It's something I'd really like to do, especially that since VHS tapes that have a vertical track sync issue don't have a static position of the desync normally, but instead fluctuates as time goes on.

Hello,
That's funny I was just working on enabling frei0r filters keyframing (available for quite some time in MLT, just needing declaration in Kdenlive).
On Linux if you use a standard installed package just use this command:

Code: Select all

sudo sed -i 's/"constant"/"animated"/' /usr/share/kdenlive/effects/frei0r_nosync0r.xml

If on Windows, edit the share/effects/frei0r_nosync0r.xml file and replace "constant" with "animated"...
Enjoy!

Almost, but I got it thanks to your help! The plugin was in 'Kdenlive-18.08.0\data\effects' (Using 18.08.0 at least)