FLKFSAnalyzer | Unreal Engine 5.8 Documentation

API > API/Runtime > API/Runtime/SignalProcessing

FLKFSAnalyzer computes Loudness K-Weighted FS (LKFS) metrics for interleaved audio channels. Uses a sliding window approach and an internal perceptual energy analyzer. Produces instantaneous energy and loudness as well as short term, integrated, gated LKFS and optionally the loudness range (based on EBU-3342).


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

Syntax

class FLKFSAnalyzer

Constructors

Name	Remarks	Include Path	Unreal Specifiers
FLKFSAnalyzer ( int32 InNumChannels, float InSampleRate, const FLKFSAnalyzerSettings& InSettings )	Construct analyzer	DSP/LKFSAnalyzer.h

Classes

Name	Remarks
FLoudnessRange	Holds state for Loudness Range calculation (for a single channel).

Structs

Name	Remarks
FAggregateLoudnessStats	Holds aggregated loudness statistics calculated over a history of energy measurements.

Variables

Protected

Name	Type	Remarks	Include Path
AggregateLoudnessStats	TSortedMap< int32, FAggregateLoudnessStats >	Per channel stats for short-term, integrated and gated loudness, and optional loudness range.	DSP/LKFSAnalyzer.h
ChannelEnergyHistory	TCircularBuffer< float >	Channel interleaved history buffer of energy measurements.	DSP/LKFSAnalyzer.h
ChannelPerceptualEnergy	TArray< float >		DSP/LKFSAnalyzer.h
InternalBuffer	TSlidingBuffer< float >		DSP/LKFSAnalyzer.h
InternalWindow	TArray< float >		DSP/LKFSAnalyzer.h
LoudnessAnalyzer	FMultichannelLoudnessAnalyzer		DSP/LKFSAnalyzer.h
LoudnessRangeStatePerChannel	TSortedMap< int32, FLoudnessRange >	Per channel state for calculating Loudness Range.	DSP/LKFSAnalyzer.h
NumAnalysisHopWindows	int32	Number of windows between each loudness analysis.	DSP/LKFSAnalyzer.h
NumAnalysisWindows	int32	Number of windows inspected for each loudness analysis.	DSP/LKFSAnalyzer.h
NumAnalyzedBuffers	int32		DSP/LKFSAnalyzer.h
NumChannels	int32		DSP/LKFSAnalyzer.h
NumEnergyHistory	int32		DSP/LKFSAnalyzer.h
NumIntegratedHistoryResults	int32	Number of values in the "EnergyHistory" to analyze for integrated and gated loudness.	DSP/LKFSAnalyzer.h
NumIntegratedHopHistoryResults	int32	Number of values in the "EnergyHistory" between integrated and gated loudness anlysis.	DSP/LKFSAnalyzer.h
NumShortTermHistoryResults	int32	Number of values in the "EnergyHistory" to analyze for short term loudness.	DSP/LKFSAnalyzer.h
NumSlidingWindowHopFrames	int32		DSP/LKFSAnalyzer.h
OverallEnergyHistory	TCircularBuffer< float >		DSP/LKFSAnalyzer.h
OverallPerceptualEnergy	TArray< float >		DSP/LKFSAnalyzer.h
SampleRate	float		DSP/LKFSAnalyzer.h
Settings	FLKFSAnalyzerSettings		DSP/LKFSAnalyzer.h

Functions

Public

Name	Remarks	Include Path	Unreal Specifiers
void Analyze ( TArrayView< const float > InAudio, FLKFSAnalyzerResults& OutLKFSResults )	Analyze audio to obtain LKFS values (see FLKFSAnalyzerResults and FLKFSResult for more details)	DSP/LKFSAnalyzer.h
const FLKFSAnalyzerSettings & GetSettings()	Return const reference to settings used inside this analyzer.	DSP/LKFSAnalyzer.h

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