Boku no Natsuyasumi (PS1) - BOKU_XA.XAM by AnonRunzes at 12:26 PM EDT on May 13, 2017
So, I came across this game that seems to store interleaved XA files. As in, storing 0x930 bytes of one audio file after another without a way to actually distinguish between them(such as a straightforward way of storing XA files like in many PS1 games that use the CD-XA format) in some "partitions".
For example, there is one partition(when extracted through VGMToolbox) that has multiple files chunked together by 0x930 bytes each even through they all sound very different.
You have to filter by channel (byte 0x11) then by file number (byte 0x10), but there's more to it... There are only 3 file numbers used for each channel, and sectors with file number 1 seems to be additional data for files 2 and/or 3, but I'm not really sure how it works.
I theorized that file 1 may be an EOF marker of sorts, but extracting it to the "most recent" file didn't seem to be the right answer (typical interleave skips are heard), so, yeah, I don't really get it..
Files 2 and 3 sound okay without the last bits though, so it's certainly okay to listen to if you're only skimming through the game's sound data.