Simple Mask baffles me

[Kalamar]

I’m not sure if it’s a bug or me who just doesn’t understand how Shotcut works. (version 20.04)

I’m trying to have my kid in multiple places in the same video.
I have two video-tracks, shot with a mounted camera.

The first video track is unaltered.
The second has a mask applied (simple shape: rectangle), to have only my the part with my kid overlayed on top of the previous track.
No matter what I do, I can’t have more than just the shape of the mask, no fusion. And there is a rectangle which comes from nowhere, like the original default shape of the mask. I am flabbergasted.

Mask properties

Track properties:
Blend Mode: Over

Result

[Hudson555x]

@Kalamar

The second has a mask applied (simple shape: rectangle), to have only my the part with my kid overlayed on top of the previous track.

Not entirely sure what you’re looking to do, so I’m guessing you want to see the the different video tracks clips apart which the mask does not do. That would be for the Size & Position or Rotate & Scale filters. You can still apply the mask filter after positioning.

In this example these three images would be on top of each other if I didn’t apply Size & Position filters to the clips on V2, V3, V4.

In this example I didn’t apply any positioning filters yet moved the position of the mask on each picture clip.

[Kalamar]

What I want to do is something similar to this (with 7 tracks) https://www.youtube.com/watch?v=1rmRU4otAYk
All tracks are properly positioned from the get go, since they were shot from exactly the same spot on a mounted camera.

[Hudson555x]

After looking at the video and your screenshot again, I overlooked you applied the Mask filter to the whole track and not the individual clip. I also believe you masked V1 video track as well, which the mask should only apply to a clip, and not a video track for what you want to accomplish.

In this example it shows that mask is applied to both tracks (not any selected clips) thus duplicating your screenshot.

[Kalamar]

I am even more confused, I didn’t know you could apply the same filter to multiple tracks.
I am not sure what you mean when you make the distinction between ‘clip’ and ‘track’ but my “background” track, the lowest one has no filter applied at all:

[Hudson555x]

Perhaps you have applied a Mask filter applied to your clip in V1, thus making your first screenshot.

To select a clip, click on it, and it will have a red border around it, and the track will turn olive green.

Another example of a selected clip, tracker header is olive green.

When selecting a track, it will have a red box around the track header, where a clip is not selected. Track header is blue, and any remaining space on the track is olive green.

[Kalamar]

Finally! Thank you for your explanations!
I know understand that you can apply a filter on a track OR on a clip and the clip below had a mask too!
I don’t know how that happened (I had ended up using OpenShot, but ShotCut seems so much more powerful, I really wanted to make it work).