[PD] my inability to grok digital signals

Maurizio Umberto Puxeddu umbpux at tin.it
Tue Dec 31 13:59:40 CET 2002


I'm not sure what's the reason for that.

Without samphold~ (but with sig~ and phasor~ connected to *~) the patch
still works fine but when you load another sample sig~ is updated *right
away* and so is the left inlet of the *~. This means that if you load
the patch when the phasor is at 0.5 (50% of the sample old) the
"playback cursor" will jump to 50% of the new sample.
Using samphold~ the left inlet of *~ is updated only when the loop
starts again. In this case the current loop is completed as if the array
was filled with the old sample. It means that if the unit was reading
sample 1003 of the old sound, it will continue reading from sample 1004
without regard to the real size of the new sound. The sound size (used
to remap the output of the phasor from the [0, 1) range to the [0,
nsamples) range) will be updated by samphold~ only when the phasor value
decreases. This happens only when the phasor is restaring its loop and
jumps from 1 down to 0.

I don't know what's the purpose of the original patch but if the new
sample is sensibly shorter than the previous one, this mean you will
hear a silence.
If the new sample is longer than the old one, with samphold~ you are
sure you will always hear it from the beginning as quickly as possible
(maybe this is the reason).

I guess most people is happy with you using root priviledges on
pure-data.org as you do now.

Don't know about the delay. How large is the sample?

Maurizio Umberto Puxeddu.

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