I designed and/or installed systems that functioned they way Edrick described but that was years ago before scalers were common. Now it's to the
point that it would probably only be justified is someone was trying to do it as cheap as possible and perhaps not even then.
There are a myriad or manufacturers out there for
switcher/scalers and seamless switchers As ruin noted, the basic difference is that a
switcher/
scaler has one
scaler and switches the video before the
scaler. Basically, it is doing the same thing the
projector does when switching between inputs but instead of seeing glitches while it resyncs it displays a still of the last frame, black or a saved
logo until there is time for sync to be reestablished. A seamless
switcher uses two or more identical scalers, thus you are switching between already matching signals.
If you are looking for simple, glitch free switching between
VGA, Y/C and composite sources then there are likely a number of options well within you budget, but that may depend on some of the specifics. I typically start with looking at exactly how many of what type of inputs and outputs need to be supported, including any assumptions for future expansion or capability (which may or may not include digital sources). Whether the
switcher also needs to
switch audio can be a major factor as many devices
address only video and require audio to be mixed or switched separately. The control is also something to consider, would it be front panel control or are a remote control panel, handheld remote, serial control,
network control or some other form of control required? Sometimes there may also be specific criteria such as
fitting within a certain amount of rack space. These factors can sometimes start to quickly narrow down the viable options.