# 📹🎙️Node.js realtime SDK for LiveKit [](https://npmjs.com/package/@livekit/rtc-node) [](https://github.com/livekit/node-sdks/actions/workflows/rtc-node.yml) Use this SDK to add realtime video, audio and data features to your Node app. By connecting to a self- or cloud-hosted LiveKit server, you can quickly build applications like interactive live streaming or video calls with just a few lines of code. > This SDK is currently in Developer Preview mode and not ready for production use. There will be bugs and APIs may change during this period. > > We welcome and appreciate any feedback or contributions. You can create issues here or chat live with us in the #dev channel within the [LiveKit Community Slack](https://livekit.io/join-slack). ### Warning Avoid running this with hot reloads (ex. [bun's hot reload](https://bun.sh/guides/http/hot)). This is known to cause issues with WebRTC connectivity. ## Using realtime SDK ### Connecting to a room ```typescript import { RemoteParticipant, RemoteTrack, RemoteTrackPublication, Room, RoomEvent, dispose, } from '@livekit/rtc-node'; const room = new Room(); await room.connect(url, token, { autoSubscribe: true, dynacast: true }); console.log('connected to room', room); // add event listeners room .on(RoomEvent.TrackSubscribed, handleTrackSubscribed) .on(RoomEvent.Disconnected, handleDisconnected) .on(RoomEvent.LocalTrackPublished, handleLocalTrackPublished); process.on('SIGINT', () => { await room.disconnect(); await dispose(); }); ``` ### Publishing a track ```typescript import { AudioFrame, AudioSource, LocalAudioTrack, TrackPublishOptions, TrackSource, } from '@livekit/rtc-node'; import { readFileSync } from 'node:fs'; // set up audio track const source = new AudioSource(16000, 1); const track = LocalAudioTrack.createAudioTrack('audio', source); const options = new TrackPublishOptions(); options.source = TrackSource.SOURCE_MICROPHONE; // note: if converting from Uint8Array to Int16Array, *do not* use buffer.slice! // it is marked unstable by Node and can cause undefined behaviour, such as massive chunks of // noise being added to the end. // it is recommended to use buffer.subarray instead. const sample = readFileSync(pathToFile); var buffer = new Int16Array(sample.buffer); await room.localParticipant.publishTrack(track, options); await source.captureFrame(new AudioFrame(buffer, 16000, 1, buffer.byteLength / 2)); // cleanup resources await track.close(); ``` ### RPC Perform your own predefined method calls from one participant to another. This feature is especially powerful when used with [Agents](https://docs.livekit.io/agents), for instance to forward LLM function calls to your client application. #### Registering an RPC method The participant who implements the method and will receive its calls must first register support: ```typescript room.localParticipant?.registerRpcMethod( // method name - can be any string that makes sense for your application 'greet', // method handler - will be called when the method is invoked by a RemoteParticipant async (data: RpcInvocationData) => { console.log(`Received greeting from ${data.callerIdentity}: ${data.payload}`); return `Hello, ${data.callerIdentity}!`; } ); ``` In addition to the payload, your handler will also receive `responseTimeout`, which informs you the maximum time available to return a response. If you are unable to respond in time, the call will result in an error on the caller's side. #### Performing an RPC request The caller may then initiate an RPC call like so: ```typescript try { const response = await room.localParticipant!.performRpc({ destinationIdentity: 'recipient-identity', method: 'greet', payload: 'Hello from RPC!', }); console.log('RPC response:', response); } catch (error) { console.error('RPC call failed:', error); } ``` You may find it useful to adjust the `responseTimeout` parameter, which indicates the amount of time you will wait for a response. We recommend keeping this value as low as possible while still satisfying the constraints of your application. #### Errors LiveKit is a dynamic realtime environment and calls can fail for various reasons. You may throw errors of the type `RpcError` with a string `message` in an RPC method handler and they will be received on the caller's side with the message intact. Other errors will not be transmitted and will instead arrive to the caller as `1500` ("Application Error"). Other built-in errors are detailed in `RpcError`. ## Examples - [`publish-wav`](https://github.com/livekit/node-sdks/tree/main/examples/publish-wav): connect to a room and publish a .wave file - [`rpc`](https://github.com/livekit/node-sdks/tree/main/examples/rpc): simple back-and-forth RPC interaction ## Getting help / Contributing Please join us on [Slack](https://livekit.io/join-slack) to get help from our devs & community. We welcome your contributions and details can be discussed there.