[PD] pix2sig and back

[Peter P.]

* cyrille henry <ch at chnry.net> [2017-10-24 13:32]:
> 
> 
> Le 24/10/2017 à 13:18, Peter P. a écrit :
> > Hi list,
> > 
> > I am trying to convert an audio signal to pixel data using pix_sig2pix~
> > and then back to audio data using pix_pix2sig~ without further
> > manipulations. Please see attached patch.
> > 
> > I do scale the audio signal from -1 to 1 to lie in a range compliant
> > to pixel data, which I assume to be 0 to 1.
> > 
> > Not having connected an input to the subpatch, this signal will hence be
> > 0.5 and will display in the red color channel.
> > 
> > Converting that red channel back to audio signals and doing the opposite
> > scaling operation, I am getting a 51dB constant signal at the output
> > even without having attached a signal to the input of pix_sig2pix~.
> > Checking with a snapshot~ object indicates a constant signal of 0.003921
> > 
> > I assume this to be due to limited resolution numbers in the pixel data
> > and wonder what their resolution is?
> 
> 8 bits / channels
> 
> so resolution is 1/256 = 0.0039...
> 
> You can code MSB in Red, and LSB in green is you want 16 bits...
> 
> > 
> > Then I texture the pixel data onto a rectangle. This rectangle
> > does flicker and flip diagonally from time to time and I wonder if it is
> > an error on my machine only and where it could come from.
> 
> I don't see any flicker in your patch. (linux / intel GPU)

Thank you Cyrille for this helpful information!

Jack, I am on Debian GNU/Linux with an onboard Intel graphics controller
(i915 variant).

P