[PD-dev] Re: [PD] Re: YUV textures

daniel heckenberg daniel at bogusfront.org
Wed Dec 4 00:42:43 CET 2002

i've moved this one to PD-dev.

chris clepper writes:

> >AFAIK, YUV textures are only available using Direct3D under windows... I
> >think Apple is the only OpenGL vendor to include general support for YUV
> >textures.  Can anyone confirm/deny this?
> that may indeed be the case at this point in time.

hmmm... a pity. it wouldn't seem like much work on the part of the vendors
to add this support to openGL.

> >Is it possible to do HW assisted YUV->RGB(A) conversion using texture
> >transfer options and a colour matrix in OpenGL?
> all the cards seem to have that feature listed in their specs, but i 
> have no idea how to tap into that using a common api/lib other than 
> opengl.  i attempted to write a yuv->pix object but didn't have much 
> success.  not sure what sort of performance hit that will be doing 
> the conversion in software.  it could wipe out any speed gains of yuv 
> processing.

which YUV format is being used?  UYVY packed into 32bits?  that could be
done using a openGL 1.2 color matrix if the double Y resolution is
sacrificed.  might be possible to do something clever to achieve full
resolution Y but can't quite see how to do it off the top of my head...  i
don't know how fast non-standard pixel transfer is anyway, for that

if the effects are convenient/efficient in yuv and there's any significant
amount of buffer copying going on in the processing chain then i'd guess
that YUV should still come out ahead even with a last step sw or hw

this all begs for some code and experimentation.  i'll get around to it
eventually if nobody gets there first!


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