"Extracting" the midi data from beneath a steel sky isn't that simple, because BASS doesn't use midi data, but it's own proprietary format, "Sound Images Generation 2" by Tony Williams. Apparently it was created as some kind of Amiga thing which got ported to the PC platform.
ScummVM reads this data and outputs the midi data. However, writing a comversion tool, to actually write a .mid file would be complicated, because I have *no* idea about music and midi, etc.. I disassembled the code back then and converted it to C++ for scummvm, but I only understood like half of what it does
Maybe you can provide some more info on what exactly you need. Are there any tools which can be used to "capture" the midi data that ScummVM outputs? That would be the easiest way, if possible.
If you need some special functions in ScummVM like a command to start a given piece of music or play only the intro part / only the looping part, that'd be quite easy to implement. Just tell me if you need such a function.
And, well as I said, writing .midi files would mean a lot of work, so I'd only do it if you say that it's really necessary.
Extracting and replacing SFX is a simple task. The number of SFX in the game is quite limited, too. Also, drop me a line if you want me to extract them and zip them up for you. But I suppose music comes first
I'm sure that Tony Warriner will be very pleased about your efforts. Joost said he's going to send him a mail to ask for official permission.