Masks in VSE?

Support Compositing and Post Processing
1

Is there any way to do a mask in the VSE?

2

If you want to mask a specific part of a sequence you can make an image with an alpha channel. Something in a .png is good but anything with an alpha channel will work. Place the image over the sequence you want to mask and set it to “alpha over”.

You have lots of options here. You can make an animated mask with an image sequence or a video format that supports transparency. You can also make an alpha gradient either with blender or any photo editing software.

You can also render out the masked sequence as an image sequence and combine it with other sequences using the same method.

3

thanks for the reply but I was talking about using a greyscale image to mask out stuff

4

You mean like overlay a 2D object on top of footage? If so, it’s the same principle really.
Create an animated shape using e.g. the rotobezier addon in the 3d viewport, render it out as an image sequence with transparency, and overlay the sequence on top of footage in the VSE.

5

I don’t think it’s possible. I’ve tried to achieve it myself with different meta-strip blending tricks, but no luck.

And yeah - it’s easy to figure out workarounds with separate renders and compositor tricks, but the issue is achieving it within the VSE. This feature would enable a whole new category of methods and tricks without pre-processing the footage.

6

If we’re talking about the same effect, I don’t really see what the problem is. You don’t really need any metastrips for such an effect. A plain good old alpha over blend mode should do the trick if all you want to do is to “hide” something in the footage with a grayscale mask. I could post a sample blend file if you want one.

7

yes please :slight_smile:

8

Here you are, pretty straightforward, straight from the 3d viewport into the VSE without involving the compositor at all.
Had I not been too lazy, I’d have rendered a still first and overlay that. That would eliminate the need for importing the scene into the sequencer.
This is a still as a proof of concept. With real footage where either the camera or the subject is moving within the frame, you simply need to animate the mask using the magical rotobezier addon.

Is this what you were asking? Cos it’s so elementary that I’m beginning to think that I must have misunderstood something.

Sintel_poster_sample.blend (799 KB)

9

For some reason I couldn’t get your blend file to work so I recreated it in a new blend file and It worked :slight_smile: thanks