[PD] [Gem] pix_video comments ...

james tittle tigital at mac.com
Sat Jun 18 20:23:04 CEST 2005

On Jun 18, 2005, at 1:02 PM, Georg Holzmann wrote:

> Hallo!
> I have some problems with pix_video:
> With my webcam _and_ dv1394 I get red/blue swapped.
> (with colorspace YUV no problem !)
> Has anyonw else the same problems?

...can't speak for anything but the osx stuff, and we don't see that  
channel switching...

> I can hack it if I swap the colors in
> GEM_EXTERN void imageStruct::fromYV12
> in GemPixUtil.cpp, but this is of course no good solution.
> And why is RGBA and BGRA the same ? Maybe this is the problem?
> Or should we add an option to pix_video to swap red/blue?

...welcome to the wacky world of endian insanity!  The RGBA/BGRA  
stuff actually works because the type/format (I forget which exactly)  
is appended "*_REV", which make everything ok on bigendian  
machines...confusing indeed, but not to say that gempixutil.cpp  
couldn't use quite a bit more scrutiny...certainly has a lot of  
#ifdef's, but that's where it's at...

...I should also note that I don't remember making the YV12  
conversions correct for pdp across the board, but it's really a  
simple function overloading change (char to short)...

...finally, I'm not sure how motivated I am to complete the altivec  
conversions of important space changes, but will get to them as we  
have at least a year before I move to "mactel":  is anyone up to  
doing SSEn speed ups here?  I imagine I'll be getting into that when  
I get a machine, but that's a year away too...


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