A video router, also known as a video matrix switch or SDI router, is an electronic switch designed to route video signals from multiple input sources such as cameras, VT/DDR, computers and DVD players, to one or more display devices, such as monitors, projectors, and TVs.

Inputs and outputs

The number of inputs and outputs varies dramatically. Routers are normally described by ''number of inputs by number of outputs'' e.g. 2x1, 256x256, 576x1152. Some video routers, by the use of additional drop-in cards, allow the system to be expanded for more inputs or outputs, or to support other formats.

Signals

The signal format that the router transports can be anything from analogue

composite video Composite video is an analog video signal format that carries standard-definition video (typically at 525 lines or 625 lines) as a single channel. Video information is encoded on one channel, unlike the higher-quality S-Video (two channels) a ...

using

PAL Phase Alternating Line (PAL) is a colour encoding system for analogue television. It was one of three major analogue colour television standards, the others being NTSC and SECAM. In most countries it was broadcast at 625 lines, 50 fields (25 ...

and

NTSC The first American standard for analog television broadcast was developed by National Television System Committee (NTSC)National Television System Committee (1951–1953), Report and Reports of Panel No. 11, 11-A, 12–19, with Some supplement ...

. Also multi-format routers can route more than one Digital video signal format, Serial Digital Interface (SDI), HD-SDI,

component video Component video is an analog video signal that has been split into two or more component channels. In popular use, it refers to a type of component analog video (CAV) information that is transmitted or stored as three separate signals. Compon ...

. Some routers have the ability to internally convert digital to analog and analog to digital. For HD Video, HDMI Matrix switch can be used to switch any

HDMI High-Definition Multimedia Interface (HDMI) is a proprietary audio/video interface for transmitting uncompressed video data and compressed or uncompressed digital audio data from an HDMI-compliant source device, such as a display controlle ...

source to any connected HDTV using a HDMI connection. More recent developments have allowed audio embedding and de-embedding within the router, this allows for audio to be routed along with video.

Crosspoints

Because any of the sources can be routed to any destination, the internal arrangement of the router is arranged as a number of crosspoints which can be activated to pass the corresponding source signal to the desired destination. This architecture has guaranteed bandwidth and is non-blocking. Crosspoints can also be switched in the

vertical interval In a raster scan display, the vertical blanking interval (VBI), also known as the vertical interval or VBLANK, is the time between the end of the final visible line of a frame or field and the beginning of the first visible line of the next fram ...

to avoid losing picture information, for this the router would need to be

genlock Genlock (generator locking) is a common technique where the video output of one source (or a specific reference signal from a signal generator) is used to synchronize other picture sources together. The aim in video applications is to ensure the ...

ed to either

black and burst Black and burst, also known as bi-level sync and black burst, is an analogue signal used in broadcasting. It is a composite video signal with a black picture. It is a reference signal used to synchronise video equipment, in order to have them ...

tri-level sync Tri-level sync is an analogue video synchronization pulse primarily used for the locking of high-definition video signals (genlock). It is preferred in HD environments over black and burst, as timing jitter is reduced due to the nature of its ...

Control

Many types of broadcast automation systems can be used to control a video router via IP or

serial communications In telecommunication and data transmission, serial communication is the process of sending data one bit at a time, sequentially, over a communication channel or computer bus. This is in contrast to parallel communication, where several bits are ...

such as

RS-422 RS-422, also known as TIA/EIA-422, is a technical standard originated by the Electronic Industries Alliance that specifies electrical characteristics of a digital signaling circuit. It was meant to be the foundation of a suite of standards that ...

. Video routers can also be controlled by other types of user interfaces, including front panel buttons, IR remote control, or application software running on a PC. Video Matrix Switches and Bandwidth
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Future prospects

With the advent of 4K/UHD TV, the traditional 'baseband' video router has become something of a victim to the data rates. UHD TV requires 3840x2160P @ 50 Hz or 60 Hz. Traditional crosspoint based devices have therefore been reduced in size by a factor of 4 as the UHD signal is split into 4x1080P@50 Hz/60 Hz 3 Gb/s streams. A few smaller manufacturers (Blackmagic Design, Utah Scientific, Ross Video, PESA) have taken on 12 Gb/s routing over copper coax cable and fiber. Although their router sizes cannot compete with the ~576x1152 size of HD routers, and the distance achievable on copper is somewhat limited. This may mean that baseband architectures start to migrate over to IP based infrastructures. Where UHD TV can be transmitted (albeit compressed) over a single 10 Gb/s link using IT hardware.

Manufacturers

Ampex Ampex is an American electronics company founded in 1944 by Alexander M. Poniatoff as a spin-off of Dalmo-Victor. The name AMPEX is a portmanteau, created by its founder, which stands for Alexander M. Poniatoff Excellence.AbramsoThe History ...

Blackmagic Design Blackmagic Design Pty Ltd. is an Australian digital cinema company and hardware manufacturer based in Port Melbourne, Victoria, Australia. It designs and manufactures broadcast and cinema hardware, most notably high-end digital-movie camer ...

Evertz Microsystems In 1997, it was purchased and reorganized by a group of former employees of Leitch Technology (now owned by Harris Corporation). Evertz held an initial public offering in June 2006 and raised $67 million CAD, listing its stock on the Toronto Sto ...

Imagine Communications Imagine Communications is an Irish internet service provider and telecommunications operator, who provide WiMAX, wireless broadband and resell Eircom telecommunications wholesale packages. The company operates in Ireland, the United Kingdom, the ...

Pulse-Eight Pulse-Eight Limited (Pulse-Eight) is a hardware designer and manufacturer based in the United Kingdom producing consumer electronics for the home entertainment and custom install industry. On 22 October 2012, it was reported that Pulse-Eight h ...

Sony , commonly stylized as SONY, is a Japanese multinational conglomerate corporation headquartered in Minato, Tokyo, Japan. As a major technology company, it operates as one of the world's largest manufacturers of consumer and professional ...

Thomson Grass Valley Grass Valley (formerly known as Thomson Grass Valley and Grass Valley Group) is a manufacturer of television production and broadcasting equipment. Headquartered in Montreal, Quebec, it was formed by the March 2014 merger of the original Grass V ...

References

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