Re: [Linuxsampler-devel] [PATCH] fine tuning of the velocity curves

[Christian S. <sch...@so...>]

Es geschah am Sonntag 21 November 2004 11:57 als Andreas Persson schrieb:
> > So you actually measured Gigasampler's original velocity curves?
>
> Yes, I did a lot of measurements of GS 2.5. Input was a minimal gig with
> a sawtooth sample and a MIDI sequence of the same note repeated with all
> 127 different velocities. Output was a wav, which I run through a small
> program to get data for a velocity x volume graph. I did this for all 15
> curves with scaling set to 20, and for some curves I also varied the
> scaling parameter.

Very good!

> > Do you think it might be worth to approximate a polynomial function
> > instead of using linear segments? Btw here
>
> When looking at the graphs for the measured nonlinear curves, it seems
> as GS also uses linear segments. For the special curves  I'm not so
> sure, perhaps some of them or some segments of them could be replaced
> with polynomials or perhaps exponential functions, but I doubt it would
> be worth it.

Ok, then we forget about that.

> Uh-oh, It seems as somebody else than me has spent a lot of time and
> effort on this, I didn't mean to step on any toes... I started doing
> this tuning when I noticed that my favorite piano gig was not feeling
> right, It was not audible at all when playing soft. It uses curve type
> nonlinear, range 1 and scaling 0.

Np :), at least for me it wasn't much work, even though you might get that 
impression, but I just fed Maxima with the data from Mark and the curve 
fitting was done in few minutes that way. Fortunately Mark already did those 
time consuming measurements.

> Here's a plot of a measured nonlinear-1-20 curve together with my
> line-segment-approx and the original linuxsampler function:
>
> http://hem.spray.se/andreas56/plotfile.png

Looks very good! If you have plots of the other two functions as well, please 
let me know. Just in case you already have, that doesn't mean you have to 
create them. But it would be nice for the docs to have comparison graphs 
between our curves and the original ones.

> > Has somebody already tested Andreas' patch? Do the new curves feel more
> > accurate? Mark perhaps?
>
> Well, I have :). Apart from some artificial tests, the piano feels
> better with the patch. Other than that I have not tested the feel that
> much.

Ok, I'll apply it today.

Thanks!
Christian