I tried to look at it before but since the game uses that special 32-bit DOS extender (PMODE/W if anybody’s curious), I gave up. As I mentioned in one of previous posts, I need either to find a way to dump unpacked and properly loaded executable reliably or write such decompressor from the binary specification—and I’m not eager to do either of those things.
Luckily somebody bothered to decompile the engine in order to make game work on modern OSes without DOS emulation. I use the term “decompile” because a lot of the parts are slightly prettified direct translations of the assembly. Anyway, this can be improved and it probably work good enough already to make game fans rejoice.
Here’s the decompiled cutscene player and what follows is my understanding of the code given there.
So, HAF files start with 16-bit number of the frames followed by two tables, one byte per entry each. First table contains sound effects that should be played starting at that frame (or zero), second table gives frame duration at 70fps. Then actual frame data follows: 16-bit frame size, 768-byte palette and then LZW-compressed image. And looks like they lifted LZW compression from GIF as it’s not only the basic parameters of LZW compression being the same (dictionary size limited to 4096, having restart code and arbitrary initial number of bits) but also LZW data is packed into chunks prefixed with its size. I can’t outright remember any other format doing that—or having a need to do that when total data size is known beforehand.
Maybe I’ll add support for this format to na_game_tool eventually but I’ll find something else to do for now.