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 void pan(double azimuth, double elevation, const AudioBus* inputBus, AudioBus* outputBus, size_t framesToProcess) override;
42 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 double tailTime() const override;
50 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