DAHUA IP PRO-AI 8MPX: any way to reduce the ghosting behind moving objects?

O

Olli Raatikainen

n3wb
Nov 26, 2016
16
1
Hi all.

We are streaming live kids football from an airdome. The setting is kinda challenging, because the distance between the camera and the farthest corner of the airdome is circa 70m, it's sub-zero temps during the winter when there are no football practice, walls are very close the the field borders, the camera has to be very durable and permanently mounted etc. etc. Luckily our lighting is top notch, so that's not a problem.

Currently we're using only one cam, because there's no-one to act as a "director" for the camera(s)/stream and watching football stream with multiple cameras displayed at once (split screen in OBS or something else) is not really very entertaining... To overcome this, I figured to use only one camera and maximum resolution/bitrate to get as much details as possible with that one camera. Here are the technical specs:

-Dahua IP Pro 8MP, maximum bitrate is ca. 16000Kbps, latest fw.
-Ryzen U4500/8GB/512SSD laptop with Win10
-250/50 Mbps internet connection
-Latest OBS/Restreamer = no processing done for the camera stream, only passthrough.
-Platform: Youtube (or something else, whatever gives the best results and is easily accessible for the kids parents etc.), tested with Youtube.

After fiddling with the camera settings for a while, I'm pretty pleased with the results. Currently the stream is like this:

-1080P
-16Mbps
-25fps (PAL=it's the maximum)
-H.264
-Smart codec is OFF

However there's this "ghosting" or "trailing" behind all moving objects (kids, ball etc.) It's not the laptop or the streaming software (e.g. CPU load or something like that). The stream is perfectly smooth also, there's no problems with the connection or anything like that, so I'd say the "problem" is at the camera's end.

As the combination of all those settings in the Dahua settings interface is pretty overwhelming with pure luck/trial and error, would someone have a clue how could I try to reduce the ghosting? Also it seems that there's quite much "noise" in the picture without the 3D noise filter on, but that's a minor problem compared to the ghosting.
 
Last edited:
Was it the exposure setting - sounds like auto and the gain is too high. Change to a manual shutter where you can set the shutter speed and the gain. Try a shutter at 0-8ms and gain 0-35. Ghosting is usually from too much gain. Then adjust from there until you are happy with the results.

The faster the shutter, the more light is needed. Too high gain causes the ghosting.

All these cameras need noise reduction - try to run as low as you feel comfortable with. Try 20 and then go up or down from there until it is a problem.

Common issues with camera image

Here is a quick guide to what might go wrong with the image of your cctv camera, and how to fix this. MOTION BLUR: This is probably the most common issue, new camera owners run into. Many times on this forum I've seen posts like: "I bought a set of cameras recently. The image looks great on...
ipcamtalk.com ipcamtalk.com
 
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wittaj said:
Was it the exposure setting - sounds like auto and the gain is too high. Change to a manual shutter where you can set the shutter speed and the gain. Try a shutter at 0-8ms and gain 0-35. Ghosting is usually from too much gain. Then adjust from there until you are happy with the results.

The faster the shutter, the more light is needed. Too high gain causes the ghosting.

All these cameras need noise reduction - try to run as low as you feel comfortable with. Try 20 and then go up or down from there until it is a problem.

Common issues with camera image

Here is a quick guide to what might go wrong with the image of your cctv camera, and how to fix this. MOTION BLUR: This is probably the most common issue, new camera owners run into. Many times on this forum I've seen posts like: "I bought a set of cameras recently. The image looks great on...
ipcamtalk.com ipcamtalk.com
Click to expand...

Thank you for a detailed answer wittaj :) I'll try this later today and adjust the shutter speed and gain. I'll report back :)
 
Lowering the gain helped quite a bit, thank you! :) There's still little "haze" around moving objects, I really don't know if there's anything to make it better still. The Iris, Exposure compensation etc. settings seems to affect the picture quite a bit also. Would you happen yo have any hints compared to the screenshot below. I'm operating the streaming machine and Dahua remotely via TeamViewer, which means that testing the end result in Youtube is not really straightforward. Any obvious problems in the settings below would help me to get closer to the target :)
1611741939671.png
 
Can you post a short clip or at least image sample?
 
Yeah, a short clip or image will help.

But I suspect there might not be much you can do with that little "haze" or halo - I have noticed that can happen when there is a contrast between the subject and background, or too big a range on gain or the bitate is too low. What bitrate are you running?

Since it is enclosed, the ambient light is generally gonna be the same regardless of time of day, so try to find the gain that works and then run the same gain low and high, so if it works at 30, then make it 30-30.

You could try a faster shutter too, but I suspect you found that to be the optimal that "gets the action" while still not being too dark. You might be able to run a faster shutter and then make the gain a little higher. You could probably take gain to 45-45 before the ghosting starts to return. I wanted you to start at a lower number that would knock it out, so now it is add it back to bring brightness while still not ghosting.

You may also want to try the anti-flicker at the other option as well- the lights in an airdome may need a different frequency.

And finally, running the iris at 100 can cause that as well.

Every camera is different obviously, even between the same brands, but generally you try to keep them closer to the middle settings range, so I would try backing the iris down to 50-60 range.
 
Last edited:
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Thank you for the replies :) It's the "halo", I guess. You can see a screenshot below, although it's not so obvious compared to a video clip. The screenshot is so tiny as I just wanna keep things "safe" and not post any recognisable stuff, since nowadays it's kinda risky.

I've played with the Gain and other settings a bit more and it's get s better. The halo seems to be there always when the shutter is of value that does not give too dark picture. I've tried all bitrates from 6000Kbps all the way up to 16000 kbps. Result is basically the same. I guess it's the contrast since the artificial grass vs. moving objects makes quite a contrast.

1611773798229.png
 
Yeah, between the speed of motion and the contrasting background, the halo may always be present to some degree.

Did you try a faster shutter speed and then adjust the image parameters like brightness, contrast, sharpness, and gamma? You can probably squeak a little faster shutter by bumping up the brightness a bit and the gamma without impacting quality too much. Bump sharpness up a bit as well and see if that can reduce the size of the halo.
 
Olli Raatikainen said:
Hi all.

We are streaming live kids football from an airdome. The setting is kinda challenging, because the distance between the camera and the farthest corner of the airdome is circa 70m, it's sub-zero temps during the winter when there are no football practice, walls are very close the the field borders, the camera has to be very durable and permanently mounted etc. etc. Luckily our lighting is top notch, so that's not a problem.

Currently we're using only one cam, because there's no-one to act as a "director" for the camera(s)/stream and watching football stream with multiple cameras displayed at once (split screen in OBS or something else) is not really very entertaining... To overcome this, I figured to use only one camera and maximum resolution/bitrate to get as much details as possible with that one camera. Here are the technical specs:

-Dahua IP Pro 8MP, maximum bitrate is ca. 16000Kbps, latest fw.
-Ryzen U4500/8GB/512SSD laptop with Win10
-250/50 Mbps internet connection
-Latest OBS/Restreamer = no processing done for the camera stream, only passthrough.
-Platform: Youtube (or something else, whatever gives the best results and is easily accessible for the kids parents etc.), tested with Youtube.

After fiddling with the camera settings for a while, I'm pretty pleased with the results. Currently the stream is like this:

-1080P
-16Mbps
-25fps (PAL=it's the maximum)
-H.264
-Smart codec is OFF

However there's this "ghosting" or "trailing" behind all moving objects (kids, ball etc.) It's not the laptop or the streaming software (e.g. CPU load or something like that). The stream is perfectly smooth also, there's no problems with the connection or anything like that, so I'd say the "problem" is at the camera's end.

As the combination of all those settings in the Dahua settings interface is pretty overwhelming with pure luck/trial and error, would someone have a clue how could I try to reduce the ghosting? Also it seems that there's quite much "noise" in the picture without the 3D noise filter on, but that's a minor problem compared to the ghosting.
Click to expand...
Did you try CBR instead of VBR? Turn all noise reduction down for testing.
 
wittaj said:
Yeah, between the speed of motion and the contrasting background, the halo may always be present to some degree.

Did you try a faster shutter speed and then adjust the image parameters like brightness, contrast, sharpness, and gamma? You can probably squeak a little faster shutter by bumping up the brightness a bit and the gamma without impacting quality too much. Bump sharpness up a bit as well and see if that can reduce the size of the halo.
Click to expand...

Yes, I tested with various faster shutter speeds. It seems 4ms is pretty good compromise regarding the amount of light and speed :)

3D noise reduction is likely the culprit here since it works by combining frames with earlier frames. Turn that down. Turn 2D noise reduction back up if needed to compensate.
Click to expand...

Yeah, that seems to add some halo, thanks for the tip :)

spammenotinoz said:
Did you try CBR instead of VBR? Turn all noise reduction down for testing.
Click to expand...

I'm running CBR.

All in all the settings are now pretty good. I actually changed the stream to be 4K (16000 kbps) for the most tech savvy parents out there to be able to watch the games in 4K ;) I'm now running Restreamer, which just passes the streams through without any encoding. We have a custom, self-made (browser based) score board/clock operated with a smart phone, which I was hoping to be able to overlay on top of the video in the corner, but at the current stream settings our reasonably powerful laptop can't handle it using OBS :/ Oh well, time upgrade the hardware :)

Thank you all for the guidance, now the stream is as good as it can be :)
 
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