Here’s the latest blog article: Gig Performer | Scrolling your lyrics or lead sheets
Nice one! (as always)
You can add lyrics to a MIDI file itself. This approach takes a bit of time, but it is not hard to do. Most MIDI editors (if not all) allow for events editing.
You open the Events editor and literally type in the lyrics/chord changes/queues, etc. and enter the time for each syllable. And it is still a MIDI file.
You may also stumble upon the .KAR file format (“MIDI-Karaoke”), designed by Tune 1000 Corp. (They have abandoned it, but it is still the prevailing file format in shareware/public domain market)
It is an “unofficial” extension of MIDI files, used to add synchronized lyrics to standard MIDI files.