Integrated Systems

Control room displays

by Mark Rowe

Simplifying the display of multiple cameras from multiple sources has always been a challenge, writes the Chinese manufacturer Dahua Technology.

Early analogue systems used multiplexers and matrix switches, with many monitors. This created complexity. Control rooms were large and required many operators. Energy costs to operate these control rooms were high. Technology has enabled the simplification of the control room and the display of video sources and other vital information.

As the industry migrates from traditional analogue devices to IP networks, consolidation of equipment is shrinking the space required for control rooms. TCP/IP connectivity is enabling the linking of information systems such as weather and traffic with the video feeds. New display technology allows multiple images to be put together on a single display or span many displays. Content can now be dynamically assigned and moved throughout the control room display wall. LED monitors are now more energy efficient and more durable when viewing 24/7 without the “burn-in” issues. Dahua Technology provides front-end cameras, NVRs, DVRs, as well as complete control centre solutions.

Splicing video wall

Dahua has been a manufacturer of video wall solutions since 2007 and adds that it’s one of the largest splicing video wall providers in China.

Splicing video walls normally use LCD screens (LED backlight) with a very slim physical bezel, which is important when displaying an image across several monitors. The most common bezel in the market is around 5.5 millimeter. Dahua offers bezel sizes from 3.5mm. Dahua video wall monitors are available in 46-inch and 55-inch panel sizes, and brightness levels from 500 nits to 700 nits to ensure a good view in all ambient light settings. All display panels are designed for 24/7 operation.

The surveillance industry requirement for video splicing walls far exceeds the requirements of digital signage applications. Surveillance requires many types of inputs from devices including: IPCs, DVRs, NVRs and local HDMI/DVI/VGA video signals; and the number of the channels is often above 200. The ability to view many inputs with a single output or arrange inputs and outputs to meet the specific requirement can be a challenge.

To meet those requirements, Dahua offers network video encoding and decoding technology . Several technologies of video wall display are on the market. One way is using PC based or server based hardware to extend graphics cards and develop software to control the output of the graphics card (called “virtual matrix” by some video management software vendors). Virtual matrix switches have disadvantages such as operating system vulnerabilities, graphic card limitations, and limited scalability, according to the firm.

Dahua’s network video matrix is an embedded hardware designed for video walls. Based on Advanced Telecom Computing Architecture (ATCA), it offers a redundant design for many important parts, such as fans and power, which enhance reliability and stability, the makers claim. To lengthen service life, the company uses a modular design. The matrix consists of three parts: mainframe, encoding card and decoding card. The mainframe offers power, control, network and high bandwidth backplane for different cards. For the encoding card, the manufacturers offer multiple kinds of video interfaces including HDMI/ DVI/ VGA/ HDSDI/ HDCVI/ CVBS, etc. A user can input any kind of supported signal to this matrix with just the selection of the corresponding encoding card. Besides all these local video signals, it has capacity for network video streams such as IPCs, and network and digital recorders. For the decoding card, it provides high network video decoding ability and offers the video output channel for both network video and local video signal as well. For pure network application, one matrix can decode 160ch@1080P/ 640ch@D1 network video streams and support up to 40 screens.

Combine this network video matrix with the video wall to provide a solution for central visualization in surveillance applications.

In splicing video wall applications, LCD and DLP technology is already mature and has been used in the market for several years. LED modular products are growing market share. DLP use has dropped with the trend towards LCD and LED modules. The smaller pixel pitch of LED Modules is leading to higher adoption for indoor use. LED modules have Dahua says advantages including: No physical seams, 281 trillion colours, high brightness, high refresh frequency, long lifespan, and easy maintenance. The firm believes that with costs reduced, LED modules will become a new force in video wall applications.

LED modules are being used for many indoor applications including: Performance Venues, Advertising, Information Display, and Promotional Video. Hybrid systems of LED modules and LCD displays are being used in surveillance control rooms, the company adds.

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