Download and install WIDI Recognition System Professional (www.widisoft.com).
Open the program. Under "Select Action," choose "Transcribe Pre-recorded MP3, Wave or CD." Click "Next."
Click "Browse." Locate the MP3 file you want to convert, highlight it and click "Open." Click "Next" and wait for the program to analyze the audio.
Click "Settings" to adjust the recognition settings, or click "Next" to use the default settings. The program will convert your MP3 to MIDI. Click "Finish" to view your file, then "Save."
Download and install MuseScore (www.musescore.org), a free music notation software. You can also use Finale, Sibelius or any other music notation software that allows you to open MIDI files.
Click "Open" and select your converted song. Choose the smallest note value in the piece. This will affect the time signature. If you're not sure, experiment with different options until the time signature makes sense.
Edit the music notation. Since MP3s are more complex than MIDI files, important information such as instrumentation and voicing may have been lost. However, you have all the notes. All you must do is assign them to the right musical part, as well as add information such as tempo markings and lyrics.