"Travelling" Transparency Matte?

[danielsangeo]

Hello! I've been searching all day for how to do this and I'm at my wit's end trying to figure out how to do what should be a very simple thing. At this point, I don't even know what to search for.

Here's what I want to do.

I have two video clips as sequential PNG files. I would like to use a mask or matte or something to cut out part of one of the video clips so you can see the other video clip inside the cutout. The shape of the cutout changes over the course of the video. I am trying to figure out how to do this, such as creating a new video clip with the transforming cutout shape, but I don't know if that's the best course of action or what I even need to do.

What do you folks think is the best course of action for this? I'm using Vegas Pro 10.

Thanks so much in advance!

[poisondeathray]

You can use an animated mask with keyframes, or use a "track matte" which is really a "travelling transparency matte" as you call it. They have different names in different programs. The choice of what to use is determined by what you are doing specifically. If you can provide more details then there might be an easier/better/preferred method vs. difficult more time consuming method

The first method just uses keyframes and the pen tool, setting keyframes as you go. The generic term for this for all programs is called "rotoscoping" - but it just boils down to animated masks

The 2nd method is just a black/white clip determining areas of transparency (shades of grey are intermediate in transparency blending between 2 layers) . If you already have a matte (e.g. generated from another program in another workflow), then this method is usually preferred. I can provide more details if you choose this, but it basically uses the vegas mask generator tool with luminance key. It's just a method of layer compositing in vegas

[budwzr]

Vegas Pro has a "Cookie Cutter" tool. Of course, you can animate the shape using keyframes.