Network and Digital Video Recorders for Security Systems

Posted by Daniel 06/30/2016 0 Comment(s)

In the world of security systems, there are two types of video recorders. Network Video Recorders (NVR) take advantage of Ethernet-based networks or wireless and the Internet Protocol (IP) to provide the connection between the security cameras and the video recording unit. Digital Video Recorders (DVR) use legacy cable systems or Ethernet cable, but do not take advantage of existing IP-based networks. Instead, DVRs use other High Definition video protocols.

NVRs use the IP protocols to transfer the High Definition (HD or 720p/1080p) data between the IP cameras and the NVR unit. This means they can use pre-existing Local Area Networks (LAN) or even the Internet to provide connections between the camera and the NVR. This saves significantly on cabling especially if the NVR is being used in large buildings, expansive premises, or even have IP cameras in one location, but recording in another. For example, IP cameras at an internet-equipped cottage transmit video to a NVR at home for recording and alerting. In some cases, you do not even need cables if the IP cameras are Wi-Fi equipped; the IP cameras transmit to the Wi-Fi router which then sends the signal across the LAN/Internet to the NVR. However, the IP cameras have to be fairly close to the Wi-Fi router. Since the IP cameras encode the video in IP data streams, the NVR does not need specialised video coding software. They cameras and NVR may be equipped with H.264 video compression software to save on bandwidth.

Another variation on the NVR is special NVR software loaded into a Network Video Server on a personal computer. No special hardware is needed; just at Wi-Fi or Ethernet connections. This saves on hardware costs that are propriety and limited to 4, 8, or 16 connections. A PC-based NVR is only limited by the practical aspects of how many video feeds you can display on the screen and your graphics processer capabilities. There are also Cloud NVRs where you can subscribe to the NVR software as a service and you do not need to install the server or NVR software.

DVRs use other video streaming algorithms to transmit HD video. DVRs can send alerts and using peer-to-peer technology or DDNS technology, you can remote into the video recordings or what live streams. DVRs use existing coaxial cables or Ethernet (Cat5 or Cat6). They have no network capability between the cameras and the DVR so the range is limited to 1500 feet unless using repeaters. DVR cameras usually send their video signals in a raw signal format using the algorithms. Currently there are 4 DVR video formats: HD-SDI, HD-TVI, HD-CVI, and AHD. HD-TVI offers the best video quality, range, cabling options, and camera options. AHD  DVRs, while not offering as good as quality of a signal, do allow you to using existing cables while upgrading your cameras and then upgrading your DVR. AHD is a possible option for those with limited spending at one time.

NVRs do share some commonalities with DVRs: they both have data storage and you can connect to the video recordings remotely. Hybrid NVRs can also use both IP networks and DVR type cameras and coaxial cabling. depend upon whether or not you have pre-existing coaxial cable or Cat5/6 cable in place and your budget. If you have cable you can re-use, then DVR technology makes sense because the cameras are cheaper. But if a Wi-Fi, LAN or Internet is available, then that is the way to go because your cabling costs are next to nothing. What you save in cabling will allow you to buy more expensive IP cameras.

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