AudioBufferDistanceAttenuation.h

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// Copyright Epic Games, Inc. All Rights Reserved.
 
#pragma once
 
#include "HAL/CriticalSection.h"
#include "Math/Vector2D.h"
#include "DSP/AudioLinearCurve.h"
 
namespace Audio
{
    // Settings for audio buffer distance attenuation
    struct FAudioBufferDistanceAttenuationSettings
    {
        FAudioBufferDistanceAttenuationSettings() = default;
        ~FAudioBufferDistanceAttenuationSettings() = default;
 
        // The min and max distance range to apply attenuation to the voip stream based on distance from listener.
        FVector2D DistanceRange = { 400.0f, 4000.0f };
 
        // The attenuation (in Decibels) at max range. The attenuation will be performed in dB and clamped to zero (linear) greater than max attenuation past the max range.
        float AttenuationDbAtMaxRange = -60.0f;
 
        // A curve (values are expected to be normalized between 0.0 and 1.0) to use to control attenuation vs distance from listener.
        Audio::FLinearCurve AttenuationCurve;
    };
 
    // Processes the audio buffer with the given distance attenuation
    // InOutAudioFrames - The audio buffer to attenuate. Note there is a function override for int16 and float formats.
    // InFrameCount - The number of frames of audio in the buffer
    // InNumChannels - The number of channels of audio in the buffer
    // InDistance - The current distance to use to compute the attenuation
    // InSettings - The settings to use to compute the attenuation
    // InOutAttenuation - The input value of previous attenuation and the output value after performing the current distance 
    //                    attenuation. Use -1.0 if this is the first call to this function. The value is used to interpolate the attenuation smoothly.
    SIGNALPROCESSING_API void DistanceAttenuationProcessAudio(
        TArrayView<int16>& InOutBuffer,
        uint32 InNumChannels, 
        float InDistance, 
        const FAudioBufferDistanceAttenuationSettings& InSettings, 
        float& InOutAttenuation);
    
    SIGNALPROCESSING_API void DistanceAttenuationProcessAudio(
        TArrayView<float>& InOutBuffer,
        uint32 InNumChannels, 
        float InDistance, 
        const FAudioBufferDistanceAttenuationSettings& InSettings, 
        float& InOutAttenuation);
 
}