It uses ffmpeg behind the scenes.
It seems to have suffered from stability issues in the past (the wikipedia article mentions lots of negative reviews) but seem pretty stable now, so you might want to give it a ... shot.
It has been very useful for its quick install process, intuitive interface and reliability: haven't had a single crash in a very long time, with more than 200 videos on our channel [3] (albeit none required anything fancy editing-wise).
OpenShot's goal might not appear to be as grandiose as Olive's so I would love if there was a comparison of both out there.
Looks like we're off trying Olive to compare. Thanks and good luck to the Olive team.
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[1] https://en.wikipedia.org/wiki/OpenShot
[2] https://en.wikipedia.org/wiki/AppImage
[3] https://www.youtube.com/channel/UCgsdHWWQBMHP1plylPrrgpA