One of my long-term goals is to assess the possibility of porting music from other PSX games into Chrono Cross, and also the possibility of entirely new fan compositions for the
Darkness Beyond Time project. First thing to do is actually identify whereabouts instrument data for music is stored on a Chrono Cross disc.
If you'd be interested in actually rummaging through the music/instrument/sound data and getting a feel for it, I'd recommend making a dump of your first Chrono Cross CD if you have it on hand, according to the
instructions in this wiki. You'll want a 2048 byte/sector format ISO. I recommend the free version of ISOBuster. Oh, do you have 600+ megs of free space on your hard drive?
I'd then download
PSound and run your freshly-extracted ISO through it and play through some of the sounds, just to get a feeling for how the separate instruments and sounds are stored separately. Unfortunately PSound can't export sounds in their native format (it can only export to WAV if I remember correctly). However, it will still be extremely useful for identifying where sound data is located in the folders produced by the Yazoo dump utility modified by Ramsus back in 2007.
So an additional thing to do is to download
this dumping utility and use it on your Chrono Cross CD1 ISO. Then you can scan the MISC folder for music data, because I highly suspect the music instruments and sequencing data are stored there. When we find which dumped files the music instruments are stored in, it will be easier to find the sequencing data I hope.
EDIT: Oh, shoot, dumping with the dump.exe I link to above will require another 600MB of free space on your hard drive. If that's doable, consider yourself on the forefront of Chrono Cross sound exploration! I'm glad to see that you're already experienced with PSound -- you probably know more about the program than I do at this point.
EDIT: Also, you may wish to research any Playstation music/sound findings jotted down on the
Qhimm forums. Some good search terms would be simply "music" and also "AKAO," which is an ASCII tag placed on sound and instrument data in Final Fantasy games as well as Chrono Cross.