[u-u] Electronic signage...
Greg A. Woods
woods at weird.com
Wed Jul 13 13:45:03 EDT 2016
On 2016-07-13, at 6:37 AM, Colin McGregor wrote:
> This is a topic I will plan on picking brains at during this evening's
> UU meeting.
Sorry I can't be there to join in the discussion! :-)
> The first part of displaying the above is easy enough, a browser the
> like of Chromium set up in kiosk mode.
Even if it seems simpler from a first glance, why the heck would you want
to run upwards of 5 million lines of code (plus however many million lines
are in your chosen Linux kernel and the Xserver), etc., etc., etc., just
to display what is a relatively static layout of graphics, video, and images
with a text overlay?
Especially on a RPi? Even on the latest greatest RPi-B2 or B3 (where such
extravagance might actually be possible without running out of memory)?
If you're running any JS in the browser, and you would be, then you can expect
a browser window with that kind of display to require upwards of 500MB of memory
plus the main browser process at another 150MB, plus the X server, etc., and
the browser would be in very serious threat of suffering major memory leaks and
require restarting at least every 24 hours, if not far more often. (Though
Chrome has been getting better at keeping JS from leaking memory in the past
few months, but by no means can you trust it.)
You probably need less than a thousand lines of C to make a reasonably easy
to maintain and adapt form that could display graphics, video, and text, and
also pull the data from some kind of service or set of services (weather
underground or similar, plus perhaps some USB or RS-232 connected local
weather station). Assuming a good support library or two of course.
It's probably half that many lines in Go or Python.
On a good day there should be enough Go and/or Python programmers in the room
to rough out a general working version during the meeting. Assuming they don't
try to paint too many bikesheds at the same time, of course. :-)
BTW, I'm assuming the video camera is a directly attached RPi camera module,
though I suppose one could do it with a USB camera, or assuming a LAN and a
local server, something running on a separate but local machine.
Greg A. Woods
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