Mrs Pavane still uses MIDI backing tracks - easy to change key, tempo, and instruments using software "wot I wrote" for her laptop.

She used to use a MIDI file player (Roland Sound Canvas) but this only used 720k disks which are now impossible to get. (It still works to produce the sound but you have to send the file in via the MIDI IN port instead)

The designers of MIDI files made sensible decisions to make the format extensible/open-ended, but unfortunately Roland didn't have the same approach with the hardware.

But BEWARE - using unlicensed MIDI files as backing tracks for public performance is not allowed (in the UK). Files bought from the file suppliers are licenced forthis, but Karaoke files are NOT, and nor are files you make yourself for any copyright music.