11.1. Overview
With Video On Demand (VOD), the user can start the video when he
wants, make pauses, go forward and back in the video. It is of course
the best in video streaming and the dream for every user.
VOD is a very big consumer of resources for the server and the
network. VOD is unicast, not multicast : this means that the network
and server resources needed are directly proportional to the number of
clients.
The design of VideoLAN's VOD solution is very simple. The idea
is to do HTTP streaming, i.e. stream an MPEG video encapsulated in
HTTP. The regulation of the bitrate between the client and the server
is done automatically by TCP. With HTTP version 1.1, there is the
possibility to seek in a file downloaded, that's what we use to seek in
the video.