I made this little tool because, after I ripped my whole CD collection using Sound Juicer, I realized that it had only put an ID3v2.4 tag to every song. While this is good for pretty much any decent media player, my car stereo seems to only understand ID3v1.1 tags. Not wanting to re-rip the whole collection with different settings, or to change every file manually one by one, I made a C++ tool that would add (or replace) the ID3v1.1 tag for one file, with the info taken from the ID3v2.4, and a shell script to iterate recursively though my music directory to apply it to all the mp3 files.