Subscriber Discussion

Video Issue In Store - LED Lighting, WDR - How Can I Improve It?

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Kyle Folger
•May 01, 2016
IPVMU Certified

So I just installed some cameras in a newly remodeled store. I installed the original cameras 5-6 years ago and they were analog surface mounted cameras. The architect drew some circles on the new plans and called them cameras and said they should be flush mount. I redrew the camera locations based off the dimensions and thought it would be nice to do some flush mount cameras since I generally don't do a whole lot of new construction.

I used the IPVM product search and past discussion searches and used one 3MP Dahua for the door camera and then used the Vivotek FD816C-HF2 for the overview cameras. They are working well but they are supposed to work with WDR on. The problem is I have a flickering issue and the whole entire store from the ceiling light fixtures to the display cases are 100% LED. If I adjust the flicker which adjusts the exposure settings, the problem goes away. However, once you turn on WDR pro, the flicker settings are grayed out and the issue comes back. The benefit of WDR in this case is to get a better view of the display cases. Now the IP cameras work much better than the analog ever did, but I'm not sure how to resolve this issue. Below are images. Please note these are photos of the screen but you should be able to see the problem. Thanks. I don't have the issue with the Dahua camera, but it also doesn't have WDR and is facing the door entry and WDR isn't necessarily needed.

WDR Pro ON:

WDR Pro OFF with flicker settings enabled:

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JH
John Honovich
•May 01, 2016
IPVM

Kyle, thanks for sharing, very informative!

The benefit of WDR in this case is to get a better view of the display cases

In our testing, WDR generally delivers its maximum benefit when the variation of light is extreme and there is a single bright/ hot area, like so:

In your case, the light variance is nowhere near as extreme and is alternating. So I do not think anyone's WDR would help much there.

I am not sure what settings, beyond WDR, will make the most difference, but I have shared this with Vivotek and we will promote the discussion to get more ideas.

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Kyle Folger
•May 01, 2016
IPVMU Certified
In reply to John Honovich

Traditionally, on analog cameras the display cases are always the brightest area of any scene and often appear like as shown in your included scene. However, IP cameras do often deal with light a lot better than analog. The reason for this is that all jewelry cases are individually lit up and then lit from above with spots and because jewelry is often highly reflective it makes the issue worse.

The WDR Pro was good enough in the scene above considering these are overview cameras but the lighting issue and not being able to adjust the flicker when WDR pro on becomes the problem.

Another point I forgot to add. When you have WDR completely off and flicker off, the problem still exists but its only easily seen on playback which appears as shadow-like horizontal lines that slowly move upward.

Since I didn't include a video, the multi-color lines are moving upward and aren't static. I have had issues with video before and LED lighting but it's usually at concerts when non-flicker free LED lighting is used.

The small back office has the original fluorescent lighting and the issues don't exist there to my knowledge. I can confirm that later today or tomorrow.

Now I didn't purchase these cameras with WDR as my first priority. I was looking for one of the smallest cameras to really make the remodel look good (and it did). I just wish the cameras had pre-construction brackets. The woman from corporate walked through for the punch-list meeting and I was still installing the POS system. She made a comment to the GC:

"So does the sprinkler guy still need to come back and put the caps on the heads."

GC:"No those are cameras."

Corporate: "Those are really small."

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U
Undisclosed #1
•May 01, 2016
IPVMU Certified
In reply to Kyle Folger

Kyle, the reason for the flicker during WDR is likely because of the fast shutter speed used during one of the two (?) exposures per frame that the camera now requires.

Since its trying to catch even the brightest elements of the scene without distortion, the fast exposure of the WDR may be as fast as 1/120, which may, dependening on the persistence of the luminaire and the line frequency, might cause certain exposures to be taken in between cycles, when the light output reaches a minimum. This is what causes the flicker.

You should make sure that the line frequency parameter is set correctly to 50 or 60.

Outside of that you need to do *something* to slow down the SS during the one half of the WDR. I'm not sure what parameters it will let you mess with in WDR mode, but maybe if the gain was higher, or the Iris smaller (if it's even controllable), it would get the SS under the 1/120 mark.

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AL
Albert Lin
•May 19, 2016

Hi Kyle,

The reply of Undisclosed 1 is correct about the exposure time of WDR pro. Since from the pictures you provided, it's a scene with a lot of white objects, which would make the exposure time even shorter, and make the overall exposure level lower as well. To improve the flicker issue, I would suggest two ways, either of them should help based on auto exposure theory.

1. Increase the exposure level. That will longer the exposure time.

2. Change the exposure measure windows from full view (majorly white scene) to a smaller windows which covers a relatively gray area (e.g. the down-right side of view).

I hope my suggestion helps. Thank you for adopting VIVOTEK products.

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Kyle Folger
•May 26, 2016
IPVMU Certified
In reply to Albert Lin

Thanks so much for the additional suggestions. I haven't had a moment to log back in the system and test the different options to see what removes the flicker. I will report back once I am able to log in and try different settings. I loved the the size of the cameras and they were relatively easy to install.

If I were to suggest one thing it would be metal pre-construction brackets so the drywallers can zip the holes on install and a cable holder to keep the cable out of the way to prevent it from getting cut. I was fortunate to have a good contractor that was careful around the cable stub-outs since this was a drywall ceiling. Other contractors may not always be that careful and considering how small the hole is your wire may get lost in the ceiling. I always try and use pre-construction brackets when available as they always speed up the finish. This is especially true with loudspeakers as those are typically much larger holes.

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Albert Lin
•May 26, 2016
In reply to Kyle Folger

Hi Kyle,

Thank you a lot for the valuable feedback. The idea of pre-construction bracket is new for our development team in Taiwan but it makes perfect sense and really can facilitate the installation. I will forward this information to our team and see if we can provide the bracket to the customers.

Kindly let me know if the suggested adjustment helps and we'd love to provide our best support.

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Kyle Folger
•Nov 29, 2016
IPVMU Certified
In reply to Albert Lin

I know it has been awhile since I responded. I am here to report back on a new install on the same cameras but new location but same store type. The difference is this is an outdoor mall. The other store was indoors. However, the greatest benefit of WDR for this would be overcoming the intensity of the display case lighting.

1. Increase the exposure level. That will longer the exposure time.

I could only do this with WDR pro turned off so there wasn't much I could do. What worked best was turning off WDR pro and turning on the flicker free option.

2. Change the exposure measure windows from full view (majorly white scene) to a smaller windows which covers a relatively gray area (e.g. the down-right side of view).

I tried this with WDR pro ON and it helped but without the option to adjust the shutter speed with that turned on, it just made the scene brighter or dimmer. With WDR pro OFF, changing the exposure measure settings had little effect.

Through all of this WDR enhanced was ON, but I don't believe this is True WDR.

I have WDR turned on for the Hikvision door cameras and they don't suffer from the LED flicker. The only thing I didn't try was a shot of the whole room with the Hikvision camera.

Aside from this issue, I still like the camera due to it's size. If I use these cameras for a similar project for pre-construction drywall install, I will probably get some sheet metal punched to act as pre-construction brackets. However, there isn't a lot of margin for error and for most projects I believe my 50mm hole saw is more acurate than the drywall contractors rotozip.

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