Mostly because of the weather I have not been in mood to work on anything serious for weeks, but here is something rather interesting.
Apparently there are some CD-ROMs represented on discmaster titled “Moving Puzzle: …” that have some .mv files (inside media.pak archive) that supposedly give motion to those puzzles. And of course somebody had to look at the format.
Obviously the format was inspired by QuickTime as it has the header with all those chunks defining per-track data including e.g. sample-to-chunk mapping. There are two main differences though: the format is flat as first you have header size and header chunks following each other without any nesting (so when you encounter the second track header chunk the following chunks will belong to this new track); and the data is little-endian there, both numbers and tags (e.g. “ssiz” which is sample sizes chunk is written as “ziss” instead, same for e.g. codec IDs). Luckily I could ignore most of it as the data seems to be stored without gaps, so reading palette, then seeking to the first video chunk and reading individual samples(frames) from there works fine.
And it has its own two codecs, RLE and LZSS. RLE has two modes, both coded the same but inter mode storing the difference from the previous frame (not even XOR, simple subtraction by modulo). LZSS is not the usual flavour either. Unlike the most widespread scheme of “read 8/16/32-bit flags, treat the following bytes until next flags as either literals or packed 16-bit LZ offset+copy length combination” here it is a continuous bitstream with offset and length bits being signalled in the bitstream header and offset zero being used to skip decoded data (since you decode to the frame buffer, it leaves some bytes of it unchanged). Nothing groundbreaking but you most implementations hardly make any changes from the original LZSS.C and right now I can only think of JAM format which implemented LZSS with copying from the reference picture.
IMO this is an over-engineered system but that’s what makes it interesting to look at.