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 38 namespace blink { 39 40 class PeriodicWave : public GarbageCollectedFinalized<PeriodicWave>, public ScriptWrappable { 41 DEFINE_WRAPPERTYPEINFO(); 42 public: 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 66 private: 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
