• cyrille henry ch@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

OK, I tested your patch and on my side, i get a solid red square. No flicker. ++

Jack

Le 24/10/2017 à 18:33, Jack a écrit :

Hello,

Le 24/10/2017 à 11:24, Peter P. a écrit :

...

• cyrille henry ch@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).

OK, i guessed you were on nvidia because if you are not sync to vblank, you often get a line diagonaly separating two pictures. It is called "screen tearing". I didn't test your patch yet... ++

Jack

...

P

---

Pd-list@lists.iem.at mailing list UNSUBSCRIBE and account-management -> https://lists.puredata.info/listinfo/pd-list

---

Pd-list@lists.iem.at mailing list UNSUBSCRIBE and account-management -> https://lists.puredata.info/listinfo/pd-list

• Jack jack@rybn.org [2017-10-25 00:33]:

[...]

...

...

...

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).

OK, i guessed you were on nvidia because if you are not sync to vblank, you often get a line diagonaly separating two pictures. It is called "screen tearing".

Thank you, in my case it is not a missing sync to vblanc but a more drastic flicker. Also thanks for testing my patch and getting back to me on that, it is much appreciated!

P