MaskedMerge: Resize only the 1st mask plane if first_plane=1
MaskedMerge: Resize only the 1st mask plane if first_plane=1

The other two planes are not used.

Kamekameha/vapoursynth,Kamekameha/vapoursynth,vapoursynth/vapoursynth,vapoursynth/vapoursynth,vapoursynth/vapoursynth,Kamekameha/vapoursynth,vapoursynth/vapoursynth,Kamekameha/vapoursynth