The AACgain site has a scary waring about it possible corrupting your AAC files.

How stable is the application, really? What are the chances of it screwing up my files if I AACgain them?

I am aacgain's author.

The main risk with AACgain is if Apple addes new iTunes tags that the program doesn't handle correctly. Those might result in the output being unplayable.

Always keep an un-aacgained backup of your music files, just in case. Better to be safe than sorry. Add your favorite aphorism here...

Dave

Well I don't use iTunes, I tag all my AACs with foobar, so I guess I should be alright then.

I have all my music backed up to FLAC, so it wouldn't be the end of my collection anyway.

Couldn't aacgain blindly copy atoms that it doesn't recognize?

aacgain uses the open source library mpeg4ip/mp4v2 to handle the mp4 container's tags. That code does try to ignore atoms it is not aware of. However, in the past, it has not always gotten things right.

I belive the chances of file corruption are small, but no one should use this software without backing up your music files first.

Dave