Recordings get grainy then clear, repeatedly

ipslascam

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I have a Dahua IPC-HFW1831E (EmpireTech) that I'm using a Synology Surveillance station to record with. Looking at the camera's live view, it seems fine, but looking through the recordings, at certain times of the day I'm seeing the picture starts to get artifacts and very grainy, then clear up. It does this every 20 seconds or so. I attached some screenshots to give an idea.

The reason I didn't post under the Dahua sub-forum is because I'm not sure if this is a camera problem or something else. I've actually been having problems with my install for a while and had similar problems with a Hikvision camera previously. Since the PoE cable going to the camera runs near some power wires, I was advised that I should switch them to shielded cables. I just ran new shielded cat 6 cable and speed tests and ping work great with no packet drops, but the bad picture remains.

Is it possible the problem is with the camera's settings, or with the Surveillance station configuration? Any suggestions for how I should troubleshoot what's going on?
 

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fenderman

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I have a Dahua IPC-HFW1831E (EmpireTech) that I'm using a Synology Surveillance station to record with. Looking at the camera's live view, it seems fine, but looking through the recordings, at certain times of the day I'm seeing the picture starts to get artifacts and very grainy, then clear up. It does this every 20 seconds or so. I attached some screenshots to give an idea.

The reason I didn't post under the Dahua sub-forum is because I'm not sure if this is a camera problem or something else. I've actually been having problems with my install for a while and had similar problems with a Hikvision camera previously. Since the PoE cable going to the camera runs near some power wires, I was advised that I should switch them to shielded cables. I just ran new shielded cat 6 cable and speed tests and ping work great with no packet drops, but the bad picture remains.

Is it possible the problem is with the camera's settings, or with the Surveillance station configuration? Any suggestions for how I should troubleshoot what's going on?
Post your cameras video settings. This is common when set to vbr and long iframe intervals.
Who ever told you to change cables really wasted your time. These are ip cameras and dont suffer that kind of "interference" we used to see in analog cams that would cause noise in the video.
 

ipslascam

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Post your cameras video settings. This is common when set to vbr and long iframe intervals.
Who ever told you to change cables really wasted your time. These are ip cameras and dont suffer that kind of "interference" we used to see in analog cams that would cause noise in the video.
System Info

System Version: 2.622.0000000.18.R, Build Date: 2019-01-09

Camera Conditions

Picture settings: 50 for all of them
Exposure:
  • Anti-flicker: Outdoor
  • Mode: Auto
  • 3D NR: On
  • Grade: 20
Backlight: Off
WB: Auto
Day and Night:
  • Mode: Auto
  • Sensitivity: Middle
  • Delay: 6s
IR Light: Auto

Video

Encode Mode: H.264
Smart Codec: Off
Resolution: 3840
Frame Rate: 5
Bitrate Type: VBR
Quality: 6 (Best)
Max Bitrate: Customized 6656
I Frame Interval: 10
 

wittaj

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Try the following. As mentioned the VBR is lowering the bitrate without motion.

Match Frame Rate and Iframe interval
Bitrate CBR
Bitrate 10,240
 

wittaj

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And you should consider taking everything off auto/default settings. When the perp comes by in the middle of the night, auto settings will fail you.

Here is my "standard" post that many use as a start for dialing in day and night that helps get the clean captures.

Every field of view is different, but I have found you need contrast to usually be 6-8 higher than the brightness number at night.

We want the ability to freeze frame capture a clean image from the video at night, and that is only done with a shutter of 1/60 or faster. At night, default/auto may be on 1/12s shutter or worse to make the image bright.

In my opinion, shutter (exposure) and gain are the two most important parameters and then base the others off of it. Shutter is more important than FPS. It is the shutter speed that prevents motion blur, not FPS. 15 FPS is more than enough for surveillance cameras as we are not producing Hollywood movies. Match iframes to FPS. 15FPS is all that is usually needed.

Many people do not realize there is manual shutter that lets you adjust shutter and gain and a shutter priority that only lets you adjust shutter speed but not gain. The higher the gain, the bigger the noise and see-through ghosting start to appear because the noise is amplified. Most people select shutter priority and run a faster shutter than they should because it is likely being done at 100 gain, so it is actually defeating their purpose of a faster shutter.

Go into shutter settings and change to manual shutter and start with custom shutter as ms and change to 0-8.3ms and gain 0-50 (night) and 0-4ms exposure and 0-30 gain (day)for starters. Auto could have a shutter speed of 100ms or more with a gain at 100 and shutter priority could result in gain up at 100 which will contribute to significant ghosting and that blinding white you will get from the infrared or white light.

Now what you will notice immediately at night is that your image gets A LOT darker. That faster the shutter, the more light that is needed. But it is a balance. The nice bright night static image results in Casper blur and ghost during motion LOL. What do we want, a nice static image or a clean image when there is motion introduced to the scene?

In the daytime, if it is still too bright, then drop the 4ms down to 3ms then 2ms, etc. You have to play with it for your field of view.

Then at night, if it is too dark, then start adding ms to the time. Go to 10ms, 12ms, etc. until you find what you feel is acceptable as an image. Then have someone walk around and see if you can get a clean shot. Try not to go above 16.67ms (but certainly not above 30ms) as that tends to be the point where blur starts to occur. Conversely, if it is still bright, then drop down in time to get a faster shutter.

You can also adjust brightness and contrast to improve the image.

You can also add some gain to brighten the image - but the higher the gain, the more ghosting you get. Some cameras can go to 70 or so before it is an issue and some can't go over 50.

But adjusting those two settings will have the biggest impact. The next one is noise reduction. Want to keep that as low as possible. Depending on the amount of light you have, you might be able to get down to 40 or so at night (again camera dependent) and 20-30 during the day, but take it as low as you can before it gets too noisy. Again this one is a balance as well. Too smooth and no noise can result in soft images and contribute to blur.

Do not use backlight features until you have exhausted every other parameter setting. And if you do have to use backlight, take it down as low as possible.

After every setting adjustment, have someone walk around outside and see if you can freeze-frame to get a clean image. If not, keep changing until you do. Clean motion pictures are what we are after, not a clean static image.
 

ipslascam

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Post your cameras video settings. This is common when set to vbr and long iframe intervals.
Who ever told you to change cables really wasted your time. These are ip cameras and dont suffer that kind of "interference" we used to see in analog cams that would cause noise in the video.
And you should consider taking everything off auto/default settings. When the perp comes by in the middle of the night, auto settings will fail you.

Here is my "standard" post that many use as a start for dialing in day and night that helps get the clean captures.

Every field of view is different, but I have found you need contrast to usually be 6-8 higher than the brightness number at night.

We want the ability to freeze frame capture a clean image from the video at night, and that is only done with a shutter of 1/60 or faster. At night, default/auto may be on 1/12s shutter or worse to make the image bright.

In my opinion, shutter (exposure) and gain are the two most important parameters and then base the others off of it. Shutter is more important than FPS. It is the shutter speed that prevents motion blur, not FPS. 15 FPS is more than enough for surveillance cameras as we are not producing Hollywood movies. Match iframes to FPS. 15FPS is all that is usually needed.

Many people do not realize there is manual shutter that lets you adjust shutter and gain and a shutter priority that only lets you adjust shutter speed but not gain. The higher the gain, the bigger the noise and see-through ghosting start to appear because the noise is amplified. Most people select shutter priority and run a faster shutter than they should because it is likely being done at 100 gain, so it is actually defeating their purpose of a faster shutter.

Go into shutter settings and change to manual shutter and start with custom shutter as ms and change to 0-8.3ms and gain 0-50 (night) and 0-4ms exposure and 0-30 gain (day)for starters. Auto could have a shutter speed of 100ms or more with a gain at 100 and shutter priority could result in gain up at 100 which will contribute to significant ghosting and that blinding white you will get from the infrared or white light.

Now what you will notice immediately at night is that your image gets A LOT darker. That faster the shutter, the more light that is needed. But it is a balance. The nice bright night static image results in Casper blur and ghost during motion LOL. What do we want, a nice static image or a clean image when there is motion introduced to the scene?

In the daytime, if it is still too bright, then drop the 4ms down to 3ms then 2ms, etc. You have to play with it for your field of view.

Then at night, if it is too dark, then start adding ms to the time. Go to 10ms, 12ms, etc. until you find what you feel is acceptable as an image. Then have someone walk around and see if you can get a clean shot. Try not to go above 16.67ms (but certainly not above 30ms) as that tends to be the point where blur starts to occur. Conversely, if it is still bright, then drop down in time to get a faster shutter.

You can also adjust brightness and contrast to improve the image.

You can also add some gain to brighten the image - but the higher the gain, the more ghosting you get. Some cameras can go to 70 or so before it is an issue and some can't go over 50.

But adjusting those two settings will have the biggest impact. The next one is noise reduction. Want to keep that as low as possible. Depending on the amount of light you have, you might be able to get down to 40 or so at night (again camera dependent) and 20-30 during the day, but take it as low as you can before it gets too noisy. Again this one is a balance as well. Too smooth and no noise can result in soft images and contribute to blur.

Do not use backlight features until you have exhausted every other parameter setting. And if you do have to use backlight, take it down as low as possible.

After every setting adjustment, have someone walk around outside and see if you can freeze-frame to get a clean image. If not, keep changing until you do. Clean motion pictures are what we are after, not a clean static image.
Thanks - I'm outside trying out these settings at night right now. 1/120 shutter speed is fairly dark. 1/100 is not bad. I tried adjusting the gain up to 60 and it didn't seem to add ghosting. That said, it seems I can adjust the shutter speed or the gain and get similar pictures. Of those two, which would you prefer to adjust first?
 

wittaj

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It is a tradeoff and every camera and field of view is different.

It really comes down to test it both ways and see which gives the best results. Some cameras ghost and artifact at 60 gain, while others can go to 70 before issues.

1/100 shutter is a decent speed and will get clean captures of all but the fast movers.
 
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