[u-u] Electronic signage...

Colin McGregor colin.mc151 at gmail.com
Thu Jul 14 11:55:12 EDT 2016

On Wed, Jul 13, 2016 at 1:45 PM, Greg A. Woods <woods at weird.com> wrote:
> 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.

For me right now Humber Bay Sailing is the right place, a place I can
learn / master sailing, but... at some time 2 years? 5 years? I will
want to get my own boat and move on. Finding someone to carry this
project forward from within the volunteer talent pool of a sailing
club will then become the issue. Which will be easier to find, someone
who knows HTML or Python? For all its' flaws (and it has many) HTML
appears to be the safer choice. The resource demands of the web server
/ browser are non issue when for $35 (US) + shipping you can get
sort-of (there will be a few additional accessories needed for a few
more $) get a computer that is adequate to the task. Further given the
Raspberry Pi foundation's history there will likely be another,
better, version of the Pi within 18 months that will make resource
usage even less of an issue.

As well, my initial focus is setting something up in the main entrance
hall, but the thought of having satellite displays in say the
Dockmaster's office and/or the 2nd floor classroom has crossed my
mind. With a web based solution adding extra displays, each with
slightly different layouts to compensate for display capabilities is
totally trivial.

I am still working my way through this problem so yes there will
likely need to be a bit of code in a conventional programming language
(ie: C) that will take some sensor data and turn it into something
that can be easily dealt with in HTML, but I want to keep that bit as
small as possible...

> 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.

Might not be using the RPi camera module. What I would want is feed a
view of the harbour into parts of the building where you can't see the
harbour. In other words be able to see which club boats are at dock,
arriving and/or departing. The solution would be setting up a camera
on the second floor (or roof) looking out and somehow streaming that
feed through the building. This could be an extra Pi, or it could just
as easily be some sort of IP security camera...

All the best.


> --
>                                                 Greg A. Woods
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