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Traditional video distribution has come a long way since the days of analogue radio frequencies and higher resolution RGBHV signals.
The digital world brought us HD (High Definition) television, but with brand new technical challenges. HDMI (High Definition MultiMedia Interface) was introduced as a HD signal standard with a higher bandwidth requirement for more information transfer between source and sync (display) devices. Because of this, multi-media signals over copper cables are limited by distance. In addition, the HDMI equipment did not accommodate multiple source/multiple display architecture. Another challenge brought about by HDMI is HDCP (High-bandwidth Digital Content Protection). The latter is a control protocol embedded within the HDMI signal. Word on the street has it that Hollywood orchestrated this in an attempt to reduce the criminality around counterfeit copies sold on the black market, which costs content producers in dishonoured royalty obligations. HDCP ensures that both source and sync devices are conforming to a protocol – a digital handshake between licensed devices prohibiting the user from duplicating material.
HDMI soon became the norm in residential set-ups and later on in the professional audio-visual industry where many new technologies facilitated the distribution challenges. In professional video systems, one is more often than not faced with system architecture that requires video signals to reach greater distances than intended for HDMI’s design.Certain systems require video switching between multiple sources and others require multiple displays showing the same content. More advanced systems need a combination of both multiple source and multiple display devices with full routing flexibility. Many different technologies introduced solutions to some of these challenges.
Balun (Balanced/Unbalanced) systems with transmit and receiver hardware on either side of a STP (shielded twisted pair) cable increased distribution distances but at an expense. More recently, HDMI optical fibre cables function in a similar style with transmit/receiver components integrated at both ends of optical fibre cables with power supplied by the HDMI ports. Fibre cables thus eliminate various components and instead provide a single point of failure with a neater installation appearance. The latest breakthrough in distribution technology is video distribution over IP (Internet Protocol). As more and more audio-visual systems integrate with IT systems, it was only a matter of time before IP networks were introduced to distribute HD multi-media signals. Technologies continue to develop with higher resolutions and current recording, distribution and display devices are capable of 4K UHD (Ultra-High Definition) signals with a resolution of 3840x2160 – four times that of Full HD(1920x1080). Video over IP has changed the architecture limitations of conventional video routing systems.
Based on customer requirements, conventional systems select a frame to accommodate the configuration required before being populated with components. The negative side to this solution is that the frame size is established by either the number of inputs or outputs to be accommodated. This then results in the other side of the solution having to use the exact same frame even if only a fraction of the real estate is used. IP distribution systems utilise one multi-port switch with transmitters and receivers at both ends of the solution. Each transmitter will convert the HD signal to IP and send it to the IP switch. The receiving end will dictate an IP address where the required source is transmitted from and thus switched to the desired display. This design only requires an IP switch to accommodate the total number of connections (sources and displays) needed in a system.
The greatest benefit of a video over IP system is that it utilises IT network infrastructure but in order to distribute uncompressed HD or UHD video, network infrastructure must be capable of 10Gb/s bandwidth. This might increase cost but will prepare networks for future IT requirements, assuming that the pace of development around the ‘internet of things’ remains the same. Certain video over IP systems will use video compression and thus require much lower bandwidth capabilities. This makes these systems more appealing because of an attractive bottom line. The question to ask is whether the objective of distributing true HD or UHD video is achieved. Another important factor to keep in mind is the HDCP protocol explained earlier. It might not be required when a local presentation is sent over a network as the content belongs to the presenter. However, the moment one decides to send a HD news broadcast or the latest release blockbuster over a network that is not HDCP enabled, the signal will be rejected by the display device, resulting in a ‘no show’. It is also of high importance to have the initial IT functionality still available on the IT network.
On a 10Gb/s system, each video endpoint is capable of delivering 1Gb/s allocation for internet only. Systems should also be capable of sending USB protocols over the same network and to make it more attractive to the AV professional. Control integration at each endpoint must be capable of delivering Infrared and RS232 protocols. Video over IP technologies are also readily available for the entertainment and staging industry where signal distribution has always been a challenge. System architecture is slightly different with a FOH (Front of House) sender unit – where source components connect – and a back stage distributor switch sending various commands and signals to relevant systems. Both components are linked by a single, two cable connection for redundancy. Some of the supported signals include audio and video as well as control protocols such as Dante and Artnet for lighting control – an important aspect of the live entertainment industry. Equipment is built for rugged on-the-road conditions and the architecture has revolutionised the requirements around live event set-up. In short: the future of video distribution lies with IP networking, with high enough bandwidth to accommodate all the components and technologies in today’s digital world.
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