Paolo Scaffardi wrote:
> i am developing on a PowerPC embedded processor (MPC823) and i want to run
> an X-server on its video-controller that can handle YCbYCr data format
> (4:2:2) in memory. It simply stores 2 bytes per pixel, depending of even of
> odd position, YCb or YCr.
>
> I ported GGI and XGGI on my board, but the problem is that XGGI doesnt use
> GGI primitives, but its directbuffer feature, that permit the program access
> directly to the memory buffer that it supposes to be a RGB framebuffer, not
> YCbYCr.
>
> I heard of KGI and its PhoeniX & X11 but i dont know how they works togheter
> and if they access directly to the memory or if they use other library
> primitives.
>
> Have you any hint for me?
The only chance is probably to use the YCbYCr buffer as a direct color buffer
(fixed pixel value to color mapping) and use a translation table/function
to convert RGB into palette values. Also you will probably only be able
to use half the resolution in x-direction, as the color values are shared
among two neighbouring pixels.
Another method could be to have a shadow buffer (rgb) and translate it into
YCbYCr when blitting it to the screen. The memory visual of libGGI/XGGI
does probably allow for this, at least it could probably be modified to do so.
However, PhoeniX so far works only with 8bbp, and needs at least the pallette
setting implemented. I would not recommend it for your application if you need
to get it going quickly.
Steffen
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Steffen Seeger mailto:[EMAIL PROTECTED]
