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Flickering alpha shrink soft effect: why is it flickering?

User avatar TheDiveO
Registered Member
I don't know whether this is a bug or a feature, hopefully someone here can enlighten me! I've put an alpha effect on a title clip, set it to "shrink soft" with an amount of "2". My idea is to slightly soften the rather harsh alpha channel that Kdenlive's built-in title generator produces. I'm now surprised to find out that there is some flickering in the final rendered output. :(

Any ideas as to why this happens? You can see the flickering in this short flickering alpha shrink effect test video (YouTube). Please watch this video in full size, as otherwise the flickering will barely be noticable. In any case, the undesired effect is more visibly with the small type text when you watch the example video in small size.

As the title is static I can't see a reason why there should be any flickering at all. I'm dazzled. ???

TheDiveO on YouTube: diving videos and aerial (quadcopter) videos, all made with Kdenlive.
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Registered Member
I have the same flickering trouble. I believe it must be a bug or glitch with the Alpha Operations effect. Removing the alpha operations effect eliminates the flickering for me, but I'm stuck with a somewhat ugly result.

I've also uploaded a video here that shows the severity of the issue.

EDIT: I was told on a different forum that this is caused by having more than one thread on the MLT framework, and that it should be reduced to 1 thread.

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