metro vs. samm~ [was: Re: [PD] Re: pix_film more questions]

[Roman Haefeli]

On Mon, 2007-02-19 at 04:39 +0000, padawan12 wrote:
> 
> If I understood Erics paper correctly [samm~] allows you to specify
> which sample of a block is set consistently, if you like a periodic 
> version of [dirac~]. That's surely useful if you want to do somthing
> in the signal domain like convolution with a impulse train. 
> 
> What I couldn't figure, is this really equivilent to
> 
> [phasor~ 0.0173474647]  very accurate signal phasor

hehe, i think the number format used in pd doesn't allow such a high
accuracy ;-)

> |
> [>=~ 0.9999999999999]  "floated" 1.0 so we get an equivilence
> 
> which should give a single sample set on the top of each phasor
> cycle. But I seem to remember this not working properly for some
> reason.

not each edge of a signal generated by [phasor~] lies exactly on 1 or 0
because of the grid introduced by the samplingrate. see attached patch.

roman



> 
> 
> On Sun, 18 Feb 2007 13:53:52 +0100
> Frank Barknecht <fbar at footils.org> wrote:
> 
> > Hallo,
> > schiemer at uow.edu.au hat gesagt: // schiemer at uow.edu.au wrote:
> > 
> > > If you're worried by metro's irregularity then you should use Eric
> > > Lyons' samm~ (sample accurate multiple metronomes). This is
> > > described in
> > > http://www.sarc.qub.ac.uk/~elyon/LyonPapers/SampleAccurate-Lyon-ICMC2006.pdf
> > 
> > Note that samm~ is almost exactly as sample-accurate as Pd's metro. I
> > tried to illustrate this in attached patch. samm~ however is also
> > available for Max, where the metro according to Eric's paper is not as
> > accurate as the one in Pd, so if you need to move patches between both
> > systems, samm~ is a good choice. Of course Eric's system has some
> > convenient extensions to generate polyrhythms etc., but timing alone
> > IMO is no reason to exchange [metro] with [samm~] on Pd.
> > 
> > Ciao
> > -- 
> >  Frank Barknecht                 _ ______footils.org_ __goto10.org__
> > 
> 
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#N canvas 736 523 450 300 10;
#X obj 74 166 tabwrite~ array;
#X obj 60 124 bng 15 250 50 0 empty empty empty 17 7 0 10 -262144 -1
-1;
#X obj 95 210 table array 40;
#X msg 184 74 44100;
#X floatatom 62 37 5 0 0 0 - - -;
#X obj 184 98 / 8;
#X obj 65 7 hsl 128 15 0 1 0 0 empty empty empty -2 -8 0 10 -262144
-1 -1 7100 1;
#X obj 88 125 phasor~;
#X obj 184 45 loadbang;
#X msg 143 77 7237;
#X text 232 71 <- choose frequency;
#X text 212 10 <- set phase;
#X text 211 211 <- watch signal;
#X connect 1 0 0 0;
#X connect 3 0 5 0;
#X connect 4 0 1 0;
#X connect 4 0 7 1;
#X connect 5 0 7 0;
#X connect 6 0 4 0;
#X connect 7 0 0 0;
#X connect 8 0 3 0;
#X connect 9 0 7 0;