VideoLAN Wiki - User contributions [en]

HTTP

2005-11-15T05:33:11Z

Hyrulian:

HTTP stands for HyperText Transport Procotol. It's a application network layer developed in early days of Internet for transmit html and text files. Today it's used for every kind of media, thanks to it's flexibility.
VideoLAN can use this protocol for multimedia [[streaming]]. It can read a stream from an HTTP server like Apache, or act like a HTTP server dumping multimedia to the network.

Multicast

2005-11-15T05:32:08Z

Hyrulian:

Multicast is one of three ways you can use the IP protocol.

With multicast one computer sends traffic to [http://www.cisco.com/univercd/cc/td/doc/cisintwk/ito_doc/ipmulti.htm#xtocid4| a special IP address]. Other people can then choose to register to this IP address and then receive the traffic. Its advantage is that the server can send a single datastream, and then an endless number of clients can receive this data. This avoids having to send the same data on a single network connection. (The negotiation process to setup this connection is called the [[IGMP]] protocol.)

Multicast is not always supported. Your OS needs to know how to handle it (Windows, Mac OS X, and the Linux kernel do). And you need suitable network equipment (routers, switches etc.). Also you can only do multicast on internet if your ISP is connected to the [[MBONE]]. Only a limited amount of end users can receive multicast from the internet; most of them would be universities and research centers.

However, most LANs can easily support Multicast. Beware that if your switch or routers don't support it, some types of network equipment actually broadcast the traffic. This might be a very undesirable behaviour.

See Also:
[http://www.cisco.com/univercd/cc/td/doc/cisintwk/ito_doc/ipmulti.htm Cisco detailed Multicast explanation]

UDP

2005-11-15T05:30:20Z

Hyrulian:

UDP is a what they call a 'send and pray' protocol. You throw data onto the network and you have no guarantee if the data reaches its destination or when. Because of this, it is extremely fast, efficient, but also 'unreliable'.

It is next to [[TCP]] one of the primary basic [[IP|Internet Protocols]] that every major OS supports.

It is extremely suited for streaming live video. In this case it is not important that you receive ALL data, as long as you receive SOME data continuously and fast.

VLC supports this protocol for streaming, however not all types of video can be streamed over UDP. See the matrices here: http://www.videolan.org/streaming/features.html