Source/modules/webaudio/WaveShaperDSPKernel.h

/*
 * Copyright (C) 2011, Google Inc. All rights reserved.
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 * Redistribution and use in source and binary forms, with or without
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#ifndef WaveShaperDSPKernel_h
#define WaveShaperDSPKernel_h

#include "platform/audio/AudioArray.h"
#include "platform/audio/AudioDSPKernel.h"
#include "platform/audio/DownSampler.h"
#include "platform/audio/UpSampler.h"
#include "modules/webaudio/WaveShaperProcessor.h"
#include "wtf/OwnPtr.h"

namespace blink {

class WaveShaperProcessor;

// WaveShaperDSPKernel is an AudioDSPKernel and is responsible for non-linear distortion on one channel.

class WaveShaperDSPKernel FINAL : public AudioDSPKernel {
public:
    explicit WaveShaperDSPKernel(WaveShaperProcessor*);

    // AudioDSPKernel
    virtual void process(const float* source, float* dest, size_t framesToProcess) OVERRIDE;
    virtual void reset() OVERRIDE;
    virtual double tailTime() const OVERRIDE { return 0; }
    virtual double latencyTime() const OVERRIDE;

    // Oversampling requires more resources, so let's only allocate them if needed.
    void lazyInitializeOversampling();

protected:
    // Apply the shaping curve.
    void processCurve(const float* source, float* dest, size_t framesToProcess);

    // Use up-sampling, process at the higher sample-rate, then down-sample.
    void processCurve2x(const float* source, float* dest, size_t framesToProcess);
    void processCurve4x(const float* source, float* dest, size_t framesToProcess);

    WaveShaperProcessor* waveShaperProcessor() { return static_cast<WaveShaperProcessor*>(processor()); }

    // Oversampling.
    OwnPtr<AudioFloatArray> m_tempBuffer;
    OwnPtr<AudioFloatArray> m_tempBuffer2;
    OwnPtr<UpSampler> m_upSampler;
    OwnPtr<DownSampler> m_downSampler;
    OwnPtr<UpSampler> m_upSampler2;
    OwnPtr<DownSampler> m_downSampler2;
};

} // namespace blink

#endif // WaveShaperDSPKernel_h