Multiple mask / black / transparency issue?

[qmr]

23.09.29 win10 6600k 16gb

V2 has graphics
V1 video track

I have placed these filters on V1 mask simple shape, mask simple shape, blur, mask apply

mask 1 operation minimum
mask 2 operation maximum

If V2 visibility is toggled off, the masks and filters work as desired.

If V2 is toggled on most of the output becomes black save the graphic in v2, and the masks on v1

the graphic on v2 is a PNG with transparent background.

1. While troubleshooting I read that shotcut mixes down to a black background instead of transparent for performance reasons, is that related to the issue I am having? I tried adding a blank v3 that did not help

2. other tutorials referenced having 2 copied video tracks and doing some crop to get the effect I want. then other things I read said that is not necessary in newer versions. should I try that?

[SergeC]

Hi, @qmr. I’m not sure what you want to see as background.
If you want to see the video clip, you can drag it to V1 and V2.
PNG with transparency (Lego) on V3.
Apply Mask filters to V2, 1st = Minimum, 2nd = Add.
Add Blur filter.
Mask Apply not necessary, since there’s a track below.

[qmr]

thanks for reply. I tried minimum and add and it’s still not working.

of course the video should be the background. V1 is video as stated in original post.

why 3 tracks exactly? 1 for image 1 for video, what is the third for?

[qmr]

copying the video to a lower track gives expected behavior, but I’m not following why this is necessary

[shotcut]

You need to apply a workaround explained here:

Transparency lost when using add operation in mask, it's a bug?

Please improve the subject line. Otherwise, people (including developers) will probably overlook it as useless when scanning through the list in the category at a later time. We are rarely going to try to fix a problem as soon as we read about it. The problem is that Mask:Apply does not reset the alpha channel. That might be a feature for some, but a bug for others. You can see that by hiding V2 and adding a Alpha Channel: View after the Mask: Apply. The, track blender - by design - combines th…

Basically, after Mask: Apply add Alpha Channel: Adjust and set Mode to Reset. Then, click the Invert checkbox.

Alternatively, you can use Mask: Draw (Glaxnimate) to draw multiple shapes inside one mask, and then you do not need to reset the alpha channel (because the image before masking has no alpha channel, which implies opaque).