How it works
Drop in a file. The page runs Basic Pitch, an open-source model from Spotify's audio lab, which listens for every pitch it can hear, several at once, and marks where each note starts and stops. The notes fill the piano roll from left to right as it goes. It also finds the song's tempo and writes it into the MIDI file.
When it's done, play the notes back on a piano, with the song quietly underneath if you want to check them against it. The Notes slider sets how picky it is: towards Fewer, only the notes the model is sure of stay; towards More, quieter notes and inner voices come in. Then download the MIDI.
WAV to MIDI, and other formats
WAV works the same way as MP3, and so do M4A, AIFF and FLAC: anything your browser can play. A video file works too, and the page converts its sound. Files can be up to 10 minutes long.
What converts well
One instrument on its own converts cleanly: a piano part, a guitar riff, a bass line, a sung melody, a synth lead. A full mix is harder. With drums, reverb and a dozen instruments at once, the roll fills with overlapping notes, and some of them are overtones or drum hits heard as pitches.
If you need one part of a song, split it into stems first and convert the stem. Moving the Notes slider towards Fewer also clears out a lot of the noise. The MP3 to MIDI guide compares the desktop options on a Mac, from Logic's Flex Pitch to Melodyne.
Open it in Logic, Ableton or FL Studio
The file is a standard MIDI file with one track, at the tempo shown next to the Notes slider. In Logic Pro or GarageBand, drag it into the tracks area. In Ableton Live, drag it onto a MIDI track. In FL Studio, drag it onto the Playlist. Set the project to the same tempo, put the original audio at bar 1, and the notes line up with it.
