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
#N canvas 507 117 649 576 10;
#X obj 17 84 inlet;
#X text 13 63 trigger;
#X obj 17 132 sel 0;
#X obj 221 316 del \$2;
#X obj 240 342 f \$4;
#X msg 17 192 stop;
#X text 75 304 ATTACK;
#X obj 240 525 outlet~;
#X text 54 74 if zero;
#X text 55 91 release;
#X text 44 109 bang if attack;
#X text 320 2 When you send this patch a nonzero trigger it schedules
a line~ to do an attack and decay \, and if zero \, it starts the release
ramp.;
#X obj 240 413 vline~;
#X obj 240 370 pack 0 0;
#X obj 240 497 *~;
#X obj 267 107 inlet A;
#X obj 317 107 inlet D;
#X obj 368 107 inlet S;
#X obj 419 107 inlet R;
#N canvas 0 22 490 340 graph1 0;
#X array \$0-envCurve 102 float 0;
#X coords 0 1 101 0 100 100 1;
#X restore 500 272 graph;
#X text 604 364 0;
#X text 603 264 1;
#X text 192 341 DECAY;
#X text 347 275 RELEASE;
#X obj 141 130 f;
#X obj 422 454 outlet switch;
#X obj 389 322 pack 0 \$5;
#X obj 240 447 tabread4~ \$0-envCurve;
#X obj 422 428 r \$0-activate;
#X obj 133 182 s \$0-activate;
#X msg 105 156 1;
#X obj 66 132 t b b b;
#X obj 362 296 t b b;
#X obj 363 357 del \$5;
#X msg 363 382 0;
#X text 385 506 - when finished (i.e. \, end of release) \,;
#X text 386 490 - on attack: send on for dsp of parent voice;
#X text 395 520 send off for dsp of parent voice;
#X text 384 475 This outlet may be used as follows:;
#X obj 156 107 inlet attackLevel;
#X obj 492 189 change;
#X obj 502 136 loadbang;
#X obj 67 325 pack 100 \$2;
#X text 17 1 Multi-curve ADSR;
#X obj 255 474 r \$0-levelmult;
#X obj 141 153 s \$0-levelmult;
#X text 452 36 Curve Factors;
#X text 17 19 arguments: level \, attack time \, decay time \, sustain
level (proportion of overall level 0 - 100) \, release time;
#X obj 492 107 inlet curveFactor;
#X text 388 83 1 - exponential (fat) curves \, varying with C;
#X msg 502 159 1;
#X text 118 58 This adsr uses table-lookup for envelope curves \,;
#X text 119 73 so it should be pretty cpu-efficient.;
#X text 399 68 1 - linear;
#X obj 17 162 t b b;
#X text 36 409 and left-over release switch~;
#X text 48 195 (*);
#X text 35 394 (*) cancel decay \,;
#X text 388 53 1 - quartic-like (hollow) curve \, C=-0.214;
#N canvas 547 29 545 431 6886-makeCurve 0;
#X msg 21 315 0;
#X obj 104 115 - 1;
#X msg 142 94 0;
#X obj 142 120 f;
#X obj 167 120 + 1;
#X obj 71 224 f;
#X obj 318 313 expr 1 - (pow( ($f1 / 102) \, $f2) );
#X obj 285 158 t b f;
#X obj 382 156 t b f;
#X obj 318 287 spigot;
#X obj 71 289 spigot;
#X obj 325 262 0;
#X obj 351 262 1;
#X obj 78 265 1;
#X obj 104 265 0;
#X obj 71 314 expr pow( ($f1 / 102) \, $f2) -1;
#X text 361 294 exponential fat curve;
#X msg 285 133 -0.214;
#X obj 130 392 tabwrite \$0-envCurve;
#X obj 71 200 b;
#X obj 130 363 f;
#X obj 38 8 inlet curveFactor;
#X msg 38 93 102;
#X obj 29 118 sel 0;
#X obj 69 116 f;
#X obj 69 93 until;
#X obj 48 142 t f f b f;
#X obj 38 34 t b b b b f;
#X obj 226 110 sel 1;
#X obj 227 255 spigot;
#X obj 232 229 0;
#X obj 260 229 1;
#X obj 142 148 t f f f f;
#X obj 227 279 / 100;
#X obj 307 108 moses 1;
#X text 115 296 quartic-like curve;
#X obj 20 176 moses 2;
#X connect 0 0 20 0;
#X
