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Date:	Mon, 7 Jun 2004 11:18:37 PDT7
From:	Peter Skye <pskye@peterskye.com >
Reply-To:	scoug-help@scoug.com
To:	scoug-help@scoug.com
Subject:	SCOUG-Help: Re: video surveillance using OS/2 ?

Content Type: text/plain

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Mark Abramowitz wrote:
>
> I liked Sheridan's suggestion of the IP camera. I had never
> heard of them before, but they looked pretty impressive.

The all-in-one IP camera is new to me. The closest I've come to it is
when Rollin's Warp Expo West did a live video feed, but that used a
video IP box plus a separate camera. (Tim Katz did the equipment
research and setup, Dave supplied the cameras, Rollin tied it into the
SCOUG web site which was 20 miles away, and yours truly wrote the web
pages so viewers could select whatever video resolution and speed their
connection would support.)

What's great about an IP camera is that each camera doesn't need a
separate video capture card in a separate computer. The only other
one-computer solution I can think of is multiple USB cameras, and I'm
not sure there's an OS/2 driver for that. But the IP solution doesn't
need a special driver.

As for bandwidth, the local network can run at 100 or you can use
multiple NICs. I don't think there will be a cpu overload if I'm only
grabbing 2 or 4 frames per second from each camera. And if there _is_ a
cpu overload the ease of adding another computer to the network and/or
splitting the network is trivial; this solution is easily expandable.

A word on cheap cameras: I've used them, and they have crummy lenses.
You have to "test and select" to find ones which give you the
least-fuzzy image. A typical NTSC (television) image has resolution of
maybe 400x300 (I know the specs are slightly higher but there's bleed in
the system). A fuzzy lens makes the images even worse. (Now if I can
just find an HDTV IP camera I can put together a truly great system.)

> Use any one of number of file compare utilities
> to compare the latest shot with the previous one.

This is how MPEG compression works, by the way.

Also, if instead of video tape I store the video on a hard drive
(Fujitsu recently announced a 320 GB drive) then I can process it to
create (to use a studio term) a moving differential matte shot (MDMS):
If a pixel doesn't substantially change over x number of prior frames,
view it as black (don't change the pixel stored on the hard drive
however). This way you instantly see all screen activity plus anything
new but hasn't moved for x frames.

Having reviewed home surveillance tapes I can tell you it's easy to miss
the small stuff. With the MDMS you just dump all the totally-black
frames and quickly review what's left.

> If a change occurs, tell IP camera to
> increase frequency to whatever you want.

You need to check for a "substantial change". Think about what happens
when the sun comes up -- every pixel changes constantly for 30 minutes.
Then there are cloudy days, and cloudy nights when the moon is out.

But that's all software refinement. The IP camera looks like the
solution.

- Peter

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