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.