InvertedPageCurl GL transition doubt

Is there a way to change the duration of this transition?

Or maybe what I shoud ask is, how to apply this transitions to have a ‘clean’ effect. Now I can see the first clip ‘under’ the curl effect. I’ve tried dissolve and horizontal bar as default transitions to get the thing.

How to do it?

That is the nature of the Page-Curl. As the page curls it shows a faint image on the underside of the page that is curling.

The duration is however long the clip is that it is applied to. So if you apply it to a 10 second clip it will take 10 seconds to “curl the page”.

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My engish is not enough to explain it… let’s see if deepl can.

You can see the page below. In the curl effect too, of course. The curl effect is faster than the disappearance of the first clip.

I will try to make a capture, or export a part of the video to show you.


The second clip has no text

OK I see the problem. The underlying problem is that the GL-Transitions are not true transitions in Shotcut. To perform a true transition you need to be able to access the 2 images in the clips that are transitioning. With WebVfx this is not possible. The upper image (e.g. that on V2) is available, but not the lower image (V1), so I had to change the GL-Transitions to only use the upper image.

On some transitions (such as Swirl) this does not matter, while on others, such as Bounce the transition does nothing at all. This is not a deficiency in the GL-Transition filters per se, The problem is that there is no mechanism for WebVfx to pass the second image, so that it can be operated on.

By making judicious use of Shtocut’s own transitions and then applying the GL-Transitions filter to the resulting transition, it is possible to mask some of the problems, but not all unfortunately. Have a look at @sauron’s video to see what can be done. There is even a page-curl on there: GL Transitions made using Elusien's GL transitions overlay generator

This is why I do not yet provide WebGL transitions in Shotcut.

With WebVfx this is not possible.

Actually, it is possible, but not yet in Shotcut due to the fact that transitions are not yet extensible at the MLT service level (only in the custom wipe file, which is buying time). (Also, I am worried about the future of WebVfx in Shotcut.)

Some of the GL transitions work well, not all. Cube, Doorway, and Grid Flip work well.

The GL transitions work best with either an overlap transition, or using two tracks with an opacity filter. They used to work well with Mask From File, but there have been so many changes and enhancements made that they don’t work very well anymore.

The page curl transition never worked very well.

To make a decent page curl you need to use green screen footage.

I used two projects for this. The first is used to key out the black and add the images. Then created a second project, added the first project as MLT, added the images and video, keyed out the green.

If you want to use the page curl clip, It is on Google drive.


Yes I realise that the since in later versions of Qt the Chromium-based WebEngine component replaced QtWebKit it is likely that an upgrade of Qt in Shotcut will mean that WebVfx would need major work to carry across, probably too much for it to be viable. I don’t know how much effort it would take to port it to WebEngine.

There is a separate QtWebkit development effort, but I don’t think you’d want to use that as its maintenance seems somewhat questionable.

First of all, this community is one of the best, if not the best, in which I have been lucky enough to participate. The support, the help, and the willingness to teach those of us who are just starting out is simply spectacular.

About the problem with pagecurl, I will use the technique proposed by @sauron, or maybe a second video track below and make the “transition” over an empty transparent image, see what happens.

I am much more concerned about what is being said about WebVfx, now that I was starting to learn how to use it :’(

I’m even programming (at my level) a basic tool to generate the skeleton of pages with WordFlash (@jonray and @elusien) by changing animations, times, number of lines, sizes… in a simple GUI

Thank you very much!

Eek, oh no, will this mean that my text animation work (HTML, WebVfx) might be redundant in future SC versions?
The scream art by Edvard Munch

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