ReverbFast.h

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// Copyright Epic Games, Inc. All Rights Reserved.
 
#pragma once
 
#include "CoreMinimal.h"
#include "DSP/BufferVectorOperations.h"
#include "DSP/IntegerDelay.h"
#include "DSP/LongDelayAPF.h"
#include "DSP/BufferOnePoleLPF.h"
#include "DSP/DynamicDelayAPF.h"
#include "DSP/LateReflectionsFast.h"
#include "DSP/EarlyReflectionsFast.h"
 
namespace Audio
{
    // Settings for plate reverb
    struct FPlateReverbFastSettings
    {
        // EQuadBehavior describes how reverb is generated when there are 5 or more output channels.
        enum class EQuadBehavior : uint8
        {
            // Only produce reverb in front left and front right.
            StereoOnly,
            // Produce reverb in front left and front right. Copy front left to rear left and front right to rear right.
            QuadMatched,
            // Produce reverb in front left and front right. Copy front left to rear right and front right to rear left.
            QuadFlipped
        };
 
        SIGNALPROCESSING_API FPlateReverbFastSettings();
 
        SIGNALPROCESSING_API bool operator==(const FPlateReverbFastSettings& Other) const;
 
        SIGNALPROCESSING_API bool operator!=(const FPlateReverbFastSettings& Other) const;
 
        // EarlyReflectionSettings controls the initial perceived echoes from a sound, modeling the first few
        // orders of reflections from a sound source to the listener's ears. 
        FEarlyReflectionsFastSettings EarlyReflections;
 
        // LateReflectionSettings controls the long tail diffused echo modeling the higher order reflections
        // from a sound source to the listener's ears. 
        FLateReflectionsFastSettings LateReflections;
 
        // Enables / Disables early reflections.
        bool bEnableEarlyReflections;
 
        // Enables / Disables late reflections.
        bool bEnableLateReflections;
 
        // Set how reverb module generates reverb when there are 5 or more output channels. 
        EQuadBehavior QuadBehavior;
    };
 
    // The Plate Reverb emulates the interactions between a sound, the listener and the space they share. Early reflections
    // are modeled using a feedback delay network while late reflections are modeled using a plate reverb. This 
    // class aims to support a flexible and pleasant sounding reverb balanced with computational efficiency. 
    class FPlateReverbFast {
        public:
            static SIGNALPROCESSING_API const FPlateReverbFastSettings DefaultSettings;
            
            // InMaxInternalBufferSamples sets the maximum number of samples used in internal buffers.
            SIGNALPROCESSING_API FPlateReverbFast(float InSampleRate, int32 InMaxInternalBufferSamples = 512, const FPlateReverbFastSettings& InSettings=DefaultSettings);
 
            SIGNALPROCESSING_API ~FPlateReverbFast();
 
            // Copies, clamps and applies settings.
            SIGNALPROCESSING_API void SetSettings(const FPlateReverbFastSettings& InSettings);
 
            SIGNALPROCESSING_API const FPlateReverbFastSettings& GetSettings() const;
 
            // Creates reverberated audio in OutSamples based upon InSamples
            // InNumChannels can be 1 or 2 channels.
            // OutSamples must be greater or equal to 2.
            SIGNALPROCESSING_API void ProcessAudio(const FAlignedFloatBuffer& InSamples, const int32 InNumChannels, FAlignedFloatBuffer& OutSamples, const int32 OutNumChannels);
 
            SIGNALPROCESSING_API void FlushAudio();
 
            // Clamp individual settings to values supported by this class.
            static SIGNALPROCESSING_API void ClampSettings(FPlateReverbFastSettings& InOutSettings);
 
        private:
            // Copy reverberated samples to interleaved output samples. Map channels according to internal settings.
            void InterleaveAndMixOutput(const FAlignedFloatBuffer& InFrontLeftSamples, const FAlignedFloatBuffer& InFrontRightSamples, FAlignedFloatBuffer& OutSamples, const int32 OutNumChannels);
 
            void ApplySettings();
 
 
            float SampleRate;
 
            FPlateReverbFastSettings Settings;
            FEarlyReflectionsFast EarlyReflections;
            FLateReflectionsFast LateReflections;
 
            FAlignedFloatBuffer FrontLeftLateReflectionsSamples;
            FAlignedFloatBuffer FrontRightLateReflectionsSamples;
            FAlignedFloatBuffer FrontLeftEarlyReflectionsSamples;
            FAlignedFloatBuffer FrontRightEarlyReflectionsSamples;
            FAlignedFloatBuffer FrontLeftReverbSamples;
            FAlignedFloatBuffer FrontRightReverbSamples;
            FAlignedFloatBuffer LeftAttenuatedSamples;
            FAlignedFloatBuffer RightAttenuatedSamples;
            FAlignedFloatBuffer ScaledInputBuffer;
 
    };
}