I-Frame intervals settings

[smokingjoe 0]

Hi all

I have Dahua cameras connected to a new UNIVIEW NVR that I am trying out. The UNIVIEW NVR gives me the option to set the I-Frame interval in the camera setup options. The default setting is 24 I-Frames. I am recording at 20 fps. The cameras are viewing a front yard, driveway and a few out buildings. "Not a lot of activity." If I understand it right, lowering the I-Frame setting should save hard drive space but may reduce my video quality a little.

I have also heard that I should have my frame rate set to a multiple of my I-Frame setting.

Any thoughts?

[survtech 0]

It depends on a number of factors. While changing the I-frame setting can affect bit rate, it's not as simple as that. 24 probably means there is one I-frame for every 23 P-frames. When running 20fps, that means one I-frame every 1.2 seconds. So to save space, you would have to raise, not lower, that setting.

 

But a lot depends on the capabilities of the encoder. Changing I-frame intervals can affect the size of the P-frames and actually result in higher bitrates and/or lower picture quality.

 

My suggestion is to experiment. Note the original settings, then change encoder settings and observer the result.

[ssmith10pn 0]

Why are you wasting hard drive space recording at 20fps? Are you a casino? Anything over 10fps is a waste on a fixed camera.

[smokingjoe 0]

Thanks for the information. I will play around with it and see what I get.

 

ssmith10pn You are right, I really don't need 20fps, I plan on cranking it down once I get the I-frame settings and a few other things figured out. Thanks for your input also.

[ssmith10pn 0]

I generally shoot for one I frame per second. The interface is worded differently from one system to another so the way you achieve that may be different. It may also change as you change the total frame rate also. I would set your total frame rate first.

[afhuss 0]

Hi all

I have Dahua cameras connected to a new UNIVIEW NVR that I am trying out. The UNIVIEW NVR gives me the option to set the I-Frame interval in the camera setup options. The default setting is 24 I-Frames. I am recording at 20 fps. The cameras are viewing a front yard, driveway and a few out buildings. "Not a lot of activity." If I understand it right, lowering the I-Frame setting should save hard drive space but may reduce my video quality a little.

I have also heard that I should have my frame rate set to a multiple of my I-Frame setting.

Any thoughts?

 

 

I know this is a late response, but here goes...

 

I have been advised for Uniview NVRs to set the I Frame interval to double the FPS. So a 5FPS would have a 10 I Frame. You can adjust the bitrate independently as well. That being said, Uniview and Dahua don't always play well together, so you may have to log into each camera and adjust settings locally.