Standalone RTC channels

Standalone channels are for meetings, voice rooms and similar scenarios that don't depend on an IM group: users join with permission from your backend, with no ringing or incoming-call UI. In Flutter, join and leave with im.channels; audio and video come from the deeprespond_im_call package (LiveKit), on Android and iOS. Native iOS apps don't have a separate Swift SDK yet, so integrate through Flutter. For creating channels and granting access, see Channels overview in the server docs.

You want to	See
Add the packages, request permissions	Dependencies and permissions
Join, leave, show state and video	Join and leave
Restore after the app restarts	API and restore
Video widgets, behavior on sign-out and in the background	Video widgets and lifecycle

Dependencies and permissions

• Use matching versions of deeprespond_im, deeprespond_im_flutter and deeprespond_im_call that include the channel API. deeprespond_im_call provides audio and video automatically when the client is created; you don't need to set DRClientOptions.call.
• Create the client im and sign in first, as in Initialization.
• On iOS, add NSMicrophoneUsageDescription and NSCameraUsageDescription to Info.plist; on Android, declare and request the microphone and camera permissions.
• Joining doesn't turn on the microphone or camera by default; if the user denies permissions, they can still just watch and listen.
• Viewer-only participants (subscriber) can't publish, and audio-only channels (audio) can't turn on the camera.

Join and leave

import 'package:deeprespond_im_flutter/deeprespond_im_flutter.dart';
import 'package:deeprespond_im_call/deeprespond_im_call.dart';

if (!im.channels.supported) throw StateError('当前环境没有频道媒体适配');
final cancel = DRCancelToken();
final channel = await im.channels.join('meeting-demo',
  options: ChannelJoinOptions(ticket: ticketFromBusinessServer, cancel: cancel),
);
// join 成功表示媒体连接与 HTTP joined 确认完成。
await channel.setMicrophoneEnabled(true); // 在用户点击后调用。
await channel.setCameraEnabled(true); // 仅 video publisher。

final states = channel.stream.listen((snapshot) {
  print(snapshot.session.status);
});
final tracks = channel.tracks.listen((items) {
  // 完整的已授权轨道列表；sessionId 保持 String。
});
final localVideo = channel.localView();
// 实际远端 ID 来自授权 ChannelTrack.sessionId：
final remoteVideo = channel.remoteView(remoteSessionId);

await states.cancel();
await tracks.cancel();
await channel.leave();

• ticketFromBusinessServer comes from the join permission your backend returns, and remoteSessionId from a track; never log the permission. Open channels don't need a ticket.
• Cancel a join that hasn't finished with cancel.cancel(); once you have the handle, leave with leave().
• When joining fails or a connection arrives late, the SDK cleans up audio and video; even if the leave request fails, the local microphone and camera stop.

API and restore

API	Description
supported, current	Whether this device has audio/video capability; this device's current channel handle
getChannel(channelId)	Gets a channel
getCurrentSession()	This sign-in's channel session, or null if none
listParticipants(channelId, cursor:, limit:)	Current members; requires being in the channel yourself
join(channelId, options:)	Joins, without turning on the microphone or camera by default
resume(channelId:, sessionId:, cancel:)	Restores the original session without taking a new slot

final existing = await im.channels.getCurrentSession();
if (existing != null && ['joining', 'joined'].contains(existing.status)) {
  final restored = await im.channels.resume(
    channelId: existing.channelId, sessionId: existing.sessionId,
  );
  // 用户确认后才重新开启采集。
}

• A channel handle has channelId, sessionId, snapshot, stream, tracks, currentTracks, refresh(), setMicrophoneEnabled(), setCameraEnabled() and leave().
• Subscribing to stream and tracks first delivers the current value.
• ChannelSnapshot has channel, session, members, mediaState and error.
• When this device's current channel changes, the client emits a ChannelChanged event.

Video widgets and lifecycle

• ChannelVideoView(channel:, local:, sessionId:, fit:, placeholder:) shows local video or a given session's video; the handle also has localView(), remoteView(sessionId), switchCamera() and setSpeakerphoneOn().
• The SDK only provides tracks confirmed to belong to members allowed to join.
• Removing a video widget only stops displaying it; still call leave() when leaving the screen.
• The SDK sends heartbeats and renews the join permission automatically, and handles sign-out, sign-in switches, rejection and session expiry. After a different IM sign-in, the original session can't be restored.
• The server checks permission on every join; the media connection's own token refresh doesn't mean permission lasts forever.
• Channels don't use CallKit or the system incoming-call UI, and there's no incoming-call notification.
• Capturing audio or video continuously in the background needs extra work and testing, such as a foreground service and iOS background audio.

Channels are currently available as source only: no release including them has been published yet, and multi-party calls haven't been tested on real devices.