Hello, I have a strange problem with slow motion. I record 1080p 60fps video and I often do 0,5x speed of and export movie in 1080p and 30fps. One year ago there wasn’t any problems, slow motion was perfect, but 2 months ago I’ve started to see a lot of lags.
60fps + 0,5x speed = 30fps slow motion.
I have 19.01.27 version. You can clearly see this problem for example in this car test from my Youtube channel (scroll to 0:31). Every movie from my channel I made in Shotcut with Samsung Galaxy S7.
Funny thing: In Shotcut 16.11.02 everything works fine.
If you are changing the Frames/sec in Export > Advanced, that is your problem. The behavior is changed, and doing this is strongly discouraged. It now renders to the project video mode and then resamples to the altered export resolution and frame rate. This was done to address bugs, but it will have unintended side effects like this. Instead, you should start with a 30 fps Video Mode, then make your project including slowing a source 60 fps clip by a half and then export without altering the resolution, aspect ratio, or frames/sec in Export > Advanced.