What we tested
We generated a 22,050 Hz mono WAV with four isolated one-second sine tones. Their frequencies were 428.710 Hz, 440.000 Hz, 451.587 Hz, and 455.517 Hz: A4 at -45 cents, exact A4, A4 at +45 cents, and A4 at +60 cents. Each tone was separated by 0.35 seconds of silence. No public recording or named performer was used.
The file went through the local YouTube-to-MIDI converter at its default controls. The browser completed without console errors and exported a 114-byte MIDI file.
| Input tone | Frequency | Main exported result | Boundary behavior |
|---|---|---|---|
| A4 -45 cents | 428.710 Hz | A4 | Started with a 0.185 s G-sharp 4 fragment. |
| A4 exact | 440.000 Hz | A4 | A short A4 tail fragment also appeared. |
| A4 +45 cents | 451.587 Hz | A4 | An 0.081 s A-sharp 4 event overlapped near its start. |
| A4 +60 cents | 455.517 Hz | A-sharp 4 | One 0.975 s A-sharp 4 note. |
What the result means
A standard MIDI note number identifies a semitone, not a measured number of cents away from that semitone. The current draft contained only note numbers 68, 69, and 70, plus zero pitch-bend events. It did not preserve 428.710 Hz or 451.587 Hz as exact tunings.
The two 45-cent cases also show why “nearest note” is only a rough description of this transcription. Near a boundary, the detector can change its decision during one steady tone, producing a short neighboring fragment or an overlapping note. This is one controlled result, not a universal cutoff.
How to handle an out-of-tune source
- Check the reference tuning first. Compare a sustained note with a tuner before converting.
- Tune the audio if the cents matter. Correct a consistently sharp or flat recording before transcription when you need standard semitone notes.
- Review boundary notes. In the piano roll, inspect short neighboring notes around pitches that sit between semitones.
- Recreate fine tuning in the DAW. Add pitch-bend or instrument tuning after import; the current draft does not write the source cents offset.
What this test proves—and what it does not
It records the current converter's exact output for four isolated sine tones around A4. It does not establish one fixed cents threshold for vocals, guitars, vibrato, noisy recordings, chords, or every register.
For a continuously moving pitch, read the pitch-bend test. For short unwanted fragments, use the extra-note guide.