A udp:// address points to a video stream sent over UDP, usually multicast, on a local or provider-managed network. It's how many hotel, campus and internet-provider TV systems deliver channels. These streams generally only work inside the network that carries them, which is why a UDP link copied from somewhere else won't play at home.
UDP and multicast in plain terms
- UDP is a lightweight way of sending data with no retransmission. Good for live video on a reliable network, bad over the open internet.
- Multicast sends one copy of a channel that every interested receiver on the network can join, like tuning to a broadcast. IPv4 multicast uses the 224.x.x.x to 239.x.x.x address blocks assigned by IANA; local networks commonly use the 239.x.x.x block, which is reserved for use within an organization's own network.
What a UDP address looks like
udp://@239.1.1.1:1234The @ means “listen here”: join multicast group 239.1.1.1 on port 1234. VLC's documented syntax is udp://[[<source address>]@[<bind address>][:<bind port>]].
Opening a UDP stream in VLC
- Make sure your computer is connected to the network that carries the stream (for example, a building's TV network).
- In VLC, choose Media → Open Network Stream (Windows) or File → Open Network (Mac).
- Enter the address, for example
udp://@239.1.1.1:1234, and play.
Why UDP links don't work over the internet
- Home routers and the public internet generally don't route multicast traffic between networks.
- Firewalls block unsolicited incoming UDP.
- Lost packets aren't resent, so even when traffic gets through, the picture breaks up.
Internet streaming services use HTTP-based delivery instead, which works through any normal connection. See how media streaming works.