I'm having an issue with kdenlive where my project/clip monitor playback is very slow and a bit jumpy. The FPS overlay indicates there are no frames dropping, and for the most part it does go from frame to frame smoothly. I have tried variously using preview rendering, transcoding, and proxies with no improvement. This occurs at all resolutions whether or not effects are added to the clip. There are no library errors when running kdenlive and everything including muti-threaded rendering works well. However my system is a root only system, so the kio services do fail.

I've determined the issue to be with the melt implementation, but I'm having trouble pinning it down. First of all, there is no hardware acceleration available on my system and the only function video output seems to be opengl. VLC has run all my test clips flawlessly.

When I tested some clips running them with melt directly, they ran at full speed with about the same amount of jumpiness as in kdenlive. It was not perfectly smooth like vlc, but still very usable. I played a file in melt to verify it was playing properly and then launched kdenlive and played a file in it to make sure it was still playing poorly. I immediately tried to play the same file again in melt and it started playing poorly like it does in kdenlive! I don't know what exactly is causing this change. Anyhow, the slight jumpiness indicates to me that there is some issue with melt itself, but it seems there is also some issue on kdenlive's end exasperating the problem.

Any help or insight on how this system works is much appreciated.

It occurred to me that I might be experiencing the slowing down when rendering as well, I'm not sure. My system is aarm64, 8x ~2GHz cores, 6GB ram. Rendering a 7min video with 8 threads at max speed maxed my cpu for 15 min. A more modest encoder speed took about 35min to render. Admittedly, I have no idea how rendering works.