Module overlay 

Overlays composited onto the output in the grade pass (text cards, captions), backend-neutral.

An Overlay is a coverage mask (8-bit alpha) drawn in one or more colours over a range of output frames, with linear fades at its ends. The backend uploads each mask once per run and hands the visible ones to libplacebo as pl_overlays (PL_OVERLAY_MONOCHROME) on the render target, so overlays cost no extra pass and frames outside their ranges are untouched. Animated overlays (sliding, popping, typed text) carry a Motion: their placements per frame.

Structs

Mask

An 8-bit coverage mask, row-major, width * height bytes.

Motion

An animated overlay’s placements: output frame first + i draws frames[i]. Frames before first draw the first entry, frames after the last the last one.

Overlay

A mask drawn over output frames from..to (pipeline frame indices, 0 = the first frame output), fading in over the first fade_in frames and out over the last fade_out.

OverlayPart

One placement of an overlay’s mask.