Are packets duplicated in live video broadcast?

[tomthehero]

If 10 users are being served a live video broadcast stream of 1mbps bitrate by a server, does the server require 10mbps bandwidth or is 1mbps enough?

Since the server is serving exactly same data to multiple clients, does it send multiple copies of same packets with different destination addresses or does it send a single copy of a packet with a list of destination addresses?

If the commonly used protocols doesn't support this, are there any not so widely used options?

[detaro]

You can't send a packet with a list of destination addresses.

There is multicast, where clients can register "I'd like a copy of all packets to $address please", but it doesn't work on public internet. It's used by some providers for TV streaming inside their networks though.

There's also peer-to-peer approaches, where clients share the data they receive with other clients, similar to Bittorrent.

The most common approach is individual streams from the servers to the clients though.

[tomthehero]

Does youtube use multicast?

[detaro]

No. As I said, multicast generally doesn't work across networks you don't control (and also needs special clients, can't be used with browsers).

[bradknowles]

No.

[bradknowles]

What you could do is send your stream from your source machine to a streaming server, and then have the streaming server send that out to the clients.

This is how live-streaming on YouTube or twitch.tv works.