1/* 2 * Copyright (C) 2010 Google Inc. All rights reserved. 3 * 4 * Redistribution and use in source and binary forms, with or without 5 * modification, are permitted provided that the following conditions 6 * are met: 7 * 8 * 1. Redistributions of source code must retain the above copyright 9 * notice, this list of conditions and the following disclaimer. 10 * 2. Redistributions in binary form must reproduce the above copyright 11 * notice, this list of conditions and the following disclaimer in the 12 * documentation and/or other materials provided with the distribution. 13 * 3. Neither the name of Apple Inc. ("Apple") nor the names of 14 * its contributors may be used to endorse or promote products derived 15 * from this software without specific prior written permission. 16 * 17 * THIS SOFTWARE IS PROVIDED BY APPLE AND ITS CONTRIBUTORS "AS IS" AND ANY 18 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED 19 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE 20 * DISCLAIMED. IN NO EVENT SHALL APPLE OR ITS CONTRIBUTORS BE LIABLE FOR ANY 21 * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES 22 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; 23 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND 24 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 25 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 26 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 27 */ 28 29#ifndef HRTFKernel_h 30#define HRTFKernel_h 31 32#include "FFTFrame.h" 33#include <memory> 34#include <wtf/PassRefPtr.h> 35#include <wtf/RefCounted.h> 36#include <wtf/RefPtr.h> 37#include <wtf/Vector.h> 38 39namespace WebCore { 40 41class AudioChannel; 42 43// HRTF stands for Head-Related Transfer Function. 44// HRTFKernel is a frequency-domain representation of an impulse-response used as part of the spatialized panning system. 45// For a given azimuth / elevation angle there will be one HRTFKernel for the left ear transfer function, and one for the right ear. 46// The leading delay (average group delay) for each impulse response is extracted: 47// m_fftFrame is the frequency-domain representation of the impulse response with the delay removed 48// m_frameDelay is the leading delay of the original impulse response. 49class HRTFKernel : public RefCounted<HRTFKernel> { 50public: 51 // Note: this is destructive on the passed in AudioChannel. 52 // The length of channel must be a power of two. 53 static PassRefPtr<HRTFKernel> create(AudioChannel* channel, size_t fftSize, float sampleRate) 54 { 55 return adoptRef(new HRTFKernel(channel, fftSize, sampleRate)); 56 } 57 58 static PassRefPtr<HRTFKernel> create(std::unique_ptr<FFTFrame> fftFrame, float frameDelay, float sampleRate) 59 { 60 return adoptRef(new HRTFKernel(WTF::move(fftFrame), frameDelay, sampleRate)); 61 } 62 63 // Given two HRTFKernels, and an interpolation factor x: 0 -> 1, returns an interpolated HRTFKernel. 64 static PassRefPtr<HRTFKernel> createInterpolatedKernel(HRTFKernel* kernel1, HRTFKernel* kernel2, float x); 65 66 FFTFrame* fftFrame() { return m_fftFrame.get(); } 67 68 size_t fftSize() const; 69 float frameDelay() const { return m_frameDelay; } 70 71 float sampleRate() const { return m_sampleRate; } 72 double nyquist() const { return 0.5 * sampleRate(); } 73 74 // Converts back into impulse-response form. 75 std::unique_ptr<AudioChannel> createImpulseResponse(); 76 77private: 78 // Note: this is destructive on the passed in AudioChannel. 79 HRTFKernel(AudioChannel*, size_t fftSize, float sampleRate); 80 81 HRTFKernel(std::unique_ptr<FFTFrame> fftFrame, float frameDelay, float sampleRate) 82 : m_fftFrame(WTF::move(fftFrame)) 83 , m_frameDelay(frameDelay) 84 , m_sampleRate(sampleRate) 85 { 86 } 87 88 std::unique_ptr<FFTFrame> m_fftFrame; 89 float m_frameDelay; 90 float m_sampleRate; 91}; 92 93typedef Vector<RefPtr<HRTFKernel>> HRTFKernelList; 94 95} // namespace WebCore 96 97#endif // HRTFKernel_h 98