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/WebCore/platform/audio/HRTFKernel.h

https://bitbucket.org/sevear/webkit-ios
C Header | 98 lines | 43 code | 17 blank | 38 comment | 0 complexity | a4b010b2a8963c8cda04ece942af3e78 MD5 | raw file
 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
40namespace WebCore {
41
42class 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.
50class HRTFKernel : public RefCounted<HRTFKernel> {
51public:
52    // Note: this is destructive on the passed in AudioChannel.
53    // The length of channel must be a power of two.
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
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  
67    FFTFrame* fftFrame() { return m_fftFrame.get(); }
68    
69    size_t fftSize() const { return m_fftFrame->fftSize(); }
70    double frameDelay() const { return m_frameDelay; }
71
72    double sampleRate() const { return m_sampleRate; }
73    double nyquist() const { return 0.5 * sampleRate(); }
74
75    // Converts back into impulse-response form.
76    PassOwnPtr<AudioChannel> createImpulseResponse();
77
78private:
79    // Note: this is destructive on the passed in AudioChannel.
80    HRTFKernel(AudioChannel* channel, size_t fftSize, double sampleRate, bool bassBoost);
81    
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
94typedef Vector<RefPtr<HRTFKernel> > HRTFKernelList;
95
96} // namespace WebCore
97
98#endif // HRTFKernel_h