Devices, channels, streams, and media nodes

An NVR connected to four cameras is one device with four channels. An online stream exists only while one of those channels is sending media to a media node. MediaServer is the program that receives and distributes that stream.

flowchart LR
    N["Device: NVR"] --> C1["Channel: entrance"]
    N --> C2["Channel: warehouse"]
    C1 --> S["Online stream"]
    S --> V["Live view"]
    S --> R["Recording file"]
    C2 -. "No stream while offline" .-> X["Wait for recovery"]

Name	Lifetime	Where to inspect it	Common mistake
Device	Persists after onboarding	Access management or the resource tree	Registration does not prove every channel has video
Channel	Persists after onboarding or activation	Asset details	A saved channel need not have a live stream
Stream	Exists while media is being pushed or pulled	Live view and stream sessions	An accepted start request does not prove frames arrived
MediaServer	Separate media service process	Media node in System management	A running process does not prove the target stream exists

A channel can refer to a device Profile or to an RTSP/URL source. channelId is the platform's stable channel identity; mediaServerId chooses the media node; app/streamId identifies the stream at that node. Do not use a channel's display name or source URL as a business primary key.

If there is no video, check channel enablement, device reachability, stream presence at MediaServer, then the viewer's access to the playback URL. Follow No video or playback failed for the hands-on checks.

Continue with The path from live view to recording to connect these objects to a user action.