From: Jan Kneschke <jan@kneschke.de>
  To  : ggi-develop@eskimo.com
  Date: Sat, 6 Nov 1999 19:25:20 +0100

yuyv reprentation in ggi

currently i try to find a way to set up a YUV-crossblit in ggi. GGI has no
support for it yet. neither a GT_YUV422 nor a abstract and fitting
pixel-model. 
ggi_pixel_format only supports buffers that can be accessed by a shift-mask.
YUV422 is a common color-format most often used by tv-cards, mpeg-movies and
the like. two pixels are represented by 4 bytes:

Y1U1Y2V1Y3U2Y4V2....
| | | |

Y1, U1 and V1 is the first pixel.
Y2, U1 and V1 is the second pixel.
and so on.

ok. this one can be implented in ggi. i don't know, but i'm sure it can be
done. the next one is trickier.

YUV411:

Y1U1Y2U2.......
YaV1YbV2......

U and V are transmitted in two lines. GGI can't handle this.

but hey, as far as i know accelerated color-space conversion is most often
 done YUV422(packed) -> RGB, so lets try to get this one defined.

one solution could be the conversion from YUV422(packed) to YUV422(planar)
were you seperate the components into 3 buffers (Y1Y2Y3Y4)(V1V2)(U1U2) like
those bit-plane modes. but this wont give us the directbuffer a currently
need for ggitv.

all i want is a visual i can crossblit to another visual. the source would
be YUV422 and the destination a KGI(con)-visual that converts YUV422->RGB in
hardware. 

has someone a idea how intergrate it in ggi ??

thats all
  Jan

--- 
      -)=  Jan Kneschke -- Kiel -- Germany -- http://www.kneschke.de =(-