25 Apr
2004
25 Apr
'04
11:02 p.m.
Well, since no one took the bait, I had to figure this one out by myself. For the sake of future generations, I post the answer to the riddle here.
derek@x-i.net wrote:
I'm trying to build a patch which allows the order of a signalprocessing chain to be rearanged... for example, to put the delay either before or after the reverb. The problem is that when I conect the outlets and inlets of the [pd delay] and the [pd reverb] subpatches that I have created together, I get the error "DSP loop detected (some tilde objects not scheduled)".
I tried putting [*~ 0] objects in the way, or even running the signals through subpatches which can be switched on and off with [block~], but still no dice.
I was warm here, but not hot. The key was to use [send~] and [receive~] pairs, and somehow this keeps PD from discovering any DSP loops.
Patch is attached, in case anybody else gets stuck with this. Might I suggest adding this to the PD documentation?
d.
--
derek holzer ::: http://www.umatic.nl
---Oblique Strategy # 180:
"What to increase? What to reduce? What to maintain?"
#N canvas 59 -14 958 662 10;
#X msg 514 371 0;
#X msg 483 371 1;
#X msg 437 372 0;
#X msg 406 372 1;
#X obj 35 63 osc~ 440;
#X obj 36 588 dac~;
#N canvas 108 178 552 343 reverb 0;
#X obj 85 40 inlet~;
#X obj 85 150 outlet~;
#X text 81 187 This subpatch is empty. Put any DSP effect you like
in here.;
#X connect 0 0 1 0;
#X restore 35 249 pd reverb;
#N canvas 104 173 577 384 delay 0;
#X obj 85 40 inlet~;
#X obj 85 150 outlet~;
#X text 81 187 This subpatch is empty. Put any DSP effect you like
in here.;
#X connect 0 0 1 0;
#X restore 193 246 pd delay;
#X obj 406 271 tgl 15 0 empty empty empty 0 -6 0 8 -262144 -1 -1 0
1;
#X obj 406 336 select 0;
#X obj 483 336 select 1;
#X obj 406 411 s delaytf;
#X obj 483 412 s reverbtf;
#X obj 406 444 r delaytf;
#X obj 483 445 r reverbtf;
#X obj 406 473 tgl 15 0 empty empty empty 0 -6 0 8 -62784 -1 -1 1 1
;
#X obj 483 473 tgl 15 0 empty empty empty 0 -6 0 8 -258699 -1 -1 0
1;
#X obj 209 110 r delaytf;
#X obj 209 131 tgl 15 0 empty empty empty 0 -6 0 8 -62784 -1 -1 1 1
;
#X obj 210 441 r reverbtf;
#X obj 210 464 tgl 15 0 empty empty empty 0 -6 0 8 -258699 -1 -1 0
1;
#X obj 52 441 r delaytf;
#X obj 52 465 tgl 15 0 empty empty empty 0 -6 0 8 -62784 -1 -1 1 1
;
#X obj 51 111 r reverbtf;
#X obj 51 131 tgl 15 0 empty empty empty 0 -6 0 8 -258699 -1 -1 0 1
;
#X obj 35 218 *~;
#X obj 193 217 *~;
#X obj 194 528 *~;
#X obj 36 529 *~;
#X obj 226 290 r delaytf;
#X obj 226 312 tgl 15 0 empty empty empty 0 -6 0 8 -62784 -1 -1 1 1
;
#X obj 68 290 r reverbtf;
#X obj 68 312 tgl 15 0 empty empty empty 0 -6 0 8 -258699 -1 -1 0 1
;
#X obj 210 395 s~ to_reverb;
#X obj 52 395 s~ to_delay;
#X obj 223 217 r~ to_delay;
#X obj 64 218 r~ to_reverb;
#X text 406 605 derek@umatic.nl;
#X text 406 587 Riddle cracked for PD 0.37.1-devel by Derek Holzer
;
#X obj 36 87 *~ 0.5;
#X obj 52 371 *~;
#X obj 210 371 *~;
#X text 403 212 The problem is avoided here by "seperating" these subpatches
with [send~] and [receive~] pairs.;
#X text 33 22 Signal Chain: using the [send~] and [receive~] objects
to create a variable audio signal chain.;
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#X obj 51 173 line~;
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#X obj 209 173 line~;
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#X obj 210 506 line~;
#X obj 68 329 pack 0 50;
#X obj 68 350 line~;
#X obj 226 329 pack 0 50;
#X obj 226 350 line~;
#X text 564 336 0 = "delay" 1st , "reverb" 2nd (plays out left channel)
;
#X text 564 356 1 = "reverb" 1st , "delay" 2nd (plays out right channel)
;
#X text 480 492 reverb 1st;
#X text 403 492 delay 1st;
#X text 60 194 Use [line~] for click-free switching!;
#X msg 644 412 ; pd dsp 1 ;;
#X msg 724 412 ; pd dsp 0 ;;
#X text 459 269 <---click here to switch between "delay"-->"reverb"
and "reverb"-->"delay". The toggles in the patch will show you the
signal path.;
#X text 402 79 The purpose of this patch is to explain how to set up
a variable signal chain in PD. In this case , one has the choice to
put a "reverb" before or after a "delay". The subpatches "reverb" and
"delay" are both empty , so imagine them as being any two different
effects in your signal chain. Simply connecting the different outlets
and inlets together , even with a [*~] object inbetween , causes
PD to give the message "DSP loop detected" and to shutdown the audio
processing of the offending tilde objects.;
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#X obj 193 217 *~;
#X obj 194 528 *~;
#X obj 36 529 *~;
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#X obj 226 350 line~;
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#X obj 403 427 tgl 15 0 empty empty empty 0 -6 0 8 -258699 -1 -1 0
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#X text 400 446 reverb 1st;
#X text 323 446 delay 1st;
#X obj 326 365 s wdelaytf;
#X obj 326 398 r wdelaytf;
#X obj 403 399 r wreverbtf;
#X obj 403 366 s wreverbtf;
#X obj 210 441 r wreverbtf;
#X obj 52 441 r wdelaytf;
#X obj 68 290 r wreverbtf;
#X obj 226 290 r wdelaytf;
#X obj 209 107 r wdelaytf;
#X obj 51 111 r wreverbtf;
#X msg 446 325 0;
#X text 322 106 This patch does it all wrong , without sends.;
#X msg 403 224 ; pd dsp 1 ;;
#X msg 483 224 ; pd dsp 0 ;;
#N canvas 0 0 450 300 "delay-wrong" 0;
#X obj 19 25 inlet~;
#X obj 19 54 outlet~;
#X text 17 83 If these two are connected in both subpatches , then
PD would not allow audio processing to continue , and would give the
error: "DSP loop detected";
#X restore 35 248 pd "delay-wrong";
#N canvas 0 0 450 300 "reverb-wrong" 0;
#X obj 19 25 inlet~;
#X obj 19 54 outlet~;
#X text 17 83 If these two are connected in both subpatches , then
PD would not allow audio processing to continue , and would give the
error: "DSP loop detected";
#X restore 194 248 pd "reverb-wrong";
#X text 323 132 To see the error in your terminal window , open the
"delay-wrong" and "reverb-wrong" subpatches and make the connection
inside , then turn on signal processing.;
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#X restore 405 548 pd wrong;
#X text 472 548 To see the wrong way , open this subpatch!;
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