Hacking PSP game Editing

[Just Another Gamer]

I actually planned on doing this out of curiosity a while ago but gave up since I didn't know how to use UMDGen properly but after finding some articles on doing different things with UMDGen I tried again since I was planning to using some remixed BGMs for some games just for fun and i'm sure knowing how to switch files between ISOs would be more helpful to adding new things that aren't text based.

So I was able to get the JPN and USA ISO and it is decrypted already so I extracted the files I wanted and switched it over which then I found that it doesn't actually work that way so I changed its LBA position to match the original although it doesn't seem to match up correctly so out of desperateness I made the file a dummy file and compiled the ISO which allowed the ISO to boot and work properly but I wasn't able to get the FMV or the audio file to work properly in either ISO.

Just wanting to know that is there other things that i'm missing since I was trying to get the USA FMVs to work in the JPN ISO and vis versa with no luck since it would just crash when booting up on the PSP while the audio files I could switch fine but it would only work if it became a dummy file and then it won't play at all.