How do you create an opacity mask in Premiere Pro?

Creating an opacity mask in Premiere Pro is straightforward and allows you to selectively reveal or hide parts of your video. Here's how to do it:

Steps to Create an Opacity Mask

Select your Clip: First, select the video clip on your timeline to which you want to apply the mask.
Navigate to Effect Controls: In the top-left corner, locate and click on the "Effect Controls" tab.
Find Opacity Settings: Within the "Effect Controls" panel, locate the "Opacity" option.
Choose a Mask Shape: Under the "Opacity" dropdown, you'll see the "Mask" options. You will see the following options:
- Ellipse Mask: Creates an oval or circular mask.
- Rectangle Mask: Creates a rectangular or square mask.
- Pen Tool: Allows you to create a free-form mask shape.
According to the provided reference, once you choose one of the options, "you will see the shape appear over your video".
Adjust the Mask:
- Size: You can adjust the size of the mask by dragging the corners.
- Proportions: Hold down the Shift key while dragging a corner to resize the mask proportionally, making the entire mask larger or smaller.
- Position: Move the mask around the frame by clicking and dragging inside the mask boundary.
Invert the Mask (Optional): If you want to hide the area inside the mask instead of outside, click the "Inverted" checkbox under the mask settings.

Feathering: You can soften the edges of the mask by increasing the "Mask Feather" value, found within the mask settings. This creates a smoother transition between masked and unmasked areas.
Mask Expansion: Adjust the "Mask Expansion" to either grow or shrink the mask area.
Tracking: If your subject moves in the video, use the tracking options within the mask settings to automatically move the mask along with your subject.

By using these steps and tips, you can effectively create and customize opacity masks in Premiere Pro to achieve various creative effects.