Re: [GnomeMeeting-list] Bandwidth limitations in GM

[Johnny Strom <jonny strom netikka fi>]

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.


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
>
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