ANPR substream pixelated/low bitrate during any motion

[codlord]

I have several ANPR cameras but a single one has this strange issue which I have never encountered before:

The substream is set to 640x480 / Variable / Medium / 10fps / 512 Max bit rate.

The substream looks fine most of the time when there is no movement, but as soon as there is movement (e.g. a car passes) the substream goes very pixelated. I can see via iVMS that the bitrate normally is around 300kbps but during motion it drops to less than 100kbps.

I CAN work around this issue by setting the bitrate to constant but does anyone have any ideas why the substream changes like this?

I know for main stream you have setting which can change the bitrate between motion/no-motion but I have never encountered this on the substream.

It's a iDS-2CD7A26G0/P-IZHSY (H8) on the latest (UK) firmware v5.8.50 240806

 

[Kyle]

There's newer firmware on Hikvision's global site page for the camera, so try this first - V5.8.61 build 250214

If you have an SVC option in the sub stream settings, make sure it's disabled.

NVRs with V4 firmware also have a 'Dynamically Adjust Recording Writing Buffer' setting in Record>Advanced, make sure this is turned off if the camera is connected to an NVR.

Are you also seeing the pixelation and bitrate drop while connecting to the camera directly on your network, rather than via the Hik-Connect servers?

 

[codlord]

@Kyle thanks, I will try the firmware.

SVC is disabled on all streams and this is directly on the same network.

The NVR (DS-7616NI-K2 / 16P) is on v4.72.107 220914 but doesn't have that setting, on the NVR native interface under Record -> Advanced I just see:
Overwrite (Enabled)
HDD Sleeping (Enabled)
Save Camera VCA Data (greyed out for some reason...)
Alarm Storage (Disabled)
Picture Storage (Disabled)

 

[Kyle]

That setting may only be on I-Series models or later versions of the V4 firmware...
If the camera firmware doesn't help, you could try the newer NVR firmware too - V4.74.205 build 230712.

Otherwise, I'm out of ideas as it's a very unusual one - sorry!