mixed frame rates
by Mitchell Rose
on
Oct 25, 2008 at 4:03:33 pm
I'm editing an industrial at a frame rate of 29.97. For one shot, the client gave me some 23.98 footage of a man sitting at a computer. I have to motion track that shot so that I can composite in some more 29.97 footage onto the man's computer screen. What do I have to do to that 23.98 footage to get it to play nice with everybody else? (Sorry, I'm pretty frame rate clueless.) Thanks very much.
Re: mixed frame rates by Kevin Camp on Oct 27, 2008 at 3:16:56 pm
this is a sticky situation...
first off, make sure that ae is interpreting the 23.98 footage as 23.976 (23.976 is the actual frame rate of 24p, 23.98 is just pseudo-short hand for 23.976).
since you need to track the shot, you'll probably want to work in 23.976 for this piece. you could look into effects that will change the frame rate of the 29.97 clip to 23.976. timewarp can do this, but i've never felt that it was great... or maybe just not worth the extra processing time, but that's me (here's a tutorial to see it in action), twixtor is a third-party solution.
the quick and dirty solution would be to bring the 29.97 clip into the 23.976 timeline and turn on frame blending (frame mix)... ae will just 'blend' every 4th and 5th frame together to conform the 29.97 clip to 23.976. since your footage will be getting scaled and rotated to fit the screen, this may work for you, and i would try this first. it's easy to simply replace the clip and disable frame blending if it doesn't.
after you doe the track and composite the screen clip on the 24p clip, you'll need to render it with a pulldown to edit with the rest of your 29.97 material. to do that, just choose make movie for you final comp (don't adjust the framerate or put it into another 29.97 comp), then in the render settings choose to render to fields, pick a pulldown (any will be fine), notice that the frame rate will now say 29.97, then render it as you would any other clip, and it will be ready to go into a 29.97 project...
