Re: Convert CCTV to Digital

[Matt Ion <soundy@xxxxxxxxxxxxxxx>]

Bob La Londe wrote:
> "Matt Ion" <soundy@xxxxxxxxxxxxxxx> wrote in message
> news:rSKqf.52930$2k.49334@xxxxxxxxxxx
>
>>Bob La Londe wrote:
>>
>>>"Matt Ion" <soundy@xxxxxxxxxxxxxxx> wrote in message
>>>news:Wdhqf.165576$Gd6.160875@xxxxxxxxxxx
>>>
>>>
>>>>anthony.clendenen@xxxxxxxxx wrote:
>>>>
>>>>
>>>>>I am open to any solution.  My main points are to get the image storage
>>>>>up to the office so that if the store gets broken into they don't take
>>>>>the video with them and to get it to a digital signal.  Currently there
>>>>>is only the one BNC cable that is going up to the office so I was
>>>>>hoping to avoid having to run more cable and just use the one cable
>>>>>coming up to the office.
>>>>>
>>>>>Would it be possible to have the cameras connect to some kind of
>>>>>multiplexer that could send the video wirelessly up to the office and
>>>>>then to a DVR card?
>>>>
>>>>The problem is, a multiplexer by definition takes the separate signals
>>>>and provides a combined output, so even wirelessly, the MUX output would
>>>>be the same as with your single cable.
>>>
>>>
>>>Nope.  A quad does that, but a true multiplexor sends single full frame
>>>images sequentially. Some can do it based on activity.  A single channel
>
> DVR
>
>>>that has settings for different standard multiplexors will record it
>>>properly.  The DSR2000e by Kalatel will work with multiplexors upto 16
>>>channels.  It has some other problems, but...  I don't like that
>
> particular
>
>>>recorder because of other issues.
>>
>>Ah yes, you are correct... but then there's also the issue of missing
>>frames as they switch.  If the MUX outputs at 4FPS, 1FPS per camera is
>>the most you're going to get on the DVR, which on modern units is pretty
>>minimal.
>>
>>Either way, it's a rather inelegant solution.
>>
>>
>>
>
>
> Have you done it?  Actually a mux outputs typically at a much higher rate
> than that.

On the VCR output, yes, but then you'll get one input on the DVR
recording a fast sequence of changing images.  You could record it with
a higher frame rate, but it would be a serious bitch to monitor, because
you've have no way to selectively view only one camera.  It would have
to selectively show every fourth or ninth or sixteenth frame during
playback, and you would have to have it record constantly to avoid the
frames going out of sync as they would with motion-detect recording
(actually, the motion-detect function in software would probably see the
switching as motion and trigger recording constantly anyway).

DVRs are typically designed WITH multiple inputs, to record a SINGLE
source per input.  IF you could find one that will selectively show only
every fourth or ninth frame on playback, it would work, but there would
be little point to such a thing, and thus little point in anyone making
one.  If you know of such a device, I'd be interested to be proved
wrong, but I'd expect them to be pretty rare, and subsequently fairly
expensive for a single-input machine.

The point is, as I said, even if possible, it's far from elegant or
efficient.


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