Originally posted by lonny
Well... I tried and yes, you can edit displayed info, but not the tags in the file itself, i.e. if you play the song in another app (or platform) the tags won't show.
That must be you. How do you do this? Just select the song (or group of songs) you want to update the tags from and press cmd-i. This'll take you to the info pane, where you'll need the 'info' tab. Just type away and press ok.
This info DOES show in other apps.
Just to be sure, however (especially if you've gotten the tracks of of some p2p network, or usenet, or an ancient version of itunes), before adjusting the tag info, select the songs you'll update, and choose 'convert id3 tags' from the 'Advanced' menu, then check 'id3 tag version' and choose 2.4, then press ok.
I have, of about 10.000 to 15.000 songs I tagged with iTunes, had about 20 that didn't 'stick', after doing all of the above. That's when I went for mp3rage.
Of course, this is wrp MP3s, not AAC. You'll notice that mp3rage aptly starts with MP3 (meaning it is for MP3s). AAC's will have to be tagged by itunes for now. I wouldn't know though, I haven't yet encoded something into it.