Editor's Toolkit: Using Transitional Wipes with Avid®

The various mattes in the Editor's Toolkits are simply black and white animations that are used to define transparency in composited video. These animations do not have built-in alpha channel transparency like the many full-color effects and transitions in the Toolkits and therefore are slightly more complex to use.

To use an overlay matte in Avid® (e.g. Media Composer®):

1. Arrange your clips on the timeline (Figure 1):

* V3: transition wipe matte
* V2: video clip (A-Roll)
* V1: video clip (B-Roll)

Figure 1 - The initial timeline in Avid® Media Composer®.

2. Add a Matte Key to the clip on V3: Tools menu > Effects Palette > Key > Matte Key.

 
Figure 2 - Add a Matte Key to the clip on V3.

3. From the Tools menu, select Effect Editor and select the Swap Sources item (Figure 3). Different applications default to whether black is transparent or white; Avid happens to uses a film-style analogy, where black areas are transparent.

Figure 3 - Select the Swap Sources item in the Effect Editor.

4. If you preview the transition, you'll see that it all works, except that the A-Roll in Video 2 does not show up anymore. To fix this, copy and past the clip from V2 into a new track on V4 and trim it back so it doesn't cover the transition. You can do a little more trimming in V2 for neatness (Figure 4), but this isn't strictly necessary.

Figure 4 - Copy the video clip in V2 and trim to complete the effect.