pre-key/roto – to de-interlace or not to de-interlace?

[Steve Roberts]

You should separate fields, then roto in a 59.94 comp, then render that comp as 29.97. Otherwise your rendered video will only be roto’ed on every other field.

[Michael Duff]

but if i use magic bullet to de-interlace before I roto is that a suitable option? I guess the question is more about whether magic de-interlaces footage to make it suitable for fullframe roto?

i also did what you suggested, putting the footage into a 50fps comp (PAL) – but shouldn’t I then only see one field? ie every second line? when I do this I still see every line….

confused….

[Steve Roberts]

That’s just the way that AE displays the footage: in draft mode, it duplicates each line, in high quality mode it interpolates each line. Then when you render to 29.97 fields, AE stops doing that and puts the fields back where they were. Pretty much.

Basically, using MB to deinterlace before roto has the same effect as separating fields (when interpreting the footage) in AE… when you plan to render with no fields. By that, I mean “frames” or “progressive”. If you separate fields or deinterlace, you’d better be planning on rendering progressive, because you’re only placing roto keys every frame, not every field.

If, however, you want to render fields (pretty much an aesthetic choice) you must roto in a comp at twice your final frame rate to see each field, so you can place a roto key there if need be.

So if you want to render frames, go ahead and use MB. If you want to render fields, you must go into a 50fps comp.

Does that make sense?

[Michael Duff]

Great! that makes much more sense now….. you’ve cleared up something i’ve not been so sure about for a while

Cheers