Mon Apr 06, 2020 1:04 pm
I assume you have a mask node for this.
In the inspector window for the mask node you will find the control "Level" (I think it is even the first entry).
Right click on the label, not the slider or number, but the label, and select "Animate".
Now you have the little diamond on the side of it to create keyframes for the level of the mask.
You can further refine this in the "keyframes" panel.
If you have further questions, please ask.
Tech:
Win 10 pro, Ryzen 5 1600x, 64 GB, SSDs for media
GTX 980 ti (451.67), Intensity Pro, DVR Studio + Fusion 16.2.4, Desktop Video 11.5