Vegas Pro 10: Understanding Video Compositing

SONY by Gary Rebholz

Vegas Pro software features powerful video compositing tools. A video composite occurs when you do something to your video that combines two or more streams of video so that they appear simultaneously as a new single image. In Vegas Pro software you can accomplish this task with many different tools, the most obvious being the track motion controls (think about creating a picture-in-picture sequence), certain video filters (like the Cookie Cutter, the Chroma Keyer, and others which enable compositing by creating transparency in the video clips they've been applied to), pan/crop controls, and more.

But one set of compositing controls remain largely unexplored and underutilized by perhaps most Vegas Pro editors. The composite mode options give you a wide range of control over the look of your project, but many people don't understand how they work. So in this article, we'll take a look at some examples that will help you understand how composite modes work and how you can use them to enhance your projects.

Start a new project. Click the Media Generators tab, select Solid Color from the list, and add the Red preset to the beginning of a new track. In the Video Media Generators window, note that the color is represented with the RGB color model. In this model, Red, Green, and Blue are mixed together to create all other colors. The resulting color also has an Alpha value. We'll talk more about alpha values shortly.

This red has an RGB color recipe of R: 255, G: 0, B: 0 as well as an Alpha value of 255. That information will come in handy as we make our way through this discussion. Next, drag the Blue thumbnail onto track 2 on your timeline directly under the red event. In the Video Media Generators window note that this blue has an RGB recipe of R: 0, G: 0, B: 255 with an Alpha value of 255. In the Video Preview window, you don't see the blue at all.

These results highlight a critical point in understanding compositing in Vegas Pro software: The video signal flows from the bottom up. Think of this for a moment as sheets of paper. When you put the blue sheet of paper down on your desk, you can see it clearly. That is, until you lay the red sheet of paper over the top of it. Then you can see only the red.

It's the same idea here. The red event on the top track obscures your view of the blue event on the bottom track. But you can use compositing to see a combination of both colors on the screen at the same time.

Vegas Pro gives you many ways to create a video composite. I mentioned a few of these earlier. The technique you choose for creating your composite determines how the two video streams are mixed for final output. For instance, you can lower the Level value of the top track to enable the lower track to show through. Drag the Level slider for Track 1 slowly to the left. As you do, you see more and more of the blue from the event on track 2 show through and blend with the red on the top track. The Video Preview window shows the results of this blend as it passes from red toward purple and on to blue. A Level value of 0% makes the top track completely transparent and you see the completely blue results. Raise the Level slider back to 100%. read more...