[AG-TECH] room node certificates

[S.Booth]

On Tue, 30 Sep 2003, Ivan R. Judson wrote:

> We definitely need to figure out a way to coordinate (and keep track of this
> information) I know Robert Putnam is doing something ad-hoc for his cool
> spatialized audio (and maybe window highliting) work. I don't know that we
> want to keep it in the venue, it feels to me like a "per-node" cache of data
> with some interface for sending "meta-information" updates that ties
> together existing pieces of information.
> 
> Ie, the tools already assign ssrcs, if we just sent an event that said, "I'm
> node ID and my SSRCS are x, y, z" that might be sufficient to start with.
> 
> We probably should start gathering some reqiurements for what this data is
> to be used for so we can get a better handle on what we need to engineer.
> Any volunteers for requirements gathering?
> 

Ok I'm interested in helping with requirement gathering.

I'm also worried about relying on the venue to store everything 
It gives you problems with interoperating with non AG RTP equipment 
and if you are not very careful could introduce unecessary software
dependency between otherwise uncoupled components.

I think Colin is right the correct thing to do is to fix the choice
of CNAMEs My reading of RFC1889 is that this is the sole purpose of CNAMEs

 RTCP carries a persistent transport-level identifier for an
 RTP source called the canonical name or CNAME, Section
 6.4.1. Since the SSRC identifier may change if a conflict
 is discovered or a program is restarted, receivers require
 the CNAME to keep track of each participant. Receivers also
 require the CNAME to associate multiple data streams from a
 given participant in a set of related RTP sessions, for
 example to synchronize audio and video.

Therefore I would suggest that the VenueClient or NodeManager chooses
the CNAMES and gives them to the RTP engines to use. 
Normally each node would choose a single CNAME for all streams.
In an earlier email I suggested adding the certificate name to the RTCP 
info and using this instead but I don't think that this would work because
you can imagine a situation where a single node is sending multiple audio
streams, each stream associated with a different group of cameras. This
would require the Node to allocate multiple CNAMES.
The selected CNAMES could also be registered in the VenueServer in case
you ever wanted to  cross reference RTP streams with other VenueServer
info.


				Stephen




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|epcc| Dr Stephen P Booth             Project Manager           |epcc|
|epcc| s.booth at epcc.ed.ac.uk          Phone 0131 650 5746       |epcc|
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