How to Convert MP3 or WAV to MIDI and Correct Detected Notes

1. Understand the difference between MP3 and MIDI

MP3 stores compressed recordings of actual sound. MIDI instead describes performance events such as which pitches to play, when they begin and how long they last. A MIDI file does not contain the recorded voice or instrument audio.

An MP3-to-MIDI result is therefore an estimate of note events, not a perfect copy of the source track. It does not automatically produce a fully accurate musical score.

Audio to MIDI exports a MIDI file for music software or a CSV table containing the detected note timings.

2. Prepare a clip no longer than 60 seconds

Begin with a short portion of the recording. Audio to MIDI accepts one file at a time, between 0.5 and 60 seconds and up to 50 MiB. It is not intended to transcribe an entire three-minute track in one pass.

A clear, short single-instrument or melodic passage is easier to assess. Multiple instruments, percussion, background noise and harmonics can cause missed notes or false detections.

If your MP3 is too long, trim the section you need with a separate audio cutter first. If the source is a video, extract its audio into a compatible file before transcription.

3. Load an MP3/WAV or make a short microphone recording

Open Audio to MIDI and choose one MP3 or WAV file with the audio picker. Drag-and-drop is also available on desktop. M4A, AAC, OGG, FLAC and WebM may work when your browser can decode them.

If you do not have a file, select Record, allow microphone access, and capture a melody for up to 59 seconds. Stop the recording and listen to it before analysis. Recording needs browser permission and a supported recording format.

Starting with a short example makes it easier to repeat the recording or rerun note detection when the result needs improvement.

4. Select Analyze audio to detect notes

After loading the clip, leave Detection sensitivity at Standard and select Analyze audio. The bundled Spotify Basic Pitch model estimates note pitches and timing on your device.

Progress is shown while it runs. Keep the page visible or use Cancel if needed. Hiding the page stops an active analysis; it does not automatically resume when you return, so start Analyze audio again.

Processing time depends on clip length and device performance. A file below the 50 MiB limit can still consume substantial memory after decoding and during model inference.

5. Compare the original recording with synthesized notes

After analysis, switch playback between Original audio and Synthesized notes. Compare the melody and timing, checking for extra notes, missing notes or incorrect pitches.

The synthesized preview is a simple way to hear the detected note events; it does not reproduce the source piano, guitar or voice timbre. Judge the melody and event timing rather than expecting the same sound.

Zoom and scroll the piano roll to inspect individual notes. Look for short false detections and notes that were split or joined incorrectly.

6. Adjust detection sensitivity when notes are missing or excessive

If too many notes are detected, try Fewer notes and analyze again. It may reduce false positives from noise or harmonics, but can also remove weak or short musical notes.

If too few notes appear, try More notes. Advanced settings also let you change thresholds, minimum note duration and pitch range. These settings affect the next analysis; they are not guaranteed noise removal.

If you have already edited notes, reanalysis asks before replacing them. Save a MIDI or CSV copy first when you need to preserve your corrections.

7. Correct note pitch and timing in the piano roll

Select a piano-roll note to edit its pitch, start time or end time. For reference, C4 is MIDI pitch 60, and the timing buttons move in 0.05-second steps. Add a missing note or delete a false one as needed.

You can split a note or merge eligible neighboring notes of the same pitch. Removing very short notes and snapping times to a seconds-based grid can be previewed before applying. The grid is not an inferred beat grid or automatic tempo detection.

Edited notes are used for both synthesized playback and export. Up to 100 Undo/Redo operations make it easier to compare revisions and work incrementally.

8. Export MIDI (.mid) or a CSV note table

Once the notes look right, choose MIDI (.mid), enter a filename and download it. The file contains note events for compatible music software, not the original MP3 or WAV audio.

This app does not estimate the original tempo. It uses fixed 120 BPM to map seconds onto MIDI timing. Velocity is always 96, using channel 1 and a piano program; original timbre, dynamics and pitch bends are not preserved. Different music applications may render the result differently.

If you need to examine exact note timing, select Note table (.csv) instead. The CSV contains start and end times in seconds, MIDI pitch numbers and velocity 96. Music applications can interpret overlapping same-pitch MIDI notes differently, so the CSV can be useful for comparing individual intervals.

Neither format includes the source recording, and the app does not directly create a PDF score on a five-line staff. Load the exported MIDI into your music application and check the actual playback.

9. Troubleshoot unsupported input and protect your work

If input fails, check clip duration, size and whether your browser can decode the audio format. Formats beyond MP3/WAV depend on available decoders. The verified target environments are Chrome on Windows and Android; other browsers and iPhone operation are not guaranteed.

Audio decoding, model inference, note editing and export run on your device. The app does not upload the selected MP3 or microphone recording for conversion. The hosted version initially downloads its HTML, while a saved standalone HTML can operate offline in a compatible browser.

Your audio and edited note session are not restored after closing or reloading the page. Save the MIDI, CSV and any original microphone recording you need before leaving.

Tips and limitations

• Start with a short, clear melody so you can inspect every detected note.
• When Fewer notes removes false positives, check that quiet and short real notes were not lost.
• Correct note beginnings and endings as well as pitch in the piano roll.
• The 120 BPM in exported MIDI is not a tempo estimate of your song. Make tempo-related arrangements in your music software.
• Save the source recording separately if you need it; neither MIDI nor CSV export includes audio.