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

[Miguel Rodríguez <migrax terra es>]

El mié, 07-01-2004 a las 16:50, Damien Sandras escribió:
> I really believe it is not the right fix...

Maybe not for all pwlib users. But that would permit having a
gnomemeeting window of arbitrary size with automatic zoom, and
everything hardware accelerated. In modern video cards with video
smoothing also.
After all SDL is already used in GnomeMeeting.
> 
> 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!
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