Re: Kdenlive in Mint is steady for me!
Can I suggest generating smaller files - say ~15 mins and then concatenating by generating a file e.g test.txt , in the same directory consisting of :
save it , cd to the same directory and run ffmpeg
ffmpeg -f concat -i test.txt -c copy output.mp4 - that will add the .mp4s and sort out the timebase
One kdenlive gotcha I've just remembered is that I find that kdenlive, ffmpeg, melt. mlt need to be from the same repo. ( Packman)