Module: LCKStreaming | Version: 1.0 | Platforms: Win64, Android (Quest)
What is LCKStreaming?
LCKStreaming adds live streaming to your Unreal Engine project. It connects to the LIV backend to authenticate users, resolve streaming targets, and push video/audio over RTMP to YouTube, Twitch, or any manual RTMP endpoint.
The module handles the full lifecycle: device-based authentication, streaming configuration, RTMP connection management, encoder health monitoring, and automatic bitrate selection per platform.
Architecture
┌──────────────────────────────────────────────────────┐
│ Your Game │
│ │
│ ULCKStreamingSubsystem (GameInstanceSubsystem) │
│ ├── StartLogin / Authenticate │
│ ├── StartStreaming / StopStreaming │
│ └── Delegates (events) │
└──────────────────┬───────────────────────────────────┘
│
┌────────▼────────┐
│ LIV API Client │ REST (dashboard.liv.tv)
│ - Auth polling │
│ - Profile fetch │
│ - RTMP resolve │
└────────┬────────┘
│
┌────────▼────────┐
│ Native RTMP │ librtmp (Win64)
│ Bridge │ librtmp.so (Android)
│ - Mux & send │
│ - Health check │
└─────────────────┘
Module Structure
| Module | Description |
|---|
LCKStreaming | Core streaming subsystem, API client, RTMP logic |
LCKStreamingAndroid | Android-specific RTMP bridge and LIV Hub interop |
Prerequisites
All four prerequisites must be met before streaming will function. Missing any one of them causes StartStreaming() to return false silently.
- Enable streaming — Set
bEnableStreaming = true in Project Settings → Plugins → LCK SDK → Features. Defaults to false.
- Valid Tracking ID — Your project must have a Tracking ID configured in LCK Developer Settings.
- RTMP libraries loaded —
librtmp DLLs (Win64) or librtmp.so (Android) must be present and loadable at runtime. Check FLCKStreamingModule::IsRtmpAvailable().
- LIV account with subscription — The end user needs a LIV account with an active streaming subscription.
| Platform | Status | Notes |
|---|
| Win64 | Supported | Uses bundled librtmp |
| Android (Quest) | Supported | Uses librtmp.so, LIV Hub app |
| Other | — | Not supported at this time |
Streaming Targets
| Target | Description |
|---|
| YouTube | Automatic broadcast creation via LIV backend |
| Twitch | Direct RTMP ingest via LIV backend |
| Manual | User-provided RTMP URL for custom destinations |
YouTube
| Quality | Video Bitrate | Audio Bitrate |
|---|
| SD | 4 Mbps | 128 Kbps |
| HD @30 | 8 Mbps | 128 Kbps |
| HD @60 | 12 Mbps | 128 Kbps |
| 2K | 24 Mbps | 128 Kbps |
| 4K | 35 Mbps | 128 Kbps |
Twitch
| Quality | Video Bitrate | Audio Bitrate |
|---|
| SD | 3 Mbps | 96 Kbps |
| HD @30 | 4.5 Mbps | 96 Kbps |
| HD @60 | 6 Mbps | 96 Kbps |
| 2K | 9 Mbps | 96 Kbps |
| 4K | 10 Mbps | 96 Kbps |
Keyframe interval is fixed at 2 seconds for all targets, as required by YouTube and Twitch ingest servers.
Relationship to Recording
Streaming and recording share the same encoder pipeline. When both are active simultaneously, the streaming module piggybacks on the active recording encoder rather than creating a second one. This means you can stream and record at the same time with no additional encoding overhead.
If a recording is already in progress when StartStreaming() is called, the stream reuses the existing encoder. If no recording is active, streaming acquires its own encoder instance.
Streaming State Machine
| State | Description |
|---|
Idle | No streaming activity |
Pairing | Device login in progress |
Paired | Authenticated, ready to stream |
Streaming | RTMP connection active, pushing frames |
Error | An error occurred (see OnStreamError) |
Key Timing Constants
| Constant | Value | Description |
|---|
| Auth poll interval | 2.5s | How often the subsystem polls for pairing confirmation |
| Stream start timeout | 15s | Maximum wait time for a stream to begin |
| Health check interval | 5s | Frequency of encoder health monitoring |
| Health check tolerance | 2 | Consecutive failures before stopping stream |
Delegates
The subsystem exposes seven delegates for responding to streaming lifecycle events:
| Delegate | Parameters | Fired When |
|---|
OnPairingCodeReceived | FString Code | A new pairing code is generated |
OnAuthenticated | — | User successfully authenticates |
OnStreamingConfigReceived | ELCKStreamingTargetType, FLCKUserSubscription | Stream configuration loaded from server |
OnStreamStarted | — | Live stream begins |
OnStreamStopped | — | Live stream ends |
OnStreamError | FString ErrorMessage | A streaming error occurs |
OnLoggedOut | — | User logs out |
Log Category
DECLARE_LOG_CATEGORY_EXTERN(LogLCKStreaming, Log, All);
See Also
