[PD] change in compression detection

Roman Haefeli reduzent at gmail.com
Wed Jan 12 22:15:51 CET 2011

On Wed, 2011-01-12 at 13:35 -0500, Mathieu Bouchard wrote:
> On Tue, 11 Jan 2011, Roman Haefeli wrote:
> > I hope I'm not confusing dynamic range compression with wave shaping. 
> > Actually, depending on the compressor settings (short attack times, 
> > etc.) a dynamic compressor indeed acts a bit as a wave shaper.
> It can also act exactly like a waveshaper, if you give it the most extreme 
> settings.
> Similarly an echo effect and a comb filter are the same thing, but when 
> people talk about an echo effect, they usually don't mean an echo effect 
> configured to act as what is usually meant when people say a comb filter. 
> And vice-versa.
> If you pick compressor settings that cause their cutoff wavelengths to be 
> longer enough than the sounds you are compressing, they will cause no 
> (or little) distorsion in the perceived frequencies, and thus it will not 
> sound like a compressor.

Di you mean: "[...] thus it will not sound like a wave shaper"?
> > Instead of constant amplitude signals think of signal with ever changing 
> > amplitudes which I believe what we call music normally belongs to,
> But constant-amplitude sound can also be music, can't it ?

Sure, though I don't know any, I guess. Also it wouldn't be interesting
to detect compression in it.

> > The problem with calculating an average with peak amplitude is that 
> > peaks by definition occur only at certain points in time.
> A square wave is entirely made of peak points.
> What is it that makes you use such a flawed definition of peaks ?

Yeah, that came out totally wrong. I was trying to say that often
(you're correct: not always) the peaks themselves don't form a
continuous signal by themselves. The continues signal that represents
the 'peak' of the measured signal (think of a peak meter at a mixing
desk) needs to be constructed.


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