FSinOsc2DRotation | Unreal Engine 5.6 Documentation

API > API/Runtime > API/Runtime/SignalProcessing

Generates a sine wave in the given buffer with the given frequency.

Uses the method of generating a 2D point on the unit circle and multiplying with a 2d rotation matrix to advance the phase. Very accurate and very fast.

Use this unless you're changing frequency every few samples on very tiny blocks (single digit sample count)

Distortion vs directly calling FMath::Sin() is on the order of -100db, and is roughly 10x faster (for constant frequency).

Frequency changes are not interpolated across the buffer, so dramatic changes could introduce aliasing due to a discontinuous derivative in the output. If you're changing frequencies by a lot, constantly, you should probably use VectorSinCos in a loop.

Usage:

constexpr const int32 ChunkSampleCount = 480; alignas (sizeof(VectorRegister4Float)) float ChunkBuffer[ChunkSampleCount]; FSinOscBufferGenerator Generator; Generator.GenerateBuffer(48000, 400, ChunkBuffer, ChunkSampleCount);

ChunkBuffer now has 10ms of sine tone at 400hz. The next call will continue the sine tone where it left off.


Name	FSinOsc2DRotation
Type	class
Header File	/Engine/Source/Runtime/SignalProcessing/Public/DSP/Dsp.h
Include Path	#include "DSP/Dsp.h"

Syntax

class FSinOsc2DRotation

Constructors

Name	Remarks	Include Path	Unreal Specifiers
FSinOsc2DRotation ( float InStartingPhaseRadians )		DSP/Dsp.h
FSinOsc2DRotation ( FSinOsc2DRotation const& other )		DSP/Dsp.h

Variables

Protected

Name	Type	Include Path
Dx	float	DSP/Dsp.h
Dy	float	DSP/Dsp.h
LastPhase	float	DSP/Dsp.h
LastPhasePerSample	float	DSP/Dsp.h
QuadDxVec	VectorRegister4Float	DSP/Dsp.h
QuadDyVec	VectorRegister4Float	DSP/Dsp.h

Functions

Public

Name	Remarks	Include Path	Unreal Specifiers
void GenerateBuffer ( float SampleRate, float ClampedFrequency, float* Buffer, int32 BufferSampleCount )	Generates the sine tone, continuing from the last phase.	DSP/Dsp.h

Operators

Name	Remarks	Include Path	Unreal Specifiers
FSinOsc2DRotation & operator= ( FSinOsc2DRotation const& other )		DSP/Dsp.h

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