MP3 to MIDI Converter

How to use this MP3 to MIDI converter

1. Add your file. Drop an audio file, or a video whose audio track you want. Nothing leaves your device.
2. Pick a mode. Melody tracks one note at a time — use it for vocals, flute, bass lines, guitar riffs and any single-line part. Chords reads several notes at once and is experimental.
3. Set the note range. Narrowing the range to what your source actually plays removes octave-jump errors. A bass line does not need C7.
4. Convert and take the result. Download the .mid, copy the note list, or press play to hear what was detected.

If the first pass is rough: raise Min note length when you see clusters of tiny notes, lower Sensitivity when false notes appear in quiet parts, and raise it when real notes get missed.

Supported formats

Your browser does the decoding, so what actually works depends on the browser. This page was tested in Chrome on Windows with real files in every format below; the result of that test is what is written in the table.

Video files are read for their audio track only — nothing is done with the picture. If a file fails to open, the exact browser error is shown above the controls; that message is the truth for your browser, whatever this table says.

How the conversion works

• Decode. The Web Audio API turns your file into raw samples on your device. The file is not uploaded at any point.
• Pitch tracking. In Melody mode, each short frame of audio is analysed with the YIN autocorrelation method, which estimates the fundamental frequency and how periodic the frame is. Frames that are not clearly periodic are treated as silence.
• Note building. Consecutive frames that agree on the same pitch become one note. Its loudness becomes the MIDI velocity.
• Chords mode takes a different path: it reads peaks in the frequency spectrum (FFT) instead of one fundamental, then groups pitches that hold steady. It is experimental, works best on sustained piano or pad sounds, and will miss notes in dense material.
• MIDI writing. The notes are written as a standard MIDI file (SMF format 1, 480 ticks per quarter note) with the tempo you set inside it.

This is transcription, not a format swap: the tool estimates which notes were played. It cannot recover the original performance, lyrics, or separate studio tracks.

Getting a cleaner result

• Convert a solo part or a stem, not a finished master. Single-line sources are where audio to MIDI conversion is genuinely useful.
• Trim silence and long reverb tails — reverb glues one note to the next.
• Keep the note range close to the source. Every octave you leave in is another chance for an octave error.
• Time quantisation needs a real tempo. Enter the track's BPM, or quantise only if the grid lines up with what you hear.
• Test on 20–40 seconds first, then run the whole file with the settings that worked.

What this converter actually does on different inputs

Measured in this build on synthetic-but-realistic audio (a C major scale through the page, ground truth is C4 D4 E4 F4 G4 A4 B4 C5):

• Clean recording, vibrato, reverb, plucked-string synth — 7 to 8 of the 8 notes come out at the correct pitch. Reverb sometimes splits a sustained note into two; vibrato can shift the very first note's onset by a few hundred milliseconds.
• Recording with strong background noise — the 8 correct notes are still present and in the right order, but a few extra low notes can appear in the silent gaps between notes.
• Full mix (melody over bass and drums) — the converter follows the loudest or most periodic part instead of the melody, so the result reads like the bass line, not the tune. That is the limitation, not a bug; melody mode assumes one note at a time.

These numbers are from running the page against its own soundscape. They describe the converter on the kinds of audio it is designed for; they are not a claim about how it will behave on every recording.

FAQ

Is this an MP3 to MIDI converter or an audio to MIDI converter?

Both, and it is the same engine either way. MP3, WAV, FLAC, OGG and M4A all go through the same decoder and the same pitch tracker, so the page works as an MP3 to MIDI converter, a WAV to MIDI converter and a general audio to MIDI converter without switching tools.

Do I need an account, and is my file uploaded?

No account, no upload, no e-mail. Your file is decoded and analysed by your own browser using the Web Audio API, and the MIDI file is built in memory on your device.

Can I convert a video file?

Yes, if your browser can decode its audio track. MP4, MOV and WebM audio tracks open in Chrome; AVI and MKV depend on which audio codec is inside. Only the sound is used.

Why does a full song convert badly?

Melody mode follows one pitch at a time. A finished mix stacks drums, bass, vocals and effects, so the tracker follows whatever is loudest at each moment instead of one instrument. In this build's own test (a melody over a bass line and percussion), every recovered note came from the bass part instead of the melody. Use a stem, or a recording where one part is clearly in front.

What tempo and grid does the MIDI file use?

Whatever you set. The BPM is written into the file as its tempo, and quantisation (off, 1/4, 1/8 or 1/16) snaps note starts and lengths to that grid. Off keeps the timing that was actually detected.

How long can my file be?

Decoding is limited by your device's memory; analysis is limited by the Analyse setting, which stops at 30 seconds, 60 seconds or 2 minutes unless you pick the whole file. Long files take proportionally longer — everything runs on your device, not on a server.

What do I get at the end?

A .mid file you can open in Ableton, FL Studio, Logic, GarageBand or MuseScore, plus the note list as text if you want to paste it somewhere. There is no watermark and no cap on how many files you convert.