Re: [Linuxsampler-devel] cancel release on note on?

[Vladimir S. <ha...@gm...>]

Hi Mark,
It's been awhile, nice to hear from you again! :)

> Point in case. Hit a note at 500Hz. Hit the same note exaclty 1 second
> later. Numerically the two would cancel each other. The first is going
> up while the second is going down, in sine wave terms. In the piano
> they do not. The second note always adds to the mix. So, either the
> first note gets synced to the second or the second to the first, but
> something must be happening physically.

Modelling the "real" hammer hitting the "real" string is not easy and
i don't think we have enough information from the sample file to do
that.
I think what happens here is not trivial. For example, let's make a
very simple case: a perfect hammer hits a perfectly idle string right
in the middle (note in a real piano it's not in the middle at all for
most strings). Let's say for whatever reason the string ends up in a
perfect sine at 400Hz. Let's say there is a certain amplitude A to
this sine. So every point of the string moves at the speed of
800A/sec.
But do we mean by "hits"? In reality, hammer's speed is probably in
the same order as 800A/sec if not slower!. Hammer is also not small,
so it hits the string in a relatively large area so that area will not
be in a perfect sine. But more importanly for how long is the hammer
attached to the string while hitting it? And what's going to happen
during this time? If hammer hits the string in the middle, string in
fact becomes two strings each likely to produce a sine at 800Hz rather
than 400.

Same thing is likely to happen at the time any subsequent triggering.

So as far as "real" things we are trying to do my understanding is that:
1) In most samplers (GS included) if i play a note, apply sustain,
release the note, then release sustain, then quickly reapply it, the
note will go out of release back into sustain. That's been well tested
and please correct me if i'm wrong because i firmly believe it :)
2) At the same time, if i play a note,  then release it and quickly
play it again . . . we have differences in implementation.
So the issue is what if the first note in release stage still sounded
richer than the second note. I think it really comes down to how long
the release stage is and how likely is this to happen.
Technically, i think it is "more correct" to treat case number 2 the
same as case number 1. I think that physically when the damper comes
down it affects the first sine existing in the string much more so
then a hammer hitting it. Why? Because if it's larger area and longer
time of contact. In other words, it's designed to do just that, reduce
the amplitude of the wave asap.
Hammer has more energy to it, but that just basically separates the
string into two for a very short period of time and doesn't kill the
initial vibration.

This is all getting interesting when we consider polination between
strings. In other words, it is clear that on a real piano if i hold A3
for a very long time (to the point where it's silent) and then hit A4
very loudly and immediately release A4 i'll now hear A3 again :)
As far as i know, none of the samplers do any of that yet.
But some of those "digital pianos" do from what i hear (from
unreliable sources :).

-- 
Regards,
Vladimir