It's been about 8-9 months since I researched converting MP3 to MIDI to ABC notation. I'll try digging up what programs I used.
If you have additional information on music in SoTA , please post in this thread.
Music and Instruments Original Post
Musically-inclined Avatars can play instruments and songs for the enjoyment of friends, tavern patrons, or random passers-by. At present, your character can only play music while having a hand-held instrument equipped (such a as a lute) or by interacting with an instrument placed in the world (such as the piano in the Owl’s Head tavern).
Once equipped with a musical instrument, use the /play command to ready it then use number keys 1-8 to plays notes. Non-equipped instruments like pianos do not need to be readied with /play.
You can also play musical files by placing them in the SotA Songs folder. The filepath in your SotA install is: Shroud of the Avatar_Data\Data\Songs
All music files must be in the .mml or .abc file format. By default, the game begins with a copy of RuleBritannia.abc already in this folder.
/play - Ready equipped instrument
#1-8- Plays notes. #1 is 1 Middle C pitch
/playlist- prints a list of all the songs in your songs folder
/play <songname>- plays the song, by file name, from your songs folder
/play <songname> loop- loops the song after finishing it
/play <songname> sync- prepares a song to play while in a party
/playstart- starts all party members playing their synced song
Conversion
Converting from MIDI to ABC Format
Sites
http://abcnotation.com/
LOTRO has quite a few ABC files that will work in SoTA.