Hello,
I am trying to use VU to measure the output of a signal. Is there an external like Max for [log~] or even [gain~]. ? I am trying to do the conversion db=log10(signal between 0 and 1)*20. Is there another way ? Thanks
yep, have a look at prvu~ from iemlib (it's included in modern versions of pd).
there is a help-prvu~.pd patch you will want to look at.
pix.
On Wed, 12 Feb 2003 12:49:39 +0000 Alex from Idoia alex@idoia.com wrote:
Hello,
I am trying to use VU to measure the output of a signal. Is there an external like Max for [log~] or even [gain~]. ? I am trying to do the conversion db=log10(signal between 0 and 1)*20. Is there another way ? Thanks
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On Wed, 12 Feb 2003, Alex from Idoia wrote:
I am trying to use VU to measure the output of a signal. Is there an external like Max for [log~] or even [gain~]. ? I am trying to do the conversion db=log10(signal between 0 and 1)*20. Is there another way ? Thanks
Hi, I've been wondering about this: how does square root and logarithm work for signals, because signals may get positive or negative... which means taking square roots of negatives (imaginary result), taking logs of numbers very close to zero (big negative result), equal to zero (minus infinity result), smaller than zero (complex result)... I mean, the signal itself is not complex, so how does applying square root and then applying square get back to the original signal? (maybe the answer is: it doesn't...)
(note: i have not been trying those objects myself...)
Mathieu Bouchard http://artengine.ca/matju
On Wed, 12 Feb 2003, Alex from Idoia wrote:
I am trying to use VU to measure the output of a signal. Is there an external like Max for [log~] or even [gain~]. ? I am trying to do the conversion db=log10(signal between 0 and 1)*20. Is there another way ? Thanks
Hi, I've been wondering about this: how does square root and logarithm work for signals, because signals may get positive or negative... which means taking square roots of negatives (imaginary result), taking logs of numbers very close to zero (big negative result), equal to zero (minus infinity result), smaller than zero (complex result)... I mean, the signal itself is not complex, so how does applying square root and then applying square get back to the original signal? (maybe the answer is: it doesn't...)
Don't know if it's what you wanted to know, but in typical musical or acoustic applications one would not take the instantanous sampled signal but an envelope or average of the absolute samples over some (small) timespan ("RMS value"). Thus, sqrts or logs of negative numbers can't occur. The only case is rms=0, which is easily treated as a special case (e.g. -1000 dB)
T
On Wed, 12 Feb 2003, Thomas Grill wrote:
On Wed, 12 Feb 2003, Alex from Idoia wrote:
Don't know if it's what you wanted to know, but in typical musical or acoustic applications one would not take the instantanous sampled signal but an envelope or average of the absolute samples over some (small) timespan ("RMS value"). Thus, sqrts or logs of negative numbers can't occur. The only case is rms=0, which is easily treated as a special case (e.g. -1000 dB)
Okay, that explains it. Now I'm curious about what length of timespan it is (typically), and whether it's a moving average, or a per-block average.
Mathieu Bouchard http://artengine.ca/matju
Hallo, Mathieu Bouchard hat gesagt: // Mathieu Bouchard wrote:
Okay, that explains it. Now I'm curious about what length of timespan it is (typically), and whether it's a moving average, or a per-block average.
It depends on the specific external. expr~ for example seems to calulate on single signals, env~ has a creation argument to set the window size. There are different approaches for different needs.
ciao
Frank Barknecht _ ______footils.org__
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Alex from Idoia -
Frank Barknecht -
Mathieu Bouchard -
pix -
Thomas Grill