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- Up to CL8320930 from DevOnline and 8311605 Merge Down from Main - skipped some Fortnite content/plugins/code where it tried to reintegrate files that had been moved pending investigation #rb none [CL 8321295 by Josh Markiewicz in Main branch]
53 lines
1.5 KiB
C++
53 lines
1.5 KiB
C++
// Copyright 1998-2019 Epic Games, Inc. All Rights Reserved.
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#pragma once
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#include "CoreMinimal.h"
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namespace Audio
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{
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/**
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* FOsc
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* Direct-form sinusoid oscillator.
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* Created with a biquad filter (using only feedback coefficients) with poles directly on unit circle in z-plane.
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* Setting frequency uses current filter state to compute initial conditions to avoid pops when changing frequency.
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* Extremely cheap to run but expensive to set new frequencies. Good for test tones.
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*/
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class SIGNALPROCESSING_API FSineOsc
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{
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public:
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/** Constructor */
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FSineOsc();
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/** Non-default constructor */
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FSineOsc(const int32 InSampleRate, const float InFrequencyHz, const float Scale = 1.0f, const float Add = 0.0f);
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/** Virtual destructor */
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virtual ~FSineOsc();
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/** Initialize the oscillator with a sample rate and new frequency. Must be called before playing oscillator. */
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void Init(const int32 InSampleRate, const float InFrequencyHz, const float Scale = 1.0f, const float Add = 0.0f);
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/** Sets the frequency of the oscillator in Hz (based on sample rate). Performs initial condition calculation to avoid pops. */
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void SetFrequency(const float InFrequencyHz);
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/** Returns the current frequency. */
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float GetFrequency() const;
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/** Generates the next sample of the oscillator. */
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float ProcessAudio();
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protected:
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int32 SampleRate;
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float FrequencyHz;
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float B1; // Biquad feedback coefficients
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float B2;
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float Yn_1; // y(n - 1)
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float Yn_2; // y(n - 2)
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float Scale;
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float Add;
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};
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}
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