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 * 1.  Redistributions of source code must retain the above copyright
8 *    notice, this list of conditions and the following disclaimer.
9 * 2.  Redistributions in binary form must reproduce the above copyright
10 *    notice, this list of conditions and the following disclaimer in the
11 *    documentation and/or other materials provided with the distribution.
12 *
13 * THIS SOFTWARE IS PROVIDED BY APPLE INC. AND ITS CONTRIBUTORS ``AS IS'' AND ANY
14 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
15 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
16 * DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR ITS CONTRIBUTORS BE LIABLE FOR ANY
17 * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
18 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
19 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
20 * ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
21 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
22 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
23 */
24
25#ifndef HRTFPanner_h
26#define HRTFPanner_h
27
28#include "DelayDSPKernel.h"
29#include "FFTConvolver.h"
30#include "Panner.h"
31
32namespace WebCore {
33
34class HRTFPanner : public Panner {
35public:
36    explicit HRTFPanner(double sampleRate);
37    virtual ~HRTFPanner();
38
39    // Panner
40    virtual void pan(double azimuth, double elevation, AudioBus* inputBus, AudioBus* outputBus, size_t framesToProcess);
41    virtual void reset();
42
43    size_t fftSize() { return fftSizeForSampleRate(m_sampleRate); }
44    static size_t fftSizeForSampleRate(double sampleRate);
45
46    double sampleRate() const { return m_sampleRate; }
47
48private:
49    // Given an azimuth angle in the range -180 -> +180, returns the corresponding azimuth index for the database,
50    // and azimuthBlend which is an interpolation value from 0 -> 1.
51    int calculateDesiredAzimuthIndexAndBlend(double azimuth, double& azimuthBlend);
52
53    double m_sampleRate;
54
55    // m_isFirstRender and m_azimuthIndex are used to avoid harshly changing from rendering at one azimuth angle to another angle very far away.
56    // Changing the azimuth gradually produces a smoother sound.
57    bool m_isFirstRender;
58    int m_azimuthIndex;
59
60    FFTConvolver m_convolverL;
61    FFTConvolver m_convolverR;
62    DelayDSPKernel m_delayLineL;
63    DelayDSPKernel m_delayLineR;
64};
65
66} // namespace WebCore
67
68#endif // HRTFPanner_h
69