TimecodeEstimator.h

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// Copyright Epic Games, Inc. All Rights Reserved.
 
#pragma once
 
#include "Misc/App.h"
#include "Misc/CachedLinearRegressionSums.h"
#include "Misc/FrameRate.h"
#include "Misc/LinearFunction.h"
 
#define UE_API TIMEMANAGEMENT_API
 
class IClockedTimeStep;
class UTimecodeProvider;
struct FQualifiedFrameTime;
 
namespace UE::TimeManagement::TimecodeEstimation
{
struct FFetchAndUpdateStats
{
    FQualifiedFrameTime UnderlyingFrameTime;
};
    
class FTimecodeEstimator
{
public:
 
    UE_API explicit FTimecodeEstimator(
        SIZE_T InNumSamples,
        UTimecodeProvider& InTimecode UE_LIFETIMEBOUND, IClockedTimeStep& InEngineCustomTimeStep UE_LIFETIMEBOUND
        );
 
    UE_API TOptional<FFetchAndUpdateStats> FetchAndUpdate();
    
    UE_API FQualifiedFrameTime EstimateFrameTime() const;
    
private:
 
    TOptional<double> StartClockTime;
 
    UTimecodeProvider& TimecodeProvider;
    IClockedTimeStep& EngineCustomTimeStep;
    
    FLinearFunction LinearRegressionFunction;
    
    using FClockTimecodeSample = FVector2d; // X = clock time, Y = timecode converted using FFrameRate::AsSeconds.
    FCachedLinearRegressionSums ClockToTimecodeSamples;
    
    FFrameRate LastFrameRate;
};
}
 
#undef UE_API