[PD] GEM & RPi

Peter P. peterparker at fastmail.com
Wed May 16 12:54:08 CEST 2018


* michael strohmann <itsnotfair9 at gmail.com> [2018-05-16 12:41]:
> Hi!
> the short question:
> what would be the least resource intense method to display a 10min Countdown?
> (need to listen to a trigger on netreceive)
> the long version :
> I am running pd and GEM on a RPi 3B+
> i display a countdown with GEM and some “text2d” objects on 1920x1080
> The RPi CPU meter says that it uses 24%, the RPi temperature is at around 65 degree.
Do you know what is using CPU? Is it Gem (switch rendering/gemwindow on
and off to check), is it DSP? Is it message processing?

> as the thing should run 24/7 in an exhibition i am a bit concerned regarding the temperature.
I think your temperature is fine, and you should not worry about that.
The RPi should be constructed in a way that allows Gem to run on it ;)
> i was trying to bring down the cpu load, yet without success.
Have you tried lowering the Gem framerate (see gemwin helpfile) and does
that change something? In fact you can even use single-frame
(single-buffer) rendering to only render a new output frame when your
number changes.
> 1.) 
> i was using pix_image to display a new jpeg every second …. this used >90% cpu.
> obviously it is difficult for pd or the rpi do disply jpegs ?
Depends on the size of the jpgs. Possibly also depends on if you preload
images (pix_multiimage) or load every image in from disk (pix_image).

> 2.)
> so back to openGL: i don/t understand why the cpu load doubles if the gemwin window is in foreground?
> (as opposed to when the patcher window is in foreground…)
I assume: It is because then the RPi graphics card actually has to
render the window to the framebuffer. There might be better

If you don't find a solution you could try to display an image with a
different software such as Robin's xjadeo and load a 10 frame movie
which you step through using OSC commands from Pd.

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