Totally confused about FPS/key

josephny · Sep 12, 2022

I've read a bunch of threads and I just don't understand FPS, I-Frame and key.

I understand the frame rate (FPS) can be set at the camera as well as in BI (Cam properties -> Video -> Max. Rate), but I can't find where to set the i-frame.

Then I've read that I should set the i-frame so they key (which I think is the ration of FPS to i-frame) is 1.0 -- but I have no idea where to set the i-frame.

Then I read that the i-frame should be much much higher.

This all started for me because one of my cameras (371 Park lot) shows a totally gray, washed-out king of look upon playback.

Could someone please take a look at my status and advise how to improve performance?

Thank you!

sebastiantombs · Sep 12, 2022

The frame and iframe rates are set in the cameras, not in Blue Iris. Blue Iris is a "receiver" and has no way to change those, or most other settings, on a camera.

The way motion detection works in Blue Iris the frame and iframe rates should match, exactly. That way Blue Iris see a full frame of data, which is what an iframe actually is, when motion is detected and the subsequent partial frames can be properly synced and analyzed for motion. Blue Iris refers to the ratio between the frame and iframe rates as the "key" fram and that should always be "1".

The smaller the key frame the less likely Blue Iris will be able to successfully detect and record motion. For example your "C71" camera has a key frame of .17. That means almost ten frames can go by before Blue Iris sees a full frame, triggers, and starts analyzing for motion. That results in missed motion.

wittaj · Sep 12, 2022

Somehow this original post got posted twice...and the first thread got him well on his way.