You mean, like stretching it then shrinking it,
all in one pass?
Or, prep/precompose a sequence that contains
half as many frames (i.e. throwing out every other frame)
then use that (i.e. half the fps of the original) to
create a new sequence that contains twice as
many frames (i.e. same fps as the original)?
Just curious though:
how would throwing out every other frame
improve compressed video?
Having said that, I do this kind of thing
for cartoon restorations (from film) but
not for live footage. So I'm just curious...