I wrote this because I wanted a command line tool that could
add album art to (and save from) mp3 files, compute replaygain
and save them as ID3 tags (readable by Winamp, etc).

Features:

• Write (all) Text, URL and Picture frame tags, with description.
• Compute replay-gain values and set them as ID3v2.3 tags.
• Apply and Undo volume gain (as mp3gain).
• Extract pictures from mp3 files.
• Inspect ID3 v1.1, v2.3, and v2.4 tags.
• Inspect detailed info on mp3 files, including lametag data.

hydrogenaud.io/index.php/topic,49751.0
www.flumps.org/mp3z/tagging/metamp3.exe