Recording

ULCKRecorderSubsystem

The recorder subsystem manages the complete recording lifecycle as a UTickableWorldSubsystem. It handles scene capture, encoder coordination, and audio mixing each tick.

Class Definition

UCLASS()
class LCKCORE_API ULCKRecorderSubsystem : public UTickableWorldSubsystem
{
    GENERATED_BODY()

public:
    // Scene capture component for video source
    UPROPERTY(Category = "LCK", BlueprintReadOnly)
    USceneCaptureComponent2D* CaptureComponent;

    // Render target for capture
    UPROPERTY(Category = "LCK", BlueprintReadOnly)
    UTextureRenderTarget2D* RenderTarget;
};

Setup Methods

function

Initializes the recorder with parameters and optional capture component.

UFUNCTION(Category="LCK", BlueprintCallable)
void SetupRecorder(
    const FLCKRecorderParams& RecorderParams,
    USceneCaptureComponent2D* InitialCaptureComponent = nullptr
);

function

Sets or changes the scene capture component used for video source.

UFUNCTION(Category="LCK", BlueprintCallable)
void SetSceneCaptureComponent(USceneCaptureComponent2D* NewSceneCaptureComponent);

Recording Control

function

Begins recording. Returns false if already recording or encoder unavailable.

UFUNCTION(Category="LCK", BlueprintCallable)
bool StartRecording();

function

Stops recording and finalizes the video file.

UFUNCTION(Category="LCK", BlueprintCallable)
bool StopRecording();

function

Captures a single frame as a photo.

UFUNCTION(Category="LCK", BlueprintCallable)
bool TakePhoto();

Async Methods

For non-blocking operations with callbacks:

// Start recording with callback
void StartRecordingAsync(FOnLCKRecorderBoolResult OnResult);

// Stop recording with progress callback
void StopRecordingAsync(
    FOnLCKRecorderBoolResult OnResult,
    FOnLCKRecorderProgress OnProgress
);

Recorder->StartRecordingAsync(
    FOnLCKRecorderBoolResult::CreateLambda([](bool bSuccess) {
        if (bSuccess)
            UE_LOG(LogTemp, Log, TEXT("Recording started"));
        else
            UE_LOG(LogTemp, Error, TEXT("Failed to start recording"));
    })
);

Recorder->StopRecordingAsync(
    FOnLCKRecorderBoolResult::CreateLambda([](bool bSuccess) {
        UE_LOG(LogTemp, Log, TEXT("Recording stopped: %s"),
            bSuccess ? TEXT("Success") : TEXT("Failed"));
    }),
    FOnLCKRecorderProgress::CreateLambda([](float Progress) {
        UE_LOG(LogTemp, Log, TEXT("Save progress: %.1f%%"), Progress * 100.0f);
    })
);

State Queries

function

Returns true if currently recording.

UFUNCTION(BlueprintCallable, Category = "LCK")
bool IsRecording() const;

function

Returns current recording duration in seconds.

UFUNCTION(BlueprintCallable, Category = "LCK")
float GetTime() const;

function

Returns current microphone input level (0.0 - 1.0).

UFUNCTION(BlueprintCallable, Category = "LCK")
float GetMicrophoneVolume() const;

Microphone Control

function

Enables or disables microphone audio in recordings.

UFUNCTION(BlueprintCallable, Category = "LCK")
void SetMicrophoneEnabled(bool bEnabled);

function

Returns whether microphone audio is enabled.

UFUNCTION(BlueprintPure, Category = "LCK")
bool IsMicrophoneEnabled() const;

FLCKRecorderParams

Recording configuration structure.

USTRUCT(BlueprintType)
struct LCKCORE_API FLCKRecorderParams
{
    GENERATED_BODY()

    UPROPERTY(Category="LCK", EditAnywhere, BlueprintReadWrite)
    int32 Width = 1920;

    UPROPERTY(Category="LCK", EditAnywhere, BlueprintReadWrite)
    int32 Height = 1080;

    UPROPERTY(Category="LCK", EditAnywhere, BlueprintReadWrite)
    int32 Framerate = 30;

    UPROPERTY(Category="LCK", EditAnywhere, BlueprintReadWrite)
    int32 VideoBitrate = 2 << 20;  // 2 Mbps default

    UPROPERTY(Category="LCK", EditAnywhere, BlueprintReadWrite)
    int32 Samplerate = 48000;

    UPROPERTY(Category="LCK", EditAnywhere, BlueprintReadWrite)
    int32 AudioBitrate = 256 << 10;  // 256 Kbps default
};

Recommended Settings

Quality	Resolution	FPS	Video Bitrate	Audio Bitrate
SD	1280 x 720	30	4 Mbps	128 Kbps
HD	1920 x 1080	60	12 Mbps	256 Kbps
2K	2560 x 1440	60	20 Mbps	320 Kbps
4K	3840 x 2160	60	35 Mbps	320 Kbps

Higher resolutions significantly impact performance, especially on mobile VR devices. Test thoroughly on target hardware.

Delegates

FOnLCKRecorderBoolResult

Result callback for async operations.

DECLARE_DELEGATE_OneParam(FOnLCKRecorderBoolResult, bool /*bSuccess*/);

FOnLCKRecorderProgress

Progress callback for save operations.

DECLARE_DELEGATE_OneParam(FOnLCKRecorderProgress, float /*Progress*/);

Preview Mode

For live camera preview without recording:

// Start preview (capture frames but don't encode)
Recorder->StartPreview();

// Stop preview
Recorder->StopPreview();

Preview mode is useful for camera composition and settings adjustment before recording.

Core SDK

Tablet Interface

Tablet Customization

Audio

Streaming

API Reference

ULCKRecorderSubsystem

Class Definition

Setup Methods

Recording Control

Async Methods

State Queries

Microphone Control

FLCKRecorderParams

Recommended Settings

Delegates

FOnLCKRecorderBoolResult

FOnLCKRecorderProgress

Preview Mode