Join multiple channels

Understand the tech

Video SDK's multi-channel functionality is based on two key components:

• RtcConnection

  The RtcConnection object identifies a connection. It contains the following information:

  • Channel name
  • User ID of the local user

  You create multiple RtcConnection objects, each with a different channel name and user ID. Each RtcConnection instance can independently publish multiple audio streams and a single video stream.

• IRtcEngineEx

  The class contains methods tailored for interacting with a designated RtcConnection object.

  To join multiple channels, you call joinChannelEx method in the IRtcEngineEx class multiple times, using a different RtcConnection instance each time.

When joining multiple channels:

• Ensure that the user ID for each RtcConnection object is unique and nonzero.

• Configure publishing and subscribing options for the RtcConnection object in joinChannelEx.

• Use the connection parameter in each callback to identify the corresponding channel.

Prerequisites

Ensure that you have implemented the SDK quickstart in your project.

Implementation

This section explains how to join a second channel as a host after you have already joined the first channel.

1. Join the second channel

Call joinChannelEx to join a secondary channel by specifying the RtcConnection object and using a random user ID.

let token2 = "token2";
const channelId2 = "channel2";
let uid2 = 321;

// Join multiple channels
rtcEngine.joinChannelEx(
  token2,
  // RtcConnection
  {
    channelId: channelId2,
    localUid: uid2,
  },
  // ChannelMediaOptions
  {
    clientRoleType: ClientRoleType.ClientRoleBroadcaster,
    publishMicrophoneTrack: false,
    publishCameraTrack: false,
    autoSubscribeAudio: false,
    autoSubscribeVideo: false,
    publishSecondaryCameraTrack: true,
  }
);

2. Set up remote user video

Listen to the onUserJoined callback and set the remote video.

// Register callback for when a remote user joins the current channel
agoraEngine.registerEventHandler(
  {
    onUserJoined: (_connection: RtcConnection, uid: number) => {
      showMessage("remote user " + uid + " added");
      setRemoteUid(uid);
    },
  }
);

// Creating a Remote View Using RtcSurfaceView
<RtcSurfaceView
  canvas={
    {
      uid: remoteUid,
      sourceType: VideoSourceType.VideoSourceRemote,
    }
  }
  style={styles.videoView}
/>;

Reference

This section contains content that completes the information on this page, or points you to documentation that explains other aspects to this product.

Sample project

Agora provides the JoinMultipleChannel open-source sample project for your reference. Download the project or view the source code for a more detailed example.

API reference

• IRtcEngineEx
• RtcConnection
• joinChannelEx
• onUserJoined