LinearInterpFractionalDelay.h

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// Copyright Epic Games, Inc. All Rights Reserved.
 
#pragma once
 
#include "CoreMinimal.h"
#include "DSP/AlignedBlockBuffer.h"
 
namespace Audio
{
    // Fractional delay using linear interpolation.
    class FLinearInterpFractionalDelay
    {
    public:
        
        // InMaxDelay sets the maximum allowable delay that this object can support. The minimum delay is 0.0
        // InNumInternalBufferSamples sets the maximum block processing size.
        SIGNALPROCESSING_API FLinearInterpFractionalDelay(int32 InMaxDelay, int32 InMaxNumInternalBufferSamples);
        SIGNALPROCESSING_API ~FLinearInterpFractionalDelay();
 
        // Apply delay to InSamples. Fill OutSamples with data from the delay line at a delay of InDelay.
        // InDelay must be equal length to InSamples. 
        SIGNALPROCESSING_API void ProcessAudio(const FAlignedFloatBuffer& InSamples, const FAlignedFloatBuffer& InDelays, FAlignedFloatBuffer& OutSamples);
 
        // Set all values in internal delay line to zero. 
        SIGNALPROCESSING_API void Reset();
 
    private:
        void ProcessAudioBlock(const float* InSamples, const float* InDelays, const int32 InNum, float* OutSamples);
 
        int32 MaxDelay;
        int32 NumInternalBufferSamples;
 
        TUniquePtr<FAlignedBlockBuffer> DelayLine;
        AlignedInt32Buffer IntegerDelayOffsets;
        int* UpperDelayPos;
        int* LowerDelayPos;
 
    };
}