IPC-T54IR-ZE-S3 'refresh' issue

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kylegordon

n3wb
Sep 23, 2022
2
0
Scotland
Hey all, I have a new IPC-T54IR-ZE-S3 from EmpireTech (after reading all your recommendations, this is my first 'proper' camera, rather than Ubiquiti G3s and G4s).

The picture is great during the day and at night, but I'm having an issue where it seems to 'refresh' the feed every 30 seconds or so, where it drops the resolution and then gains quality again. All over the course of about 1 second. It happens on both main and the substream.

I have a large gravel driveway with black and white stones, so the resultant mess of pixels triggers motion detection in Frigate regardless of sensitivity. The event is visible in the camera feed web interface too, so it's originating at the camera.

What setting am I missing? I have the following, which is based on defaults and the Frigate recommendations, bar the FPS which I've kept at 25

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Scenes with a lot going on, like gravel and lots of leaves, need higher bitrates as it can't resolve the image clearly.

Plus most of us start at 8192 bitrate with 15FPS, so at 25 (more than big screen movies are filmed in) you would need an even higher bitrate.

Unless Frigate says something different, most people using a VMS other than the Dahua OEM NVR will match FPS and iframes on both mainstream and substream.

Your iframe being double the FPS is likely causing that pulsing at 1 second intervals.
 
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Likely Pulsing. Show a video clip if you could.

It will vary in timing depending on your Iframe rate. I’ve seen it on most every camera since 2014

I’m not smart enough to describe the complete technical reason but it has to do with the Iframe or full frame vs the in between frames
 
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Ta for the replies :-)

I've been doing some fiddling and can report back...

At 25 & 50, pulse lasts 1 second, but happens every 30 seconds.
Both iframe and FPS at 25, the pulsing happens every 2 seconds.
At 15 & 15, pulsing every 10 seconds.
Bumping bit rate to 8192 and max had no effect, and VBR causes shimmering of entire scene.
Disabling all sub-streams has no effect.
Object being tracked across scene has no effect

It's definitely some interplay between FPS and I Frame interval. I thought the I Frame interval was frames, but maybe it's seconds?

Since I've got the bandwidth and CPU power, I've set it to 25 FPS with an I Frame interval of 60, and the pulsing is gone. Motion blur seems ok.

I'll post up a video if it becomes a problem again. I feel like I've been staring at the white noise of a TV for too long already :rofl:
 
Yes, while we have always recommended matching FPS to Iframe interval, I've found doubling Iframe to FPS does help a lot of things.
I run most of my cameras now at 30FPS with an Iframe of 60

As @wittaj mentioned, its more prevalent in scenes with lots of detail such as gravel or moving water.
 
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