As outlined in Myth #9 of our previous article series, The Top 10 Myths of IP Surveillance (available in the archives of SecurityInfoWatch.com), existing analog surveillance systems can easily be upgraded to IP surveillance systems by incorporating video servers. This allows for digital delivery and control of video without the replacement of every camera with a network camera.
By connecting existing analog cameras to video servers, you can digitize, compress and transmit video over the network. This reduces installation costs by incorporating older equipment into the network video system and allowing for better scalability, storage on standard PC servers, and remote recording and monitoring.
Video Servers 101
A video server—sometimes referred to as a video encoder—eliminates the need for dedicated equipment such as monitors and DVRs by using standard IT equipment and infrastructure. Each video server can connect between one and four analog cameras to the network through an Ethernet port. Like network cameras, video servers contain built-in analog-to-digital conversion, compression, Web and FTP servers, as well as processing power for local intelligence. Incoming analog feeds are converted into digital video, transmitted over the computer network, and stored on PCs for easy viewing and accessibility.
Once the video is on the network, it is identical to video streams coming from network cameras. Analog cameras of all types—fixed, dome, indoor, outdoor, pan/tilt/zoom, and specialty cameras—can be integrated into network video systems using video servers.
A video server has a coaxial input that connects it to the analog camera. The server in turn connects to the network via an Ethernet port. All video is digitized and compressed within the video server and sent over the network via a network switch to a PC, which typically runs video management software for storing and monitoring the video.
Rack-Mounted or Stand-Alone?
Video servers save space by fitting into existing server rooms, eliminating the need for dedicated CCTV control rooms. If coax cabling has already been run to a central room, a video server rack can be used. Rack-mountable video servers come as “blades,” which are essentially video servers without their casings. This allows the video servers to be placed in server racks, which are common in IT environments.
Placing blade video servers in racks allows them to be managed centrally with a common power supply. One standard 19-inch rack that is 3U high can fit up to 48 channels—meaning that up to 48 cameras can be digitized on a single rack.
The functionality of a blade server is exactly the same as a standalone video server. Blades are interchangeable and hot-swappable in the rack, and they provide network, serial communication and I/O connectors at the rear of each slot.
In an analog camera system where coaxial cabling has not been run to a central location, it is best to use stand-alone video servers positioned close to each camera. This method reduces installation costs because it uses existing network cabling to transmit video, instead of running coaxial cabling to a central location. It also eliminates the loss in image quality that occurs over longer distances when video is transferred through coaxial cabling. A video server produces digital images, so there is no quality reduction due to distance.
Advantages of Going Digital
The Alaska Department of Transportation recognized the advantages of a network video system and recently incorporated video servers into nine of the largest ferry terminals in the Alaska Marine Highway System.