What I've been using (since before you DIY kit was available) is mencoder to convert AVIs to 'Y8' format. These are a solitary files containing Y, U, and V frames, scaled and sampled at the correct frequency. The Y frames are easily converted to 16 gray levels.
For color movies I have to convert YUV to RGB. I originally used the floating point algorithm described here ->
http://en.wikipedia.org/wiki/YUV but decided to try the 'bit shifting algorithm" since it's well suited to Action. It's much faster than BASIC and in Atari800 at full speed the conversion time is almost reasonable.
Eventually I would like to convert my tools to C (but that would mean I would have to learn C
) and do everything in linux.
This method is probably more cumbersome and slower than using individual BMP files but I prefer the projects to be in just handful of files, easier to archive to DVD (which this time I will be more diligent about doing).
I'm sure my problem is a coding error but I know I'm getting good data for all three color planes. I have to be doing something wrong while packing the data, 4 pixels to a byte, or while writing the data back to disk.
I'll figure it out (eventually).
Thanks for your tips, your tools, and your MyIDE, of course.
-Steve Sheppard