<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
<meta content="text/html;charset=ISO-8859-1" http-equiv="Content-Type">
</head>
<body bgcolor="#ffffcc" text="#330000">
lorenzo,<br>
Great! I see you have everything covered. nice job! <br>
daveC<br>
<br>
Lorenzo Miniero wrote:
<blockquote cite="mid200706101135.33647.lorenzo.miniero@unina.it"
type="cite">
<pre wrap="">Hi Dave,
to have a better view of what I mean with floor control, you can have a look
at the BFCP RFC (<a class="moz-txt-link-freetext" href="http://www.ietf.org/rfc/rfc4582.txt">http://www.ietf.org/rfc/rfc4582.txt</a>), which is exactly the
protocol we implemented.
To sum it up, a floor is a logical element: when you associate this token to a
resource (e.g. audio) or a set of resources (e.g. audio and video together),
the floor becomes the permission to access this resource. To get this
permission you need to request the floor, which is done by means of a floor
control protocol, in this case the BFCP. This way you can moderate the access
to the resources: all the requests are handled as queues, and there can be
chairs (moderators) which decide if a request has to be accepted or denied.
So, when you associate a floor to video, you basically let a video stream by a
participant be part of a conference only if this participant has been granted
the video floor. As the paper states, it can be used to limit bandwidth if
each participant in a conference with N users receives N-1 video streams, to
limit to M<N the maximum allowed active video streams for example.
However, this is not the case of the videomixer we are talking about in this
thread, since both with basic videoswitching and with video mixing involved,
you would always only get one video stream back. And in both cases you can
have floor control: you could want to have a floor-moderated video, where
only one person at a time can be granted video (floor-moderated
videoswitching, which is what we already have in our prototype), or you could
want to have a floor-moderated video, where N persons at max at a time can be
granted video (floor-moderated video mixing, where sources are enabled and
admitted in the mix only if they have the floor).
I hope I clarified it all, regards,
Lorenzo
On Sunday 10 June 2007 04:59:36 dave cantera wrote:
</pre>
<blockquote type="cite">
<pre wrap="">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:
<a class="moz-txt-link-freetext" href="http://www.parc.xerox.com/research/publications/details.php?id=5634">http://www.parc.xerox.com/research/publications/details.php?id=5634</a>
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.
<a class="moz-txt-link-rfc2396E" href="http://www.parc.xerox.com/research/publications/results.php?author=1607"><http://www.parc.xerox.com/research/publications/results.php?author=1607></a>;
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.
_______________________________________________
--Bandwidth and Colocation provided by Easynews.com --
asterisk-video mailing list
To UNSUBSCRIBE or update options visit:
<a class="moz-txt-link-freetext" href="http://lists.digium.com/mailman/listinfo/asterisk-video">http://lists.digium.com/mailman/listinfo/asterisk-video</a>
</pre>
</blockquote>
<pre wrap=""><!---->
_______________________________________________
--Bandwidth and Colocation provided by Easynews.com --
asterisk-video mailing list
To UNSUBSCRIBE or update options visit:
<a class="moz-txt-link-freetext" href="http://lists.digium.com/mailman/listinfo/asterisk-video">http://lists.digium.com/mailman/listinfo/asterisk-video</a>
</pre>
</blockquote>
<br>
<pre class="moz-signature" cols="132">--
Building Strong Relationships w/ Intelligent Customer Service
--
Interlocking Business Solutions, LLC
856-380-0894 x5000
</pre>
</body>
</html>