i've found a way to mod the musics using Hex.
There's 3 part in the header of the snd0_X.dat file ( music files in ffV) after the mtxs :
1/Make lines of 16 hex values,
2/ there is now 12 hex values following mtxs (if no check the first one)
3/ the 4 first are a mystery to me, whenever i used another music i wrote 00 00 00 00
4/ the 4 folowing define the begining of the loop, the values are reversed meaning that 00 00 01 00 is higher than 01 00 00 00
5/ the 4 last define the end of the music ( AND the loop) in the file, when you write 00 00 00 00 the game uses the whole file.

I currently need help to decipher the first 4 hex values

Originally posted by Rhopero:

This is proving to be a bit more difficult than I originally expected it to be. But I'm not ready to give up yet.

From poking around in these music files, I've discovered that the way these remastered music tracks might best be looped would be a combination of cutting them down from the end, to the exact point where you would want the loop to end, and then modify the mtsx data to get the music to restart from the right place after reaching the end.

From my tests, this does seem to be exactly how the original music tracks work. However, I'm sure there's more to it than this, as attempting to edit music so that it loops properly when you can only see the end of the file is very difficult, at least for me.

(I've managed to get the remastered track of Four Heroes to *almost* loop perfectly, though in all my editing, I've been unable to prevent there from being a slight click when the music loops)

Of course, there's also the fact that if you knew the hex format, you could likely make the loop start position closer to exactly where it should be, so the loop is less obvious.

Maybe all this that I've figured out is basic knowledge.. But for someone who doesn't consider himself to be particularly skilled at hacking, I find all this very interesting. As I said before, I'm not ready to give up yet, but I do feel the need to at least give an update on my progress.
(And perhaps encourage someone else to comment who might know more about this..? :P)

Huh can you send me what you did ? i'm actually trying things the hard way ( changing the Hex values of the Header), maybe i could find out something i dunno...