Open MLT XML as Clip with context to transparency

Hi. I created mit file with three video tracks - easy animation. All three track contains png file with fade in effect. Fade in of V1 track take 30 frames. V2 starts in frame 8, fade in ends in frame 17. V3 starts in frame 21. My source file looks like on screen 1 (sorry for this screenshots mix, but as new user I can include only one image in topic)

If I “Open MLT XML As Clip” and include into another mit file, first 8 frames has nice transparent background. Then frame 9 (in included file, frame 9 is first frame where multiple video tracks are rendered) get full black background.

You can see frame 8 and frame 9 of included source video in target video in next two images (screen 2 and 3 in my included image). There is a jump from transparent to opaque background.

My questions are:

  • Is it possible to use the effect that applies the first 8 frames to the entire source video and insert it into the target so that the background remains transparent?
  • Is there any other way to maintain transparency and paste one file into another?

I know I can use green background and chroma key to remove the background, the problem with this approach is that with each “fade” and transparency effect I would get a transition / semi transparency to green. Maintaining transparency if it does not exist background video track in the source mit file would be much better, but I have no idea how to achieve something like this.

XML MLT clips have some limitations.
See this thread.

And this post.


Thanks @sauron somehow I didn’t notice mentioned thread. The following sentence made it clear to me.

This workflow depends on Shotcut’s ability to output with transparency, which is limited: Any place where video is actively blended across multiple video tracks will be opaque.

Therefore, whenever I use multiple tracks, I cannot use transparency when importing into another project. Ok, I’ll try differently. Well thank you.

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Yeah, that’s the limitation for now. Let’s hope it will be improved soon.

One alternative that I am thinking of is to export the original project as a series of png’s with transparent background and then importing it into the new project.
I haven’t done something like this in Shotcut before but I will try it out and will let you know i f that works.

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OK. I tried it. Don’t know why I thought that would work as Shotcut has a problem exporting as transparent when there are multiple tracks. So, it’s the same result here too unfortunately. Even the png’s have a black background.So, still no workable solution unfortunately.

Ok, let’s wait for the next updates. Thank you all :cowboy_hat_face:

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