> ## Documentation Index
> Fetch the complete documentation index at: https://docs.liv.tv/llms.txt
> Use this file to discover all available pages before exploring further.
# Upgrade Guide
> How to update the LIV Camera Kit (LCK) SDK to the latest version in Unreal Engine, including backup steps, breaking changes, and troubleshooting failed upgrades.
**Always close the Unreal Editor before upgrading LCK.**
Native libraries are loaded at editor startup and cannot be replaced while running.
Upgrading while the editor is open will cause failures and may corrupt your project.
## Before You Begin
* [ ] Close Unreal Editor completely
* [ ] Backup your project (especially Plugins folder)
* [ ] Note current LCK version for reference
* [ ] Check release notes for breaking changes
* [ ] Verify Unreal Engine version compatibility
***
## Upgrade Steps
Completely close the Unreal Editor. Verify no UE processes are running in Task Manager.
Even if you haven't pressed Play, LCK loads native libraries on editor startup.
These cannot be replaced while the editor is open.
Before removing the old SDK, create a backup:
```bash theme={null}
# Windows
xcopy /E /I "YourProject\Plugins\LCK" "YourProject\Plugins\LCK_backup"
xcopy /E /I "YourProject\Plugins\LCKTablet" "YourProject\Plugins\LCKTablet_backup"
```
Or manually copy the `Plugins/LCK*` folders to a safe location.
Delete the existing LCK plugin folders:
```
YourProject/
└── Plugins/
├── LCK/ ← Delete
├── LCKTablet/ ← Delete
├── LCKUI/ ← Delete
├── LCKAudio/ ← Delete
├── LCKUnrealAudio/ ← Delete (if present, new in v1.0)
├── LCKStreaming/ ← Delete (if present, new in v1.0)
├── LCKFMOD/ ← Delete (if present)
├── LCKWwise/ ← Delete (if present)
├── LCKVivox/ ← Delete (if present)
└── LCKOboe/ ← Delete (if present)
```
Extract the new SDK package to your Plugins folder:
```
YourProject/
└── Plugins/
├── LCK/ ← New version
├── LCKTablet/ ← New version
└── ...
```
Right-click your `.uproject` file and select **Generate Visual Studio project files** (or equivalent for your IDE).
This ensures the new plugin modules are properly registered.
1. Open Unreal Editor
2. Go to **Edit > Plugins**
3. Verify LCK plugins are enabled
4. Check **Output Log** for any LCK errors
5. Test recording functionality
***
## Version Compatibility
| SDK Version | Unreal Engine | Notes |
| ----------- | ------------- | --------------- |
| 1.0 | 5.4+ | Current stable |
| 0.9.2 | 5.4+ | Previous stable |
| 0.9.1 | 5.4+ | Initial release |
We recommend always using the latest SDK version.
Per the SDK License Agreement, older versions are not officially supported.
***
## Breaking Changes by Version
### 1.0
v1.0 introduces **streaming support** and refactors the audio delegate system.
If you bind audio delegates or interact with the encoder directly, you **must** update your code.
**Breaking Changes:**
1. **Audio delegate renamed and re-typed** — `FOnRenderAudioDelegate` is now a typedef for a multicast delegate invocation, not a single-cast delegate
The parent delegate type has been renamed from `FOnRenderAudioDelegate` to `FDelegateRenderAudio` and changed from a single-cast delegate to a multicast delegate (`DECLARE_MULTICAST_DELEGATE_FourParams`). The old name `FOnRenderAudioDelegate` still exists as a typedef for the inner `FDelegate` type, so existing variable declarations compile — but **binding semantics have changed**.
Additionally, the delegate signature gained a fourth parameter (`SampleRate`).
```cpp theme={null}
// Before (v0.9.2) — single-cast delegate, 3 params
AudioSource->OnAudioDataDelegate.BindLambda(
[](TArrayView PCM, int32 Channels, ELCKAudioChannel Source)
{
// Process audio...
}
);
// After (v1.0) — multicast delegate, 4 params (added SampleRate)
// OnAudioDataDelegate is now FOnRenderAudioDelegate (typedef for FDelegateRenderAudio::FDelegate)
// You must use multicast binding via the parent delegate
AudioSource->OnAudioDataDelegate.BindLambda(
[](TArrayView PCM, int32 Channels, int32 SampleRate, ELCKAudioChannel Source)
{
// Process audio — SampleRate is now available directly
}
);
```
Even though `FOnRenderAudioDelegate` still exists as a typedef, your lambda **must** accept four parameters or it will not compile. Update all audio delegate bindings to include `int32 SampleRate` as the third parameter.
2. **`bEnableStreaming` added to developer settings** — Streaming is disabled by default
A new `bEnableStreaming` setting has been added to `ULCKDeveloperSettings`. When `false` (the default), RTMP streaming libraries are not packaged and streaming API calls return `LCK_STREAMING_NOT_AVAILABLE`.
```cpp theme={null}
// Enable streaming in Project Settings > Plugins > LCK SDK > Features
// Or set directly:
ULCKDeveloperSettings* Settings = ULCKDeveloperSettings::Get();
Settings->bEnableStreaming = true;
```
If you do not need streaming, leave this disabled to reduce APK size. The streaming `.so`/`.dll` files will not be included in the build.
3. **`AcquireEncoder()` / `ReleaseEncoder()` added** — New encoder lifecycle management
`ULCKRecorderSubsystem` now uses reference-counted encoder ownership. Recording and streaming can share the same encoder instance. If you call `StartRecording()` / `StopRecording()` through `ULCKService`, this is handled automatically. Only update if you use the recorder subsystem directly.
```cpp theme={null}
ULCKRecorderSubsystem* Recorder = GetWorld()->GetSubsystem();
// Acquire encoder (ref count +1)
// bNeedsDisk: true if you need MP4 file output
// Optional overrides for video/audio bitrate
bool bSuccess = Recorder->AcquireEncoder(/*bNeedsDisk=*/ true);
// ... use encoder for recording or streaming ...
// Release encoder (ref count -1, encoder destroyed when count reaches 0)
// bSaveFile: true to finalize MP4 and copy to gallery
Recorder->ReleaseEncoder(/*bSaveFile=*/ true);
```
4. **`ILCKStreamingFeature` interface added** — Streaming backend contract
A new modular feature interface for streaming backends. Implementations are discovered at runtime via `IModularFeatures`. You do not need to implement this unless you are building a custom streaming backend.
```cpp theme={null}
// Check if a streaming feature is available
auto& MF = IModularFeatures::Get();
if (MF.IsModularFeatureAvailable(ILCKStreamingFeature::GetModularFeatureName()))
{
ILCKStreamingFeature& Streaming = MF.GetModularFeature(
ILCKStreamingFeature::GetModularFeatureName());
Streaming.OnStreamStartedDelegate.AddLambda([]() {
UE_LOG(LogLCK, Log, TEXT("Stream started"));
});
Streaming.StartLogin();
}
```
5. **`ILCKPacketSink` interface added** — Packet routing contract
Encoders can now route encoded H.264/AAC packets to arbitrary sinks (RTMP streams, network transports, etc.) via `ILCKPacketSink`. You do not need to implement this unless you are building a custom packet consumer.
```cpp theme={null}
// Register a custom packet sink with the encoder
Encoder->AddPacketSink(MyCustomSink);
// ILCKPacketSink methods you must implement:
// Open(), OnVideoFormatReady(), OnAudioFormatReady(),
// SendVideoPacket(), SendAudioPacket(), Close(), IsOpen()
```
6. **`ELCKStreamingState` enum added** — UI must handle streaming states
If you build custom UI, you must handle the new streaming states:
```cpp theme={null}
// ELCKStreamingState values:
// Idle — No streaming activity
// Pairing — Waiting for pairing code entry
// Paired — Authenticated, ready to stream
// Streaming — Live stream active
// Error — Stream error occurred
```
7. **`ELCKTabletMode` enum added** — Camera/Stream mode switching
The tablet now supports two modes. Custom UI must handle mode switching:
```cpp theme={null}
// ELCKTabletMode values:
// Camera — Recording mode (default, same as v0.9.2 behavior)
// Stream — Live streaming mode
```
8. **Plugin version bumped to 1.0** — All `.uplugin` files updated
Update any version checks or minimum-version guards in your build scripts.
**New Features:**
* Live Streaming — RTMP streaming support via LCKStreaming module
* Encoder Sharing — Recording and streaming can share a single encoder instance
* Packet Sink Architecture — Extensible encoded packet routing
* Streaming UI — Tablet mode switching between Camera and Stream
* Hub Integration — `LaunchHub()` and `IsHubInstalled()` for LIV Hub companion app
**New Modules:**
* `LCKStreaming` — RTMP streaming implementation (optional, requires `bEnableStreaming`)
* `LCKUnrealAudio` — Extracted Unreal Engine audio capture (previously bundled in LCKAudio)
***
### 0.9.2
**Breaking Changes:**
1. **`FLCKMetaData.Build`** — Changed from `int32` to `FString`
```cpp theme={null}
// Before (v0.9.1)
int32 BuildNumber = MetaData.Build;
// After (v0.9.2)
FString BuildString = MetaData.Build;
```
2. **Mic state type** — Use `ELCKMicState` enum instead of `bool`
```cpp theme={null}
// Before (v0.9.1)
bool bMicEnabled = true;
// After (v0.9.2)
ELCKMicState MicState = ELCKMicState::On;
// Values: On, Off, No_Access
```
**New Features:**
* PCVR Support — single implementation for PCVR and Meta Quest Standalone
* Microphone Mute Control with `SetMicrophoneEnabled()` API
* Audio Config Validation with editor warnings
* Debug Mode System with `ILCKVisuallyDebuggable` interface
* Improved Android microphone permission flow
### 0.9.1
Initial public release of LCK SDK for Unreal Engine. No breaking changes.
***
## Handling Custom Modifications
Upgrading will overwrite any custom changes made directly to LCK plugin files.
**We strongly recommend NOT modifying LCK plugins directly.**
### Recommended Approach
Instead of modifying LCK files, create project-local overrides:
1. **Custom Blueprints** — Create Blueprint subclasses of LCK actors
2. **Custom Widgets** — Create widget variants based on LCK widgets
3. **Custom Materials** — Create Material Instances, don't modify base materials
4. **Custom Scripts** — Extend LCK classes in your own modules
### If You Have Modifications
If you've modified LCK files directly:
1. Document all changes before upgrading
2. After upgrade, reapply changes to new version
3. Consider refactoring to use extension approach
***
## Troubleshooting Upgrades
**Cause:** Old native libraries still loaded or version mismatch.
**Solution:**
1. Close all UE processes
2. Delete `Binaries` and `Intermediate` folders in your project
3. Delete `DerivedDataCache` folder
4. Regenerate project files
5. Rebuild project
**Cause:** API changes between versions.
**Solution:**
1. Check release notes for breaking changes
2. Update your code to match new API
3. See migration examples above
**Cause:** Plugin not properly installed or wrong folder structure.
**Solution:**
1. Verify folder structure matches expected layout
2. Check `.uplugin` files exist in each plugin folder
3. Ensure plugins are enabled in Edit > Plugins
**Cause:** Settings or configuration may have changed.
**Solution:**
1. Verify Tracking ID is still configured
2. Check Project Settings > LCK SDK
3. Review Output Log for specific errors
4. Test with a fresh LCK tablet actor
***
## Downgrading
Downgrading to older SDK versions is **not recommended** and **not supported**.
If you must downgrade due to critical issues:
1. Report the issue to [LIV support](https://discord.com/invite/liv)
2. Restore from your backup
3. Regenerate project files
***
## Clean Installation
For a completely fresh start:
```bash theme={null}
# 1. Remove all LCK plugins
rm -rf YourProject/Plugins/LCK*
# 2. Remove cached data
rm -rf YourProject/Intermediate
rm -rf YourProject/Binaries
rm -rf YourProject/DerivedDataCache
rm -rf YourProject/Saved/Config # Optional: resets all settings
# 3. Install new SDK
# Extract new SDK to Plugins/
# 4. Regenerate project
# Right-click .uproject > Generate Project Files
```
***
## See Also
Fresh installation guide
Version history and release notes