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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.

Bryce
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    Could it be from wind shaking the camera in the mount? Or perhaps correlated with a large truck driving down a nearby street? – RibaldEddie Nov 17 '21 at 06:06
  • @RibaldEddie no. The fuzz is fully stable, and persists for hours or days. – Bryce Nov 17 '21 at 06:59
  • The only other things I can think of is some kind of autofocus malfunction or electromagnetic interference. – RibaldEddie Nov 17 '21 at 07:23
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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 '21 at 09:20
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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 '21 at 09:59
  • You might try searching on [photo.se], [video.se] or even [dsp.se]. I'm not sure if the question would be on topic there, but you might find answers there as they deal with imaging more than we do here. – FreeMan Nov 17 '21 at 12:52
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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 '21 at 13:09
  • I’m voting to close this question because small appliance repair and operation is off topic here. – isherwood Nov 17 '21 at 13:38
  • I don't think the question itself is off topic because design, installation, repair and maintenance of cabling and infrastructure to support a security system is on topic. If the issue can be confirmed to be *within* the DVR and not OP's wiring or installation, I agree that further diagnosis of the issue is off topic but I don't think a good question should be closed just because in OP's instance the resolution is eventually determined to be out of scope. – jay613 Nov 17 '21 at 14:28
  • 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. If this is true the strength of the reflection may vary over time. Some of the cables are easy to replace, others not so much. – Bryce Nov 17 '21 at 15:51
  • Note it is not possible to put a TV on the other end, as the signal is HD-TVI or HD-CVI, a digital format a TV would not understand. I don't have on hand the test equipment necessary to exclude a reflection due to impedance mismatch (though I could borrow it, if things seem to go in that direction). I'd like to learn more about HD-CVI, but have not yet found any good resource. – Bryce Nov 17 '21 at 15:56
  • Is it possible there is an air conditioner, garage door opener, or other large appliance in the vicinity whose vibrations when running could travel all the way to the camera? That would explain why it's intermittent. – Steve Wellens Nov 17 '21 at 16:00
  • @Bryce the HD-TVI/HD-CVI issue is why I think you'd have better luck at one of the other sites I suggested. – FreeMan Nov 17 '21 at 16:12
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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 '21 at 22:34
  • @dandavis no, sorry, that's not it. The effect occurs on hot and cold days, it's not dusty, the fan is working, etc, etc. – Bryce Nov 20 '21 at 05:36

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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

jay613
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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 '21 at 15:53
  • @Bryce reflections will not come and go. – fraxinus Nov 17 '21 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 '21 at 17:38
  • Since the signals are analog, a strong nearby transmitter could interfere with the signal. – VE3LNY Nov 17 '21 at 20:19
  • TVI is not analog, it's compressed digital, so we can forget about "reflections" or "impedance" issues. – dandavis Nov 17 '21 at 22:28
  • @dandavis can you link to some reading on TVI? I know almost nothing, and there's a link in my answer to an article that says it's analog. So you know, I read it on the internet. – jay613 Nov 17 '21 at 22:48
  • @jay613 i googled "is tvi digital". I think the confusion stems from the fact that's its a compressed bit stream, not an encoded video stream like an IP or wifi camera would spit out. Essentially it's a compressed hi-res sampling of the analog (ccd) or raw (cmos) signal, and that's it. – dandavis Nov 17 '21 at 22:57
  • Even analog tv would not blur vertically. – Harper - Reinstate Monica Nov 17 '21 at 23:30
  • @Harper-ReinstateMonica See photos I added to my answer. – jay613 Nov 18 '21 at 03:18
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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 '21 at 03:25
  • The HD-CVI and HD-TVI formats are a digital representation of the analog video signal intended to increase resolution and transmission distance. They are simple real time signals, with all the framing and timing of an analog video signal. There is no codec involved. However reflection and impedance issues are 100% relevant. On another form power supply issues were mentioned, but I feel I've excluded for that in my tests. – Bryce Nov 20 '21 at 05:39