Re: CCTV cameras - feed to PC s/w

["patricklidstone" <patrick@xxxxxxx>]

>I really want to record any movement from any of the 5 camera's onto
>a PC. I'm looking for s/w and ways of doing this. I guess there are
>two ways of doing this:
>
> 1)	fit PIR's with each camera (which I will be doing in some of
the locations anyway) and have Comfort/HV/ACE switch the active zone
to the PC which would then record via some simple software (what
s/w???)
> 2)	Use some kind of multi-input camera card (as discussed many
times on this list) and let that decide which zone has been triggered
by it's software
>

I've had (1) working - I built a simple analogue switch circuit based
around a 4066 chip, and controlled that via the parallel port. Both
the switch and Comfort are xAP-enabled, so gluing them together was
easy. The only issue with this is that you don't necessarily get a
historical perspective - you only start recording *after* you've seen
movement. Depending on the field of vision that the camera has, this
may not capture anything useful. You can mitigate this to an extent
if the layout of your property allows you either to have the PIR
anticipate someone coming into view (e.g. a camera at the top of a
path is triggered by a PIR at the bottom of a path), or by recording
a running window of a camera with a primary view.

Option (2) is problematic: most multi-port cards only switch between
sources, they don't provide a true simultaneous feed. That means the
motion detection software would have to store a snapshot of each
feed, and retrieve and compare the snapshot on the next successive
cycle. It's not impossible, but it's less than ideal - and the
framerates are generally low on multiport cards, making the whole
thing a bit laggy. Off-the-shelf software is also limited with
multicards, since they all seem to use different techniques for
switching.

A third option is to modulate the camera feeds, and tune to the
appropriate channel when movement is detected. This can work
surprisingly well.

HTH

Patrick