juce_Oversampling.h

/*
  ==============================================================================
 
   This file is part of the JUCE library.
   Copyright (c) 2022 - Raw Material Software Limited
 
   JUCE is an open source library subject to commercial or open-source
   licensing.
 
   By using JUCE, you agree to the terms of both the JUCE 7 End-User License
   Agreement and JUCE Privacy Policy.
 
   End User License Agreement: www.juce.com/juce-7-licence
   Privacy Policy: www.juce.com/juce-privacy-policy
 
   Or: You may also use this code under the terms of the GPL v3 (see
   www.gnu.org/licenses).
 
   JUCE IS PROVIDED "AS IS" WITHOUT ANY WARRANTY, AND ALL WARRANTIES, WHETHER
   EXPRESSED OR IMPLIED, INCLUDING MERCHANTABILITY AND FITNESS FOR PURPOSE, ARE
   DISCLAIMED.
 
  ==============================================================================
*/
 
namespace juce::dsp
{
 
//==============================================================================
template <typename SampleType>
class JUCE_API  Oversampling
{
public:
    enum FilterType
    {
        filterHalfBandFIREquiripple = 0,
        filterHalfBandPolyphaseIIR,
        numFilterTypes
    };
 
    //==============================================================================
    explicit Oversampling (size_t numChannels = 1);

    Oversampling (size_t numChannels,
                  size_t factor,
                  FilterType type,
                  bool isMaxQuality = true,
                  bool useIntegerLatency = false);

    ~Oversampling();
 
    //==============================================================================
    /* Sets if this processor should add some fractional delay at the end of the signal
       path to ensure that the overall latency of the oversampling is an integer.
    */
    void setUsingIntegerLatency (bool shouldUseIntegerLatency) noexcept;

    SampleType getLatencyInSamples() const noexcept;

    size_t getOversamplingFactor() const noexcept;
 
    //==============================================================================
    void initProcessing (size_t maximumNumberOfSamplesBeforeOversampling);

    void reset() noexcept;

    AudioBlock<SampleType> processSamplesUp (const AudioBlock<const SampleType>& inputBlock) noexcept;

    void processSamplesDown (AudioBlock<SampleType>& outputBlock) noexcept;
 
    //==============================================================================
    void addOversamplingStage (FilterType,
                               float normalisedTransitionWidthUp,   float stopbandAmplitudedBUp,
                               float normalisedTransitionWidthDown, float stopbandAmplitudedBDown);

    void addDummyOversamplingStage();

    void clearOversamplingStages();
 
    //==============================================================================
    size_t factorOversampling = 1;
    size_t numChannels = 1;
 
   #ifndef DOXYGEN
    struct OversamplingStage;
   #endif
 
private:
    //==============================================================================
    void updateDelayLine();
    SampleType getUncompensatedLatency() const noexcept;
 
    //==============================================================================
    OwnedArray<OversamplingStage> stages;
    bool isReady = false, shouldUseIntegerLatency = false;
    DelayLine<SampleType, DelayLineInterpolationTypes::Thiran> delay { 8 };
    SampleType fractionalDelay = 0;
 
    //==============================================================================
    JUCE_DECLARE_NON_COPYABLE_WITH_LEAK_DETECTOR (Oversampling)
};
 
} // namespace juce::dsp