Conferencing

Multimedia conferencing
- Synchronized Multimedia Integration Language (SMIL) to enable other media (e.g., text, graphics and URLs) to be added to audio/video streams for synchronized display [SMIL 1998]
- SMIL documents are XML 1.0 documents
Multipoint conferencing
- can exploit multicast where available
Call control for conferencing
Floor control [RFC 4376]
- this a particular focus of Push-to-talk service [RFC 4354]
- see Florian Maurer’s push-to-talk service for minisip (formerly available from http://push2talk.floHweb.ch)
- An example of a floor control protocol is given in RFC 4582
RFC 4575 defines a SIP Event Package for Conference State

Slide Notes

Synchronized Multimedia Integration Language (SMIL) 1.0 Specification, W3C Recommendation 15-June-1998 http://www.w3.org/TR/REC-smil/ Links to an external site.

P. Koskelainen, J. Ott, H. Schulzrinne, and X. Wu. “Requirements for Floor Control Protocols”, IETF, RFC 4376, February 2006 http://www.rfc-editor.org/rfc/rfc4376.txt Links to an external site.

J. Rosenberg, H. Schulzrinne, and O. Levin, “A Session Initiation Protocol (SIP) Event Package for Conference State”, Internet Request for Comments, RFC Editor, RFC 4575 (Proposed Standard), ISSN 2070-1721, August 2006, http://www.rfc-editor.org/rfc/rfc4575.txt Links to an external site.

M. Garcia-Martin,"A Session Initiation Protocol (SIP) Event Package and Data Format for Various Settings in Support for the Push-to-Talk over Cellular (PoC) Service", IETF, RFC 4354, January 2006 ftp://ftp.rfc-editor.org/in-notes/rfc4354.txt Links to an external site.

G. Camarillo, J. Ott, and K. Drage, “The Binary Floor Control Protocol (BFCP)”, Internet Request for Comments, RFC Editor, RFC 4582 (Proposed Standard), ISSN 2070-1721, November 2006 http://www.rfc-editor.org/rfc/rfc4582.txt Links to an external site.

Transcript

[slide443] One of the big advantages of being able to do SIP conferencing is that we can support multimedia conferencing. So we can easily exchange, not only voice and video, but we can synchronize media presentations. So that means we can have a whole bunch of different streams that play out together in some timed representation. So you might have slides that are timed to music or something like that. How do you describe that? Well, there's a language called SMIL, the Synchronized Multimedia Integration Language, that lets you be able to integrate these things together. A very big interest, because remember we put RTP on top of UDP, which means we can multicast, is to be able to exploit multipoint conferences. So it's very easy to have a distributed conference setting and multicast between them. There's also a question about call control for conferencing. Who sets up and who can tear down the sessions? Who has floor control? Who gets to talk at a given time? And there's been an earlier research project by Florian Maurer who implemented push-to-talk as a service on top of Minisip. And RFC 4582 gives an example of floor control protocols. The problem is, how do you, in a multi-person setting, control who's the next person who gets to speak? Who manages that? Who keeps track of the queue? Etc. And there's even a SIP event package for conference state. So you can have a conference that goes on a break. What do you do then? What do you do when it returns from it? What do you do whenever some exception occurs? A fire in the building, whatever. So you have to describe all of this, and now of course you can manipulate it.