round corner mask

[David Bogie]

We used to do this (somewhat tediously) by adding control points to a square mask and pulling the handles out.

bogiesan

This is my standard sigfile so do not take it personally: “For crying out loud, read the freakin’ manual.”

[Peter Van der zee]

copy-paste is the fastest method, because in 6.5 you’ll have to do the mask manualy.
make a square mask, add extra maskpoints in the corners, delete the original corner mask-points, convert the others to bezier and shape it to your needs. (a grid will help a lot)

vanderzee.tv

[Brian Kowalenko]

Easiest way is to make your rectangle mask, then go into the mask shape and contract the dimensions by the bevel amount you want on each side. Then go into the mask expansion option and expand it until you’ve got a nice bevel going. Requires a tiny bit of math but at least you can do all the work right inside After Effects.