Why would you want to convert audio to MIDI?
MIDI (Musical Instrument Digital Interface) isn't audio — it's data. Instead of storing sound waves, a MIDI file stores musical instructions: which notes played, when, how long, and how hard. That makes it incredibly useful for musicians and producers.
Converting audio to MIDI lets you:
- Transcribe a melody you recorded or found — without having to figure out the notes by ear
- Import a bassline or chord progression into your DAW and play it with any instrument
- Edit timing and pitch of a recorded performance
- Build a new production from the transcribed notes of an existing song
- Learn a song by seeing its notes laid out in a piano roll
It used to require expensive software or uploading your files to third-party services. Now it runs entirely in your browser — free, private, instant.
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How audio-to-MIDI conversion works
Audio is a continuous waveform — a recording of actual sound pressure over time. MIDI is a sequence of discrete musical events. Converting between the two requires pitch detection: analyzing the audio signal to identify which musical notes are present and when.
Filesmith uses a YIN algorithm with FFT-based autocorrelation to detect pitch frame by frame across your audio. It identifies the fundamental frequency of each frame, maps it to the nearest MIDI note number, and assembles the result into a playable MIDI file. For multi-track modes, it first runs HPSS (Harmonic-Percussive Source Separation) to split the audio into melodic content and rhythmic content before running pitch detection on each stem separately.
The entire process runs in JavaScript using the Web Audio API — no files leave your device at any point.
Step-by-step: convert audio to MIDI on Filesmith
1
Go to filesmith.io and drop your audio file onto the page — or click Browse files. Accepts MP3 WAV OGG FLAC M4A and more.
2
Make sure you're on the Audio tab. Your file will appear in the sidebar and the audio player will load.
3
Click the 🎹 → MIDI button in the controls panel. This opens the MIDI conversion panel below the audio controls.
4
Choose your conversion mode (A, B, or C — see the table below) and click Convert to MIDI.
5
When processing completes, a Download .mid button will appear. Click it to save your MIDI file.
Which conversion mode should you choose?
| Mode | Output | Best for |
|---|
| A — Full Mix | 1 MIDI track | Solo instruments, vocals, simple melodies, monophonic recordings |
| B — 2 Tracks | Melody + Drums | Recordings with a clear beat, pop/electronic tracks, when you want drums separated |
| C — 4 Tracks | Drums, Bass, Melody, Other | Full productions, when you want individual stems as MIDI, complex arrangements |
If you're not sure, start with Mode A. It's the fastest and works well for anything with a single dominant pitch — guitar, bass, voice, piano melody, or synth lead.
Tips for better results
- Use WAV when you have it. WAV is uncompressed, giving pitch detection a cleaner signal than MP3. If you have both, prefer WAV.
- Simpler is better. A solo instrument will transcribe far more accurately than a dense mix. If you're trying to extract a bassline from a full song, Mode C will do its best — but expect some imperfection.
- Trim to what you need. Processing a shorter clip is faster and reduces unwanted notes from transitions or build-ups.
- Check the result in a piano roll. Open the MIDI in your DAW and look at the piano roll. You can manually clean up any stray notes or adjust timing there.
- Avoid heavy reverb or distortion. These effects blur the pitch signal and make detection harder. A dry recording transcribes more accurately.
Opening MIDI files in your DAW
The output is a standard .mid file. It opens in every major DAW without any special steps:
- FL Studio — drag the .mid file directly into the playlist or channel rack
- Ableton Live — drag into a MIDI track, or use File > Import MIDI Clip
- GarageBand — drag into a software instrument track
- Logic Pro — drag into a software instrument track or use File > Import > MIDI File
- Reaper — drag and drop onto a track
Once imported, you can assign any virtual instrument, edit individual notes in the piano roll, quantize timing, transpose, and more. The MIDI is fully editable — that's the whole point.
What audio converts well — and what doesn't
Audio-to-MIDI transcription works best on monophonic audio — recordings where one note plays at a time. A single guitar, bass guitar, lead vocal, flute, trumpet, or synth lead are all good candidates. The clearer and more isolated the pitch, the better.
Polyphonic audio — chords, full mixes, layered harmonies — is significantly harder to transcribe accurately. The multi-track modes (B and C) help by separating the audio into components before detection, but the results on dense polyphonic material will be imperfect. Think of the output as a useful starting point rather than a perfect transcription.
That said, even an imperfect MIDI transcription can save significant time. Getting 70% of the notes right and cleaning up the rest is far faster than transcribing from scratch by ear.