To some, a video switcher is the ultimate control trip. You not only get to select what people see, but, in some cases, you get to manipulate the way in which one image is transitioned to another and what it looks like when the switch is complete. To others, it is simply a means to an end: getting the right image on the screen at the right time.
From the simple, single row of four or five buttons to insanely complex multi-tiered video production switchers, you may judge switchers as the most fun tool in the video arsenal or a simple thing you need. At the top of the heap are the production switchers used by broadcasters, production and post-production facilities. These products enable a hypnotizing array of multi-input effects while at the same time stepping up the bandwidth bar to incorporate higher resolution signals such as HDTV.
However, a more typical video-switching application for the systems installer doesn't involve the need to switch more than half a dozen or so inputs, and there isn't the need for Star Wars-class effects. Rather, you need a product that is compact, reasonably priced, and able to do the standard switcher functions with only one or maybe two busses, rather than four or six. For that, you might want to investigate the use of either smaller switchers designed for news-van use, or maybe even more interestingly, switchers designed for master control use. This type of product, typified by PESA's MCLite, has dissolves, limited effects and keying, but in exchange for the rows and rows of buttons on the big guys, they add niceties such as logo storage and insertion and audio follow switching with output level control.
For video walls or large-venue applications with multiple side-by-side projectors, there are more specialized switchers from the likes of Extron, Altinex, Folsom Research and others. These types of companies understand the needs of the presentation market and the intricacies of integrating multiple forms of video or data input signals into a single, universal output. These might feed many different types of displays ranging from conventional CVBS composite video for small monitors to large-venue projectors, data displays and all points in between.
Things get even more exotic when the switcher includes the capability to spread the image across up to four video displays with carefully blended edges. Folsom's Presentation Pro, for example, has basic video with audio follow capabilities, but when it comes to doing the job on multiple screens, it is a good example of what the presentation switcher is all about.
While some think only of switchers in terms of their use in production, there is also a whole layer of video switcher products aimed toward plant infrastructure. Here one finds a group of products categorized as routing switchers. In most cases, this means a matrix switcher. Their task is to take any input it is fed and send that input to any available output. It sounds simple enough, but as the number of inputs grows, and with it the number of switching crosspoints, you see the product grow in complexity and size. And you have to become vigilant about specs for crosstalk so that what you see (and often hear) at the output is only what is intended, not any errant echo, click or pop.
When specifying a matrix switcher, particularly as it gets larger and more complex, don't forget to decide how audio will be accommodated. You must continue to consider inputs and out requirements for that "old-fashioned" mono, but also 2-channel stereo, multiple analog audio channels, serial digital (AES3-ID) audio and digital audio in other data forms. You may have to deal with some or all of those while still keeping everything in phase and sync. It can be done, there are products that do it, but if you don't remember to anticipate applications today, your new switching system may be out of date tomorrow.