Fredrik Nilsson is general manager of Axis Communications and an authority on IP surveillance.
As outlined in Myth #9 of our previous article series, The Top 10 Myths of IP Surveillance, 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 serverâ€”sometimes referred to as a video encoderâ€”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 typesâ€”fixed, dome, indoor, outdoor, pan/tilt/zoom, and specialty camerasâ€”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 â€œblades,â€ 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 channelsâ€”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.
The organization worked with integrator CamCentral to install the system, which uses video servers to digitize video from analog cameras installed throughout the ferry terminals, enabling staff, security services, and local law enforcement units to monitor the facilities, surrounding waters, and vehicle and passenger traffic via the Internet. When the terminals are closed, local law enforcement officials and other authorized users can access the system remotely and receive alerts if unusual motion is detected in the facilities. The Alaska DOT realized a number of advantages that video servers could bring to its analog surveillance systems.
Recording, management, and storage. Because video servers use standard PCs for video recording and management, they are easy to integrate with existing IT systems and can be managed as part of that infrastructure. Video servers allow video to be stored with standard storage solutions, including network attached storage (NAS), storage area networks (SAN) and Redundant Arrays of Independent Disks (RAID). These storage systems are easily expandable, reliable, cost effective, and repairable or replaceable in case of failure. By contrast, DVR systems require proprietary hardware, which is more costly and difficult to replace or upgrade. CamCentral and the Alaska DOT also took advantage of the video servers' ability to handle firewalls, passwords and other network security technologyâ€”something that can rarely be done with DVRs.
Scalability. Both video servers and DVRs leverage existing investments in analog cameras, but only video servers make total use of network infrastructure. This is particularly important when expanding the network video system. An IP surveillance system is expandable in one-camera increments. DVR systems, on the other hand, expand in larger increments. Once the capacity of a DVR is maximized, a new DVR box with 16 or more channels must be added to the system, even if only a handful of cameras need to be accommodated.
Remote recording and monitoring. Video servers allow users to access and record video at remote locations, provided they have the appropriate authorization and login information. Off-site recording can be beneficial in retail environments where it guarantees that video is protected during a theft on the premises. Off-site viewing allows security personnel to keep an eye on their establishment without being on the premises.
Decentralization. Video servers decentralize digitization and compression functions, so information is handled at the source instead of in a centralized place. This opens the door for up-and-coming applications like intelligent video, which can be used in identifying abandoned luggage at an airport or reading a license plate number in a parking garage.
In the case of the Alaska DOT, using video servers allowed CamCentral to create specialized motion-detection software that was optimized for the marine environment. A centralized processing system, like a DVR, cannot handle such applications because computing power is a scarce resource that video and analysis are forced to share. Even networked DVRsâ€”which incorporate an Ethernet port for network connectivityâ€”do not provide the same functionality as a video server system.
Video servers can provide cost savings and more functionality than analog or DVR systems. They create a truly digital surveillance system and allow users to capitalize on almost all the benefits of network video while incorporating network cameras as expansion and upgrades are required.
About the author: As the general manager for Axis Communications, Fredrik Nilsson oversees the company's operations in North America . In this role, he manages all aspects of the business, including sales, marketing, business expansion and finance. He can be reached via email at Fredrik.Nilsson@axis.com.