Putting video inside text or a logo in After Effects is easy, but perhaps not clear cut at first glance. To do this, an alpha or color channel is borrowed from one layer and used as transparency information in another layer. The borrowed shape of the text or logo is used as a matte or mask, to retain or subtract pixels from the video layer. There are two methods to accomplish this, Track Matte and channel filters, and both can present obstacles to further enhancement of the effect.

Track Mattes

Track Mattes were implemented in After Effects 3.0 and are similiar to Track Mattes in Premiere and Clipping Groups in Photoshop. Control over Track Mattes is found in Transfer Controls, which can be found under the Switches pop-up in the Time Layout window. Clicking on the gray box next to Switches is the fast way to get to the Transfer Controls. A track matte can only be borrowed from the layer directly above the layer that pulls the matte.

In this example I used a Solid Layer with the Basic Text filter to generate an alpha channel. Below the text layer, I imported 2 textures from the ArtBeats "ReelTextures" CD. The bottom background layer is the PICT file "Aged Wood." The middle layer is "Green Flight," a QuickTime movie that will appear inside the text "Clearcut." Green Flight's Transfer Controls are set to Alpha Matte "Solid text", which pulls the alpha from the text above and applies it to the movie. The text layer's visibility is turned off automatically as shown below.

Since the result is a little flat, adding a few Perspective filters can give the effect some depth. The picture just above shows the result of adding the Bevel Edges and Drop Shadow filters -- nothing. This is because After Effect's Rendering Pipeline calculates Track Matte (and Tranfer Mode) last; the filters are applied to "Green Flight" before the Clearcut alpha. Composition Nesting of "Clearcut" and "Green Flight" is required pre-composite the video-in-text so it becomes one object. Using the Pre-compose command is the fastest way to accomplish this; it effectively sends current layers to newly created compositions in the past. Just select the layer(s) that need pre-compositing and choose Layer>Pre-compose. Most often "Move all attributes" is the choice to make in the Pre-compose dialog because it creates the new comp the in same size of the current composition not the layer size. Now the perspective filters will add depth, as shown in the GIF at the top of the page.

Using a Track Matte may seem involved but it is actually quick, and avoids certain obstacles associated with using Channel filters (discussed here). You may prefer using the Set Channel or Set Matte filters, especially when you need more access to channel information.