1/*
2 * Copyright (C) 2012 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 PeriodicWave_h
30#define PeriodicWave_h
31
32#include "bindings/core/v8/ScriptWrappable.h"
33#include "platform/audio/AudioArray.h"
34#include "wtf/Float32Array.h"
35#include "wtf/Forward.h"
36#include "wtf/Vector.h"
37
38namespace blink {
39
40class PeriodicWave : public GarbageCollectedFinalized<PeriodicWave>, public ScriptWrappable {
41    DEFINE_WRAPPERTYPEINFO();
42public:
43    static PeriodicWave* createSine(float sampleRate);
44    static PeriodicWave* createSquare(float sampleRate);
45    static PeriodicWave* createSawtooth(float sampleRate);
46    static PeriodicWave* createTriangle(float sampleRate);
47
48    // Creates an arbitrary periodic wave given the frequency components (Fourier coefficients).
49    static PeriodicWave* create(float sampleRate, Float32Array* real, Float32Array* imag);
50
51    // Returns pointers to the lower and higher wave data for the pitch range containing
52    // the given fundamental frequency. These two tables are in adjacent "pitch" ranges
53    // where the higher table will have the maximum number of partials which won't alias when played back
54    // at this fundamental frequency. The lower wave is the next range containing fewer partials than the higher wave.
55    // Interpolation between these two tables can be made according to tableInterpolationFactor.
56    // Where values from 0 -> 1 interpolate between lower -> higher.
57    void waveDataForFundamentalFrequency(float, float* &lowerWaveData, float* &higherWaveData, float& tableInterpolationFactor);
58
59    // Returns the scalar multiplier to the oscillator frequency to calculate wave buffer phase increment.
60    float rateScale() const { return m_rateScale; }
61
62    unsigned periodicWaveSize() const { return m_periodicWaveSize; }
63
64    void trace(Visitor*) { }
65
66private:
67    explicit PeriodicWave(float sampleRate);
68
69    void generateBasicWaveform(int);
70
71    float m_sampleRate;
72    unsigned m_periodicWaveSize;
73    unsigned m_numberOfRanges;
74    float m_centsPerRange;
75
76    // The lowest frequency (in Hertz) where playback will include all of the partials.
77    // Playing back lower than this frequency will gradually lose more high-frequency information.
78    // This frequency is quite low (~10Hz @ 44.1KHz)
79    float m_lowestFundamentalFrequency;
80
81    float m_rateScale;
82
83    // Maximum possible number of partials (before culling).
84    unsigned maxNumberOfPartials() const;
85
86    unsigned numberOfPartialsForRange(unsigned rangeIndex) const;
87
88    // Creates tables based on numberOfComponents Fourier coefficients.
89    void createBandLimitedTables(const float* real, const float* imag, unsigned numberOfComponents);
90    Vector<OwnPtr<AudioFloatArray> > m_bandLimitedTables;
91};
92
93} // namespace blink
94
95#endif // PeriodicWave_h
96