Ooh, thank you again! I see your script is using some of the values listed in
these conversion tables. Through reading several aspect ratio threads here on Doom9, I was led to that page some months ago, and had planned to use those numbers instead of what I've got now, but I believe I had some sort of issue with the way I was rounding certain values at certain points in the script (that, and I couldn't find anything about widescreen ratios on that page; I just decided to stick with what VirtualDub uses in its preview pane context menu).
It's been a while since I've tested that, however, so I should probably revisit the subject. It may take a bit, though, since I'm just in the process of finishing up my first proper plugin. It turns an input clip into a mosaic built out of pieces of a custom tilesheet that you supply. Mock up a sheet of solid colors, gradients, ASCII text, whatever you want, tell the plugin the tile dimensions, and it does the rest, picking tiles according to the channel of your choosing. Nothing mindblowing, but fun to play with, and has helped me focus my efforts to learn C++. Should be finished in a few days.