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 "HRTFDatabaseLoader.h"
31#include "Panner.h"
32
33namespace WebCore {
34
35class HRTFPanner : public Panner {
36public:
37    explicit HRTFPanner(float sampleRate, HRTFDatabaseLoader*);
38    virtual ~HRTFPanner();
39
40    // Panner
41    virtual void pan(double azimuth, double elevation, const AudioBus* inputBus, AudioBus* outputBus, size_t framesToProcess) override;
42    virtual void reset() override;
43
44    size_t fftSize() const { return fftSizeForSampleRate(m_sampleRate); }
45    static size_t fftSizeForSampleRate(float sampleRate);
46
47    float sampleRate() const { return m_sampleRate; }
48
49    virtual double tailTime() const override;
50    virtual double latencyTime() const override;
51
52private:
53    // Given an azimuth angle in the range -180 -> +180, returns the corresponding azimuth index for the database,
54    // and azimuthBlend which is an interpolation value from 0 -> 1.
55    int calculateDesiredAzimuthIndexAndBlend(double azimuth, double& azimuthBlend);
56
57    RefPtr<HRTFDatabaseLoader> m_databaseLoader;
58
59    float m_sampleRate;
60
61    // We maintain two sets of convolvers for smooth cross-faded interpolations when
62    // then azimuth and elevation are dynamically changing.
63    // When the azimuth and elevation are not changing, we simply process with one of the two sets.
64    // Initially we use CrossfadeSelection1 corresponding to m_convolverL1 and m_convolverR1.
65    // Whenever the azimuth or elevation changes, a crossfade is initiated to transition
66    // to the new position. So if we're currently processing with CrossfadeSelection1, then
67    // we transition to CrossfadeSelection2 (and vice versa).
68    // If we're in the middle of a transition, then we wait until it is complete before
69    // initiating a new transition.
70
71    // Selects either the convolver set (m_convolverL1, m_convolverR1) or (m_convolverL2, m_convolverR2).
72    enum CrossfadeSelection {
73        CrossfadeSelection1,
74        CrossfadeSelection2
75    };
76
77    CrossfadeSelection m_crossfadeSelection;
78
79    // azimuth/elevation for CrossfadeSelection1.
80    int m_azimuthIndex1;
81    double m_elevation1;
82
83    // azimuth/elevation for CrossfadeSelection2.
84    int m_azimuthIndex2;
85    double m_elevation2;
86
87    // A crossfade value 0 <= m_crossfadeX <= 1.
88    float m_crossfadeX;
89
90    // Per-sample-frame crossfade value increment.
91    float m_crossfadeIncr;
92
93    FFTConvolver m_convolverL1;
94    FFTConvolver m_convolverR1;
95    FFTConvolver m_convolverL2;
96    FFTConvolver m_convolverR2;
97
98    DelayDSPKernel m_delayLineL;
99    DelayDSPKernel m_delayLineR;
100
101    AudioFloatArray m_tempL1;
102    AudioFloatArray m_tempR1;
103    AudioFloatArray m_tempL2;
104    AudioFloatArray m_tempR2;
105};
106
107} // namespace WebCore
108
109#endif // HRTFPanner_h
110