What we tested
We generated three mono 16-bit PCM WAV files at 22,050 Hz. Each file contained a tone centered on 440 Hz A4, beginning at 0.250 seconds, lasting 2.000 seconds, reaching the same 0.72 peak amplitude, and using the same 0.02-second edge envelope.
The only changing variable was pitch modulation at 5 Hz: none, plus or minus 25 cents, or plus or minus 80 cents. We ran every file through the current local converter at its default controls and inspected the exported MIDI.
| Pitch movement | MIDI events | Detected pitches | Velocity range | File size |
|---|---|---|---|---|
| None | 1 | A4 | 78 | 59 bytes |
| ±25 cents | 15 | A4 only | 65-83 | 178 bytes |
| ±80 cents | 26 | G♯4, A4, A♯4 | 33-44 | 259 bytes |
What changed in the MIDI
The unmodulated tone produced one A4 from 0.221 to 2.254 seconds. The 25-cent vibrato did not cross into a neighboring MIDI pitch in this run, but it fragmented the sustained tone into 15 adjacent A4 events.
The 80-cent vibrato produced 26 events. It alternated among the center pitch and its semitone neighbors, sometimes with overlapping events. Every run returned HTTP 200, used one musical track, and produced no console errors.
How to handle vibrato after transcription
- Compare the piano roll with the source. A cluster around one center pitch may describe one expressive note rather than repeated attacks.
- Merge fragments deliberately. Keep real note changes; combine only boundaries caused by continuous pitch movement.
- Rebuild the expression. Use a sustained MIDI note plus pitch-bend or modulation data when that better matches the performance.
- Test your own recording. Vibrato rate, width, timbre, noise, and converter settings can change the result.
What this test does not prove
It tests one synthetic A4, one modulation rate, and two pitch widths. It does not establish a universal vibrato limit or predict mixed recordings, direct YouTube-link input, other pitches, or other converters.
For a fixed pitch offset, see the detuned-note test. For a single continuous sweep, use the pitch-bend test. For periodic volume movement instead of pitch movement, see the tremolo test.