MP3 to MIDI converter

How to convert an MP3 to MIDI

1. Choose a file. Drop an MP3, WAV, M4A, FLAC or OGG file onto the box above, or tap it to pick one. Your browser decodes it locally.
2. Wait for the first pass. The first time you use the converter, your browser downloads a small transcription model (under 1 MB). After that it is cached. A three-minute song usually takes between ten seconds and a minute, depending on your device.
3. Check the piano roll. Each bar in the preview is a detected note. Press Preview MIDI to hear the notes played by a simple synth, and Play original to compare against the recording.
4. Clean it up. Move the sliders under Clean up & quantize. Changes apply instantly because the heavy analysis is not repeated — only the step that turns the analysis into notes.
5. Download. Download MIDI saves a standard .mid file that opens in Ableton Live, FL Studio, Logic Pro, GarageBand, Reaper, Cubase, Studio One, MuseScore and anything else that reads MIDI.

Why the tempo matters

Most free converters write their MIDI files at a default 120 BPM. If your song is actually at 93 BPM, the notes are still in the right place in seconds, but they drift across the bar lines of your DAW and quantizing makes them worse instead of better. xx808 measures the tempo of the recording before it transcribes, writes that tempo into the file, and snaps notes to a grid built on the real beat. Drag the file into a project at the same tempo and the notes line up with your drums. If the detector picks half or double the tempo you hear, type the right number into the tempo box and the grid is rebuilt immediately.

What the settings do

• Snap notes to grid moves note starts and ends to the nearest 1/4, 1/8, 1/16 or 1/8-triplet position. Use Snap strength below 100% to tighten timing while keeping some of the human feel.
• Note splitting controls how readily a new note is started. If a long held note is chopped into several short ones, raise it; if repeated notes are merged into one, lower it.
• Confidence sets how sure the model must be before a note is kept. Raise it to remove faint ghost notes, harmonics and reverb tails.
• Shortest note throws away blips shorter than the value you choose.
• Lowest / highest note limit the pitch range — handy for isolating a bass line (set the highest note around C3) or a vocal melody.
• Instrument only sets the General MIDI program stored in the file, so it opens with a sensible sound in players that respect it. Your DAW will usually let you pick any instrument anyway.

How it works

The converter uses Basic Pitch, an open-source note-transcription model published by Spotify's Audio Intelligence Lab under the Apache 2.0 license. The audio is mixed down to mono, resampled to 22,050 Hz and cut into overlapping two-second windows. For each window the neural network outputs three things about 86 times per second: how likely each of the 88 piano pitches is to be sounding, how likely a note is to be starting, and a finer pitch contour. A post-processing step then joins those frames into notes with a start, an end, a pitch and a loudness. That last step is the one your sliders control, which is why adjusting them is instant.

The model runs with TensorFlow.js inside a background worker in your browser, using your graphics chip when it can and the processor when it can't. To check for yourself, open the Network panel in your browser’s developer tools and convert a file: you’ll see the page, its scripts and the model files arrive, plus one anonymous page-view ping to Cloudflare Web Analytics. No request ever carries your audio.

Getting the best results

• One instrument at a time works best. A solo piano, a sung or whistled melody, a guitar part or a bass line transcribes far more cleanly than a full mix. If you only have the full song, try a stem-separation tool first and convert the isolated part.
• Dry is better than wet. Heavy reverb, delay and distortion add energy at pitches that are not really being played.
• Trim the file. Converting just the section you need is faster and gives you less to clean up.
• Expect to edit. Automatic transcription gets you most of the way; fixing a handful of wrong notes in your piano roll is normal.

Limitations

This tool transcribes pitched notes. It does not separate instruments, it does not write drum parts (the model was not trained on drums — use the drum machine to program those), and it does not produce sheet-music notation. Pitch bends from vibrato and slides are not written to the file in this version; notes are rounded to the nearest semitone. Files up to ten minutes are supported; longer files are cut at ten minutes so the browser does not run out of memory, which is mostly a concern on phones.

Example: getting a bass line into your DAW

Say you have a 96 BPM loop with a bass guitar and you want the notes on a synth. Drop the file in, check the detected tempo reads 96, set Highest note to about C3 so stray guitar notes above the bass are ignored, choose 1/16 snapping, and download. In your DAW, set the project to 96 BPM, drag the file onto a synth bass track, and the notes start on the downbeat of bar one with the original groove intact.