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Evolution of Video Matrix Switches

Posted by admin on August 28, 2015 11:24 am

In the past decade, technology has been exponentially increasing in speed, power and complexity, resulting in ever smaller smart devices that have the power of desktop computers and desktop computers that are four times as powerful as their last-gen predecessors. Now even our displays are making huge evolutionary jumps, with screens of unprecedented pixel density and ability to display a much broader range of colors, e.g. X.V. Color™ has nearly tripled the range of colors over RGB. In this current environment, which is characterized by constantly pushing the limits of multimedia quality in order to seek perfection, maintaining a top-of-the-line AV network has become more important than ever in order to keep up with the changes that are taking place.

Video switching has also evolved in order to handle new transmission mediums, connector types, compression technologies, scaling technologies and ever-increasing resolutions. Let’s take a look at some of the ways it has come forward.

Hardware

Evolution.._HardwareThe earliest matrix switches were built on the model of an old PBX switchboard. After several advances in telephone connectivity, the crossbar switch was developed in the late 1920s. It allowed calls to be dialed by storing the dialed numbers into memory devices called “registers,” and the call would not begin to be switched until all the numbers had been dialed. The register then passed the numbers to a “processor” for routing. Once the call was connected, both register and processor would release and be available for the next call. This helped increase the speed of the switch because the call would not access the switch during dialing, thus separating the control functions—the setting up and directing of the call—from the switch functions of physically creating the connections. Calls connected by sharing a dedicated wire path through the switching matrix. Crossbar switches worked by using a horizontal and vertical matrix of wires, one row connected to one column. The point at which the cross-points met established the connection; when in use, the point was closed and when not in use, the point was open.

Evolution.._Hardware_2.jpgThe telephony crossbar switch model was used to create the first video switches, only it was renamed a cross-point matrix switch. These switches had a single function, to take in one or more analog video signals of the same video type, such as Composite, and send them to one or more analog displays. In this function the switch acted as a selector, e.g. a 4:2 switch would allow for 4 Composite video sources, and from that you would select the 2 sources that would be sent to the screens.

As switches became more complex, they were able to handle audio in addition to video. Digital video and audio then were developed and DVI, which allowed for both video and audio to travel in the same stream, became the standard for many years. Now we have many different types of digital video signals, including DVI, HDMI, DisplayPort, USB and 3G HD-SDI. The matrix switches of today, such as Opticomm-EMCORE’s Genesis XD (GXD), allow for anything-in-anything-out, analog or digital (depending on the insert cards purchased). The number of connections can be as few as 8 in/8 out or as many as 32 in/32 out (or even larger).

Resolution

Display resolution has seen some of the biggest changes most recently, and is likely your primary driver to upgrading your video distribution hardware. While adoption technically started sooner, the U.S. was forced to step up its adoption of high definition (720p and 1080p resolution) video after digital video overtook analog in February of 2009. Now, less than a decade later, we’re experiencing another massive leap forward in picture clarity and pixel density: 4K/UHD content.

While 4K and UHD aren’t technically the same, they’re often referred to interchangeably. If you don’t know the difference, basically UHD (Ultra High Definition) refers to a television standard of 3840 x 2160, while “true” 4K is the cinematic standard of 4096 x 2160. There are even companies already working on filming in 8K, aka Super Hi-Vision (SHV). Although we are still quite a ways from 8K being popular, we’re very quickly moving towards a future where 4K content is widely available.

Due to the rapid evolution of resolution, we simply don’t know how quickly 8K will overtake 4K, therefore, when looking for a cross-point matrix switch, you want one that can handle up to 8K. Opticomm-EMCORE’s Genesis XD (GXD) has a 40GB backplane, which means it can handle up to 8K resolutions now, were the chipsets and content available. You can purchase whatever GXD insert cards are required for the transmission mediums and video/audio/data signal types that you need now for 4K/30Hz and then, when the chipsets for 4K/60Hz and later, 8K, become available, you will be able to upgrade the hot-swappable cards.

If you’re unfamiliar with the difference between 4K/30Hz and 4K/60Hz, hertz (Hz) refers to the refresh rate, or number of times a display is refreshed per second. 30Hz indicates that a display is refreshed 30 times per second and 60Hz is 60 times per second. The more times the image is refreshed, the smoother the image is in terms of motion rendering and flicker reduction. 30Hz is used for most movie and TV content in the U.S. at present. 60Hz is currently used in video games, and we’re seeing some adoption with the use of 48fps (frames per second) films, up from the standard 24fps, in films such as The Hobbit and Avatar 2, 3 and 4. They are also filmed in 3D, and are being called “HFR 3D.” The doubling of frames in each second allows for the creation of very fkuid slow-motion scenes, while action scenes are smoother and more lifelike, individual frames are sharper, and fast camera movements no longer cause the image to appear to jump, which is called “strobing.” Because high-frame-rate films are much sharper, there is also some talk of 1080P/144Hz competing with 4K/60Hz in quality.

Video Inputs and Outputs

Video matrix switches have evolved to accept multi-format HD and UHD inputs and outputs, where the outputs may be the same signal as the inputs or be transcoded into different signals. Current cabling and connector standards that are now (or soon will be) available and may be included in your matrix switch are:

Evolution.._Video_Inputs

Compression Standards

If you are transporting uncompressed video/audio/data through a matrix switch, you will need to use either a CATx/HDBaseT or fiber-based network—and probably a dedicated network at that—but if you want to use an IP/Ethernet network, which uses packetized video, by necessity the files will be compressed. In order to accommodate the sending of ever-increasing multimedia file sizes over IP, compression standards have evolved alongside changing resolutions and distribution needs. Matrix switches now handle IP compression/decompression internally, sans an external converter.

The compression standard in switches today is H.264 / MPEG-4 / AVC, soon to be superseded by HEVC / H.265, which supports up to 8K resolutions. They are both an evolution of earlier standards developed by the Video Coding Experts Group (VCEG) and Moving Pictures Expert Group (MPEG), who sometimes worked independently but chose to work together as the codecs progressed.

Evolution.._Compression_Standards

Sources & Displays

As long as you have some type of cabling with enough bandwidth capability to support your distance and signal requirements, plus a matrix switch with the appropriate signal cards, you should be all set. All that’s left to worry about now is your AV sources and displays. Typical sources, displays and their connector types are as follows:

Evolution.._Sources_and_Displays

4K is quickly becoming the new standard, and with it video switching has evolved to manage it. It will continue to evolve until we reach 8K…and beyond?

ebook-introduction-to-video-matrix-switching

Topics: Video Matrix Switches

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