Best Practices - LCK Documentation

Recording

Resolution & Bitrate Guidelines

Quality	Resolution	Bitrate	Target FPS	Use Case
SD	1280 x 720	2-4 Mbps	30	Mobile VR, performance mode
HD	1920 x 1080	4-8 Mbps	30	Standard recording
2K	2560 x 1440	8-12 Mbps	30	High quality
4K	3840 x 2160	12-20 Mbps	30	Maximum quality (PC)

For Meta Quest devices, start with HD (1080p) at 30 FPS. Higher resolutions may impact game performance.

Event-Driven Operations

Subscribe to recording events for responsive feedback:

// Subscribe to events
Service->OnRecordingSaveFinished.AddDynamic(this, &AMyActor::HandleSaveFinished);
Service->OnRecordingError.AddDynamic(this, &AMyActor::HandleRecordingError);
Service->OnRecordingSaveProgress.AddDynamic(this, &AMyActor::HandleSaveProgress);

// Start recording
Service->StartRecording();
ShowRecordingIndicator();

void AMyActor::HandleSaveFinished(bool bSuccess)
{
    if (bSuccess)
        ShowSuccessMessage();
    else
        ShowErrorMessage();
}

void AMyActor::HandleRecordingError(FString ErrorMessage, int32 ErrorCode)
{
    UE_LOG(LogLCK, Error, TEXT("Error %d: %s"), ErrorCode, *ErrorMessage);
    ShowErrorNotification(ErrorMessage);
}

For advanced async control, use ULCKRecorderSubsystem directly:

ULCKRecorderSubsystem* Recorder = GetWorld()->GetSubsystem<ULCKRecorderSubsystem>();
Recorder->StartRecordingAsync(FOnLCKRecorderBoolResult::CreateLambda([this](bool bSuccess) {
    if (bSuccess)
        ShowRecordingIndicator();
    else
        ShowErrorMessage();
}));

Audio

Source Priority

When multiple sources are available:

Source	Best For	Latency
LCKUnrealAudio	General use, cross-platform	Low
LCKFMOD	FMOD projects	Very Low
LCKWwise	Wwise projects	Very Low
LCKOboe	Android microphone	Very Low
LCKVivox	Voice chat capture	Low

Sample Rate Matching

// Get Unreal Audio sample rate
int32 SampleRate = ULCKUnrealAudioBPL::GetUnrealAudioSamplerate();

// Configure encoder with matching rate
FLCKRecorderParams Params;
Params.Samplerate = SampleRate;

Audio Callbacks

Audio callbacks may come from different threads. Use thread-safe patterns:

// Note: BindLambda (single delegate, not AddLambda)
AudioSource->OnAudioDataDelegate.BindLambda([this](
    TArrayView<const float> PCM,
    int32 Channels,
    ELCKAudioChannel Source)
{
    // Queue for game thread if needed
    AsyncTask(ENamedThreads::GameThread, [this, Data = TArray<float>(PCM)]() {
        ProcessAudioOnGameThread(Data);
    });
});

UI

Button Cooldown

The SDK includes automatic 0.25s cooldown - don’t add your own:

// Just bind the event, cooldown is automatic
Button->OnTapStarted.AddDynamic(this, &AMyActor::HandleTap);

Showable Groups

Group related UI for batch operations:

ULCKShowablesGroup* SettingsGroup = NewObject<ULCKShowablesGroup>(this);
SettingsGroup->Add(FOVButton);
SettingsGroup->Add(DistanceButton);
SettingsGroup->Add(SmoothnessButton);

// Batch show/hide
SettingsGroup->Show();
SettingsGroup->Hide();

Performance

Scene Capture Optimization

CaptureComponent->CaptureSource = ESceneCaptureSource::SCS_FinalColorLDR;
CaptureComponent->bCaptureEveryFrame = false;
CaptureComponent->bCaptureOnMovement = false;

Memory Management

void AMyRecorder::StopAndRelease()
{
    Service->StopRecording();
    Service->UnregisterCaptureComponent(TEXT("MainCapture"));
}

Common Pitfalls

Not handling recording state feedback

Problem: No feedback to user when recording starts/stops/fails.Solution: Subscribe to OnRecordingSaveFinished, OnRecordingError, and OnRecordingSaveProgress delegates.

Mismatched resolutions

Problem: Render target doesn’t match recording resolution.Solution: Ensure render target and recording parameters match exactly.

Forgetting to unregister capture

Problem: Memory leaks from orphaned capture components.Solution: Always call UnregisterCaptureComponent(ComponentName) when done.

Sample rate mismatch

Problem: Audio distortion or sync issues.Solution: Query and match sample rates between audio source and encoder.

Using AddLambda for audio delegate

Problem: Audio delegate is single, not multicast.Solution: Use BindLambda() instead of AddLambda() for OnAudioDataDelegate.

Platform Checklist

Android
Windows

Vulkan enabled
RECORD_AUDIO permission
WRITE_EXTERNAL_STORAGE permission
LCKOboe plugin enabled (for low-latency mic)

Debugging

Log Categories

; DefaultEngine.ini
[Core.Log]
LogLCK=VeryVerbose
LogLCKEncoding=VeryVerbose
LogLCKAudio=VeryVerbose
LogLCKUI=Verbose

Common Log Messages

Log	Meaning
`LogLCK: Recording started`	Recording began
`LogLCKEncoding: Encoder initialized`	Encoder ready
`LogLCKAudio: Audio source registered`	Audio available
`LogLCKUI: Button pressed`	UI interaction

​Recording

​Resolution & Bitrate Guidelines

​Event-Driven Operations

​Audio

​Source Priority

​Sample Rate Matching

​Audio Callbacks

​UI

​Button Cooldown

​Showable Groups

​Performance

​Scene Capture Optimization

​Memory Management

​Common Pitfalls

​Platform Checklist

​Debugging

​Log Categories

​Common Log Messages

Recording

Resolution & Bitrate Guidelines

Event-Driven Operations

Audio

Source Priority

Sample Rate Matching

Audio Callbacks

UI

Button Cooldown

Showable Groups

Performance

Scene Capture Optimization

Memory Management

Common Pitfalls

Platform Checklist

Debugging

Log Categories

Common Log Messages