Further information:

There are a number of companies who provide MIDI files for use as backing tracks for singers.

They will, for a price, (I seem to recall about £30 as an example) make a MIDI file from any music which you provide them. The files are usually made by skilled musicians who play the music on a MIDI keyboard as described above. This provides a much more natural sound than sequencing by hand.

If you plan to use the file for backing a public performance, then you need to go via this route, because the files are fully licenced for public performance - that's part of the fee you pay.

Karaoke files, and MIDI files from other sources such as the net are NOT licenced and can land you in trouble with the licencing authorities (depending where you live). In the UK, this is handled by the Performing Rights Society, who send out officials to check on live performances.

This is quite separate from any licence needed by the premises to present entertainment, and also separate from the licencing system for recording music (handled in the UK by the MCPS, the Mechanical Copyright Protection Society)