Amp.h

Go to the documentation of this file.

// Copyright Epic Games, Inc. All Rights Reserved.
 
#pragma once
 
#include "CoreMinimal.h"
#include "DSP/Osc.h"
 
namespace Audio
{
    struct FWetDry
    {
        // Level of wet signal
        float WetLevel;
 
        // Level of dry signal
        float DryLevel;
 
        FWetDry(float InWetLevel = 1.0f, float InDryLevel = 0.0f)
            : WetLevel(InWetLevel)
            , DryLevel(InDryLevel)
        {
        }
    };
 
    // Class which manages scaling audio input and performing panning operations
    class FAmp
    {
    public:
        SIGNALPROCESSING_API FAmp();
        SIGNALPROCESSING_API ~FAmp();
 
        // Initializes the amp with the mod matrix
        SIGNALPROCESSING_API void Init(const int32 InVoiceId = INDEX_NONE, FModulationMatrix* ModMatrix = nullptr);
 
        // Sets the direct gain in decibel
        SIGNALPROCESSING_API void SetGainDb(const float InGainDB);
 
        // Sets the gain modulation in decibel
        SIGNALPROCESSING_API void SetGainModDb(const float InGainModDb);
 
        // Sets the direct gain in linear
        SIGNALPROCESSING_API void SetGain(const float InGainLinear);
 
        // Sets the gain modulation in linear. Expects modulation value to be bipolar (for AM synth, etc)
        SIGNALPROCESSING_API void SetGainMod(const float InBipolarGainModLinear);
 
        // Sets the gain based on an envelope value
        SIGNALPROCESSING_API void SetGainEnv(const float InGainEnv);
 
        // Sets the gain based on an envelope value
        SIGNALPROCESSING_API void SetGainEnvDb(const float InGainEnvDb);
 
        // Change the allowed range of the gain output
        SIGNALPROCESSING_API void SetGainRange(const float InMin, const float InMax);
        
        // Sets the gain using a midi velocity value
        SIGNALPROCESSING_API void SetVelocity(const float InVelocity);
 
        // Sets the pan
        SIGNALPROCESSING_API void SetPan(const float InPan);
 
        // Sets the pan modulator
        SIGNALPROCESSING_API void SetPanModulator(const float InPanMod);
 
        // Takes mono input and generates stereo output
        SIGNALPROCESSING_API void ProcessAudio(const float LeftIn, float* LeftOutput, float* RightOutput);
 
        // Takes stereo input and generates stereo output
        SIGNALPROCESSING_API void ProcessAudio(const float LeftIn, const float RightIn, float* LeftOutput, float* RightOutput);
 
        // Generates a new gain value for left and right outputs. 
        SIGNALPROCESSING_API void Generate(float& OutGainLeft, float& OutGainRight);
 
        SIGNALPROCESSING_API void Reset();
 
        // Updates the final output left and right gain based on current settings
        SIGNALPROCESSING_API void Update();
 
        const FPatchDestination GetModDestGainScale() const { return GainScaleDest; }
        const FPatchDestination GetModDestGainEnv() const { return GainEnvDest; }
        const FPatchDestination GetModDestPan() const { return GainPanDest; }
 
    protected:
        int32 VoiceId;
 
        // The final left and right output gain values
        float LeftGain;
        float RightGain;
 
        // Values used for lerping gain values to avoid zippering
        float TargetLeftGain;
        float TargetRightGain;
 
        int32 TargetDeltaSamples;
        int32 CurrentLerpSample;
 
        float TargetLeftSlope;
        float TargetRightSlope;
        
 
        // Min and max output gain, can be changed based on need
        float GainMin;
        float GainMax;
 
        // Direct input gain control (i.e. gain slider)
        float GainControl;
 
        // Gain due to midi velocity
        float GainVelocity;
 
        // A modulated value of gain, can be used for tremolo or amplitude modulation
        float GainMod;
 
        // Gain set from envelope
        float GainEnv;
 
        // Linear pan value [-1.0, 1.0]
        float Pan;
        
        // Linear pan modulator
        float PanMod;
 
        // Mod matrix
        FModulationMatrix* ModMatrix;
        FPatchDestination GainScaleDest;
        FPatchDestination GainEnvDest;
        FPatchDestination GainPanDest;
 
        // Whether or not something changed since the last time generate was called
        bool bChanged;
 
    };
}