[PD] pix2sig and back

[Jack]

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 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).
> 
> 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
>>
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