questions about I Frame, fps and Blue Iris Main stream properties

[rotation]

a question about understanding Frame rate, iframes and BI:

1)
In my Hikvision camera I can set a frame rate and a i frame Interval.
The maximum frame rate is 20 fps, but I can also set 1/16, 1/8 and other low numbers fps.

Does that actually mean 1/16 frames per second, means one frame every 16 seconds?
What is something like this used for?

2)
I can set the I frame Interval from 1 to 250.
What does this number mean? Is it fps? It cannot be fps because that would mean 250 fps....

3)
In Blue Iris I can enter the camera settings and in General I see the properties of the main Stream.
I see 4.1 MP, 5.95/0.98 fps, 612.8 kB/s

What does the second number of 5.95/0.98 fps mean?
What is the first of this number packet, what is the second?

 

[wittaj]

FPS is how many frames per second.

Are you mixing up shutter speed that is presented as 1/16s, etc.?

For BI, it is best to match FPS and iframe. Otherwise BI could miss motion.

In BI, your example of 5.95/0.98 means it sees 5.95 FPS and the KEY is 0.98 (FPS divided by iframe), so it should be 1.00 to ensure motion isn't missed.

So your camera is probably set to 6FPS and iframe of 6 - there will be some fluctuation.

If you didn't set it that low, then you have some AI codec or smart codec that is playing with the FPS.

The 612.9 kB/s is the bitrate the camera is using.

 

[rotation]

Thank you,

here is a screenshot, it is the frame rate menu:


Edit:

Now I get it....
The I Frame Interval is in fractions...
So if it is set to 100 every 100th frame is an iframe....

 

[wittaj]

Yes that is the FPS.

15 FPS and 15 iframes works best for BI.

Do not use H264+

 

[rotation]

Thank you,

It leaves me with the question: What is a frame rate of 1/16 good for?
(I will not use it it is just curiosity)

 

[wittaj]

I guess time lapse video.