The Three Categories of Switcher
To answer the question of whether switchers are necessary, we first need to break them up into a few categories: routers, seamless switchers and broadcast switchers.
Routers are a low cost way to clean up that mess of cables behind your video rack. They allow you to plug in all your A/V sources and destinations and route among them. The trouble with routers is that you get “glitchy” cuts only — meaning you can’t dissolve between two sources, and you’re limited to just a few resolutions. Many routers will also lose sync to the destination as it moves between sources. This causes your screen to temporarily say “No input” or flash blue for a second while it tries to re-sync to the new source. This can cause a few groans when it happens in the middle of your program.
Routers are not designed (and not recommended) for switching between video sources for “live” (IMAG) video projection. Their primary purpose is for facilitating the routing of multiple video sources and/or displays to one another off-line (i.e. not “live” or any screen viewed by an audience).
The Seamless Switcher
Most seamless switchers allow you to input all types of resolutions, and output them to a common resolution. It also synchronizes sources while you switch inputs, so you don’t have the blue screen (glitch) problem. The trouble is, with the exception of high-end (expensive) scalers, you are limited to simply cutting, or creating simple transitions between sources such as fading in and out through black. A seamless switcher works best when you need to switch from several different graphic sources with different resolutions, all being sent to the same screen.
The Broadcast Switcher
A broadcast switcher sits at the top of the video switcher food chain. It is what you most expect to see when you step into the video room, and it is the most identifiable: it has the T-bar. A broadcast switcher allows you to send multiple inputs to multiple outputs (like a router) and allows you to create different seamless transitions between them, most importantly, cross-dissolves. It also provides more flexibility, such as the ability to key and use a DVE (Digital Video Effects).
In the professional video world you get what you pay for, and seamless switchers come in a wide range of price tags.
When Will You Need a Video Switcher?
Typically, you will need a video switcher if you have more than one source in any given program, but don’t always assume you need one. In a recent scenario, a church wanted a computer input at the booth in the back, a DVD player, and a computer input on stage. At three inputs you might jump to put in a switcher, but on a tight budget we elected to specify a projector that could accept all three inputs because each source would be used in a different service or event.
When the youth group used the room their source was the computer at the booth, mid-week bible studies would use the DVD player, and outside groups would need the computer input on stage.
In situations like this, where only one video source is used for an entire program, a video switcher could complicate rather than simplify. It should also be noted here that switching inputs on the projector in front of an audience in order to access a second or even third video source is definitely not recommended and is very distracting. Video projectors are not seamless switchers!