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pitch tracking at very low (and sub-audio) frequencies

March 1, 2011 | 4:39 am

i have an audio signal coming into max that i want to use to control other things. it’s a slightly mellowed-out squarewave that varies between about 100hz right on down to 0hz. I need to be able to detect the frequency.

I’ve been experimenting with jehan’s pitch~ without much luck — it doesn’t seem to be able to make much sense out frequencies in this range. Anybody have any ideas?


March 1, 2011 | 4:52 am

maybe a bank of reson~ objects?


March 1, 2011 | 5:25 am

This kind of low tech but if it’s really just a variant of a square wave and you have a guarantee of only 0 only twice per wave , why not just measure the zero crossings?


March 1, 2011 | 6:04 am

hmm yeah. what object can you use for that?


March 1, 2011 | 11:21 am

a cheap and nasty solution perhaps..
less reliable for higher frequencies of course.

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March 1, 2011 | 5:32 pm

[zerox~] doesn’t seem to work too well because i have to turn the signal vector up ridiculously high to get any usable data. kthozoid i’ll check out your method.


March 1, 2011 | 6:07 pm
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March 1, 2011 | 6:13 pm

(the minimum object~ and the three divisions aren’t really necessary.


March 3, 2011 | 6:20 pm

wow, thanks audiomatt. brilliant solution. This works very well.


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