mcast.txt

网络MPEG4IP流媒体开发源代码

The Darwin Streaming Server provides a program, PlaylistBroadcaster,
that can be used to multicast stream MPEG4 content stored in MP4 files.
Here's the step by step procedure:

SETUP
=====

To set up the multicast you need to create two files. 

The first file is a playlist file which specifies which files to play. 
Here's an example playlist file, 'playlist_example': 

*PLAY-LIST*
mycontent1.mp4
mycontent2.mp4
mycontent3.mp4

The second file specifies where to multicast.
Here's an example multicast file, 'mcast_example':

playlist_file playlist_example
play_mode sequential_looped
sdp_reference_movie mycontent1.mp4
destination_ip_address 224.10.11.12
destination_base_port 40000
multicast_ttl 15

See mpeg4ip/server/DSS/Documentation/AboutDarwinStreamingSvr.pdf for a
more detailed explanation.

The 'multicast_ttl' parameter specifies the IP time-to-live (TTL) used for the
multicast packets. It determines how many networks the multicast packets
can reach before being timed out. The default value is 1, i.e. multicast only
to the locally attached network.


TRANSMITTING
============

Once these files are setup, you tell the PlaylistBroadcaster to start 
transmitting. I.e.

$ /usr/local/bin/PlaylistBroadcaster mcast_example

Note you need root privileges to do this.

Note on some systems, it may be necessary to add a multicast route 
to the system routing table to get multicast packets to be transmitted.
I.e:

$ route add -net 224.0.0.0 netmask 240.0.0.0 eth0


RECEIVING
=========

As part of the statup procedure, PlaylistBroadcaster will automatically
generate an SDP file for the transmission. E.g 'mcast_example.sdp'
You need to get that SDP file to the clients that want to receive the
multicast transmission. This can be done via email, web site, ftp, ...

The player then opens the sdp file, and should begin receiving the
multicast content within a few seconds. I.e.

$ gmp4player mcast_example.sdp

That's it! I suggest at first that you check multicast with a server and
player on the same LAN. Once that is working, you can try it across routers
which enters the arena of configuring multicast routing which is beyond
the scope of this document.