Quality-floor mode
Invert the optimisation: set a minimum acceptable quality, then spend the least that keeps you above it.
What it is
By default the engine chases the best blended score. Quality-floor mode flips the objective: you declare a minimum acceptable quality — as a target rebuffer ratio or a minimum bitrate — and the engine spends the least it can while staying above that floor, rather than minimising cost outright or maximising quality outright.
Why it matters
For premium and contractual content there's a quality line you will not cross, but above that line you'd rather not overpay. Quality-floor mode encodes exactly that: protect the experience first, optimise cost within the remaining headroom.
The metric behind it
The floor is usually expressed against rebuffer ratio — the share of playback time viewers spent waiting on a stalled player. It's the single most-felt quality metric (lower is better), so it makes a clean, viewer-aligned floor. The engine keeps above it and treats cost as the thing to minimise underneath.