MP3 to midi conversion is not a simple thing. It is like trying to get back tomato from a tomato sauce !! Wave and MP3 files contains actual sound in compressed format !! Where as midi doesn't contain any sound inside it, but it contains only the musical notes as shown below !!
T75 I107 V117 8*f3 8*A3 8*A3 8*f4
4*c4 4*C4 8*G3 4*c4 8*f3 8*g3 16*G3
16*A3 8*D4 8*c4 16*A3 d8*g3 8*f3
8*A3 8*A3 8*f4 4*f3 8*G3 8*c4 8*C4
16*f4 16*C4 ........
( I really donno what these mean?? Someone with musical notes knowledge should help me !! )
So the truth is that the conversion is really not a good idea !! You can find and download various products, claiming to convert mp3 to midi, as trial versions and see how good or bad the conversion is !!!
(Just do a Google search on "MP3 to midi conversion" - you can get a lot of them) Also note that there is no free mp3 to midi conversion utility as far as I know. Quality is very bad and cost is very high. Again none of them seem to deliver what they promise !!
But wait, you can create a midi files using online utilities if you know your song's musical notes Online MIDI Creator !! So this is suitable only for people with good music knowledge... Not for everyone !!! Just try to ping me back your thoughts on this !!!