Audio to MIDI Converter

Converting audio to MIDI is fundamentally a pitch-detection problem. A MIDI file stores discrete note events — a note number, a start time, a duration and a velocity. An audio file stores a continuous waveform. The converter's job is to find the pitches hidden in that waveform and translate them into the note events a MIDI file expects.

The process starts by decoding the audio into raw PCM samples using the Web Audio API. Those samples are then analyzed in short overlapping windows, typically with a Fast Fourier Transform (FFT), to identify the dominant frequency in each window. That frequency is mapped to the nearest MIDI note number. Consecutive windows with the same note are grouped into a single note-on event followed by a note-off event; gaps become rests; and the result is quantized to a rhythmic grid to produce clean, readable note data.

Because the analysis runs locally, the conversion is private by design. The audio never leaves your device, and the generated MIDI is produced entirely within the browser session. When the tool is live, you will be able to upload a file, inspect the detected notes, adjust the sensitivity and quantization, and download the result as a standard .mid file.

1. Choose a clear recording. Select a solo melody, vocal line or single-instrument passage. The clearer the source, the more accurate the transcription.
2. Upload the audio file. Open an MP3, WAV, OGG, M4A or FLAC file from your device. The file is decoded locally in the browser.
3. Let the analyzer run. The pitch-detection engine identifies the dominant note in each time window and groups consecutive detections into note events.
4. Review and adjust. Inspect the detected notes against the audio, adjust the sensitivity or quantization grid, and re-analyze if needed.
5. Download the MIDI. Save the generated note data as a standard .mid file and open it in a DAW, notation editor or the Miditor editor.

When the converter is live, these steps will happen in a single browser session with a preview of the detected notes before you commit to downloading.

Not all audio transcribes equally. The single biggest factor is how many pitches are sounding at once. A solo flute, a single vocal line or a bass melody gives the analyzer one clear pitch to follow at each moment. A full band recording gives it dozens, and the analyzer has to guess which one to track.

• Recordings with one clear melodic line convert best. Solo instruments, vocals and monophonic synth lines produce the most reliable note data.
• A clean recording helps more than a loud one. Background noise, heavy reverb and distortion all make pitch detection less certain.
• Stable pitch converts better than wide vibrato. A steady tone is easier to assign a single note number to than a pitch that is constantly bending.
• Isolating a stem before converting beats converting the full mix. If you have separate tracks for each instrument, convert them one at a time.

Plan to treat the first conversion as a starting draft. Open the result in a MIDI editor to correct wrong notes, fix timing and fill in anything the analyzer missed — the same way you would refine any first transcription.

• Learning a melody by ear. Convert a recording into note data you can study, slow down or visualize in a piano roll.
• Re-instrumenting a melody. Transcribe a vocal or guitar line, then play it back with piano, strings or any MIDI instrument.
• Recovering lost MIDI files. When the original MIDI is unavailable but an audio recording survives, transcription can reconstruct an editable version.
• Preparing parts for notation. Generate a first draft of the notes before cleaning them up in a notation editor.
• Sampling and remixing. Convert a melodic phrase into MIDI to trigger it from a different sound source.

• Other conversion tools — render MIDI to MP3 or WAV, the reverse direction.
• Edit the converted MIDI — correct notes and adjust timing in the piano roll.
• Preview the result — listen to the original audio or the converted MIDI side by side.