Both Realband (2018) and BIAB (2018) can transcribe a single-note vocal or instrumental line and produce a MIDI file.
Here's how to do it...
1. Make sure the vocal is on the Audio track
2. Open "Audio Edit"
3. Select the whole track
4. Under the "Edit" option in 'Audio Edit', select transcribe
As a test, try opening the file LISTEN.MGU that's found in...
When I tried it, it did a really good job. I transcribed the audio to the Soloist track since the Melody track already contained a MIDI melody.
= = = = =
1. Open the Audio on a track
2. Select the whole track
3. Select "Edit | MIDI | Pitch to MIDI Convert"
The MIDI transcription will appear on a blank track called "Conversion from track x" where x is the track number of the audio.
Realband conversion offers greater control over interpretation parameters.
Taken with Noel's permission from the PG Music "Tips and Tricks" Forum