I've got a video in the Video Editor workspace with a Transform effect strip to scale the video and a Speed Control effect strip to double the speed. I added these effects, then found the frames where I wanted the video to start and stop. I've positioned the video so that the start point is at Frame Start for the scene, and it starts there fine. But when I want to take frames off the end, the speed changes. If I turn off "Stretch to input strip length" in the Speed Control and then try to shorten the video, it randomly freezes at some seemingly arbitrary point about halfway through and doesn't finish. How can I avoid these issues?
The UI of the Speed Strips are super unintuitive. I've tried to address the subject matter here without any success: https://developer.blender.org/D6110
There are four ways to change the speed of the strip, using the speed strip options. I hope listing them here will help you and others out:
"Stretch to input strip length"
The "Use as Speed" does exactly the same as the Multiply Speed:
If "Scale to Length" is selected the strip duration goes from 0%(first frame) to 100%(last frame) and those values needs to be animated:
When "Scale to Length" is unselected, and behaves like the previous setting, but in frame numbers.
$\begingroup$ Thanks for the documentation, that helps explain the speed strip. Good luck getting that improved. So it seems like you should just have to use Use as Speed / Multiply Speed instead of Stretch to input length, but as I stated earlier, that seemed to cause a bug. I did end up working around it by speeding the clip up by itself, exporting that as a new clip, and importing the sped-up clip. $\endgroup$ Jul 10, 2020 at 23:26
$\begingroup$ It should only freeze when it is out of frames. Other reasons for freezing could be the cache needs updating(Ctrl +R (as seen in the View menu)), or inability to play in an accurate fps.If it is the cache which needs updating - I think you could report that as a bug here: developer.blender.org $\endgroup$ Jul 11, 2020 at 15:38