A MIDI, or music instrument digital interface, was created in the early 1980s to allow different kinds of electronic instruments to communicate with each other and be controlled by a computer. Today, MIDI files often play renditions of songs and can be found free on the Internet. Converting them into MP3 and WAV files can be done in just minutes with the use of 2 kinds of free software. Transpose MIDI feature; decision converting midi to mp3 read here To mp3 converter