Fredrik Nilsson is general manager of Axis Communications and an authority on IP surveillance.
Although some digital video recorder (DVR) providers may tell users it is not possible to deploy IP surveillance after analog cameras are installed, video server technology is rapidly smashing this myth. In fact, many IP surveillance installations today combine network cameras and analog cameras that are networked via video servers.
Similar to a DVR, a video server (or video encoder) makes a digital system possible without having to discard existing analog equipment. However, a video server converts the analog video signal into a digital video stream so that it can be transmitted over the computer network, rather than over a separate coaxial network.
Under the Hood: Video Server Technology
A video server typically has one to four inputs for analog cameras, as well as an Ethernet port for connection to the network. The video server can either be located in a rack-mounted version in a server room if all coaxial cabling already exists, or be placed close to the analog camera. Like network cameras, it contains a built-in Web server, a compression chip, network and serial interfaces, and an operating system. These components enable incoming analog video to be converted into digital video, transmitted over the computer network, and then recorded and stored on standard PC servers.
Analog cameras of all types, such as fixed, dome, indoor, outdoor, fixed dome, and even pan/tilt/zoom can all be integrated into a network video system using video servers. Once the video is digitized and on the network, it is identical to a video stream coming from a network camera. Simply put, a video server turns an analog camera into a network camera. Video servers also allow users to control digital inputs and outputs, audio, serial ports, and pan/tilt/zoom (PTZ) mechanisms from any location using a standard PC.
The Future of Digital: DVRs vs. Video Servers
Video servers create truly networked surveillance systems while DVRs are just one step in the ongoing digital evolution of CCTV systems. Analog systems using DVRs are still analog systems; however video can be digitally viewed and recorded. In a DVR, videotapes are replaced with hard drives, which require the video to be digitized and compressed at the DVR level in order to store as much video as possible. Even networked DVRs - which incorporate an Ethernet port for network connectivity - do not provide the same functionality as a system utilizing video servers.
Today, many cutting-edge security integrators and resellers are recognizing these facts and will no longer recommend DVR technology to their clients. For example, David Ly, CEO of IntelaSight Corporation, has worked with DVRs in the past but found the functionality is too limited.
"Even with a network connection, DVRs offer only partial digital conversion and mediocre software support, which limits our ability to offer top-quality services," said Ly. "Although DVRs are more convenient than VHS tapes, there is no way we can continue to support this technology, particularly with large installations. DVRs simply can't handle advanced applications like intelligent video or centralized remote monitoring services, and they restrict our customers to proprietary hardware systems."
By contrast, video servers are much more flexible and offer a range of monitoring and surveillance capabilities that will make them a viable option five or even 10 years down the road. Some of these reasons include:
- Ease of management and maintenance: Because video servers use standard PC servers for video recording and management, they are easy to integrate with existing IT systems and managed as part of that infrastructure. Video servers allow the video to be stored on computer hard drives which are easily expandable and can be easily repaired or replaced in case of failure. By contrast, DVR systems require proprietary hardware, which is more costly and difficult to replace or upgrade. Also, DVRs can rarely be used with standard virus protection packages, which is another major consideration in most IT environments today.
- Expandability: Although both video servers and DVRs leverage existing investments in analog cameras, only video servers make total use of network infrastructure. This is particularly important when expanding the network video system, as an IP surveillance system is expandable in increments of one camera. A DVR on the other hand, is more difficult to expand. Once the capacity of a DVR is maximized, an entire new DVR box (usually with 16 or more channels) needs to be added to the system, even to accommodate one or two cameras.
- Wireless Functionality: Unlike DVRs, video servers allow users to create a wireless system. These systems can be expanded easily without the need to run additional coaxial cabling. This allows cameras to be placed in remote or difficult-to-reach locations that cannot be wired with coaxial cabling. For example, wireless transmission is useful in classified buildings, where the installation of cables would not be possible without damaging the interior. Wireless is also beneficial when camera locations need to changed frequently or when two sites need to be bridged without investing in costly ground infrastructure.
- Audio: While audio is now possible in a DVR system, it is much more cumbersome than with IP surveillance. DVRs create a system where audio is routed back to the DVR itself, while video servers allow the audio to be accessed from anywhere on the network. This allows users to communicate with visitors or intruders from any computer connected to the network.
- Future-proof: Video servers decentralize the digitization and compression functions found in DVRs. This helps process video faster because more information is handled at remote locations. It also 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. A DVR cannot handle such applications because video is digitized and compressed in one location, creating a system in which centralized computer power is a scarce resource that cannot handle additional functions.
Video Servers in Action
Video servers are often used in professional security systems and enable live video to be viewed remotely by authorized personnel. Easily integrated into larger, complex systems, video servers can also function as stand-alone solutions in entry-level surveillance applications. Video servers can connect to the existing IP-network and enable real-time updates of high-quality video accessible from any computer on the network. Sensitive locations can be remotely monitored in a cost-effective and simple way, over the LAN or Internet.
For example, video servers have been used in installations as large as Sydney Airport's international terminal in Sydney, Australia, and in those as small as Canton High School in Canton, Miss. The airport used video servers to network hundreds of analog cameras, while the high school used the same technology to network just 24 cameras. Despite the difference in installation size, both end users were able to use the video server technology to improve their monitoring capabilities and now have the option of easily sharing video with the proper authorities via the LAN and the Internet.
Jim Walker, vice president of CameraWATCH, the company that installed the IP surveillance system for Canton High School, believes that the biggest benefit of video servers is the ability to view images in real time over the Internet.
"It's better than having a security guard at the school because a security guard can only see what is around him, and we can see all areas of the school at one time," said Walker. "The video servers also allow us to e-mail pictures to the police so that in case there is a problem, they know exactly what to look for."
For users searching to migrate from an existing analog CCTV system to the digital world, video servers provide a cost-effective, future-proof solution that goes beyond the functionality of DVRs. As IP surveillance continues to evolve, integrators will increasingly find that DVRs simply cannot meet client demands and fall short of a truly digital system.
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 at firstname.lastname@example.org.