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Fredrik Nilsson is general manager of Axis Communications' in the Americas and author of the definitive book on networked video surveillance, titled "Intelligent Network Video."

Of the estimated 40 million surveillance cameras installed around the world today, approximately 95 percent of them are analog. Considering that the average lifespan of those cameras is five to seven years, much of that technology is still in good working condition. So for businesses considering an upgrade to newer network technology, there are sound fiscal reasons for wanting to incorporate existing analog cameras in their migration strategy.

Using video encoders to facilitate the technology shift
Rather than force security managers to choose between an IP-based or an analog-based video surveillance system, video encoders - sometimes referred to as video servers - offer a way to merge the two technologies into a single solution.The advantages are multifold. Not only can a company extend the useful life of existing investments while reaping the many benefits afforded by IP-based technology, but the solution creates a future-proof platform for ongoing surveillance initiatives.

How video encoders work. Video encoders basically convert an incoming analog video signal into a digitized video stream that is identical to one coming from a network camera. The resulting data stream, compressed through a video compression standard like Motion JPEG or H.264, is transmitted over the data network and can be fully integrated into the network video system to achieve scalability, openness and cost efficiency.

A video encoder is used for migrating the analog security system to an open IP-based video solution.

Video encoder-based network video systems
Standalone vs. high-density rack. The most common video encoder is a standalone system with a single or multi-channel (typically four) connection to analog cameras. These types of encoders operate most efficiently when positioned close to the analog cameras. They are typically used in situations where a few analog cameras are placed in a remote facility, or where the setup is some distance from the central monitoring room.

High-density rack solutions with blade versions of the encoders are more prevalent in larger, centralized video surveillance installations where analog cameras and coax cabling are already installed. Each blade supports one, four or six channels. Each rack can be outfitted with a mix of video encoder blades and can accommodate from one to 84 analog channels. This configuration provides a flexible and expandable solution for migrating large-scale analog installations to network video. With hot swapping capabilities, users do not need to power down the entire system to install or remove individual video encoder blades.