Time was, it was a simple thing to figure out how many CCTV cameras you could have running in your security system at any one time – just look at the number of plugs on the back of the recorder. These days however, the use of IP cameras makes this a far more confusing question. Network Video Recorders (or NVRs) are designed to work with a wide range of IP camera resolutions, from 1 megapixel (720p) models to huge beasts recording at 8 megapixels and over, and as a result the maximum number of cameras they can record at any one time can vary significantly. So if this is the case, just how do you figure out how many IP cameras you can connect to your recorder or network?
Bandwidth is key
The most important thing to understand when planning an IP camera system, is that everything is dictated by bandwidth, or the amount of data being handled by the network. Simply put, if your network is a water pipe, then the bandwidth would be the amount of water flowing through it. Much like the size of a pipe, every network will have a maximum limit to the bandwidth that it can handle, and if the devices on it exceed this then they won’t work properly. Because of the high resolution video that they stream, IP cameras tend to have very demanding bandwidth requirements, and as a result companies that need multi camera, multi megapixel systems will often set them up using a dedicated network.
One quick thing to mention here, your network’s maximum bandwidth is not the same as the internet speed you are getting from your Internet Service Provider. This is because your cameras are communicating directly with the recorder, not across the internet. To find out what your maximum bandwidth is, just check the specifications of any routers, switches or recorders you are using – your network will only be able to handle the lowest of these.
So I know my bandwidth limits. Now what?
Now that you know what your networks limit is, you can work out how many cameras you can add using Hikvision’s Bandwidth Calculator
Just install the software and use the simple tools to select the specifications that you need for your system:
- Device Name/Device Number: These simply let you label the devices in the software, making it easier to keep track of what you’ve added
- Device Type: Use this to select whether you want to add an IP camera or a recorder. Many people use the tool to figure out how many cameras can connect to a recorder. If this is the case, you don’t need to add the recorder itself to the list
- Stream Number: IP cameras can have more than one video stream, for example allowing you to record at full resolution whilst viewing in 720p on a mobile device.
- Resolution: Select the video resolution for the device that you’re adding. Most IP cameras will be 1 Megapixel (1MP) or above. 2MP is around the same as 1080p, and 8MP is around the same as 4K. Increasing the video resolution will significantly increase the camera’s required bandwidth
- Frame Rate: This changes how “smooth” the video appears when played back. 25fps is the frame rate for standard television, but most CCTV systems don’t need quality this high, and 15fps is suitable for most applications
- Encoding: Hikvision IP cameras can use a variety of video compression standards in order to stream footage. H.264 is the most common, with H.264+ and H.265 being respectively more efficient. The more efficient the compression is, the less bandwidth the camera will use, whilst having very little impact on image quality. Not all cameras will have the option to use H.264+ or H.265, but if yours does, then enabling it is the single best way to reduce it’s bandwidth requirements without hurting the picture.
It’s worth mentioning that, as bandwidth simply measures the amount of data being transferred by the cameras, a system that uses more bandwidth will also use up more space on a hard drive when recording. Because of this, everything you can do to reduce the bandwidth will have the added bonus of increasing your recording time.
Recorders are confusing
If you’re still following all this, then I will now do my best to throw a spanner in the works. Even though most NVRs will work with different numbers of cameras at different resolutions, many listings (including some of ours) will still describe them as being an “8 Channel NVR”. Why is this?
It’s partly down to convention, and as a way to help compare models. Something described as a “4 Channel 4MP NVR” will typically have enough bandwidth to run four 4MP cameras at high quality, whereas an “8 Channel 4MP NVR” will work with twice as many. Also, most NVRs will still have a set number of ports on the back for use with Power-over-Ethernet cameras. Some of these will – for example – have 16 PoE ports on the back to send power to cameras, but will work with more cameras if they are powered separately, and the bandwidth allows.
As a final spanner in the works, some recorders will have a recording bandwidth higher than they can output a stream of the footage. For example, our professional 8MP NVR can stream footage from up to four 8MP cameras at one time, but can record from up to eight. It just means that you can’t watch all of the cameras live at the same time.