We have added a new tool which converts conventional audio such as mp3, wav, ogg, flac, m4a, mp4, and other formats to MIDI. You can find the converter here.
MIDI is a textual format which contains device instructions like “Play score A5 for 2 bars with a piano instrument”. On the other hand “normal” audio such as mp3 or wav contains binary data by means of frequency and amplitude.
The challenge of an audio to MIDI converter is now to detect the scores, the rhythm, and the instruments. This process is complex and error prone and the quality of the resulting midi file heavily depends on the input music.
For instance, a simple melody with a single instrument will yield better results than a full blown concert with violins, piano, drums, cellos, and other instruments. Similarly a solo classic guitar piece will get better results than an e-guitar song with heavy distortions.