# What is a mask in video editing?

> A video mask limits a clip or effect to one area of the frame. See common uses, a keyframed reveal example and the AI mask tools in major editors.
- **Author**: Marxx
- **Published**: 2026-11-09
- **Category**: Video editing
- **URL**: https://marxx.ai/library-glossary/video-mask

---

A mask in video editing is a shape or cut-out that limits a clip or effect to one area of the frame. Only the part inside the mask shows or changes.

## What ads use masks for

- Reveal a product with a wipe that grows across the frame.
- Colour or brighten only the product, not the background.
- Place text behind a person.
- Hide a part of the frame, such as a stray object.

## A worked example

Say you reveal a product with a rectangle mask that grows across a 1,080-pixel-wide frame. You set two [keyframes](/glossary/keyframe) on the mask width.

| Time | Mask width |
|---|---|
| 0 s | 0 px |
| 1 s | 1,080 px |

At 0.5 seconds the width is halfway: **540 pixels**. The product is half revealed.

## AI masks

Some editors can draw the mask for you around a person or object.

| Tool | AI mask feature | Note |
|---|---|---|
| Premiere Pro | Object Mask, with AI masking and tracking | Now called Adobe Premiere |
| DaVinci Resolve | Magic Mask, one-click selection of people or objects | Studio edition |
| Final Cut Pro | Magnetic Mask, isolates people and objects without a green screen | Mac |

Features are from the makers' product pages (checked 3 Nov 2026).

Marxx's [AI video editor](/features/ai-video-editor) has masks you edit by hand and a Generate tab that removes a background (this uses credits). We make Marxx.

If you only need a person on a new background, see [chroma key](/glossary/chroma-key).

## FAQ

### What is a feathered mask?

A feather softens the edge. The masked area blends into the frame instead of ending in a hard line.

### Can a mask follow a moving subject?

Yes, with [motion tracking](/glossary/motion-tracking) or AI masks. Otherwise you move the mask with keyframes.

### Is a mask the same as a crop?

No. A crop cuts the frame to a rectangle. A mask can be any shape and can limit one effect.

---
- [More Video editing articles](https://marxx.ai/library-glossary/category/video-editing)
- [All articles](https://marxx.ai/library-glossary)