I have actually implemented an experimental decoder for the DOS version AdLib soundtrack, played back via an OPL2 emulator imported from DOSBox. My branch is here
https://github.com/nielsmh/OpenTTD/tree/adlib-music but I haven't maintained it for a while. This branch only supports playing through the emulator code, not to real hardware.
orudge wrote: 18 Dec 2019 10:19
To my ears, the AudioDrive recording sounds very close - perhaps not exactly identical, but almost exactly the same. The OPL-2 recordings also sound much the same to me.
ESS AudioDrive does not have a Yamaha OPL2 chip but instead ESS's own compatible synth, so it won't sound exactly the same as an AdLib or SoundBlaster.
kamnet wrote: 18 Dec 2019 10:05
The GM.CAT file had previously been decoded, and it contains General MIDI files. The ADLIB.CAT and ROLAND.CAT files had not been decoded, although reading back through some threads it looks like Cirdan had developed a script to decode GM.CAT and could possibly be modified to decode the other files. Still, the built-in player only has support for General MIDI and doesn't contain the drivers for Adlib or Roland MT32 support.
I have also looked at ROLAND.CAT, it's the MT-32 version of the sound track. It also depends on the LAPC1.PAT file that contains SysEx patches for the synth. I do happen to have an almost-MT-32-compatible hardware synth myself (Roland RA-50) and have mostly reverse engineered the patch loading and SysEx sending required for ROLAND.CAT + LAPC1.PAT music. It sounds quite nice, different from the SoundCanvas rendition of the GM soundtrack, I can post some recordings later.