User guide

4Sight 23
Administrator Guide
Version 3.1
Relay
4Sight acts as a relay server when it accepts a stream from a source (a
broadcaster or another streaming server) and sends it or "relays" it to one
or more other IP addresses. See “Using 4Sight as a relay” on page 42.
Broadcast
A broadcast is a stream of RTP packets generated by an application or
process external to the streaming server (it often runs on a separate
machine).
The Playlist Broadcaster reads the MPEG-4 files in a playlist and converts
them into RTP packets. It sends the packets over UDP/IP, to a specific
address bound to a defined port. This address can be either unicast or
multicast.
The Playlist Broadcaster creates a file containing all the SDP information
about the presentation needed by the client (and possibly reflector). The
Playlist Broadcaster can broadcast the SDP to port 9875 of the destination
address, or can send the SDP to the SAP address. The Playlist Broadcaster
creates a standard SDP file named filemame.m4e conforming to the SDP
standard. See “M4E file” on page 130 for a sample of M4E.
Examples of broadcasters:
• Playlist Broadcaster
(included with 4Sight)
• Envivio 4Caster
Hint tracks
To be streamed, an MPEG-4 file has to be hinted. The server uses hint
tracks in an MPEG-4 file to packetize the media into RTP streams.