Hi,
There are lots of old CCTV cameras out there. These generate a composite video signal
which is ( in B&W ) around 5MHz. Is it remotely feasible to use an Arduino ( or a faster avr )
to record the signal to an SD card for later playback?
Bruce
Basically no. For a 5MHz signal (even if it where digital) you have only 3.3 clock cycles per bit. Which is far to little to do anything use full. The best you can get from the ADC is 79.8KHz (as I recall from the spec) so that's no good.
But the good news is there are a few video shields out there, the bad news is you can not use any of them to record to SD.
Mark
http://arduino.cc/en/Reference/AnalogRead
"It takes about 100 microseconds (0.0001 s) to read an analog input, so the maximum reading rate is about 10,000 times a second."
5MHz*2 = 10MHz. (Nyquist)
That's orders of magnitude less than 10KHz. the fastest the Arduino's Analog input can sample.
OK, so sampling the video signal via A/D is a non-starter.
Can we approach this question from a slightly different perspective?
At present, I view my CCTV camera output on the pc via a widget that
does 'video capture'. I dont know what the widget does. It sends something along the
USB cable and something inside the pc transforms this into a pc compatible file (mpeg, I think )
Am I meddling in the work of the Devil here?
It seems a rotten shame I cannot use my CCTV cameras in some way without trailing
wires everywhere and, as i dont always need real-time viewing, recording the output
seems like a rattling good idea to me ( well, it would, wouldn't it ?). VCRs are hopeless:
I did it once, but the cold weather did for it. DVD maybe?
Bruce
Wireless web cams are relatively cheap and you can get weatherproof ones with pan/tilt control and motion detection etc without spending a lot of money. You just need to provide power.
There is a wide choice of software to do live video display, timed recording, motion detection triggered recording and so on.
It seems a rotten shame I cannot use my CCTV cameras in some way without trailing
wires everywhere and, as i dont always need real-time viewing, recording the output
seems like a rattling good idea to me ( well, it would, wouldn't it ?).
You might look at the various video senders that support analog cams.