SQ/BD/HD format documentation on the PS1, and differences versus SMF MIDI and PS2?

[baku-chan]

Hello there! I'm looking to inquire about how the SQ, BD, and HD file formats work the on PS1. As well as, indeed, what they're even doing there, because up until very recently I always thought that those were formats specifically for the Sony SDK's sequenced music engine on the PS2 (you might know as CSL, or the Component Sound Library). However, according to this document (https://problemkaputt.de/psxspx-cdrom-f ... ormats.htm), it would appear that SQ/BD/HD was conceived a bit before the release of the PS2 and was used on a number of PS1 games around 1999 or so. Some of these games include Alundra 2, Wild Arms 2, The Legend of Dragoon, and Arc the Lad 3 among others (notably, the former two are both associated with the production company Contrail, who apparently shared music tools between games). Normally, I would've investigated this myself by analyzing the game files themselves, but I don't have access to those right now. My next step would've been to try the existing PSF rips, but most if not all of them are MINIPSF and are also compressed on top of that, making that difficult. Can anyone here assist, including how this PS1 version of SQ/BD/HD might differ from both SMF format 0 MIDI (which SQ is supposedly very close to) and those files' PS2 equivalents? This is all quite fascinating to me and I'd love to see if this can help me with my goals of getting homebrew sequenced music working on these older PlayStation consoles!

[nocash]

Is there any documentation for the SQ BD HD format used on PS2 ?

[baku-chan]

Not directly that I know of, save for some scraps from the official Sony SDK currently on archive.org (if you're willing to use that, anyway; it refers to the whole system as "ezMIDI" in said docs). With that said, the developers of vgmtrans appear to know enough about SQ/BD/HD that opening them up in the program gives rather rich descriptions of what everything does (with color coding, even!), and they also made a SQ/BD/HD to MIDI/SF2 converter that delivers mostly competent results (save for an apparent and weird limit of only 16 MIDI tracks when PS2 sequenced music frequently goes above that, but I digress). Alas, I attempted to ask them directly about how SQ/BD/HD works and they don't seem to be willing to talk. Thus, it seems that the closest thing we have to documentation of SQ/BD/HD right now is to look at vgmtrans' code and extrapolate from that. Or to study SMF format 0 MIDI, as from people that I talked to familiar in that field, SQ is very close to that. BD is also apparently very simple too, being just raw SPU-ADPCM files stacked together. The hardest part, then (for me, at least) is probably HD, unless that itself happens to be very close to VH in the PS1...