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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/v8/ScriptWrappable.h"
     33 #include "core/platform/audio/AudioArray.h"
     34 #include "wtf/Float32Array.h"
     35 #include "wtf/OwnPtr.h"
     36 #include "wtf/PassRefPtr.h"
     37 #include "wtf/RefCounted.h"
     38 #include "wtf/RefPtr.h"
     39 #include "wtf/Vector.h"
     40 
     41 namespace WebCore {
     42 
     43 class PeriodicWave : public ScriptWrappable, public RefCounted<PeriodicWave> {
     44 public:
     45     static PassRefPtr<PeriodicWave> createSine(float sampleRate);
     46     static PassRefPtr<PeriodicWave> createSquare(float sampleRate);
     47     static PassRefPtr<PeriodicWave> createSawtooth(float sampleRate);
     48     static PassRefPtr<PeriodicWave> createTriangle(float sampleRate);
     49 
     50     // Creates an arbitrary periodic wave given the frequency components (Fourier coefficients).
     51     static PassRefPtr<PeriodicWave> create(float sampleRate, Float32Array* real, Float32Array* imag);
     52 
     53     // Returns pointers to the lower and higher wave data for the pitch range containing
     54     // the given fundamental frequency. These two tables are in adjacent "pitch" ranges
     55     // where the higher table will have the maximum number of partials which won't alias when played back
     56     // at this fundamental frequency. The lower wave is the next range containing fewer partials than the higher wave.
     57     // Interpolation between these two tables can be made according to tableInterpolationFactor.
     58     // Where values from 0 -> 1 interpolate between lower -> higher.
     59     void waveDataForFundamentalFrequency(float, float* &lowerWaveData, float* &higherWaveData, float& tableInterpolationFactor);
     60 
     61     // Returns the scalar multiplier to the oscillator frequency to calculate wave buffer phase increment.
     62     float rateScale() const { return m_rateScale; }
     63 
     64     unsigned periodicWaveSize() const { return m_periodicWaveSize; }
     65     float sampleRate() const { return m_sampleRate; }
     66 
     67 private:
     68     explicit PeriodicWave(float sampleRate);
     69 
     70     void generateBasicWaveform(int);
     71 
     72     float m_sampleRate;
     73     unsigned m_periodicWaveSize;
     74     unsigned m_numberOfRanges;
     75     float m_centsPerRange;
     76 
     77     // The lowest frequency (in Hertz) where playback will include all of the partials.
     78     // Playing back lower than this frequency will gradually lose more high-frequency information.
     79     // This frequency is quite low (~10Hz @ 44.1KHz)
     80     float m_lowestFundamentalFrequency;
     81 
     82     float m_rateScale;
     83 
     84     unsigned numberOfRanges() const { return m_numberOfRanges; }
     85 
     86     // Maximum possible number of partials (before culling).
     87     unsigned maxNumberOfPartials() const;
     88 
     89     unsigned numberOfPartialsForRange(unsigned rangeIndex) const;
     90 
     91     // Creates tables based on numberOfComponents Fourier coefficients.
     92     void createBandLimitedTables(const float* real, const float* imag, unsigned numberOfComponents);
     93     Vector<OwnPtr<AudioFloatArray> > m_bandLimitedTables;
     94 };
     95 
     96 } // namespace WebCore
     97 
     98 #endif // PeriodicWave_h
     99