Question:
I'm looking to add video surveillance to my home automation rig on the
cheap. Real cheap. Egghead.com is selling a color Vivitar PC camera
(like the Connectix QuickCam) for 39 bucks. Does anyone know if it's
possible to remove the parallel port connecter and replace with an
RCA-type jack to a monitor or VCR? (and of course, get a usable picture
out of it!) Seems like it's just a CMOS board camera inside, but I don't
know if the CPU takes over any of the functions ordinarily found on the
camera board. Like I say, trying to work this real cheap!
Where can I buy a cheap Security Camera Video Surveillance?
Answer:Originally cameras were analog tubes, and they generated a swept analog
signal (NTSC composite video). When CCD's came along, they were a pixel
oriented (say 512x512 array) and needed circuitry to take the digital
values from each pixel element and massage them into the analog NTSC
signal all the rest of the world was used to seeing.
Of course, to use this in a computer, you needed to take that analog NTSC
video signal, and digitize it back into bits so the computer could deal
with it.
Connectix recognised that it was dumb to take a digital array, convert it
to an analog signal, then use a digitizer board to take the analog back
to digital again. So they built cameras that took the digital values from
the CCD elements, and streamed them out as digital values either via a
parallel port a byte at a time, or in a serial fashion over a serial
connection for Macs. Removes the cost (and D/A and A/D errors) of the two
unneeded conversions, so they can be cheaper.
But, that means that the connectix, and other cams with parallel or
serial ports, don't have the circuitry on board to make the analog signal
that your monitor or VCR is built to accept. They make a stream of
digital values, the monitor and vcr expect an analog signal. Sorry.
