Click the START button to convert the midi/kar files to mp3 format. If you are using the "Free Version" of Kanto Karaoke, the conversion will stop after 1 minute (only 1 minute will be converted to mp3 file). by Contributing Writer miditomp3 answer straight from the source midi to mp3 online free converter Difference Between MIDI and MP3 Files MP3 is a digital music format which allows CD tracks to be reduced to around a tenth of their normal size without a significant loss of quality. MP3 gets rid of a lot of the information recorded in a song that our ears are not able to hear and then uses complex algorithms to reduce the file size. This then enables you to get hundreds of songs on to a CD and it also has opened up a new market over the internet - the download market as download times have been significantly reduced.