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 Computer, 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 <wtf/OwnPtr.h> 34 #include <wtf/PassOwnPtr.h> 35 #include <wtf/PassRefPtr.h> 36 #include <wtf/RefCounted.h> 37 #include <wtf/RefPtr.h> 38 #include <wtf/Vector.h> 39 40 namespace WebCore { 41 42 class AudioChannel; 43 44 // HRTF stands for Head-Related Transfer Function. 45 // HRTFKernel is a frequency-domain representation of an impulse-response used as part of the spatialized panning system. 46 // For a given azimuth / elevation angle there will be one HRTFKernel for the left ear transfer function, and one for the right ear. 47 // The leading delay (average group delay) for each impulse response is extracted: 48 // m_fftFrame is the frequency-domain representation of the impulse response with the delay removed 49 // m_frameDelay is the leading delay of the original impulse response. 50 class HRTFKernel : public RefCounted<HRTFKernel> { 51 public: 52 // Note: this is destructive on the passed in AudioChannel. 53 // The length of channel must be a power of two. create(AudioChannel * channel,size_t fftSize,double sampleRate,bool bassBoost)54 static PassRefPtr<HRTFKernel> create(AudioChannel* channel, size_t fftSize, double sampleRate, bool bassBoost) 55 { 56 return adoptRef(new HRTFKernel(channel, fftSize, sampleRate, bassBoost)); 57 } 58 create(PassOwnPtr<FFTFrame> fftFrame,double frameDelay,double sampleRate)59 static PassRefPtr<HRTFKernel> create(PassOwnPtr<FFTFrame> fftFrame, double frameDelay, double sampleRate) 60 { 61 return adoptRef(new HRTFKernel(fftFrame, frameDelay, sampleRate)); 62 } 63 64 // Given two HRTFKernels, and an interpolation factor x: 0 -> 1, returns an interpolated HRTFKernel. 65 static PassRefPtr<HRTFKernel> createInterpolatedKernel(HRTFKernel* kernel1, HRTFKernel* kernel2, double x); 66 fftFrame()67 FFTFrame* fftFrame() { return m_fftFrame.get(); } 68 fftSize()69 size_t fftSize() const { return m_fftFrame->fftSize(); } frameDelay()70 double frameDelay() const { return m_frameDelay; } 71 sampleRate()72 double sampleRate() const { return m_sampleRate; } nyquist()73 double nyquist() const { return 0.5 * sampleRate(); } 74 75 // Converts back into impulse-response form. 76 PassOwnPtr<AudioChannel> createImpulseResponse(); 77 78 private: 79 // Note: this is destructive on the passed in AudioChannel. 80 HRTFKernel(AudioChannel* channel, size_t fftSize, double sampleRate, bool bassBoost); 81 HRTFKernel(PassOwnPtr<FFTFrame> fftFrame,double frameDelay,double sampleRate)82 HRTFKernel(PassOwnPtr<FFTFrame> fftFrame, double frameDelay, double sampleRate) 83 : m_fftFrame(fftFrame) 84 , m_frameDelay(frameDelay) 85 , m_sampleRate(sampleRate) 86 { 87 } 88 89 OwnPtr<FFTFrame> m_fftFrame; 90 double m_frameDelay; 91 double m_sampleRate; 92 }; 93 94 typedef Vector<RefPtr<HRTFKernel> > HRTFKernelList; 95 96 } // namespace WebCore 97 98 #endif // HRTFKernel_h 99