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diff --git a/dom/media/gtest/AudioVerifier.h b/dom/media/gtest/AudioVerifier.h
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+++ b/dom/media/gtest/AudioVerifier.h
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+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at https://mozilla.org/MPL/2.0/. */
+
+#ifndef DOM_MEDIA_GTEST_AUDIOVERIFIER_H_
+#define DOM_MEDIA_GTEST_AUDIOVERIFIER_H_
+
+#include "AudioGenerator.h"
+
+namespace mozilla {
+
+template <typename Sample>
+class AudioVerifier {
+ public:
+  explicit AudioVerifier(uint32_t aRate, uint32_t aFrequency)
+      : mRate(aRate), mFrequency(aFrequency) {}
+
+  // Only the mono channel is taken into account.
+  void AppendData(const AudioSegment& segment) {
+    for (AudioSegment::ConstChunkIterator iter(segment); !iter.IsEnded();
+         iter.Next()) {
+      const AudioChunk& c = *iter;
+      if (c.IsNull()) {
+        for (int i = 0; i < c.GetDuration(); ++i) {
+          CheckSample(0);
+        }
+      } else {
+        const Sample* buffer = c.ChannelData<Sample>()[0];
+        for (int i = 0; i < c.GetDuration(); ++i) {
+          CheckSample(buffer[i]);
+        }
+      }
+    }
+  }
+
+  void AppendDataInterleaved(const Sample* aBuffer, uint32_t aFrames,
+                             uint32_t aChannels) {
+    for (uint32_t i = 0; i < aFrames * aChannels; i += aChannels) {
+      CheckSample(aBuffer[i]);
+    }
+  }
+
+  float EstimatedFreq() const {
+    if (mTotalFramesSoFar == PreSilenceSamples()) {
+      return 0;
+    }
+    if (mSumPeriodInSamples == 0) {
+      return 0;
+    }
+    if (mZeroCrossCount <= 1) {
+      return 0;
+    }
+    return mRate /
+           (static_cast<float>(mSumPeriodInSamples) / (mZeroCrossCount - 1));
+  }
+
+  // Returns the maximum difference in value between two adjacent samples along
+  // the sine curve.
+  Sample MaxMagnitudeDifference() {
+    return static_cast<Sample>(AudioGenerator<Sample>::Amplitude() *
+                               sin(2 * M_PI * mFrequency / mRate));
+  }
+
+  bool PreSilenceEnded() const {
+    return mTotalFramesSoFar > mPreSilenceSamples;
+  }
+  uint64_t PreSilenceSamples() const { return mPreSilenceSamples; }
+  uint32_t CountDiscontinuities() const { return mDiscontinuitiesCount; }
+
+ private:
+  void CheckSample(Sample aCurrentSample) {
+    ++mTotalFramesSoFar;
+    // Avoid pre-silence
+    if (!CountPreSilence(aCurrentSample)) {
+      CountZeroCrossing(aCurrentSample);
+      CountDiscontinuities(aCurrentSample);
+    }
+
+    mPrevious = aCurrentSample;
+  }
+
+  bool CountPreSilence(Sample aCurrentSample) {
+    if (IsZero(aCurrentSample) && mPreSilenceSamples == mTotalFramesSoFar - 1) {
+      ++mPreSilenceSamples;
+      return true;
+    }
+    if (IsZero(mPrevious) && aCurrentSample > 0 &&
+        aCurrentSample < 2 * MaxMagnitudeDifference() &&
+        mPreSilenceSamples == mTotalFramesSoFar - 1) {
+      // Previous zero considered the first sample of the waveform.
+      --mPreSilenceSamples;
+    }
+    return false;
+  }
+
+  // Positive to negative direction
+  void CountZeroCrossing(Sample aCurrentSample) {
+    if (mPrevious > 0 && aCurrentSample <= 0) {
+      if (mZeroCrossCount++) {
+        MOZ_ASSERT(mZeroCrossCount > 1);
+        mSumPeriodInSamples += mTotalFramesSoFar - mLastZeroCrossPosition;
+      }
+      mLastZeroCrossPosition = mTotalFramesSoFar;
+    }
+  }
+
+  void CountDiscontinuities(Sample aCurrentSample) {
+    mDiscontinuitiesCount += fabs(fabs(aCurrentSample) - fabs(mPrevious)) >
+                             3 * MaxMagnitudeDifference();
+  }
+
+  bool IsZero(float aValue) { return fabs(aValue) < 1e-8; }
+  bool IsZero(short aValue) { return aValue == 0; }
+
+ private:
+  const uint32_t mRate;
+  const uint32_t mFrequency;
+
+  uint32_t mZeroCrossCount = 0;
+  uint64_t mLastZeroCrossPosition = 0;
+  uint64_t mSumPeriodInSamples = 0;
+
+  uint64_t mTotalFramesSoFar = 0;
+  uint64_t mPreSilenceSamples = 0;
+
+  uint32_t mDiscontinuitiesCount = 0;
+  // This is needed to connect the previous buffers.
+  Sample mPrevious = {};
+};
+
+}  // namespace mozilla
+
+#endif  // DOM_MEDIA_GTEST_AUDIOVERIFIER_H_