Note off velocity

A similar question came up a while ago and it made me think about note-off velocity, which I hadn't considered before. Not all keyboards transmit note-off but many do. It's easy to check if yours does by watching the vertical bars which appear as you play (in the note-off window). If the bars come up in different positions you have a variable note-off keyboard and can adjust your note-off velocity curve to take advantage of it.

With my Roland FP-30 I set it like this: Note-Off Velocity = [0, 41, 127; 5, 41, 127] . I set the minimum velocity to 5 because a '0' setting can sometimes sound as if the piano's dampers are defective!

Interesting.
I've never had a stuck note with Pianoteq, for me that's probably unique, whether standalone or VST versions of virtual instruments. So whatever they're doing they are doing it right!

Stuck notes seem to be a very serious problem with MIDI.

I have grappled with this myself and haven't gotten too far:  I have a QRS PNOscan II laser key reading bar, which I believe should have variable note-off capability, but I've not figured out how to set it to do such.

Variable Note-off is of greatest effect with soft slow pieces, where slow re-engagement of the damper can produce 'rounded ends' to each note.  It adds a subtlety which again differentiates such an equipped keyboard and VST from most others, making them sound more 'real', and adding variation to the character of each note.  In speedy loud pieces, however, variable note-off would be unnoticed, I believe.

Even better would be tying the return of the damper to the strings with each key connected to Aftertouch, which would allow you to re-engage the dampers as fast or slow as you want for each and every key, essentially recreating the technique of "key-pedalling" for each note, rather than using your foot on the sustain pedal.

Comparing MIDI functions to real instruments becomes the difficult:  For each keypress, MIDI sends a "Note on" command, initiating the sound process.  The key velocity during Note-on is detected, and used to modify the resultant sound.  The return of the key to the upright position then initiates Note "Off", which returns the dampers to the strings and brings about the end of the note.  The velocity of the key as it passes through the note-off detector sets the shapes of the end of the note by electronically setting the rate of damper reengagement.  If Note-Off is not variable, then the VST designer chooses a re-engagement rate for the dampers, and each note is muffled at the same rate.

Even better would be to mate the Aftertouch function to the dampers on a VST piano, rather than to the tone itself, as is commonly done with Aftertouch in synthesizers, etc.  This is because in a real piano, once the hammer is 'thrown' by the action, there is nothing else that the piano player can do to change hammerstrike.  But, if aftertouch is linked to damper position, in essentially the same way that the sustain pedal functions, then you can have variable damping of the played tone, and even some off-and-on damping as the note rings out, if you raise and lower the key subtly as the note resonates.  This would mimic what happens in a real piano, as each keypress serves not only to throw the hammer for hammerstrike, but also to control the damper as if you have 88 separate sustain pedals, one for each note.

I see your point. If you had a faulty keyboard, or a note-off event was deleted during editing, then you might get stuck notes. There may be other factors coming in to play, but it would need an expert in the field of midi data to give you more details. When I got my 'piano with defective dampers' effect, the note-offs were still being transmitted, but they were not always quite strong enough to fully damp the notes (because of the note-off curve setting).

Many, many keyboards do not send note-off messages. They send note-on at value 0. Pianoteq converts that into note-off messages. In those keyboards, silent notes are note-on at value 1. If a VST is unprepared to deal with note-on=0 not being a silent note but a end of note event, then all sort of problems may occur...