Troubleshooting Sub stream blink in Black and white at night

[xebra]

I've tried searching for information like this, but nothing comes up. I must be using the wrong search terms.
I have continuous record on this one camera. The recordings are an hour long so I clipped a section to show what's happening.
This affect of blinking (defocusing?) doesn't occur during the day in color, but randomly in Black and white at night, with and without the IR LED on.
I forced a recording for about an hour during the day in color but no blinking on the main stream or anytime during the day.
I'll need to rewatch the camera this evening, directly through the camera web interface to see if the blinking occurs there too. I should have thought of that earlier..
The last change I made was to the bit rate for the sub stream up to 1280 but haven't had it overnight at that bit rate.
Any advice will be appreciated.
In the video clip, the blink occurs at 6:01:16 and again at 6:01:33. In an hour recording I'll see 5 or more at seemingly random intervals.

The camera is a Dahua

Varifocal Turret IPC-T54IR-ZE-S3

FW :

V3.142.15OG003.0.R,Build Date: 2024-12-21

View attachment Frontblink.20250405_060000.mp4

 

[wittaj]

If you notice, there is a light flash from the light at the far garage just before those times and it appears that is changing the exposure of the camera due to the rapid change in available light.

That is why you don't see it during the day.

Might be a short in that garage light causing it to flicker intermediately.

 

[xebra]

Thanks for the quick response!
I have a recording from last night and it does the same thing. The owner repaired the lights on the garage across the street yesterday afternoon.

 

[xebra]

Further investigation showed that with a color sub stream recording up until midnight, no blink.
Just after midnight the sub stream changed to B & W and I saw several blinks
I'm nearly certain this is a refurbished camera I got from Empiretech in the past 3 months, so it makes me wonder if it was originally returned for this issue...

 

[wittaj]

Post a video of it after the neighbor fixed the garage light

 

[bigredfish]

If you notice, there is a light flash from the light at the far garage just before those times and it appears that is changing the exposure of the camera due to the rapid change in available light.

That is why you don't see it during the day.

Might be a short in that garage light causing it to flicker intermediately.

^^^^
This

 

[wittaj]

If it is still happening and the neighbors light isn't wonky, then I would look at turning off smart IR if you have it on, and if not backing down the IR hotspot. And make sure WDR isn't on.

Further, you have exceeded many of the limits we suggest for settings. Gain and gamma over 60 can be problematic, along with NR over 50, and a shutter range of 18-33ms is too slow for freeze frame of a perp.

All of those higher numbers can also cause the exposure issue you are seeing.