[PD] [multiCurveAdsr] v.2

[Phil Stone]

I found and fixed a condition that kept some sustain changes from being
propagated.  I cleaned other stuff up a little, too.


(tweaked text from previous announcement:)

> I have been working on envelopes lately, and I have come up with
> something that I'd like to share. I started out with the basic ADSR in
> Miller's examples; I wanted variable envelope curves, but I didn't want
> the overhead of on-the-fly sqrt's or complex expr's. Therefore,
> [multiCurveAdsr] uses table-lookup for enveloping, with just one
> multiplication for level-scaling. The lookup table only needs to be
> computed when the "curve factor" is changed.
>
> Three basic curve types are possible. C (curve factor) = 1 gives the
> basic linear envelope. C > 1 gives a continuous range of fatter,
> "ead"-like envelopes. C < 1 is a special case; for any value of C less
> than 1, you get one "quartic"-like, hollow curve. (I really like the
> way this one sounds, by the way).
>
> The math in the [pd makeCurve] subpatch is not elegant -- I took an
> empirical approach, tweaking things until I got the shapes I wanted --
> but it works well enough. One little hitch I ran into was that sustain
> level varied with different curve factors, so I made a corrective
> subpatch that keeps sustain values consistent across the different
> curves. This subpatch only comes into play when the sustain value or 
> curve factor changes.
>
> The right output emits 1 on attack, and 0 after release is complete. I
> use this to switch~ the voice being enveloped, for further CPU-cycle
> economy.
>
> The help patch shows the effect of the different curve factors
> graphically. I don't think there are any dependencies outside of
> "Miller Vanilla" PD.
>
> I use [multiCurveAdsr] for my own synthesis abstractions, and find that
> it sounds pretty good, plus it's thrifty on CPU-usage, even with many
> voices. I hope somebody else finds it useful. Any suggestions for
> improvement will be greatly appreciated.


Phil Stone



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