Re: [GnomeMeeting-list] H261PixelEncoder : H.261 bad geometry: 320x240

[Damien Sandras <damien sandras it-optics com>]

I really believe it is not the right fix...

Le mer 07/01/2004 à 16:22, Miguel Rodríguez a écrit :
> I think the best solution here would be to have pwlib[1] return the
> unmodified image and make GnomeMeeting do the scaling. Maybe we can use
> XVideo or the SDL library to show the image in the GUI, having the
> scaling possible hardware accelerated in that case.
> 
> Sadly I don't have the necessary skills/time to do that myself soon.
> 
> [1] For the logitech camera this also means fixing the driver to not
> return sizes not supported by the hardware.
> 
> El mié, 07-01-2004 a las 12:03, Damien Sandras escribió:
> > Hi,
> > 
> > Le mer 07/01/2004 à 10:04, Van Duc Uy a écrit :
> > > Hi all,
> > > I use gnomemeeting-0.98.5 on Mandrake linux 9.2.
> > > camera is Logitech Quickcam Pro 4000. 
> > > 
> > > it's because gnomemeeting always display the picture with a
> > > BIG "Gray border" (as i know GM_QCIF_HEIGHT/WIDTH). 
> > > 
> > > so i want to choose another mode GM_SIF_WIDTH/HEIGHT that
> > > displayed at 320/240 pixels. 
> > > After i modified the gnomemeeting code, and rebuilt it, 
> > > the video can display very well without border anymore. ..
> > > 
> > > But, when i try to make a connection to another host (Netmeeting 3.0),
> > > at the console i saw the message :
> > > 
> > > H261PixelEncoder : H.261 bad geometry: 320x240
> > > Segmentation fault
> > > 
> > > and then gnomemeeting crashed.
> > > 
> > > Can anyone explain for me about the problem ?
> > 
> > You modified things without understanding. If it was possible to do it
> > so easily, it would already be a feature ;)
> > 
> > > why H.261 can not encoder with 320/240 pixel ?
> > 
> > Actually, the H.323 standard specified that at least H.261 QCIF must be
> > supported by endpoints. So, if you are sending SIF or QSIF, there is no
> > guarantee that the remote endpoint will be able to decode it. The
> > OpenH323 H.261 encoder, which is the vic encoder, only supports QCIF and
> > CIF.
> > 
> > > If i don't want to see the "Gray border", how can i do ?
> > > 
> > 
> > There are 2 possibilities :
> > - Buy a camera that supports exactly QCIF and CIF
> > - Modify vconvert.cxx in pwlib so that it supports image scaling.
> > Currently, pwlib will ask to the driver to capture in QCIF, if the
> > driver supports it, it will work. If the driver doesn't support QCIF,
> > pwlib will try the next size and surround it with borders. So it will
> > try QSIF, for example, and surround it with borders so that it becomes
> > QCIF. You could extend the methods so that the QSIF is scaled in QCIF
> > instead of surrounded by borders. However, that won't work with the
> > logitech quickcam, because when you request QCIF, the driver will itself
> > send QSIF surrounded by borders, without the intervention of the
> > library, there are thus 2 things to do :
> > 	* extend pwlib colour converters so that they support scaling 	instead
> > of cropping/borders
> > 	* fix the driver so that it fails when QCIF is asked, instead of
> > 	adding itself the borders
> > 
> > Good luck!
> _______________________________________________
> GnomeMeeting-list mailing list
> GnomeMeeting-list gnome org
> http://mail.gnome.org/mailman/listinfo/gnomemeeting-list
-- 
 _      Damien Sandras
(o-     
//\     It-Optics s.a.
v_/_    GnomeMeeting: http://www.gnomemeeting.org/
        FOSDEM 2004:  http://www.fosdem.org
        H.323 phone:  callto:ils.seconix.com/dsandras seconix com