Troubleshooting NVR and IP Camera Systems

Question from our customer: 

I am very disappointed with the Dahua vertical NVRs that I have purchased. I was under the impression from the specs online and conversations I have had with tech support in the past that I should have no problem running 16 cameras at 1080p on that NVR… 

I am forced to run these cams at 720P and 10 fps or less just to get them to stay up. However, this results in lagged and low quality video at playback time. I feel that these 16 channel NVRs cannot actually handle 16 HD channels as advertised. I need a solution for this client asap as they are not too happy with me right now. What would be the chance of me returning this 16 channel and buying a 32 channel device. Do you think the 32 channel device will handle the 16 cameras at 1080p and 10fps?

Our answer: 

What most people don’t realize is that IP systems involve technical design and a high amount of pre-configuration for the system to function properly. When compared to other video surveillance technologies such as HD-SDI, HD-CVI, or traditional analog, IP systems require the highest level of technical design and configuration for a successful deployment. The main advantages of IP are an unlimited recording resolution (depending on the VMS and hardware), and complete control over the output quality. It’s like driving a manual-transmission car instead of an automatic transmission. It’s a lot more work, but you have a lot more control over the vehicle. For a more plug-and-play solution, we recommend HD-SDI or HD-CVI. Or if you insist on IP, I recommend you consult with our technical team prior to deploying your surveillance system so that you know the proper frame rate and bit rate so as not to exceed your system’s capability.

The specifications online for your latest NVR show 16 channels at 1080p real-time viewing. Is this not the case for you? Keep in mind there is usually a maximum bit rate associated with NVRs. The newer Dahua NVRs advertise the maximum viewing and recording bit rate, and it has been my experience with all of these standalone, non-PC based NVRs that one should not exceed 75 to 80% of the bit rate for a stable system without dropping of IP cameras. The same is true for the aggregated network traffic, whether the network is 10/100 or Gigabit. The specifications of these discontinued vertical NVRs don’t show the maximum total bit rate, but I can check with a Dahua technician if you want me to find out for you.

You should use a bit rate calculator to see what your current usage is, and to see how to lower the usage. I like to use this one. You will see that 16 cameras at H.264 at 10fps at the best quality puts you at nearly 70Mbps, which is nearing the maximum threshold of the network. Unless the camera network is separate from the main network, I would look into reducing bit rate because other devices on the network are probably causing the total bandwidth usage to overload the network, which results in packet loss and in your case dropped cameras. You can reduce the bit rate down using a lower frame rate, a lower quality, or a lower bit rate. You can actually set your NVR to cap out the bit rate at 3500kbps constant bit rate instead of using variable bit rate.

Another limitation is the built-in PoE on these standalone NVRs. It is not ideal to use them on cable runs longer than 50 feet. I recently heard this piece of information from a Dahua engineer, and she said it applies to all standalones on the market; not only Dahua. You just won’t get the same level of power output on the NVR as you would on a dedicated PoE switch, even if the level of power in watts is supported on the NVR with built-in PoE switch.

The newer NVRs do advertise the bit rate in the specifications, and we usually put these bit rates in our titles because that is primarily how one will determine if the NVR will be able to accommodate all the cameras at the desired recording preferences. Some of the newer NVRs also support gigabit LAN, as well as dual-gigabit LAN, the latter which can separate the main network from the camera’s network. Separating the network ideal for network traffic management (IP cameras, VOIP, web browsing, database server, etc.), as well as better security. It also helps to understand how much traffic is on a network, so as not to exceed the 75-80% bandwidth limit of the network’s capacity.

Lastly a best practice is to set all the IP Cameras and NVR to a static IP address. Dynamic IPs on the NVR can affect the remote viewing of the camera system, and dynamic IPs on the cameras can result in dropped cameras.

So unless your IP cameras are set to DHCP, or unless you are exceeding 75-80% of your network’s capability at this customer’s site, or unless you are using cable runs longer than 50 feet with the built-in PoE, I would recommend setting up an RMA for that unit.

To return the NVR now and exchange it for another model will only be possible if the vertical NVR is not in stock. And since it has been discontinued, you have a pretty good chance of getting an exchange for another unit. It all depends on Dahua’s stock. We did an RMA for someone else last week on an older DH-NVR5232, and Dahua swapped it out for the newer DH-NVR4232-P.

This Dahua DH-NVR5216 16 channel NVR supports 160Mbps, which should be more than enough for your 1080p cameras. It will also support cameras up to 5MP, whereas your old vertical NVR had a limited recording resolution if 1080p.

The Dahua DH-NVR7432 32 channel I quoted you a couple weeks ago support 256Mbps live and 192Mbps recording, and has dual-Gigabit LAN ports. It supports a maximum recording resolution of 1080p.

Another good option for economical standalone NVRs and IP cameras is Hikvision.

Contact me if you have any more questions.

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Raymond K. Shadman

eDigitalDeals, Inc.

Office:         310.370.9500, ext. 101

Toll-Free:   877.DEALS.79 (877.332.5779), ext. 101

Fax:              310.370.9555

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