Page 28 - Security Today, February 2017

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The deployment of a multicast enabled video security sys- tem requires significantly more planning and setup time than a unicast system. The network equipment, cameras, and VMS must be configured properly for multicast to function. This increases planning and installation time, and deployment may require specialized skill sets from installers all adding to the system cost.
If planning for a situation where a major security event oc- curs and multitudes of users want to see video of the event live, the Multicast may provide a benefit, but those circumstances are quite limited.
Transcoding
Using transcoding, bandwidth consumption related to streaming live video can be reduced by a greater amount than other meth- ods detailed herein. Transcoding involves modification of the compression format, resolution or other elements of the video stream received from the camera.
As an example, if a 1080P monitor is used to display 16 cam- eras, the display resolution allocated to each camera is 0.125 megapixels. Any higher amount of resolution streamed will not result in increased image quality on the display. If each camera is 1080P resolution, then without some type of resolution reduc- tion technique such as multi streaming or transcoding, the VMS server would stream 32 megapixels of video to display on a screen with only 2 megapixels of display resolution.
With transcoding, the VMS client application communicates the size of the area allocated for display to the VMS server. The
VMS server then scales the video stream to that target resolu- tion, therefore only the resolution that will be used by the client is transmitted over the network.
The same process would take place on any digital video surveil- lance system at the client, but with transcoding, the process takes place at a different location - on the server prior to transmitting video over the network, which results in the bandwidth savings.
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VMS BANDWIDTH