[Ffmpeg-devel] [PATCH] V.Flash PTX decoder

[Ivo]

Hi,

While I was reading Mike Melanson's blog, I stumbled upon this article about 
V.Flash V.disc cartridges. I decided to give the .ptx files a try and they 
are just RGB555 files with a 44 byte header. Turns out there are actually 
three (and room for four) images contained in one image.

Mike's blog entry:
http://multimedia.cx/eggs/vdisc-analysis/

The output of _114kw_pic.ptx:
http://ivop.free.fr/ptx/114kw_pic.png

Due to the limitted number of samples, I was unable to figure out all the 
header fields, but enough to read and display/convert the images. Looks 
like the width and height are repeated in the header and the few other 
non-zero bytes might refer to the colorspace or some yet unknown flags. I 
need more samples.

I also noticed that the most significant bit of each pixel is used as a 
mask, probably for internal use by the V.Flash console. The bit is set if 
the pixel is part of one of the four images. It could be seen as a 1-bit 
alpha channel.

--Ivo
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