Epic Games' plugin framework for streaming real-time data into Unreal Engine from external sources – including motion capture systems, virtual cameras, face tracking, control surfaces, and other animation data, enabling immediate preview and recording of performances in virtual production environments.
What is Live Link?
Live Link is Epic Games' plugin framework for Unreal Engine that streams real-time data from external sources into the engine. It forms the backbone for virtual production, motion capture, and interactive preview systems.
Basic Principle
| Aspect | Description |
|---|---|
| Function | Real-time data streaming |
| Platform | Unreal Engine |
| Protocol | UDP-based |
| Latency | Minimal (ms range) |
Supported Data Sources
| Source | Application |
|---|---|
| Motion Capture | Vicon, OptiTrack, Xsens |
| Face Tracking | iPhone, ARKit |
| Virtual Camera | iPad, iPhone |
| Control Surfaces | Lighting consoles, faders |
Architecture
| Component | Function |
|---|---|
| Source | Data source (external) |
| Subject | Individual data stream |
| Plugin | Source-specific |
| Client | Unreal Engine |
Motion Capture Integration
| System | Live Link Support |
|---|---|
| Vicon | Native Plugin |
| OptiTrack | Motive Plugin |
| Xsens | MVN Plugin |
| Rokoko | Studio Plugin |
Virtual Camera
| Feature | Description |
|---|---|
| vCam App | iOS application |
| Tracking | Device to UE camera |
| Preview | Real-time on device |
| Recording | Take-based |
Face Tracking
| Method | Description |
|---|---|
| ARKit | iPhone TrueDepth |
| LiveLink Face | Dedicated app |
| Audio2Face | NVIDIA integration |
| Faceware | Professional |
Workflow
| Step | Description |
|---|---|
| 1 | Activate plugin |
| 2 | Configure source |
| 3 | Assign subject |
| 4 | Receive animation |
Subject Types
| Type | Data |
|---|---|
| Animation | Skeleton poses |
| Transform | Position/Rotation |
| Camera | Camera parameters |
| Light | Light values |
Retargeting
| Aspect | Description |
|---|---|
| Source Skeleton | Mocap rig |
| Target Skeleton | UE Character |
| Mapping | Bone assignment |
| Preprocessing | Filters, offsets |
Blueprint Integration
| Function | Description |
|---|---|
| Get Subjects | Available sources |
| Evaluate | Current data |
| Record | Start recording |
| Playback | Playback |
Timecode
| Aspect | Description |
|---|---|
| Sync | Genlock/Timecode |
| Provider | External signal |
| Recording | With Timecode |
| Playback | Synchronized |
Virtual Production Setup
| Element | Function |
|---|---|
| nDisplay | LED wall cluster |
| Live Link | Tracking data |
| Genlock | Camera sync |
| Timecode | Recording sync |
Presets
| Preset Type | Application |
|---|---|
| Source Presets | Source configuration |
| Subject Presets | Assignments |
| Retarget Assets | Bone mapping |
| Animation BP | Processing |
Latency Optimization
| Measure | Description |
|---|---|
| Buffer Size | Minimal |
| Network | Dedicated LAN |
| Timecode | Genlock |
| Interpolation | Optional |
Troubleshooting
| Problem | Solution |
|---|---|
| No Subject | Firewall, network |
| Jitter | Adjust buffer |
| Drift | Check Timecode |
| Lag | Optimize network |
Plugins
| Plugin | Application |
|---|---|
| LiveLinkVicon | Vicon systems |
| LiveLinkOptiTrack | OptiTrack |
| LiveLinkXR | XR headsets |
| LiveLinkOSC | OSC protocol |
Recording
| Aspect | Description |
|---|---|
| Take Recorder | Record in UE |
| Sequencer | Save animation |
| Level Sequence | For playback |
| Baking | Final animation |
Best Practices
| Practice | Reason |
|---|---|
| Dedicated Network | Stability |
| Timecode Sync | Multi-source |
| Test before Shoot | Identify issues |
| Backup Recording | Safety |
Today
Live Link has become the standard technology for real-time workflows in Unreal Engine. From small indie projects with iPhone tracking to large virtual production stages with professional mocap systems, the ability to seamlessly integrate external data streams is revolutionizing film and game production alike.