Overview
LiveKit Room Composite Egress enables recording of all participants' tracks in a room. This document explains its functionality and customization options.
Built-in LiveKit Recording View
The recording feature in LiveKit is built on a web-based architecture, utilizing a headless Chrome instance to render and capture output. The default view is built using LiveKit's React Components. There are a handful of configuration options available including:
- layout to control how the participants are arranged in the view. (You can set or change the layout using either
StartRoomCompositeEgress()
orUpdateLayout()
.) - Encoding options to control the quality of the audio and/or video captured
For more advanced customization, LiveKit supports configuring the URL of the web application that will generate the page to be recorded, allowing full customization of the recording view.
Building a Custom Recording View
While you can use any web framework, it's often easiest to start with the built-in React-based application and modify it to meet your requirements. The source code can be found in the template-default
folder of the LiveKit egress repository. The main files include:
Room.tsx
: the main component that renders the recording viewSpeakerLayout.tsx
,SingleSpeakerLayout.tsx
: components used for thespeaker
andsingle-speaker
layoutsApp.tsx
,index.tsx
: the main entry points for the applicationApp.css
,index.css
: the CSS files for the application
The built-in Room.tsx
component uses the template SDK, for common tasks like:
- Retrieving query string arguments (Example: App.tsx)
- Starting a recording (Example: Room.tsx)
- Ending a recording (Example: EgressHelper.setRoom())
If you are not using Room.tsx
as a starting point, be sure to leverage the template SDK to handle these and other common tasks.
Building your Application
Make a copy of the above files and modify tnem to meet your requirements.
Example: Move non-speaking participants to the right side of the Speaker view
By default the Speaker
view shows the non-speaking participants on the left and the speaker on the right. Let's change this so the speaker is on the left and the non-speaking participants are on the right.
Copy the default components and CSS files into a new location
Modify
SpeakerLayout.tsx
to move theFocusLayout
aboveCarouselLayout
so it looks like this:return (<div className="lk-focus-layout"><FocusLayout trackRef={mainTrack as TrackReference} /><CarouselLayout tracks={remainingTracks}><ParticipantTile /></CarouselLayout></div>);Modify
App.css
to fix thegrid-template-columns
value (reverse the values). It should look like this:.lk-focus-layout {height: 100%;grid-template-columns: 5fr 1fr;}
Deploying your Application
Once your app is ready for testing or deployment, you'll need to host it on a web server. We recommend using Vercel for its simplicity, but many other options are available.
Testing Your Application
We have created the egress test-egress-template
subcommand in the LiveKit CLI to make it easier to test.
The egress test-egress-template
subcommand:
- Creates a room
- Adds the desired number of virtual publishers who will publish simulated video streams
- Opens a browser instance to your app URL with the correct parameters
Once you have your application deployed, you can use this command to test it out.
Usage
export LIVEKIT_API_SECRET=SECRETexport LIVEKIT_API_KEY=KEYexport LIVEKIT_URL=YOUR_LIVEKIT_URLlk egress test-template \--base-url YOUR_WEB_SERVER_URL \--room ROOM_NAME \--layout LAYOUT \--publishers PUBLISHER_COUNT
This command launches a browser and opens: YOUR_WEB_SERVER_URL?url=<LIVEKIT_INSTANCE WSS URL>&token=<RECORDER TOKEN>&layout=LAYOUT
Example
export LIVEKIT_API_SECRET=SECRETexport LIVEKIT_API_KEY=KEYexport LIVEKIT_URL=YOUR_LIVEKIT_URLlk egress test-template \--base-url http://localhost:3000/lk-recording-view \--room my-room \--layout grid \--publishers 3
This command launches a browser and opens: http://localhost:3000/lk-recording-view?url=wss%3A%2F%2Ftest-1234567890.livekit.cloud&token=<RECORDER TOKEN>&layout=grid
Using the Custom Recording View in Production
Set the custom_base_url
parameter on the StartRoomCompositeEgress()
API to the URL where your custom recording application is deployed.
For additional authentication, most customers attach URL parameters to the custom_base_url
. For example: https://your-template-url.example.com/?yourparam={auth_info}
(and set this as your custom_base_url
).
Recording Process
For those curious about the workflow of a recording, the basic steps are:
- The
Egress.StartRoomCompositeEgress()
API is invoked - LiveKit assigns an available egress instance to handle the request
- The egress recorder creates necessary connection & authentication details
- A URL for the rendering web page is constructed with these parameters:
url
: URL of LiveKit Servertoken
: Access token for joining the room as a recorderlayout
: Desired layout passed toStartRoomCompositeEgress()
- The egress recorder launches a headless Chrome instance with the constructed URL
- The recorder waits for the web page to log
START_RECORDING
to the console - The recording begins
- The recorder waits for the web page to log
END_RECORDING
to the console - The recording is terminated