I have a screencast recorded from iPad with QuickTime Player on macOS.
When I open the original recording in QuickTime Player for playback, I can see the playback controls as below:
I processed the video with the following command (full log):
ffmpeg -i test-source.mov test-result.mov
Resulting video in QuickTime Player
Then, when I open the result in QuickTime Player, I see the controls as below:
The part with more sparse "dots" plays in slow motion, I can drag the bars to change the start and end of this part and minimise it to zero-length (the overall length changes from 03:06 to 01:00 then and full video plays at normal speed).
Resulting video in iMovie 10
Similarly, when add the video in iMovie with Import Media, I see "Speed"-control already applied on the source:
I can turn it off before adding to the timeline, but if I don't, the clip shows with the following decorators indicating normal speed (left and right) and slow (the middle section with the turtle):
(for this screenshot I added a black overlay to hide the video)
Both the limits of the speed sections and slowdown rate differ between QuickTime Player (1 min. movie expanded to 3:06) and iMovie (expanded to 1:30).
VLC does not notice it, plays the video at normal speed.
What is this feature called?
How to avoid this slow motion part in the output of FFmpeg?