std.Merge(clip clipa, clip clipb[, float[] weight = 0.5])

Merges clipa and clipb using the specified weight for each plane. The default is to use a 0.5 weight for all planes. A zero weight means that clipa is returned unchanged and 1 means that clipb is returned unchanged. If a single weight is specified, it will be used for all planes. If two weights are given then the second value will be used for the third plane as well.

Values outside the 0-1 range are considered to be an error. Specifying more weights than planes in the clips is also an error. The clips must have the same dimensions and format.

How to merge luma:

Merge(clipa=A, clipb=B, weight=[0, 1])

How to merge chroma:

Merge(clipa=A, clipb=B, weight=[1, 0])

The average of two clips:

Merge(clipa=A, clipb=B)

The frame properties are copied from the first clip.