Recording totally pixelated after a few seconds

[Nightwatcher]

Hello
I have to ask again for a little something.
If one of my four 5MP DS-2CD2155FWD-I cameras detects and records an event, the image will initially be in full resolution for a few seconds and really sharp, but after about 5sec total pixelated for the rest of the recording.
As I've seen, that's been going on for several weeks, on all channels. This was not the beginning of the day.
Suspect that the frames or the bit rate are too much but normal should the NVR (DS-7604NI-K1 / 4P) do it?
At event he makes me on the appropriate channel a full screen, I thought the recording and simultaneous full screen would be too much, but even if this is switched off, he unfortunately still takes on pixelated.
Do you have a guess or a few recommendations for testing?

Image of the mainstream from the camera is of course in the best possible quality:
Resolution: 3072X2048
Video quality: ++++++
Frame rate: 20fps
Max bitrate: 6144
Coding: H.264
I-frame: 20

substream:
Resolution: 640X360
Video quality: ++++++
Frame rate: 20fps
Max bitrate: 512
Coding: H.264
i-frame: 20

 

[FrankMCN]

Check the record settings for event. Also bump up your bit rates, 6144 is a bit on the low side for 5MP @ 20fps with matching iframes. Change the settings from the NVR it will give you recommended bit rate ranges for your settings.

Consider switching to H265.

 

[Nightwatcher]

Thank you for your answer.
Can it be that the bitrate affects you so seriously on all network traffic? Have switched in a camera now from 6144Kbps to next larger 8192Kbps and now my free bandwidth in the network from 10Mbps to 8.192Kbps down - that's too low?!?!

With the H.265 encoding, I initially had problems, all four cameras me in the sub-stream to display simultaneously on the monitor ... I was advised in another forum to H.264, because less computing power?
Basically H.265 is probably better?

Maybe the small 4 channel recorder for the large resolutions is a bit overwhelmed? Would an 8 channel with only 4 connections be better?

 

[Nightwatcher]

Have just tested, with increased bitrate and H.265 encoding the same problem...

 

[FrankMCN]

You should have 40meg of incomming bandwidth to play with between your 4 cameras, but keep in mind that this also include the substream (Mainstream + Substream x4 cameras).

I would look at dropping the frame rate to 15fps for any camera that is just for pedestrian traffic - I only use higher fps for faster moving stuff so off that bat that should save you 25% of your bandwidth requirement.

Yes H265 is twice the work for encoding/decoding, but remember the camera takes care of the encoding and should be more then capable of doing that since their speced for it, the recorder only needs to decode for live view or playback - if you keep the substream in H264 your live view set to substream then it should be okay and your mobile devices running ivms4500/Hikconnect should have an easy life as long as your just viewing the substream.

 

[FrankMCN]

Also drop your substream fps, I only run mine at 12fps and run the iframe @ 4X the fps (so 48 in your case).

 

[Nightwatcher]

These are great recommendations from you FrankMCN, yesterday I set the values down with me, attached the current frames and bit rates of the cameras.
Unfortunately, I just get 15Mbps free bandwidth in the network ... somewhere there still has to be a bottleneck?
Of course, the quality of the videos also drops noticeably and what I have noticed now is that the event recordings only run for 3 seconds. Before the recording was 5sec before event and 5sec after (at least 10sec)
Camera 1 is very important to me because heir the cars are, so I want the best quality here.

At the moment I am very helpless ....