BlockCorrelator.h

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// Copyright Epic Games, Inc. All Rights Reserved.
 
#pragma once
 
#include "CoreMinimal.h"
#include "DSP/BufferVectorOperations.h"
#include "DSP/AudioFFT.h"
#include "DSP/FFTAlgorithm.h"
 
namespace Audio
{   
    struct FBlockCorrelatorSettings
    {
        int32 Log2NumValuesInBlock = 10;  // 2^10 = 1024
 
        EWindowType WindowType = EWindowType::Blackman;
 
        bool bDoNormalize = true;
    };
 
    class FBlockCorrelator
    {
        public:
            SIGNALPROCESSING_API FBlockCorrelator(const FBlockCorrelatorSettings& InSettings);
 
            SIGNALPROCESSING_API const FBlockCorrelatorSettings& GetSettings() const;
 
            SIGNALPROCESSING_API int32 GetNumInputValues() const;
 
            SIGNALPROCESSING_API int32 GetNumOutputValues() const;
 
            SIGNALPROCESSING_API void CrossCorrelate(const FAlignedFloatBuffer& InputA, const FAlignedFloatBuffer& InputB, FAlignedFloatBuffer& Output);
 
            SIGNALPROCESSING_API void AutoCorrelate(const FAlignedFloatBuffer& Input, FAlignedFloatBuffer& Output);
 
 
        private:
            // No normalization or windowing.
            void CyclicCrossCorrelate(const FAlignedFloatBuffer& InputA, const FAlignedFloatBuffer& InputB, FAlignedFloatBuffer& Output);
 
            // No normalization or windowing.
            void CyclicAutoCorrelate(const FAlignedFloatBuffer& Input, FAlignedFloatBuffer& Output);
 
            void InitializeNormalizationBuffer();
 
            FBlockCorrelatorSettings Settings;
 
            int32 NumValuesInBlock;
            int32 NumValuesInFFTRealBuffer;
            int32 NumValuesInFFTComplexBuffer;
 
            TUniquePtr<IFFTAlgorithm> FFTAlgorithm;
 
            FWindow Window;
            FAlignedFloatBuffer NormalizationBuffer;
 
            FAlignedFloatBuffer WindowedBufferA;
            FAlignedFloatBuffer WindowedBufferB;
 
            FAlignedFloatBuffer ComplexBufferA;
            FAlignedFloatBuffer ComplexBufferB;
 
            FAlignedFloatBuffer ComplexCorrelationBuffer;
 
            FAlignedFloatBuffer FullOutputBuffer;
    };
}