Why is the presence of another track affecting the filter chain on a track?

[ZorgoZ]

Hello, this might or might not be a bug, but it looks like one to me.

What I am experiencing is that the Vertigo filter for example, applied on top of a text filter, looks totally different when anything else is to be shown on a totally different track:
https://drive.google.com/file/d/1wZEWSqvMM8rONWeDwbeUyKOhM94dMGmw/view?usp=sharing
…compared to when it is on its own:
https://drive.google.com/file/d/1XfqOrV18glli4pRH0g6y6X1FDe6an1dl/view?usp=sharing

Is that an intended behavior? If yes, what can I do to make the filter unaware of the other track? If not, is there any workaround?

Thank you.

PS: Sorry for using google drive links, but as a new user, I am not allowed to embed media files. I wanted to link a little demo project also, but, I am allowed only two links… Well…

[TimLau]

You should give public access to the files your share, like this

[ZorgoZ]

Sorry about that, should work now.

[Elusien]

@ZorgoZ

If not, is there any workaround?

You need to change the BLEND MODE of track V2. It is probably set to “Over”, you need to set it to “None”. To do this, select the TRACK, not the CLIP and click on Properties, then using the dropdown list choose BlendMode: None.

[ZorgoZ]

Well, in that case, I lose the overlap altogether, which is definitely not what I want.

It seems to me, that blending applies to the text only, not to the effect created by the filter.

[Elusien]

Of course it does. I must have had a “senior moment” when I suggested that. What version of Shotcut are you using?

[TimLau]

try adding a Chroma Key: Advanced filter and set the key color to black

[Elusien]

This doesn’t work I’m afraid. The problem is something to do with blending the images produced by the vertigo filter and Chroma Key doesn’t sort this out.

[TimLau]

Not totally, but for lower of vertigo zoom most of the effect is transparent

[ZorgoZ]

I have version: 21.12.24

[ZorgoZ]

Ok. It seems, the vertigo breaks alpha totally.
The closest I could get is with:
Chroma key color black and blend mode: hard light.

Thank you for the suggestions, they put me on the right track.

[shotcut]

@ZorgoZ

It seems, the vertigo breaks alpha totally.

Not exactly:

As you can see it respects the alpha channel and is confined by it. If you change the color in Properties to something opaque you get

If it did not respect the alpha channel, then someone would report it as a bug. In fact someone did, and it was fixed at some point:

commit 1f75f4b87bbc7df37df6fe89b589823c6d2b37d6
Date: Sun, 13 Oct 2019 14:55:26 -0700

fix vertigo not preserving inframe alpha channel

[TimLau]

I see what goes on here, The vertigo effect don’t change the alpha channel of original picture, so even if it looks like the effect is is adding semi transparent pixels, they are not shown when blended with the layer below, because the alpha channel is the same as on the picture before the effect is added.

[ZorgoZ]

Yes, that should be the case. The pixels added by the effect remain totally transparent. But I don’t think that this was the intention.