A quality gate is an automated check that compares a measurement to a threshold and fails a release when the score drops too far, so a bad encoder change is blocked before a viewer sees it. Borrowed from software CI/CD, it points the same pass-fail logic at the picture: encode a fixed test clip, score it (use a perceptual metric like VMAF, not PSNR, because an encoder can raise PSNR while the picture gets worse), and refuse to merge below the bar. A robust gate runs two checks: an absolute floor (never ship below a set score) and a regression check against a golden reference (never drop more than a small margin from the last good build). The catch is sizing that margin from the metric's own noise rather than a guess, and reading the worst frames (a low percentile), not just the mean. Decide deliberately whether each failure is a hard gate that blocks or a soft gate that only warns; deploy new checks soft, then harden.
