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. Join and leave with DRClient.instance.channels; audio, video and the video view come from the im-call module. For channel rules, see Channels overview in the server docs; for installing modules, see the Android overview.

You want to	See
Add the modules, request permissions	Dependencies and permissions
Join, leave, restore after an app restart	Join, cancel and restore
Show members and video	State and video
Behavior on sign-out and in the background	Lifecycle and limits

Dependencies and permissions

• Add im and im-call at the same version. im-call provides media for channels automatically; you don't need the system incoming-call options.
• Without im-call, channels.supported is false and join fails right away with unsupported, without taking a slot on the server.
• Your app requests the microphone permission RECORD_AUDIO and camera permission CAMERA through Android's permission APIs. The SDK never shows permission prompts itself; without the permission it returns permission_required.
• Turning on the microphone or camera must be triggered by a user action. Viewer-only participants (subscriber) can't publish, and audio-only channels (audio) can't turn on the camera.

Join, cancel and restore

Use this in a coroutine of a signed-in Activity / Fragment; ticketFromBusinessServer comes from your backend:

import com.deeprespond.im.ChannelJoinOptions
import com.deeprespond.im.DRClient

val channels = DRClient.instance.channels
check(channels.supported)
val handle = channels.join(
    "meeting-demo",
    ChannelJoinOptions(ticket = ticketFromBusinessServer),
)
// 默认不采集；完成媒体连接和服务端 joined 确认后才返回。
handle.setMicrophoneEnabled(true) // 用户操作且 RECORD_AUDIO 已授权。
handle.setCameraEnabled(true) // video publisher，且 CAMERA 已授权。
handle.leave()

• Open channels don't need a ticket.
• ChannelJoinOptions also has clientSessionId, microphoneEnabled and cameraEnabled; the last two default to false, so joining doesn't turn on the microphone or camera.
• When the SDK retries the same join, it reuses the same join identifier, so you never join twice.
• Cancelling the coroutine running join releases the slot it took; even if the leave request fails, the local microphone and camera stop.

val existing = channels.currentSession()
if (existing != null && existing.status in setOf("joining", "joined")) {
    val restored = channels.resume(existing.channelId, existing.sessionId)
    // 恢复只使用原会话，不新占位，也不自动采集。
}

• current is this device's current channel handle (a StateFlow); currentSession() asks the server for this sign-in's channel session, for restoring after the app restarts.
• Only this sign-in's session can be restored; a different sign-in can't. A session in leaving must finish cleaning up first, and one in left can't be restored.
• IDs are strings; don't convert them to Int or truncate them.

State and video

The UI observes two StateFlows:

• handle.snapshot (ChannelSnapshot): channel, session, members, mediaState, microphoneEnabled, cameraEnabled, error.
• handle.tracks (List<ChannelTrack>): the audio and video tracks. Remote tracks only appear here once they're confirmed to belong to members allowed to join.

val stateJob = lifecycleScope.launch {
    handle.snapshot.collect { snapshot -> renderChannelState(snapshot) }
}
val tracksJob = lifecycleScope.launch {
    handle.tracks.collect { tracks ->
        val video = tracks.firstOrNull { it.kind == "video" && !it.local }
        channelVideoView.bind(handle, video)
    }
}
// 页面结束时停止观察，解绑画面，并在可完成清理的协程中 leave。
stateJob.cancel()
tracksJob.cancel()
channelVideoView.unbind()
handle.leave()

renderChannelState is your app's render function; channelVideoView is a com.deeprespond.im.call.DRChannelVideoView, supporting FIT / FILL, mirror and bind / unbind. Only show tracks given in tracks; don't assemble video from a username or media of unknown origin.

Lifecycle and limits

• The SDK sends heartbeats and renews the join permission automatically. On a sign-in switch, sign-out or media failure, it stops the local connection.
• The server still checks permission for every join; the media connection's own token refresh doesn't replace that check.
• Join permissions, media tokens and handles are never saved locally.
• Channels don't use the system incoming-call UI (DRCallUI, Core-Telecom), and there's no ringing or incoming-call notification.
• Channels currently only support foreground use. Capturing audio or video continuously in the background needs a foreground service, an ongoing notification and extra platform work, tested on its own.
• Call leave() when leaving the screen; don't just unbind the video view.

The channel code and automated tests are done, but no APK / AAR containing it has been released yet, and multi-party calls haven't been tested on real devices. For the Java API, see Java; for full signatures, see the API reference; for types, see Data types.