copy constructor for ::testing::Values(...).
+  TestScenario(const TestScenario& other)
+      : expected_power_(other.expected_power_),
+        expected_clipped_(other.expected_clipped_) {
+    bus_ = AudioBus::Create(other.bus_->channels(), other.bus_->frames());
+    other.bus_->CopyTo(bus_.get());
+  }
+
+  const AudioBus& data() const {
+    return *bus_;
+  }
+
+  float expected_power() const {
+    return expected_power_;
+  }
+
+  bool expected_clipped() const {
+    return expected_clipped_;
+  }
+
+ private:
+  // Creates an AudioBus, sized and populated with kFramesPerBuffer frames of
+  // data.  The given test |data| is repeated to fill the buffer.
+  void CreatePopulatedBuffer(
+      const float* data, int num_channels, int num_frames) {
+    bus_ = AudioBus::Create(num_channels, kFramesPerBuffer);
+    for (int ch = 0; ch < num_channels; ++ch) {
+      for (int frames = 0; frames < kFramesPerBuffer; frames += num_frames) {
+        const int num_to_copy = std::min(num_frames, kFramesPerBuffer - frames);
+        memcpy(bus_->channel(ch) + frames, data + num_frames * ch,
+               sizeof(float) * num_to_copy);
+      }
+    }
+  }
+
+  const float expected_power_;
+  const bool expected_clipped_;
+  scoped_ptr<AudioBus> bus_;
+
+  DISALLOW_ASSIGN(TestScenario);
+};
+
+// An observer that receives power measurements.  Each power measurement should
+// should make progress towards the goal value.
+class MeasurementObserver {
+ public:
+  MeasurementObserver(float goal_power_measurement, bool goal_clipped)
+      : goal_power_measurement_(goal_power_measurement),
+        goal_clipped_(goal_clipped), measurement_count_(0) {}
+
+  int measurement_count() const {
+    return measurement_count_;
+  }
+
+  float last_power_measurement() const {
+    return last_power_measurement_;
+  }
+
+  bool last_clipped() const {
+    return last_clipped_;
+  }
+
+  void OnPowerMeasured(float cur_power_measurement, bool clipped) {
+    if (measurement_count_ == 0) {
+      measurements_should_increase_ =
+          (cur_power_measurement < goal_power_measurement_);
+    } else {
+      SCOPED_TRACE(::testing::Message()
+                   << "Power: goal=" << goal_power_measurement_
+                   << "; last=" << last_power_measurement_
+                   << "; cur=" << cur_power_measurement);
+
+      if (last_power_measurement_ != goal_power_measurement_) {
+        if (measurements_should_increase_) {
+          EXPECT_LE(last_power_measurement_, cur_power_measurement)
+              << "Measurements should be monotonically increasing.";
+        } else {
+          EXPECT_GE(last_power_measurement_, cur_power_measurement)
+              << "Measurements should be monotonically decreasing.";
+        }
+      } else {
+        EXPECT_EQ(last_power_measurement_, cur_power_measurement)
+            << "Measurements are numerically unstable at goal value.";
+      }
+    }
+
+    last_power_measurement_ = cur_power_measurement;
+    last_clipped_ = clipped;
+    ++measurement_count_;
+  }
+
+ private:
+  const float goal_power_measurement_;
+  const bool goal_clipped_;
+  int measurement_count_;
+  bool measurements_should_increase_;
+  float last_power_measurement_;
+  bool last_clipped_;
+
+  DISALLOW_COPY_AND_ASSIGN(MeasurementObserver);
+};
+
+}  // namespace
+
+class AudioPowerMonitorTest : public ::testing::TestWithParam<TestScenario> {
+ public:
+  AudioPowerMonitorTest()
+      : power_monitor_(
+            kSampleRate,
+            base::TimeDelta::FromMilliseconds(kTimeConstantMillis),
+            base::TimeDelta::FromMilliseconds(kMeasurementPeriodMillis),
+            &message_loop_,
+            base::Bind(&AudioPowerMonitorTest::OnPowerMeasured,
+                       base::Unretained(this))) {}
+
+  void FeedAndCheckExpectedPowerIsMeasured(
+      const AudioBus& bus, float power, bool clipped) {
+    // Feed the AudioPowerMonitor.  It should post tasks to |message_loop_|.
+    static const int kNumFeedIters = 100;
+    for (int i = 0; i < kNumFeedIters; ++i)
+      power_monitor_.Scan(bus, bus.frames());
+
+    // Set up an observer and run all the enqueued tasks.
+    MeasurementObserver observer(power, clipped);
+    current_observer_ = &observer;
+    message_loop_.RunUntilIdle();
+    current_observer_ = NULL;
+
+    // Check that the results recorded by the observer are the same whole-number
+    // dBFS.
+    if (observer.measurement_count() > 0) {
+      EXPECT_EQ(static_cast<int>(power),
+                static_cast<int>(observer.last_power_measurement()));
+      EXPECT_EQ(clipped, observer.last_clipped());
+    } else {
+      // Edge case: AudioPowerMonitor reported no measurements.  This infers it
+      // decided not to report any redundant measurements, which we assume is an
+      // unclipped "zero power" result.
+      EXPECT_EQ(static_cast<int>(-std::numeric_limits<float>::infinity()),
+                static_cast<int>(power));
+      EXPECT_EQ(false, clipped);
+    }
+  }
+
+ private:
+  void OnPowerMeasured(float power, bool clipped) {
+    CHECK(current_observer_);
+    current_observer_->OnPowerMeasured(power, clipped);
+  }
+
+  base::MessageLoop message_loop_;
+  AudioPowerMonitor power_monitor_;
+  MeasurementObserver* current_observer_;
+
+  DISALLOW_COPY_AND_ASSIGN(AudioPowerMonitorTest);
+};
+
+TEST_P(AudioPowerMonitorTest, MeasuresPowerOfSignal) {
+  const TestScenario& scenario = GetParam();
+
+  scoped_ptr<AudioBus> zeroed_bus =
+      AudioBus::Create(scenario.data().channels(), scenario.data().frames());
+  zeroed_bus->Zero();
+
+  // Send a "zero power" audio signal, then this scenario's audio signal, then
+  // the "zero power" audio signal again; testing that the power monitor
+  // measurements match expected values.
+  FeedAndCheckExpectedPowerIsMeasured(
+      *zeroed_bus, AudioPowerMonitor::kZeroPowerDBFS, false);
+  FeedAndCheckExpectedPowerIsMeasured(
+      scenario.data(), scenario.expected_power(), scenario.expected_clipped());
+  FeedAndCheckExpectedPowerIsMeasured(
+      *zeroed_bus, AudioPowerMonitor::kZeroPowerDBFS, false);
+}
+
+static const float kMonoSilentNoise[] = {
+  0.01f, -0.01f
+};
+
+static const float kMonoMaxAmplitude[] = {
+  1.0f
+};
+
+static const float kMonoMaxAmplitude2[] = {
+  -1.0f, 1.0f
+};
+
+static const float kMonoHalfMaxAmplitude[] = {
+  0.5f, -0.5f, 0.5f, -0.5f
+};
+
+static const float kMonoAmplitudeClipped[] = {
+  2.0f, -2.0f
+};
+
+static const float kMonoMaxAmplitudeWithClip[] = {
+  2.0f, 0.0, 0.0f, 0.0f
+};
+
+static const float kMonoMaxAmplitudeWithClip2[] = {
+  4.0f, 0.0, 0.0f, 0.0f
+};
+
+static const float kMonoContainsInfinity[] = {
+  0.0f, 0.0f, 0.0f, std::numeric_limits<float>::infinity()

[DaleCurtis, 2013/07/02 22:26:34]

Static initializer.

[miu, 2013/07/09 00:59:56]

Done.

+};
+
+static const float kMonoContainsNaN[] = {
+  0.5f, -0.5f, 0.5f, std::numeric_limits<float>::quiet_NaN()

[DaleCurtis, 2013/07/02 22:26:34]

Ditto.

[miu, 2013/07/09 00:59:56]

Done.

+};
+
+static const float kStereoSilentNoise[] = {
+  // left channel
+  0.005f, -0.005f,
+  // right channel
+  0.005f, -0.005f
+};
+
+static const float kStereoMaxAmplitude[] = {
+  // left channel
+  1.0f, -1.0f,
+  // right channel
+  -1.0f, 1.0f
+};
+
+static const float kRightChannelMaxAmplitude[] = {
+  // left channel
+  0.0f, 0.0f, 0.0f, 0.0f,
+  // right channel
+  -1.0f, 1.0f, -1.0f, 1.0f
+};
+
+static const float kLeftChannelHalfMaxAmplitude[] = {
+  // left channel
+  0.5f, -0.5f, 0.5f, -0.5f,
+  // right channel
+  0.0f, 0.0f, 0.0f, 0.0f,
+};
+
+static const float kStereoMixed[] = {
+  // left channel
+  0.5f, -0.5f, 0.5f, -0.5f,
+  // right channel
+  -1.0f, 1.0f, -1.0f, 1.0f
+};
+
+static const float kStereoMixed2[] = {
+  // left channel
+  1.0f, -1.0f, 0.75f, -0.75f, 0.5f, -0.5f, 0.25f, -0.25f,
+  // right channel
+  0.25f, -0.25f, 0.5f, -0.5f, 0.75f, -0.75f, 1.0f, -1.0f
+};
+
+INSTANTIATE_TEST_CASE_P(
+    Scenarios, AudioPowerMonitorTest,
+    ::testing::Values(
+         TestScenario(kMonoSilentNoise, 1, 1, -40, false),
+         TestScenario(kMonoMaxAmplitude, 1, 1,
+                      AudioPowerMonitor::kMaxPowerDBFS, false),
+         TestScenario(kMonoMaxAmplitude2, 1, 2,
+                      AudioPowerMonitor::kMaxPowerDBFS, false),
+         TestScenario(kMonoHalfMaxAmplitude, 1, 4, -6, false),
+         TestScenario(kMonoAmplitudeClipped, 1, 2,
+                      AudioPowerMonitor::kMaxPowerDBFS, true),
+         TestScenario(kMonoMaxAmplitudeWithClip, 1, 4,
+                      AudioPowerMonitor::kMaxPowerDBFS, true),
+         TestScenario(kMonoMaxAmplitudeWithClip2, 1, 4,
+                      AudioPowerMonitor::kMaxPowerDBFS, true),
+         TestScenario(kMonoContainsInfinity, 1, 4,
+                      AudioPowerMonitor::kZeroPowerDBFS, true),
+         TestScenario(kMonoContainsNaN, 1, 4,
+                      AudioPowerMonitor::kZeroPowerDBFS, false),
+         TestScenario(kStereoSilentNoise, 2, 1, -46, false),
+         TestScenario(kStereoMaxAmplitude, 2, 2,
+                      AudioPowerMonitor::kMaxPowerDBFS, false),
+         TestScenario(kRightChannelMaxAmplitude, 2, 4, -3, false),
+         TestScenario(kLeftChannelHalfMaxAmplitude, 2, 4, -9, false),
+         TestScenario(kStereoMixed, 2, 4, -2, false),
+         TestScenario(kStereoMixed2, 2, 8, -3, false)));
+
+}  // namespace media