Not requiring this leads to unexpected result, since Rav1e's current
two pass API has no way to fail in such a case.
Signed-off-by: Derek Buitenhuis <derek.buitenhuis@gmail.com>
Rav1e currently uses the time base given to it only for ratecontrol... where
the inverse is taken and used as a framerate. So, do what we do in other wrappers
and use the framerate if we can.
Signed-off-by: Derek Buitenhuis <derek.buitenhuis@gmail.com>