Video
Scaler vs Switcher
01 — Definition
Two boxes that get confused. A scaler converts an incoming signal to a fixed output resolution and frame rate — enough to let mismatched sources share one display. A switcher (seamless switcher / production switcher) picks between several synchronised sources and runs the transitions (cut, dissolve, wipe). A presentation switcher does both: it scales every input to a common format, then switches seamlessly. A raw switcher with unmatched inputs, on the other hand, glitches on every transition.
02 — In the field
For a conference with laptops at assorted resolutions, you need a scaling presentation switcher, not a plain SDI switcher. A plain switcher wants every source genlocked and format-matched, or the cut will flash.