ILCKStreamingFeature (Unreal)

What Problem Does This Solve?

ILCKStreamingFeature abstracts live streaming so multiple backends can coexist:

LIV cloud streaming (built-in)
Custom RTMP backends
Third-party streaming services

The interface uses Unreal’s modular features system, allowing streaming implementations to register at runtime without compile-time dependencies.

When to Use This

Read this if:

Building a custom streaming backend
Integrating a third-party streaming service
Understanding how ULCKService discovers streaming providers

Skip this if: You’re using the built-in streaming subsystem. Use ULCKStreamingSubsystem directly.

Interface Definition

class LCKCORE_API ILCKStreamingFeature : public IModularFeature
{
public:
    virtual ~ILCKStreamingFeature() = default;

    DECLARE_MULTICAST_DELEGATE_OneParam(FOnPairingCode, const FString&);
    DECLARE_MULTICAST_DELEGATE(FOnAuthenticated);
    DECLARE_MULTICAST_DELEGATE(FOnStreamStarted);
    DECLARE_MULTICAST_DELEGATE(FOnStreamStopped);
    DECLARE_MULTICAST_DELEGATE_OneParam(FOnStreamError, const FString&);
    DECLARE_MULTICAST_DELEGATE(FOnLoggedOut);
    DECLARE_MULTICAST_DELEGATE(FOnStreamingConfigChanged);

    FOnPairingCode OnPairingCodeDelegate;
    FOnAuthenticated OnAuthenticatedDelegate;
    FOnStreamStarted OnStreamStartedDelegate;
    FOnStreamStopped OnStreamStoppedDelegate;
    FOnStreamError OnStreamErrorDelegate;
    FOnLoggedOut OnLoggedOutDelegate;
    FOnStreamingConfigChanged OnStreamingConfigChangedDelegate;

    static FName GetModularFeatureName() noexcept;

    virtual void StartLogin() = 0;
    virtual void CancelLogin() = 0;
    virtual void Logout() = 0;
    virtual bool IsAuthenticated() const = 0;

    virtual bool StartStreaming() = 0;
    virtual void StopStreaming() = 0;
    virtual bool IsStreaming() const = 0;
    virtual bool IsStartingOrStreaming() const;

    virtual void LaunchHub() = 0;
    virtual bool IsHubInstalled() const;
    virtual FString GetStreamingTargetName() const;
    virtual FString GetLastLogoutReason() const;
    virtual int32 GetPriority() const;
};

Delegates

Delegate	Signature	Description
`OnPairingCodeDelegate`	`FOnPairingCode(const FString& Code)`	New pairing code generated during login
`OnAuthenticatedDelegate`	`FOnAuthenticated()`	User successfully authenticated
`OnStreamStartedDelegate`	`FOnStreamStarted()`	Live stream has started
`OnStreamStoppedDelegate`	`FOnStreamStopped()`	Live stream ended normally
`OnStreamErrorDelegate`	`FOnStreamError(const FString& Error)`	Streaming error occurred
`OnLoggedOutDelegate`	`FOnLoggedOut()`	User logged out or was logged out
`OnStreamingConfigChangedDelegate`	`FOnStreamingConfigChanged()`	Streaming configuration changed remotely

Methods

Authentication

Method	Signature	Description
`StartLogin`	`virtual void StartLogin() = 0`	Begin device-code login flow
`CancelLogin`	`virtual void CancelLogin() = 0`	Cancel in-progress login
`Logout`	`virtual void Logout() = 0`	Log out and clear credentials
`IsAuthenticated`	`virtual bool IsAuthenticated() const = 0`	Check if user is authenticated

Streaming

Method	Signature	Description
`StartStreaming`	`virtual bool StartStreaming() = 0`	Start the live stream (returns false on failure)
`StopStreaming`	`virtual void StopStreaming() = 0`	Stop the live stream
`IsStreaming`	`virtual bool IsStreaming() const = 0`	Check if currently streaming
`IsStartingOrStreaming`	`virtual bool IsStartingOrStreaming() const`	True during startup or active streaming (default: `IsStreaming()`)

Platform & Utility

Method	Signature	Default	Description
`LaunchHub`	`virtual void LaunchHub() = 0`	—	Open the LIV Hub companion app
`IsHubInstalled`	`virtual bool IsHubInstalled() const`	`true`	Check if LIV Hub is installed
`GetStreamingTargetName`	`virtual FString GetStreamingTargetName() const`	`""`	Display name of streaming target
`GetLastLogoutReason`	`virtual FString GetLastLogoutReason() const`	`""`	Reason for last automatic logout
`GetPriority`	`virtual int32 GetPriority() const`	`0`	Priority when multiple backends registered

Discovery via Modular Features

The modular feature name is "LCKStreamingFeature". Streaming features are discovered at runtime:

#include "LCKStreamingFeature.h"

ILCKStreamingFeature* FindStreamingFeature()
{
    auto& ModularFeatures = IModularFeatures::Get();
    FName FeatureName = ILCKStreamingFeature::GetModularFeatureName();

    if (ModularFeatures.IsModularFeatureAvailable(FeatureName))
    {
        TArray<ILCKStreamingFeature*> Features =
            ModularFeatures.GetModularFeatureImplementations<ILCKStreamingFeature>(
                FeatureName);

        // Sort by priority (highest first)
        Features.Sort([](const ILCKStreamingFeature& A, const ILCKStreamingFeature& B)
        {
            return A.GetPriority() > B.GetPriority();
        });

        return Features.Num() > 0 ? Features[0] : nullptr;
    }

    return nullptr;
}

Usage Example

void UMyStreamingWidget::StartStream()
{
    ILCKStreamingFeature* Feature = FindStreamingFeature();
    if (!Feature) return;

    Feature->OnPairingCodeDelegate.AddLambda([this](const FString& Code)
    {
        ShowPairingCode(Code);
    });

    Feature->OnStreamStartedDelegate.AddLambda([this]()
    {
        ShowLiveIndicator();
    });

    if (!Feature->IsAuthenticated())
    {
        Feature->StartLogin();
    }
    else
    {
        Feature->StartStreaming();
    }
}

Key Takeaways

Modular features — Runtime discovery, no compile-time coupling

Priority system — Multiple backends can coexist, highest priority wins

Delegate-driven — Subscribe to events for async state changes

Auth before stream — Always check IsAuthenticated() before StartStreaming()

Streaming Subsystem — Blueprint-friendly wrapper
Streaming Types — Enums and data types
Packet Sink Interface — Custom transport layer
Encoder Interface — Video/audio encoding

Core SDK

Tablet Interface

Tablet Customization

Audio

Streaming

API Reference

What Problem Does This Solve?

When to Use This

Interface Definition

Delegates

Methods

Authentication

Streaming

Platform & Utility

Discovery via Modular Features

Usage Example

Key Takeaways

​What Problem Does This Solve?

​When to Use This

​Interface Definition

​Delegates

​Methods

​Authentication

​Streaming

​Platform & Utility

​Discovery via Modular Features

​Usage Example

​Key Takeaways

​Related

What Problem Does This Solve?

When to Use This

Interface Definition

Delegates

Methods

Authentication

Streaming

Platform & Utility

Discovery via Modular Features

Usage Example

Key Takeaways

Related