Re: CCTV

[James Derrick <james@xxxxxxx>]

On Wed, 12 Apr 2000 13:16:05 +0100, you wrote:

>Hi All
>
>I want to get a few cameras up and running but there are so many
options I
>don't know which way to go.
>
>Anyone on this list got a nice CCTV system up and running?
Yes- Linux to the rescue again!

I fitted a Haupperge WinTV card to my Linux box and after adding 4
lines to config.modules and installing a program called xawtv, I was
watching the output from my composite video camera. The installation
was remarkably easy, although I can't get the combined radio to work.

xawtv comes with lots of C source code, including "webcam", a
program
to take a single image and save it to a JPEG for automatic FTP upload
to a WWW site. I cut this code down to simply save the image in a
directory and run this regularly as a timed job via cron.

This gives me a directory full of images each day, which can be viewed
via an automatically generated WWW page or animated with xanim.

e.g. Today has a directory called 19, containing many images:
19/2000-04-19_174500.jpg

I live on a grand new estate and the plot to my North is still being
built. By saving an image each day I have a time-lapse video of the
house being built that can be quite amusing to watch- the Great
British Workman definitely does not work at a linear rate!

Later I will add a PIR to the system and trigger video capture
straight to disk. I've tried a command line tool for this and it works
fine on my Celeron 433.

Another idea is to switch several cameras via a bank of relays,
although I'm told you can't do this continuously to videotape as the
video signals are not synchronized so the image will roll for a
fraction of a second before the timing is reestablished each time a
camera is switched. I my case, it seems easy to switch cameras, wait a
second and then capture an image once the signal settles down.

I did wonder if movement could be detected by simply comparing images
(e,g XOR), but there are large variations in contrast as the sun
disappears behind clouds and shadows track across the garden.

If anyone is interested I can pass on my code and scripts to produce
the time coded HTML page of images.

Jams
---
James Derrick    james@xxxxxxx, Cramlington, Near Newcastle, England
Forwarding Service: jderrick@xxxxxxx
Beyond the Horizon of the place we lived when we were young,
In a World of Magnets and Miracles. Pink Floyd.

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