Karaoke aka "Empty Orchestra" has changed greatly over the years. The way it used to work was that karaoke music was sold on special CD's or DVD's. The format of the karaoke music was CD+G (graphics). You needed a special CD player (that had a composite video output) to read the discs. These discs often got scratched and the video locked up very often.
The way that KJ's (karaoke jocks) now play songs are via computer files. The most popular format is now called MP3+G.
One of the most popular programs currently sold for Karaoke is Virtual DJ.
Incidently, Virtual DJ LE comes FREE with most of the controllers we sell.
You will need the full version of Virtual DJ to play MP3+G files (karaoke files)
and this will require an upgrade from the LE (limited edition) software
that comes with most controllers to the full professional version.
This is always done on-line via the Virtual DJ website.