What we tested
We generated a two-channel WAV file at 22,050 Hz. C4 and G4 existed only in the left channel; E4 and B4 existed only in the right. Each tone lasted 0.8 seconds, with 0.3 seconds of silence between tones. 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 113-byte MIDI file.
| Input tone | Audio channel | Exported pitch | Main note start |
|---|---|---|---|
| C4 | Left only | C4 · MIDI 60 | 0.255 s |
| E4 | Right only | E4 · MIDI 64 | 1.358 s |
| G4 | Left only | G4 · MIDI 67 | 2.451 s |
| B4 | Right only | B4 · MIDI 71 | 3.566 s |
What the result means
Both input channels contributed notes to the draft, so a note does not disappear merely because it is hard left or hard right in this controlled file. However, the converter deliberately renders decoded audio into one 22,050 Hz mono buffer before running note detection.
The exported file contained one musical track on MIDI channel 1 and zero MIDI pan controller events. It therefore kept the detected pitches and timing, not the original left/right placement. Three short 0.070-second edge fragments also appeared after C4, E4, and G4; the stereo result does not remove the need to review extra notes.
How to handle a stereo source
- Listen to each side first. If the instrument you need sits mostly on one side, isolate that channel in an audio editor before conversion.
- Convert the isolated part. A cleaner source can be easier to review than both sides mixed together.
- Rebuild placement in your DAW. Set track pan after importing the MIDI; the draft does not carry the source position.
- Check for cancellation. Opposite-polarity material can change when channels are combined, so audition the mono mix before relying on the transcription.
What this test proves—and what it does not
It records the exact output for four isolated sine tones assigned alternately to the left and right channels. It does not predict results for a wide stereo mix, stereo effects, phase-shifted duplicates, or overlapping instruments.
If your concern is separating instruments rather than left and right placement, read the track-separation test. For short output fragments, use the extra-note guide.