Is it possible to use a video/image sequence as a mask?

[alberto.linkvids]

Hi!
I've been trying to paint some brush strokes on top of a video with alpha and i want them to remain confined to the shapes of the video, i mean, not going into the background. I have been trying to use the video as a mask, both as a .mov and as image sequences (png and tga) but the mask doesn't update as the frames of the video change.

Does anyone know if theres a way to do this?
Thanks in advance!

[slowtiger]

This should definitely work, I've just tested again.

1. Take care to really have an alpha channel - you have to prepare that in the video. (Greenscreen/Colour key in Moho might work, I've never tested.)
2. Save in a format which preserves alpha (Video: PNG codec wth millions+ colours).
3. Create the correct masking setup (mask video and masked layer within the same folder).

[alberto.linkvids]

Thank you for the answer! Yes, I have followed these steps. The mask works but it looks as if it only catches the first frame, as the video moves, the mask remains the same and doesn't synchronize with the video as it plays.

[slowtiger]

That's strange, it works here. You have checked if the video plays elsewhere, I suppose.

We're talking about a rendered video from Moho, not the Project Window View, right?

[alberto.linkvids]

Thank you! Thats was the issue, I thought I could watch it on the project preview windows on real time, I have rendered it now and it works perfectly!

[slowtiger]

Glad it works now!

[SimplSam]

You can alternatively import the PNG sequence as an FBF sequence (Scripts > Image > Import Image Sequence), and use that as the mask layer - and it will update in the Edit view on every frame.