RTP Quality Matrix
==================

The Real-time Transport Protocol, RTP [1], provides quality of service
feedback with reception reports sent alongside the media stream. If the
media is sent via IP multicast it is possible for a third party to snoop 
on these reception reports, displaying reception quality for all members
of a group. The RQM application performs such snooping.

Usage: 	rqm address/port 	(eg: rqm 224.2.172.238/51482)
	rqm -version

The distributed binaries support IPv4 addresses, it is also possible to
compile RQM to support IPv6.

When running RQM displays a matrix with participant details on the left,
and a number of cells to the right of these. Each row of cells denotes 
the packet loss rate observed for data sent from the participant indicated
at the left of that row (point to a cell and a popup will appear giving
the names of the source and destination of the traffic represented by that
cell).

The colours of the cell start as green (no loss) and fade to red (20% loss).
A white cell indicates that no information is available. A light blue cell
indicates that the receiver is not receiving media data from a particular
sender (at present light blue is only used when an empty reception report
is received, indicating that a receiver can hear no-one).

Clicking on a cell will initiate an mtrace [2] between the indicated
participants, if you have mtrace installed and available in your path.

Comments, suggestions and bug reports should be sent to 
	c.perkins@cs.ucl.ac.uk
more information is available from
	http://www-mice.cs.ucl.ac.uk/multimedia/software/rqm



References:

[1]	Schulzrinne, H., Casner, S., Frederick R., and V. Jacobson, "RTP: A
 	Transport Protocol for Real-Time Applications", RFC 1889, January 1996.

[2] 	Fenner, W. Multicast traceroute, software available online from
	ftp://ftp.parc.xerox.com/pub/net-research/ipmulti/mtrace-5.2.tar.gz