User guide

20 Chapter 2
Overview
Version 3.1
Streaming session
A streaming session is a set of streams (such as video, audio or BIFS for
MPEG-4) that is sent from a server to a client.
A stream can contain a live track from a broadcast MPEG-4 movie (for
example, audio or video generated by the Playlist Broadcaster or Envivio
4Caster), or from a stored MPEG-4 file.
1. To begin a streaming session, the client sends a request for a movie.
2. To start the session, the server first gives a full description of the movie
using SDP (Session Description Protocol), including:
• the types of media,
• the number of streams,
• the codec to be used for each stream.
3. The server then sends each media in a separate stream of RTP packets.
Unicast streaming
Unicast means communication between a single server (sender) and a
single client (receiver) over a network. Unicast is contrasted with multicast
(a single server, several clients).
1. For real time streaming in a unicast session, the client sends a request
for a movie to the server using RTSP.
2. Using the same protocol, the server sends a description of the movie to
the client.
3. Then the client sets up the session, and the server begins to send the
streams to the client.
In the case of unicast streamed stored content, the user has the ability to
jump anywhere in the movie (the server simply begins streaming the
movie from this new point).