user39333: How can I interplote a 30FPS video to a 50 FPS video without affecting the length of the video?
I have used the VSDC video editor to do so. I have set the reframing mode to optical flow.
However, I found that it just inserted a previous frame between the adjacent frames.
I have tried the mkvtoolnix, unfortunately, it just shortened the video duration.
Is there any better solution?

user39340: Several commercial solutions seem only to support full integers as multipliers for frame rate conversion. Assuming VSDC works a similar way, thus you might try to go via the LCM of 30 and 50 frames per second and first do a upconversion to 150 frames/sec and afterwards reduce it to 50 frames/sec.
Sadly the official docs do not say anything about that.

39333: <p>How can I interplote a 30FPS video to a 50 FPS video without affecting the length of the video?</p>
<p>I have used the VSDC video editor to do so. I have set the reframing mode to optical flow.
However, I found that it just inserted a previous frame between the adjacent frames.</p>
<p>I have tried the mkvtoolnix, unfortunately, it just shortened the video duration.</p>
<p>Is there any better solution?</p>
 39340: <p><a href="https://en.wikipedia.org/wiki/Frame_rate#Instruments" rel="nofollow noreferrer">Several commercial solutions</a> seem only to support full integers as multipliers for frame rate conversion. Assuming VSDC works a similar way, thus you might try to go via the LCM of 30 and 50 frames per second and first do a upconversion to 150 frames/sec and afterwards reduce it to 50 frames/sec.
Sadly <a href="https://www.videosoftdev.com/how-to-achieve-perfect-slow-motion-effect-with-reframing" rel="nofollow noreferrer">the official docs</a> do not say anything about that.</p>
