Here's an extract from our forum.. this is a FAQ ! so spare me the typing !
"" It seems like a good idea. After all, MIDI files are much smaller than huge WAV or even compressed MP3 files. Unfortunately, the nature of MIDI makes conversions from digital audio extremely limited at best.
Unlike MP3, WAV, and other digital audio files, MIDI files don't really contain recorded music. Instead, the music is stored as a series of numbers which tells a synthesizer how the music is to be played back. Yes, a MIDI file must be played on a synthesizer. You may not know it, but the sound card in your computer also contains a MIDI synthesizer.
Here's a simplified explanation of how MIDI works. To reproduce the sound of a piano playing a C note, the MIDI file, or sequence, contains digital information that says, "this is a piano sound." Another number says, "a note has been played," and other numbers convey information such as, "the note is middle C," "the key was struck very softly," "the note has now stopped," etc. Musicians love MIDI because it's easy to edit the files.
MIDI files aren't recorded, they are "sequenced." Most MIDI files are made by a musician playing on a synthesizer keyboard. Each instrument must be entered separately, but since MIDI can have multiple tracks, the resulting sequence sounds like the instruments are all playing simultaneously.
The fact that MIDI sequences must be created one instrument at a time prevents almost all digital audio files from being converted. There are several "pitch to MIDI" software programs such as WAV to MIDI Converter and Intelliscore that CAN convert a file to MIDI. The catch is that the audio file must be of a solo instrument.
Finally, since MIDI must be played on a synthesizer, you can't record vocals or other sounds that are not available on the synthesizer. That's why you can't convert an MP3 file of a pop song to MIDI. ""
