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Using analog cameras with video servers
Analog cameras of all types, such as fixed, dome, indoor, outdoor, fixed dome, pan/tilt/zoom, as well as specialty cameras, can all be integrated in a network video system using video servers. The coax cable from the analog camera is simply connected to the analog input on the video server, which then digitizes, compresses, and sends the video over a local network or across the Internet. Once the video is on the network, it is identical to a video stream coming from a network camera, and ready to be integrated into network video systems. Simply put – a video server turns an analog camera into a network camera.
Depending on the configuration, number of cameras, camera type, and whether or not coax cabling is installed, different types of video servers can be used.
Rack-mounted video servers
Most companies use a dedicated control room in order to centralize equipment to one location and efficiently monitor operations in a safe and secure environment for critical information. In a building containing a large number of analog cameras, this means that vast amounts of coax cabling run to the control room.
If all coax cabling has already been installed and is available from the central room, the installation would benefit from using a video server rack which allows for a great number of blade video servers to be placed in one rack and managed centrally. The rack contains slots for up to 12 interchangeable blade video servers and provides network, serial communication and I/O connectors at the rear of each slot, as well as a common power supply. One 3U 19-inch rack can typically fit up to 48 channels with full frame rate, providing a high density solution, saving valuable rack space.
Rack fully populated with coax cables
Standalone video servers
In a video surveillance system where investments have been made in analog cameras but coaxial cabling has not yet been installed, it is beneficial to connect a standalone video server close to analog cameras in the system.
In addition to the reduced cost of the cabling to transport the video,
this adds the benefit of not having reduced image quality over longer distances, which is the case with coax cabling
where image quality deteriorates with increased distances. A video server produces digital images, so there is no quality reduction due to distance.
Video servers with PTZ and dome cameras
PTZ cameras can be connected to standalone video servers as well as rack-mounted video servers using the serial port (RS232/422/485), which is built into the video servers. In cases where a single port video server is used and located close to the camera, there is the benefit of not having to run separate serial wiring to control the PTZ mechanism, as well as the capability of performing PTZ control over large distances using the Internet. A specific driver must be available in the video server to control a specific PTZ camera. In an Axis video server, PTZ drivers for most popular PTZ and dome cameras are available and can be uploaded to the video server. A driver located on the PC running the video management software can also be used if the serial port is set up as a serial server, which just passes through the commands.
Video decoder
In some installations, there is a need to monitor the network video and audio streams on existing analog monitoring equipment. By using a network video decoder, the network video and audio streams are converted back to analog signals that can then be used by regular TV sets, analog monitors and video switches.
Using an encoder/decoder is also a very cost-effective way to transport analog video over long distances (analog – digital – analog). With a network video decoder, existing analog monitors can be used to receive video and audio from distant analog cameras or systems as though they were placed locally with the operator - even though they might be located in a different city. See schematic.
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