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Ok, sometimes my home security camera produces this image: Shadow on Lorex CVI camera image fuzzy Sometimes for hours or days on end it will show: enter image description here

This is a big deal, because I spent considerable time running the Siamese cables to the places needed: if it's a cable issue it's a lot of work to change the cable.

The issue is stable, and not related to motion. Cleaning the lens has no effect, nor does shaking or remaking the connections (other than power as noted below).

The issue occurs across several different brands of cable, power supply, specific camera and encoding format (with some cameras I can switch AHD, HD-CVI, HD-TVI or Pure Analog). The issue comes and goes, and sometimes but not always fixes itself if I power cycle the camera. It sometimes but not always fixes itself if I change video formats on the camera end.

Sometimes I think it's humidity, other times not so sure. Sometimes I can get it to clear up by power cycling, other times it sticks over multiple cycles.

Here's another image: enter image description here

What could be going wrong? This even happens on different length cables (I have not yet correlated if the apparent offset can be changed by adding cable length, as that requires higher voltage to offset voltage loss in the cable). I have not yet tried an attenuator. I assume it's a reflection on the length of the cable, but not positive.

The DVR is from a well known Chinese company that merged with or bought out an American name.

Has anyone seen this? How did you solve it?

Update: I have inserted an extra 75' of cable to CAM1 both power and video. At this time the issue is not happening with or without the extra cable. But the video is stable.

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  • 1
    Could it be from wind shaking the camera in the mount? Or perhaps correlated with a large truck driving down a nearby street? Nov 17, 2021 at 6:06
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    The fuzz does not happen on the "CAM 8" or date/time text. So the issue occurs upstream of whatever adds the text. If this text is added by the camera on top of the picture, then you know it doesn't come from anything downstream from the camera. If the text is added by the recorder, then the problem could be upstream of the recorder. Which one is it?
    – bobflux
    Nov 17, 2021 at 9:20
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    It looks almost like a double exposure - a hard edge becomes 2 edges rather than one blurred edge (parallel lines, not a fade). Strange that it happens with multiple brands of camera and multiple modes. It doesn't sound like tried changing the receiver/recorder. Can you put a TV on the other end of the cable to test? Ideally simultaneously with the recorder, and you may need analogue mode to have a common standard
    – Chris H
    Nov 17, 2021 at 9:59
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    Picking up on above comments: 1) It is likely the DVR is adding the subtitles because CAM8 doesn't know it's CAM8, only the DVR knows that. 2) It is unlikely that multiple camera models using different encodings would all exhibit the same unusual behavior. So the problem is most probably in the DVR signal processing pipeline. You should probably contact the DVR maker's support team or if it's under warranty just get a different one. Connecting one camera to a TV to confirm this is a good idea.
    – jay613
    Nov 17, 2021 at 13:09
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    Open and blow out your DVR's case, it could be overheating. That explains the intermittent nature. Heat can cause RAM (incl video ram) to miss a refresh. It can also cause the main processor to slow down and drop frames, which could cause the video encoder problems generating its P-frames, which can sometimes present as ghosting.
    – dandavis
    Nov 17, 2021 at 22:34

1 Answer 1

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According to the information you have provided it appears as though the cameras, cabling, and installation are all in working order. Very helpful that you provided good and bad images and images from multiple cameras!

As noted in the comments above, it seems most likely the problem is within your DVR appliance. The solution is to look at the fault-finding section of the manual and/or call the maker's support team. We can't help here with device-specific problems like this.

Based on my (admittedly very limited) "research" and the comment below from @Bryce, another possible problem is physical cabling problems. The noted video formats are analog. With analog signals, it is possible to have the noted effects (ghosting, doubling) given certain cable problems like bad terminations, kinks, and others. If there are best practices, diagnostics, debugging techniques, that would help homeowners and installers build infrastructure for newer HD security systems, that would be great information here.

Observation 1: This is pure ghosting, no blurring, pixelation or other fuzziness

enter image description here

Observation 2: The ghosting is purely horizontal

Cam1 enter image description here

Cam8 enter image description here

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  • I suspect the problem is an impedance mismatch in the cabling, resulting in a reflection of the video signal, which travels back to the camera, and bounces back to the DVR. I'm surprised this would affect the semi digital formats like HD-CVI, but here we are.
    – Bryce
    Nov 17, 2021 at 15:53
  • @Bryce reflections will not come and go.
    – fraxinus
    Nov 17, 2021 at 17:14
  • @bryce I don't know what "semi digital" means. My learning about these video formats is limited to the last 5 minutes, but they are analog and so issues like impedance mismatch could cause them. I've added your theory to my answer.
    – jay613
    Nov 17, 2021 at 17:38
  • Since the signals are analog, a strong nearby transmitter could interfere with the signal.
    – VE3LNY
    Nov 17, 2021 at 20:19
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    @dandavis If it's byte samples it's digital. There has to be an encoding of word starts and ends, and maybe some kind of error detection or correction. Unless the bytes/words are being replicated perfectly we wouldn't see the flawless ghosting we see in the photos, we'd see a lot more noise or total signal loss. And if it's compressed and there was mangling at the wire level, we'd only see total signal loss. Unless the compression had a ton of redundancy and error correction. But I think you're saying it's more simplistic. Again, I can't find a codec spec so I'm not claiming expertise.
    – jay613
    Nov 18, 2021 at 3:25

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