pulsating refresh look to image. I Frame issue maybe?

B

billtetley

n3wb
Jul 22, 2015
16
1
I have been playing around with the i frame settings on my cameras. The default is 50. My cameras are running at 3mp and 1/30 for exposure. I changed the i frame to 20 to match the fps setting of 20. I'm getting this weird pulsating look to the image. I uploaded a clip. You can really notice it in the driveway and grass. It seems to happen every second. Any thoughts?

[video]https://youtu.be/KWBIzyMcbTo[/video]
 
It is the i-frames causing the pulsing effect. I-frames are big and they consume a large amount of the total bit rate. If the bit rate is not high enough, the iframes will often cause a distinct drop in quality.

So I recommend you increase your bit rate to at least 8 Mbps, when running 3 MP @ 20 FPS. If you are encoding with VBR (variable bit rate) then choose a higher quality setting also, otherwise the camera may not be using all of your assigned bit rate.

If this does not reduce the effect enough, then you can increase the i-frame interval and/or reduce the frame rate. Best results will be if you do both.
 
I'm running variable bit rate and the default bit rate of 4096 I think? So I should change it to constant and 8192? Let me give that a shot.
 
VBR 4096 is normally fine I find. Give VBR 8192 a go.

It's going to be trial and error but you've got nothing to lose... just a bit of time.
 
tried it with constant and 8192 and it improved, but was still there...just not as noticeable. Maybe if I change the iframe rate, but i'm not sure where to go with it. I know default is 50, but is there any sort of recommended setting for it? should it match your fps or is it more of a personal preference type of deal?
 
Maybe a red-herring but what type of cable are you using... just that I used some non-twisted cheap stuff and had issues once.

Try i-frame of 20, 40 and 60.

Was it working fine before?
 
Del Boy said:
Maybe a red-herring but what type of cable are you using... just that I used some non-twisted cheap stuff and had issues once.

Try i-frame of 20, 40 and 60.

Was it working fine before?
Click to expand...

It looked alright at 50, but then I started playing with settings after looking at the review done by network camera critic on this particular camera. It's at 20/20 and VBR with 8192 bit rate and it's better....if you look for it, you can see it. Wiring is belden home a/v cat 5e wire. Same that I used on other cameras.
 
If it looked alright at 50 and 4096, then maybe putting it back to this setting is the best idea. Just cos NCCs worked for him doesn't mean it's best for all, otherwise they'd be no settings to play with.
 
So I changed bit rate to VBR and 6144. I changed the i-frame to 40. I still notice when the iframe changes, but since it's not as often it doesn't bother me as much. I also went through and got the day/night settings setup in the scheduler. Man, that is a great feature since the best day settings don't work well and night and vice versa. I think I've finally got it dialed in.
 
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