[PD] pix2sig and back

[Jack]

By red I mean a RGB value (0.5, 0, 0).
++

Jack



Le 24/10/2017 à 19:07, Jack a écrit :
> 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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