If you were using a iPhone I would say Quicktime Pro... I have no idea about other formats, because I use a camera and don't ever work with VFR files
You might ask Samsung (and, for the future, look at your device options to see if you can force it to use a Constant Frame Rate)
Otherwise, use Google or post a new message with a title of
How do I convert MP4 VFR to Constant Frame Rate?
And see what other people use