[Asterisk-video] Simple vidéo conference

[dave cantera]

sorry, I am a neophyte to video over IP... I didn't know what floor 
control was so I googled it...

from this Parc Research paper:

    http://www.parc.xerox.com/research/publications/details.php?id=5634

it looks like implementors would have a challenge with bandwidth along 
with encoding/decoding.  if I am running a videoconferencing server and 
connecting all channels in and out, that is really sucking up my 
bandwidth.  could make the application too expensive for most. 

would it be appropriate to put a throttle option in the config files to 
limit bandwidth or video updates to every other frame or every 4th frame 
unless you are the speaker then you get full throttle?  I would not 
mention the throttling ability except I can see that if development 
shoots for four streams you know that four will want to invite eight, 
and eight sixteen.  before you know it everyone will want to use it and 
that would be cost prohibitive for the provider and make it only 
available to those who can pay the high bandwidth rates the provider 
will have to charge.  don't know if throttling is possible but it is 
better to talk about it sooner than later...

below is the parc research abstract...  I don't know what licensing 
requirements would be from parc...
daveC

Floor control alternatives for distributed videoconferencing over IP 
networks

Garcia-Luna-Aceves, J. J. 
<http://www.parc.xerox.com/research/publications/results.php?author=1607>; 
Mantey, P. E.; Potireddy, S. N. Floor control alternatives for 
distributed videoconferencing over IP networks. Proceedings of IEEE 
CollaborateCom 2005: The First International Conference on Collaborative 
Computing: Networking, Applications and Worksharing; 2005 December 
19-21; San Jose; CA; USA.

Applications that require the communication of multiple video streams 
can consume considerable bandwidth and computing resources, which poses 
a challenge for the widespread use of videoconferencing over the IP 
Internet. On the one hand, the bandwidth of the link connecting a given 
participant to a videoconferencing session may not be enough to support 
many video streams at bit rates of 500 kbps or more, especially when the 
participant is connecting to the rest of the Internet through a wireless 
link. On the other hand, the processing capacity of a participating site 
may not be enough to decode several video streams in real time. This 
paper explores the use of floor control over videoconferencing 
applications as a means to support videoconferences with many 
participating sites, but with a processing and communication overhead 
per site that is equivalent to a two-party videoconference. The main 
tradeoff we explore is the scalability attained with floor control 
versus the latencies incurred with floor transitions, which can be much 
too disruptive to the videoconference participants. We present a viable 
compromise in which only the video stream of the "floor holder" is sent 
to all sites, but the floor-passing protocol is such that it supports a 
brief overlap of the transmissions from the old and the new floor 
holder, such that the participants in the videoconference can 
instantaneously switch over to the media streams of the next speaker in 
an apparently seamless transition. Experimental results and 
implementation in a research video-conferencing system show that the 
proposed protocol can run effectively, eliminating race conditions, 
while maintaining scalability and reliability.