Frame drop, and its twin frame insert or duplicate, is the blunt instrument for correcting timing errors: when audio and video have drifted apart or a buffer is running away, the system simply discards or repeats a frame to claw the alignment back. It is cheap and immediate — no signal processing required — which is why fallback paths and simple players use it. The cost is that a careless drop in audio is audible as a click or a tiny gap, and dropping or repeating video frames shows as a stutter. Smarter pipelines prefer resampling, which corrects drift continuously and inaudibly, reserving drops for when they fall too far behind to recover gently.
