[PS1] Replace rubbish in-game music w/higher quality tracks?

[Double44]

Is any of this possible? I would like to extract the ISO, add/edit/replace on top of what audio layers are already there, and re-zip.

[Vibhor]

Romhacking.net would be a better place to ask that question.
I don't think you will be able to do something beyond the PS1's capabilities though.

[Zorlon]

XA audio or CDDA audio both is possible depending on the game, CDDA is very easy to do in some games other may not be though XA is a pain in the backside to do plus you need to rebuild the disc correctly adding the XA header not only to the XA audio files but any STR FMV files and or containers, these are added, not to the actual files but as part of the disc build so those are added while re-building the disc with the official Sony PSX CD tools (I'm almost certain those can not be ran on a modern OS, it was made for windows 95 I believe, though I'm sure I will of been on Windows 2000 at the time), the Later Sony CD/DVD tools can't be used though as they are aimed at PS2 discs that do not use the XA header in there build, the other issue is if the game uses checksums and or LBA checks that would both be messed up replacing any file this can break the game totally or even make it play the incorrect file/track within a file, I had a strange issue with my Monopoly mod that plays one of the FMV's twice I also had more planned for that mod, that I had to scrap due to this issue repeating itself.

One reason I know this, I'm the one that made the Uncut Directors cut of Resident Evil for the PSX and the Emuparadise Monopoly mod, though I enjoyed making those they also made me want to rip all my hair out at the time, though that was a long while back now .