Music importer & randomizer

Working out some glitches, found out some stuff through test that I want to share early because it affects anyone using custom music from various sources in their hack -- or even using the music from the base game together with custom songs.

All of the songs in FF6 include the F7 and F8 commands at the beginning, usually F7 00 46 F8 00 00. Most of the custom songs posted here avoid these commands because they're prone to causing glitches.

Well, the thing is, avoiding the command isn't good enough to avoid the glitch. Anyone who's done their own music probably has noticed that reverb level (F2) doesn't reset between songs -- if you leave it out, you'll get whatever random reverb level was set in the previous song. F7 is also a reverb control. (I'm not entirely clear on it, but I believe they correspond to controls on a standard delay effect -- F2 as wet/dry, F7 xx as length, and F7 yy as feedback)

So if we go too far afield on our delay effect, we get glitches. The problem is, when you're mixing music from a bunch of different sources, some using F7 and others studiously avoiding it, eventually you'll run into a track that uses high F7 in a safe, controlled fashion (the intro to Phantom Train, for instance) -- and then switch to another song without F7 and everything blows up. It seems like the only ways to be safe are to either not include F7 at all (in something like Gi's total conversion hack) or to include it in every single track.

As for the other commands, I'm not sure yet. I don't know offhand of anything using F8 in FF6 successfully, so it's hard to know how important zeroing it at the start of a track is. (The only application I can think of for a whole-song filter effect is whitenoise SFX tracks? Maybe one of those uses it...) I'm not able to produce any NEGATIVE effects of zeroing it, so it may be better to include the F8 00 00 just in case. F0 and F2 need to be set, but that's not news. I did re-confirm that F4 does NOT need to be set; switching from a F4 20 song to a song without any F4 still played the second song at normal volume.

edit: like F4, F8 seems safe to ignore. Got a song nice and glitchy with it and it didn't corrupt later songs like F7 does.