Source/WebCore/Modules/webaudio/WaveShaperDSPKernel.h

/*
 * Copyright (C) 2011, Google Inc. All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
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 *
 * THIS SOFTWARE IS PROVIDED BY APPLE INC. AND ITS CONTRIBUTORS ``AS IS'' AND ANY
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#pragma once

#include "AudioArray.h"
#include "AudioDSPKernel.h"
#include "DownSampler.h"
#include "UpSampler.h"
#include "WaveShaperProcessor.h"
#include <memory>

namespace WebCore {

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

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

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

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

private:
    // 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);

    bool requiresTailProcessing() const final;

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

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

} // namespace WebCore