[PD] Pd 20% idle CPU usage on MBP

[Roman Haefeli]

On Sun, 2010-11-14 at 12:00 -0500, Mathieu Bouchard wrote:
> On Tue, 9 Nov 2010, chris clepper wrote:
> 
> > By default CoreAudio does a lot of processing on audio when using the 
> > built-in outputs.  It used to mainly be limiting to keep the shitty 
> > speakers from blowing, but it has expanded over time.  There is 
> > obviously a way to tell CoreAudio to cut that out, but how that is done 
> > via PortAudio is a question for the PA developers.
> 
> Why does it do that in the application instead of inside some daemon ? I 
> mean, what if you run 3 sound apps at once, does it does the same 
> transformation on three signals (or pairs of signals) before mixing them ?
> 
> (I ask because, if that transformation is all linear, it's a waste)

Judging from my ears, the sound coming out of the MBP built-in speakers
is dynamically processed. To me it sounds somewhat similar to the kind
of processing that is applied to broadcast audio of radio stations
before the signal goes on-air. Try turning on and off an [osc~] with a
toggle. It sounds crisper than it normally would without processing. 

Actually, I don't think that this processing is applied to each source
separately. Also, it would make more sense to apply it only to the mixed
signal in order to avoid clipping, even if more than one source are set
to maximum gain. 

Roman