At the surface, the track matte and the mask seem like they do basically the same thing in Adobe After Effects. In many cases this is true, using one or the other will result in the same final product. However, they differ in a critical area which makes each useful in it’s own way.
Difference Between Track Matte and Mask
Both of these tools have the same general effect. They cut out a portion of a layer, to reveal the layers beneath them. This is useful to create reveals, to key something out, or to generate things like shapes. The key difference between the two however is that a mask is dependent on a specific layer, while a track matte is independent of the layers.
What do I mean by this? Think of it like you are working with building a real life art project. You have a bunch of pieces of papers (layers) all ready to be glued onto a large art-board. A mask is if you took one of the layers, and cut off a portion of it. No matter where you move this layer, that cut is still going to be present. It follows the layer and is dependent on the layer. It is essentially just a property of the layer.
A track matte however would be if you got a layer that was the same color as the background art-board, and placed it somewhere on the project, always making sure all other layers are behind it. The track matte here is stationary. It doesn’t matter which layers are present, it is doing one job. Making sure nothing is displayed in a certain portion of the project. You can move all the layers around, and the track matte will stay right where it is.
Imagine you want to create an invisible line for text to come out of in After Effects. If you create some text, and then drag a mask onto one end of the text. Moving the text will move the mask along with it. This means you would have to both animate the text, and then reverse animate the mask along with it. It would become a tedious process.
So instead, we can use a track matte. We create a rectangle shape, and then track matte our text to that shape. This makes it so we can move the text, and it will either be cut off, or revealed within this rectangle. Our effect is then really easy to work with. (Check the video above for a demonstration)
These two although very similar have a very strong difference. Understanding this difference will allow you to better utilize each tools strength, and speed up your workflow.
Other Premiere Pro Tutorials: