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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:

  *

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  *     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.

  * 3.  Neither the name of Apple Computer, Inc. ("Apple") nor the names of

  *     its contributors may be used to endorse or promote products derived

  *     from this software without specific prior written permission.

  *

  * THIS SOFTWARE IS PROVIDED BY APPLE AND ITS CONTRIBUTORS "AS IS" AND ANY

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  * DISCLAIMED. IN NO EVENT SHALL APPLE OR ITS CONTRIBUTORS BE LIABLE FOR ANY

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 #ifndef HRTFKernel_h

 #define HRTFKernel_h

 #include "nsAutoPtr.h"

 #include "nsAutoRef.h"

 #include "nsTArray.h"

 #include "mozilla/FFTBlock.h"

 #include "mozilla/MemoryReporting.h"

 namespace WebCore {

 using mozilla::FFTBlock;

 // HRTF stands for Head-Related Transfer Function.

 // HRTFKernel is a frequency-domain representation of an impulse-response used as part of the spatialized panning system.

 // For a given azimuth / elevation angle there will be one HRTFKernel for the left ear transfer function, and one for the right ear.

 // The leading delay (average group delay) for each impulse response is extracted:

 //      m_fftFrame is the frequency-domain representation of the impulse response with the delay removed

 //      m_frameDelay is the leading delay of the original impulse response.

 class HRTFKernel {

 public:

     // Note: this is destructive on the passed in |impulseResponse|.

     // The |length| of |impulseResponse| must be a power of two.

     // The size of the DFT will be |2 * length|.

     static nsReturnRef<HRTFKernel> create(float* impulseResponse, size_t length, float sampleRate);

     static nsReturnRef<HRTFKernel> create(nsAutoPtr<FFTBlock> fftFrame, float frameDelay, float sampleRate);

     // Given two HRTFKernels, and an interpolation factor x: 0 -> 1, returns an interpolated HRTFKernel.

     static nsReturnRef<HRTFKernel> createInterpolatedKernel(HRTFKernel* kernel1, HRTFKernel* kernel2, float x);

     FFTBlock* fftFrame() { return m_fftFrame.get(); }

     size_t fftSize() const { return m_fftFrame->FFTSize(); }

     float frameDelay() const { return m_frameDelay; }

     float sampleRate() const { return m_sampleRate; }

     double nyquist() const { return 0.5 * sampleRate(); }

     size_t sizeOfIncludingThis(mozilla::MallocSizeOf aMallocSizeOf) const

     {

         size_t amount = aMallocSizeOf(this);

         amount += m_fftFrame->SizeOfIncludingThis(aMallocSizeOf);

         return amount;

     }

 private:

     HRTFKernel(const HRTFKernel& other) MOZ_DELETE;

     void operator=(const HRTFKernel& other) MOZ_DELETE;

     // Note: this is destructive on the passed in |impulseResponse|.

     HRTFKernel(float* impulseResponse, size_t fftSize, float sampleRate);

     HRTFKernel(nsAutoPtr<FFTBlock> fftFrame, float frameDelay, float sampleRate)

         : m_fftFrame(fftFrame)

         , m_frameDelay(frameDelay)

         , m_sampleRate(sampleRate)

     {

     }

     nsAutoPtr<FFTBlock> m_fftFrame;

     float m_frameDelay;

     float m_sampleRate;

 };

 typedef nsTArray<nsAutoRef<HRTFKernel> > HRTFKernelList;

 } // namespace WebCore

 template <>

 class nsAutoRefTraits<WebCore::HRTFKernel> :

     public nsPointerRefTraits<WebCore::HRTFKernel> {

 public:

     static void Release(WebCore::HRTFKernel* ptr) { delete(ptr); }

 };

 namespace WebCore {

 inline nsReturnRef<HRTFKernel> HRTFKernel::create(float* impulseResponse, size_t length, float sampleRate)

 {

     return nsReturnRef<HRTFKernel>(new HRTFKernel(impulseResponse, length, sampleRate));

 }

 inline nsReturnRef<HRTFKernel> HRTFKernel::create(nsAutoPtr<FFTBlock> fftFrame, float frameDelay, float sampleRate)

 {

     return nsReturnRef<HRTFKernel>(new HRTFKernel(fftFrame, frameDelay, sampleRate));

 }

 } // namespace WebCore

 #endif // HRTFKernel_h