But if you have a lot of audio files that need "mass editing" and looking for a free tag editor that a lot of additional audio formats, then Mp3Tag (Windows only) is an app that's worth trying. It supports all of the recent meta container versions starting from ID3 version 1.1 to 2.4 and has a simple yet a features rich window that makes the mass metadata editing a breeze.
*. File formats supported: MP3, MP4 (i-Tunes), WMA, Ogg Vorbis (opensource competitor with the proprietary MP3), AAC, FLAC, APE, MPC, TTA are among the few.
*. Edit things such as: Artist Name, Title, Genre, Year, Cover-album art, Rename the actual file name, Change album-art cover genre, etc.
*. Add comments.
*. Add individual files or folder importing.
*. Export tag data and save to disk.
*. Arrange imported lists by Genre, Bitrate, Frequency, Album, etc.
*. Manage files once loaded using play-lists.
*. Case conversions (add/remove upper/lower characters).
*. Automatic tag data fetching via online sources such as: freedb, discogs, MusicBrainz, etc.
Once you've loaded your file/s to the main window, you'll see the extracted data of the tags to your left and by clicking on the appropriate field you'll be able to edit them with ease. As mentioned, you can use the online data fetching to fully automate the task (as long as you have proper file name or some tag data that denotes the actual audio file info such as Artist, Album, etc) as well.
Anyhow, if you're looking for a completely free (no ads, malware... nada, completely clean :D) mass audio tag editor that can be used in Windows XP/Vista and 7, then Mp3Tag is a pretty excellent one. If interested, you can get it from this page. Enjoy!.