Hi all,
I'm pretty new to the world of video making, and I'm suddenly having an issue when I'm using chromakey.

At the beginning of the chromakeyed clip I get a green 'flash' like this.
[img]
https://ibb.co/XYFXWsh
[/img]

It goes away after a second or two.
[img]
https://ibb.co/5rXpS3j
[/img]

It's not present in the video in KDENLive, so I take it it has something to do with rendering.

It's not a huge deal in a teaching video, but it makes it look a little bit less professional and I want to step up my video-making game. What is it due to, and how do I avoid it in the future.

My system:
Debian 10.6
Nvidia GT218 with nouveau driver
KDENLIve 18.12.3
MLT 6.12.0
FFMPEG
I render to Webm:
f=webm vcodec=libvpx acodec=libvorbis crf=%quality vb=0 quality=good aq=%audioquality max-intra-rate=1000
I've tried KDENLive v20.08.0 as well, and it's the same issue

Thanks in advance

I suggest to go to a newer version of kdenlive. 20.08.2 was released just a few days ago. If your distro doesn't have it as a package you can use the appimage instead.

I just tried 20.08.2 as well. The issue persists.

I had a similar problem at the end of a chromekey in a video rendered as an mp4, and yet you can't see it during the project. Tried trimming the clip and transitioning to transparent but nothing worked. Didn't have time to find a solution (it was snow for a nativity) so just had to delete the chromekey section.

please can you post somewhere (youtube?) a small piece of video with the issue? (zone rendering)