Cliff Notes query?

[Phil.g00]

Cliff Notes quotation below:
"They also offer NVR’s without PoE power that require a separate PoE switch to power the cameras. While more expensive, this allows greater flexibility, and makes it easier to directly access cameras."

I am a Noob, but I would've thought that a POE-capable NVR would be able to supply some cameras with POE and still use other cameras supplied by an alternative POE source.
I infer from Cliff Notes that I am mistaken.
Please can someone enlighten me as to the error of my ways?

 

[jarrow]

You are right. You can use both, as long as you don't exceed the amount of cams the NVR is made for.
So for a 8 channel NVR with POE, you could for instance feed 6 from the ports on the back and 2 from an external source (switch/injector), but the total can't exceed 8.

 

[Phil.g00]

Thank you for your reply.
Another question, if I may.
Do I have to use an NVR port per camera?
If I had a multi-channel POE capable switch that fed eight cameras, could I use only one ethernet capable between the switch and a single NVR port?
Would I still use all eight channels on the NVR?

 

[wittaj]

Yes, only one camera per POE Port on the NVR.

If you use an external POE switch, then you connect it to the WAN/LAN port of the NVR not a POE port. You will then have to manually add each camera to the NVR.

Contrasted with if the camera is plugged into the NVR POE port, then it usually will find it and set it up automatically.

 

[Phil.g00]

In my case, it will be convenient to use fibre between outbuildings with multiple cameras on them. So an NVR without POE could be an option,
However, I do not want to sacrifice internet access by using the WAN/LAN port or are they equipped with more than one? (I refer to DHI-NVR5208-4KS2E range). The specs are unclear. Or is there another network workaround?

The DH 5208 & 5216 4K2E NVRs specs show a Decoding Capability of 4-ch@8MP(30fps). I interpret this to mean that after using four 4K cameras, the open unutilized NVR channels on both the 8 and the 16-channel NVRs are unusable due to a lack of bandwidth.
Is this a correct interpretation?

 

[jarrow]

Just plug your router in one of the ports of the external switch, like this picture I got from the internet:

The DH 5208 & 5216 4K2E NVRs specs show a Decoding Capability of 4-ch@8MP(30fps). I interpret this to mean that after using four 4K cameras, the open unutilized NVR channels on both the 8 and the 16-channel NVRs are unusable due to a lack of bandwidth.
Is this a correct interpretation?

I believe this has to do with the amount of live views the NVR can decode on the HDMI/VGA port. So if you plug a TV in the back of the NVR, you can only view four 4K cams at a time.

The Network Capability specification above that is the amount of bandwidth the NVR can handle, so that can be more than four 4K stream, if you stay under the 320 Mbps of bandwidth.

 

[wittaj]

You hook your internet, NVR, and the cameras to the same switch. A POE switch can handle non-POE devices.

 

[Phil.g00]

Thank you both for that.
That seems simple enough.
Any idea about the 4k camera bandwidth question?

 

[jarrow]

Any idea about the 4k camera bandwidth question?

I added that to my post above.

 

[Phil.g00]

Sorry, @jarrow I see you answered my bandwidth question.

Is there any rule of thumb as to how many 4K cameras a 320Mbps NVR can continuously record at say 30fps?

 

[Perimeter]

Is there any rule of thumb as to how many 4K cameras a 320Mbps NVR can continuously record at say 30fps?

I am currently kind of working on the very same problems in this thread. I got some answers, perhaps some might help you too.

Please help me underderstand these specs:

It is about the Dahua NVR2108HS-I2, but applies to all really: It has 8 channels. The specs state for decoding capability: AI disabled: 1-channel 12MP@30 fps; 1-channel 8MP@30 fps; 2-channel 5MP@30 fps; 3-channel 4MP@30 fps; 6-channel 1080p@30 fps AI enabled: 1-channel 8MP@30 fps; 1-channel...

ipcamtalk.com

 

[wittaj]

You don't want to run at 30FPS - movies are shot on the big screen at 24FPS, so most here run 10 to 15 FPS. Cutting FPS in half will increase the availability to run more cams.

Shutter speed is more important than FPS.

It is easy to overload the capacity of the NVR.

@Parley understands these decoding issues and has to run several NVRs for his system, so I pinged him here to add his thoughts.

 

[Phil.g00]

Thanks, I understand about lowering FPS; Presumably, halving the FPS halves the bandwidth requirement.
I just wanted to add an arbitrary constant FPS to compare apples with apples.
We can call it 15FPS if that's the norm.

 

[jarrow]

Depends on the bitrate.

If you run the cams with CBR (Constant BitRate, so always the same) at 8192 kbps, it doesn't matter if its a 4K cam running at 30 fps or a 2MP at 8 fps. It just means that each frame gets way more bandwidth with the latter.

So theoretically you could fit 39 cams with that bitrate of 8192 kbps (320 Mbps / 8.192 Mbps = ~ 39), but in pratice its always a bit lower. I don't have a 'general rule of thumb' for that.

For a test I once tried to run 16 cams with VBR (Variable BitRate) up to 20480 kbps, which when added up combines to 327 Mbps. Then at some point a lot of cams had movement so it somehow exceeded the maximum bandwidth and all of the cams were 'removed' from the NVR. I know for sure the bandwidth of just the mainstream didn't get to the 320 Mbps but with the substream and other triggers it was too much.

 

[Perimeter]

Can the HDD handle that writing speed?

 

[wittaj]

Can the HDD handle that writing speed?

WD Purple can support 64 cameras. Not that you want to push that, but it will be fine.

So you need to check the capacity of the drives you use.

 

[jarrow]

Used multiple Seagate Skyhawk's in that project, they can handle up to 180 MB/s or 1440 mb/s of writing.

 

[Phil.g00]

OK, it appears for the time being that an NVR 5208 should be pretty capable with eight 4K cameras at 15 FPS.
(Speak up if someone disagrees).
A WD purple HDD seems capable as well.
So onto an external switch supplying POE, what is the POE requirement?
POE, POE+ or POE++.
I can't see some of those PTZ cameras operating at 12 watts.
What would be recommended if I wanted to get a POE switch that could handle PTZ cameras?
Or is this a whole new setup again?

 

[wittaj]

I would go with POE+ because you never know LOL

 

[Parley]

You don't want to run at 30FPS - movies are shot on the big screen at 24FPS, so most here run 10 to 15 FPS. Cutting FPS in half will increase the availability to run more cams.

Shutter speed is more important than FPS.

It is easy to overload the capacity of the NVR.

@Parley understands these decoding issues and has to run several NVRs for his system, so I pinged him here to add his thoughts.

Yes, I was up to 4 NVR's at one point. This was because as I was upgrading cameras to 4K the NVR's could not keep up with the added data. So, to solve the problem I would add an NVR and spread the 4K cameras out over 4 NVRs. Then recently I noticed that Hikvision now has NVR's out that are tailored to handle 4K cameras. So, I bought a couple to try out and they do work, but IVMS_4200 cannot keep up with the added data over time. I am not sure what the problem is but after an hour or so the data starts lagging in IVMS-4200 and the picture quality suffers. The cure at this point in time is to reboot the IVMS-4200 program which takes about 20 seconds. The network is only running at 4% max utilization. Mostly in the 2-3% range.

So, I am currently running 3 NVR's with one shut down. One is only for my 4 License cameras and they are in black and white. The other two run the rest of my 16 cameras in color. Of the 16, 12 are 4K. Those cameras I run in the back yard are at 12FPS. Those that cover the front of the house and the street where most of the action is, I run 15 or 16 FPS. That is the latest from my end.