Re: [GnomeMeeting-list] Bandwidth limitations in GM



Le jeu, 17/06/2004 à 10:26 +0300, Johnny Strom a écrit :
> 
> Hi
> 
> This bandwith limitation is starting to be a problem here quite soon,
> I would like to be able to say that one can use GM with really high
> quality and high frame rates 25/s here becouse we are starting to plan 
> and build fiber networks here to the home. Fiber networks can be the 
> next big thing and it would be nice to be able to use GM on these 
> networks. We need GM to be ready for the future and the future is
> already here at some places.
> 
> So I am talking about networks that can deliver 1Gbit/s.
> 

I can add a checkbox for the limitation for 1.2. Notice that CVS doesn't
permit you anymore to choose the framerate/quality as it was confusing
for most users. It is replaced by a quality/speed slider.


> 
> Craig Southeren wrote:
> > On Wed, 16 Jun 2004 23:09:28 +0200
> > Kilian Krause <kk verfaction de> wrote:
> > 
> > ..deleted
> > 
> > 
> >>>Also, when I open the GM preferences, there is a form box containing a 
> >>>number for Maximum video bandwidth of ___ kB/s under the "Codecs... 
> >>>Video Codecs" tab, but I cannot seem to set it to higher than 100 kB/s 
> >>>even though our network connection and gatekeeper are capable of much 
> >>>more.
> >>
> >>That's an OpenH323 limitation.
> > 
> > 
> > There is no such OpenH323 limitation, but it could be a GM bug.
> > 
> > If this value is the max bandwidth that is passed to H323EndPoint, then
> > you need to know that H323Endpoint expects the value in multiple of
> > 100bps, so 100,000 actuallty represents 10,000,000.
> > 
> > If you want to know why, then read on.....
> > 
> > OpenH323 allows a user to indicate a bandwidth limit in the H323EndPoint
> > in order drive the algorithm that chooses codecs when a call is started.
> > For example, if the user indicates that they have a bandwidth of 50kbps,
> > then OpenH323 will not choose G.711, even if it is available to both
> > endpoints, because that codec requires 64kpbs. This stops users from
> > getting crappy calls when they don't have the bandwidth, and it mirrors
> > a similar feature in NetMeeting (and most other clients)
> > 
> > Unfortunately, this limitation does not work well when video codecs are
> > used, because it uses the bandwdith of the maximum possible video
> > quality at the specified frame rate, not the dynamic bandwidth as
> > determined by the actual frame rate or scene complexity. So, normally,
> > we don't recommend that applications use this value - unless they are
> > only using audio.
> > 
> > Unless the application specifies a value, OpenH323 will use a default
> > bandwidth of 10Mbps (i.e. Ethernet speed) which will result in selecting
> > the highest bandwidth codec (and presumably also highest quality codec)
> > that can be agreed upn between the two endpoints.
> > 
> > The H.323 specification uses this value in multiples of 100 bps, so a
> > value of 100,000 actually means 10 times that. Hence, a value of 100,000
> > actually means 10 x 100,000 = 10,000,000 bps
> > 
> >    Craig
> > 
> > -----------------------------------------------------------------------
> >  Craig Southeren, craigs postincrement com http://www.postincrement.com
> >  Post Increment - Software, Consulting and Services
> >  Co-founder of the only open source H.323 project
> >  Phone: +61 2 43654666   Fax: +61 2 43673140   Mobile: +61 417 231046
> >  MSN: craig_southeren hotmail com      ICQ: #86852844
> >  Jabber: CraigS jabber voxgratia org   Blog: http://www.southeren.com/blog
> >  PGP :http://www.postincrement.com/pgp.txt
> > 
> > _______________________________________________
> > GnomeMeeting-list mailing list
> > GnomeMeeting-list gnome org
> > http://mail.gnome.org/mailman/listinfo/gnomemeeting-list
> 
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-- 
 _      Damien Sandras
(o-     GnomeMeeting: http://www.gnomemeeting.org/
//\     FOSDEM      : http://www.fosdem.org
v_/_    H.323 phone : callto:ils.seconix.com/dsandras seconix com

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