多频道

const chA: Channel = await srtc.joinChannel(tokenA, { autoSubscribeAudio: true });
const chB: Channel = await srtc.joinChannel(tokenB, { autoSubscribeAudio: true });

srtc.channels;          // [chA, chB]，按加入先后排序
srtc.defaultChannel;    // chA

const camera = srtc.createLocalCameraTrack(cameraPreset720p());
await camera.startCapture();          // 只采集一次

await chA.publishLocalVideoTrack(camera);
await chB.publishLocalVideoTrack(camera);   // 同一条轨道，发给两个频道

await chA.unpublishLocalVideoTrack(camera);   // chB 还在发，采集继续
await chB.unpublishLocalVideoTrack(camera);   // 都不发了
await camera.stopCapture();                   // 这时才真正关摄像头

// chA, chB 都在
await srtc.leaveChannel();     // 离开 chA；此后 defaultChannel 变成 chB
await srtc.leaveChannel();     // 离开 chB

const delegate: ChannelDelegate = {
  onUserJoin: (channel: Channel, user: UserInfo) => {
    const name = channel.token.channel;      // 哪个频道
    console.info(`[${name}] ${user.uid} 加入`);
  }
};

chA.delegates.add(delegate);
chB.delegates.add(delegate);                 // 同一个 delegate 可以复用

ForEach(this.tiles, (tile: Tile) => {
  SRTCVideoView({
    track: tile.channel.getRemoteTrack(tile.uid, tile.trackId),
    trackKey: `${tile.channelName}:${tile.trackId}`
  })
}, (tile: Tile) => `${tile.channelName}:${tile.trackId}`)