[FFmpeg-devel] [PATCH] PC Paintbrush PCX decoder
Sun Dec 30 00:49:50 CET 2007
On Saturday 29 December 2007 22:21, Mike Melanson wrote:
> Ivo wrote:
> > No, CGA paletted images were the only ones I could not find.
> Here you go:
> >From my contact: "These all load perfectly under *REAL* PC Paintbrush
> >4.0 in DOS on a CGA card, so if your decoder screws it up, it's the
> >fault of your decoder!"
> 2008 is almost here-- we need CGA PCX support in FFmpeg fast! :)
Thanks! Alas, there's a problem. From ZSoft's specs:
> CGA Color Palette Information
> NOTE: This is no longer supported for PC Paintbrush IV/IV Plus.
The sample files:
CGA_BW.PCX - Renders correctly with the current code (contains 2 RGB
triplets in the header)
CGA_FSD.PCX - Renders correctly with the current code (contains 4 RGB
triplets in the header specifying the most common palette)
The other two do not render correctly, either without or with added code to
handle the CGA palette according to the spec (4 bits of byte 16 determine
the background color and 3 bits of byte 19 determine foreground palette).
For example, the intensity bit is set in both files, but the text in the
images clearly states that one has it on and the other has it off. The
choice of 4-color CGA palette seems to go well, but that might just be pure
luck. And both files have the color_burst bit set, which should have been
All in all, I can't make it work for all cases. Perhaps it would be possible
to write exactly the same image (preferably CGA_TST1.PCX) in all eight
formats? color_burst color/monochrome, intensity dim/bright and palette
yellow/white makes eight combinations. Maybe I can find out how PC
Paintbrush >= 4 stores that information.
If possible, it would also be nice to have the same images written by
Paintbrush < 4 :-)
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