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diff --git a/dom/media/webaudio/blink/HRTFPanner.h b/dom/media/webaudio/blink/HRTFPanner.h
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+++ b/dom/media/webaudio/blink/HRTFPanner.h
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+/*
+ * Copyright (C) 2010, Google Inc. All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1.  Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2.  Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY APPLE INC. AND ITS CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
+ * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+ * DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR ITS CONTRIBUTORS BE LIABLE FOR
+ * ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+ * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+ * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#ifndef HRTFPanner_h
+#define HRTFPanner_h
+
+#include "FFTConvolver.h"
+#include "DelayBuffer.h"
+#include "mozilla/MemoryReporting.h"
+
+namespace mozilla {
+class AudioBlock;
+}  // namespace mozilla
+
+namespace WebCore {
+
+typedef nsTArray<float> AudioFloatArray;
+
+class HRTFDatabaseLoader;
+
+using mozilla::AudioBlock;
+
+class HRTFPanner {
+ public:
+  HRTFPanner(float sampleRate,
+             already_AddRefed<HRTFDatabaseLoader> databaseLoader);
+  ~HRTFPanner();
+
+  // chunk durations must be 128
+  void pan(double azimuth, double elevation, const AudioBlock* inputBus,
+           AudioBlock* outputBus);
+  void reset();
+
+  size_t fftSize() const { return m_convolverL1.fftSize(); }
+
+  float sampleRate() const { return m_sampleRate; }
+
+  int maxTailFrames() const;
+
+  size_t sizeOfIncludingThis(mozilla::MallocSizeOf aMallocSizeOf) const;
+
+ private:
+  // Given an azimuth angle in the range -180 -> +180, returns the corresponding
+  // azimuth index for the database, and azimuthBlend which is an interpolation
+  // value from 0 -> 1.
+  int calculateDesiredAzimuthIndexAndBlend(double azimuth,
+                                           double& azimuthBlend);
+
+  RefPtr<HRTFDatabaseLoader> m_databaseLoader;
+
+  float m_sampleRate;
+
+  // We maintain two sets of convolvers for smooth cross-faded interpolations
+  // when then azimuth and elevation are dynamically changing. When the azimuth
+  // and elevation are not changing, we simply process with one of the two sets.
+  // Initially we use CrossfadeSelection1 corresponding to m_convolverL1 and
+  // m_convolverR1. Whenever the azimuth or elevation changes, a crossfade is
+  // initiated to transition to the new position. So if we're currently
+  // processing with CrossfadeSelection1, then we transition to
+  // CrossfadeSelection2 (and vice versa). If we're in the middle of a
+  // transition, then we wait until it is complete before initiating a new
+  // transition.
+
+  // Selects either the convolver set (m_convolverL1, m_convolverR1) or
+  // (m_convolverL2, m_convolverR2).
+  enum CrossfadeSelection { CrossfadeSelection1, CrossfadeSelection2 };
+
+  CrossfadeSelection m_crossfadeSelection;
+
+  // azimuth/elevation for CrossfadeSelection1.
+  int m_azimuthIndex1;
+  double m_elevation1;
+
+  // azimuth/elevation for CrossfadeSelection2.
+  int m_azimuthIndex2;
+  double m_elevation2;
+
+  // A crossfade value 0 <= m_crossfadeX <= 1.
+  float m_crossfadeX;
+
+  // Per-sample-frame crossfade value increment.
+  float m_crossfadeIncr;
+
+  FFTConvolver m_convolverL1;
+  FFTConvolver m_convolverR1;
+  FFTConvolver m_convolverL2;
+  FFTConvolver m_convolverR2;
+
+  mozilla::DelayBuffer m_delayLine;
+
+  AudioFloatArray m_tempL1;
+  AudioFloatArray m_tempR1;
+  AudioFloatArray m_tempL2;
+  AudioFloatArray m_tempR2;
+};
+
+}  // namespace WebCore
+
+#endif  // HRTFPanner_h