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      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