Re: [GnomeMeeting-list] Bandwidth limitations in GM



Le jeu, 17/06/2004 à 13:18 +1000, Craig Southeren a écrit :
> 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.

Neither of them, it is by design. That's just a bandwidth limit on the
video codec.

> 
> 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
-- 
 _      Damien Sandras
(o-     GnomeMeeting: http://www.gnomemeeting.org/
//\     FOSDEM      : http://www.fosdem.org
v_/_    H.323 phone : callto:ils.seconix.com/dsandras seconix com

Attachment: signature.asc
Description: Ceci est une partie de message =?ISO-8859-1?Q?num=E9riquement?= =?ISO-8859-1?Q?_sign=E9e?=



[Date Prev][Date Next]   [Thread Prev][Thread Next]   [Thread Index] [Date Index] [Author Index]