Genlock (generator locking) is how multiple video devices are forced to run on exactly the same timing reference — the same frame start, the same scan rate — so their outputs can be cut between, mixed or composited without a visible glitch.
Without it, two cameras (or a camera and a graphics system) are each running their own internal clock, fractionally out of step with each other. On a single source that's invisible. The moment you switch or composite between sources that aren't locked together, you get a visible frame tear or glitch at the cut point — because the new source's frame didn't start at the same instant as the old one.
Genlock matters in any live multi-camera production where sources are being switched or layered in real time: studio production, live sports, multi-camera events, virtual sets. It generally doesn't matter for single-source recording or streaming, or for IP-based NDI workflows where frame alignment is handled differently over the network rather than via a dedicated reference signal.
Worth flagging honestly: dedicated genlock/reference-in hardware sync isn't a feature on the Magewell capture and encoding range we stock. Most modern multi-camera workflows we supply into — software switchers, NDI-based production — handle frame alignment a different way rather than through a dedicated reference signal. If genlock specifically is a hard requirement for your setup, get in touch and we'll talk through what will and won't work for your workflow.
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