Notty.
Play MIDI files, in Minecraft!
This is a Datapack. You can add it in any world without Resource Pack.
Usage is pretty simple. The music will play for every player having the notty tag.
/tag @s add notty
There is actually only two commands you care about :
/function notty:stop
to stop the music playing and
/function notty:songs/{song-name}
to play a song you uploaded.
Uploading a Music
Find a music in the MIDI format. I recommend music comming from http://onlinesequencer.net/ as they should all be supported. Some MIDI files won't work (due to some tempo changes, maybe in a future version).
Then upload it to https://tonejs.github.io/Midi/ and copy the output JSON.
Last step, paste your JSON to this website https://openvoxel.studio/notty (or open the notty.html file in the datapack) and download the result file. The result is a .mcfunction file and should be placed in your datapack inside the [DATAPACK]/data/notty/songs/ folder.