what is replaygain and what is it's use?

vha

http://replaygain.hydrogenaudio.org/

Each format has its own implentation of replaygain.
Specific questions are a lot easier to answer but I think that link should give you a good idea about the concept.

Tx a lot, Jan

vha

I want to ask something about replay gain......

if my mp3 is compile with alt-preset extreme.......would replay gain be of any benefit?

p/s : I know it is a stupid question, but I still don't understand what is replay gain after reading about it from the post about.........

Yes.

Replaygain is a loudness management system. It's purpose is to provide a system for determining the perceived loudness of a file so that you can play back multiple files at the same loudness (typical "normalization" in most audio programs do not achieve this). It has nothing to do with encoding quality (--alt-preset extreme) or audio format's per se.

thank you.