What does Keyframe mean?
A keyframe is a picture or access point that supports independent entry into a compressed video sequence, subject to the codec and stream structure. It helps a decoder begin or recover without relying on an unlimited chain of earlier pictures.
Why it matters
Many other frames describe changes relative to reference pictures, which reduces data requirements. A player joining live video may need suitable entry information before presenting a clean image. Startup delay can therefore involve encoding structure as well as buffering and access processing. The term should not be used to diagnose every slow channel change without observing the actual stream and player.
A practical example
A channel can take a moment to open and then play smoothly for an hour. That differs from repeated stalls during steady playback. Record startup behaviour separately, because increasing broadband speed does not necessarily remove every wait for a usable decoder entry point.
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Related terminology: Judder, Knockout competition.
For practical setup and troubleshooting, browse the journal or support guides.