BufferOnePoleLPF.h

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// Copyright Epic Games, Inc. All Rights Reserved.
 
#pragma once
 
#include "CoreMinimal.h"
#include "DSP/Dsp.h"
#include "DSP/BufferVectorOperations.h"
 
namespace Audio
{
 
    // Simple 1-pole lowpass filter
    class FBufferOnePoleLPF
    {
    public:
 
        // Constructor 
        SIGNALPROCESSING_API FBufferOnePoleLPF(float InG = 0.0f);
 
        // Set the LPF gain coefficient
        SIGNALPROCESSING_API void SetG(float InG);
 
        // Resets the sample delay to 0
        SIGNALPROCESSING_API void Reset();
 
        // Resets the audio to silence.
        SIGNALPROCESSING_API void FlushAudio();
 
        // Sets the filter frequency using normalized frequency (between 0.0 and 1.0f or 0.0 hz and Nyquist Frequency in Hz) 
        SIGNALPROCESSING_API void SetFrequency(const float InFrequency);
 
        // Process InSamples and place filtered audio in OutSamples
        SIGNALPROCESSING_API void ProcessAudio(const FAlignedFloatBuffer& InSamples, FAlignedFloatBuffer& OutSamples);
 
    protected:
        float CutoffFrequency;
 
        // Filter coefficients
        float B1;
        float A0;
 
        // 1-sample delay
        float Z1;
    };
 
    
 
}