[PD] pix_data issue

Derek Holzer macumbista at gmail.com
Tue Feb 27 23:50:18 CET 2018

Dear Pd list,

the [pix_data] object has me very confused! I am using it for analysis 
of a live webcam video or recorded video clip from [pix_video] or 
[pix_film]. However, I cannot for the life of me figure out where it is 
getting the analysis data from!

I can disconnect the Gemlist from the second inlet, so that it is only 
getting the metro bangs at the first inlet and the X and Y coordinates 
to analyze at the third and fourth inlet, and still it gives data output.

I know that it is still getting the changing video signal and not just 
reading the last frame that came in the Gemlist, because I use the 
analysis data to reconstruct the image with audio signals on an external 
analog vector monitor, and I see that image changing and moving even if 
the [pix_data] receives no Gemlist.

Basically, if I use [pix_video] or [pix_film], I can completely 
disconnect their outlets from anything, and as long as they were 
connected to [pix_data] through an active Gemlist before I disconnect 
them, then [pix_data] will still continue to see them in realtime.

Also, no scaling transformations I do to the output of [pix_video] or 
[pix_film] (for example by texturing it on a rectangle with a [scale] 
object in front of it) have any effect on what is seen by [pix_data].

Does [pix_data] read the pixel values from some other place than the 
Gemlist? A buffer of some kind? How can I apply any transformations to 
what it "sees"?

Thank you for clearing up any confusion here!

derek holzer

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