Does anyone know how to make an "enveloppe follower" in pd?
The id is to use audio dynamic to control a video parameter

Thanks

Take a look at [env~].

Check out Help Browser -> 3.audio.examples -> H06.envelope.follower.pd for an explanation on how to make one.

Basically you square the signal, pass that through a lop~ at a low frequency (between 1 and 20Hz) and then get the square root of that. The higher the frequency of the low pass filter the more responsive the follower will be.

That's basically what env~ does.

thanks for that explanation saturno.

If you want a super accurate follower than you'll need to use a linear phase FIR low pass filter. But that will give you phase delay anywhere between 2 and 6 ms.

For most applications you don't need a super accurate follower. I might be mistaken but I believe env~ has a slightly more accurate low pass filter than lop~

i was just thinking that with the method you described, it would be easy to adjust the cutoff of the lop~ in realtime, and make some nice effects.

ok thanks everyone.
very usefull

By the way, does a "pitch follower" exist?

@halflifebe said:

By the way, does a "pitch follower" exist?

[fiddle~] is forseen for that purpose, but it's not always very easy to tame...