Bake a mask's result, frame by frame, and lock it in place. Once a layer is locked, scrubbing and playback read the cached mask instead of recomputing it, and the qualifier, shape, or Segment controls that produced it are frozen so a later tweak elsewhere in the stack can't quietly change a selection you already signed off on.
Every masking method in Transduce — qualifiers, geometric shapes, Segment layers — normally re-evaluates as you scrub, since the underlying frame or the layer's own parameters can change. That's the right default while you're dialing a selection in, but it has a cost: the more expensive the mask (a multi-subject Segment pass is the obvious case), the slower scrubbing gets, and the more exposed you are to a mask drifting on a frame or two you already checked.
Mask Lock closes both gaps. Locking a layer runs it once across the clip's frame range and stores the result per frame in a bake cache; from then on, the viewer and export both read that cache instead of recomputing the mask live. The layer's mask controls disable while locked — you can't edit the qualifier range, nudge a shape, or re-run Segment on it — so the frozen selection can't be moved by mistake. Unlocking re-enables editing but doesn't throw the cache away, so undoing a lock to make one small change doesn't cost you the bake.
| State | What's true |
|---|---|
| Unlocked | Mask recomputes live from the layer's qualifier, shape, or Segment parameters on every frame. Controls are fully editable. |
| Locked | Playback and export read the cached mask for each frame. Mask controls are disabled for this layer until it's unlocked again. |
| Locked, bake-stale | The layer is locked but the current frame has no cached result yet — a frame added to the range after the bake, for instance. Shown with a stale indicator until it's re-baked. |
Bake once, scrub fast, and keep every layer above it honest.