Features
- Playback speed change setting picks what happens to a video's frames when you speed it up or slow it down
Keep frames raises the frame rate along with the speed, so a 2x speed-up of a 30fps clip plays back at 60fps and looks smoother
Drop frames stays at the source frame rate for a smaller file
Set it in Settings > Videos, under Optimisation rules
Fixes
- Optimised videos keep every frame of the source. Screen recordings suffered the most: a 60fps recording that holds still between bursts of motion averages out to ~23fps, and more than half its frames were being thrown away, so anything that moved stuttered
- Changing a video's playback speed twice applies the new factor to the original, so 2x then 1.5x gives 1.5x instead of 3x. Same for audio