-
Rotoscoping w/ 23.976 footage…
Yes, a field thread again…
And yes, I’ve checked previous messages but with no luck at understanding if it really applies to my problem. Here’s the deal:
I received footage at 23.976 and I need to do some rotoscoping. The image has alot of movement. I tried various ways of removing the fields and all, but there’s always a ghost effect (like 2 shots merged into one but one with a lighter blend) that confuses me as of where I should put my mask on.
What is the perfect (step by step, please!) method to make the video frames clean enough to work my masks easily.
Pulldowns, putting it back in 29.97 and doubling the comp’s frame rate… I’ve tried all of this (or maybe in the wrong order) and I’m really wondering if the fact that the footage is 23.976 to begin with just messes up the whole process.
Thanks,
Pat
-
8 Replies
-
23.976 has no fields. If you try to separate fields it will look weird.
-
I spoke too soon. Sorry – of course it has fields, since it’s 29.97 (60i) on the tape. If you have been given footage that way, you need to remove pulldown before you roto.
So:
1. Import the footage into AE, and set field separation “off”.
2. alt-double-click on the footage and step through it with the pageDn key. If you see interlacing, it’s 29.97.
3. Re-intepret the footage, field sep “lower first”, and remove pulldown — try guessing.
4. do step 2, for about 10 clicks or more. If you see fields, AE guessed wrong, and you need to re-interpret with a different cadence.
5. Once you’ve eliminated the fields that way, drag the footage onto the “new comp” button at the bottom of the project window and go to work.Did that help?
-
But how do you explain the ghosting effect? May be the motion blur, but how am I suppose to rotoscope when the doubling scrambles the masking area into an awful mess…?
Pat
-
Oops, replied to soon too!
But the confusion part is the fact that to begin with, the video lists in its properties (even outside of AE) as being 23.976. So should I assume it really is 29.97 in disguise, or still 23.976 but interlaced?
Pat
-
Then my first post holds. Do not try to separate fields. If you interpret it as sep fields “off”, and you see no interlacing in AE, then there’s no interlacing. Don’t try to separate fields — that will give you ghosting if there were no interlacing in the first place.
Are we there yet?
-
Hum…
To Steven : footage (no interpretation & fields off, as given by default) dragged onto a comp = I see both the jagged edges of interlacing and the ghost effect (de-doubling), but sometimes just the ghost…
To Dave : “check to make sure it’s actually 23.976 full frames.” Tried as described, and indeed the frame moves every other frame, but still the random interlacing & ghosting is happening…
I’ll ask the guy in the meantime, but feel free to add any though.
Meanwhile thanks for helping me figuring out this mystery…
Pat
-
[Dave LaRonde] “Everybody thinks working at a film frame rate is soooooooo cool… but if you don’t know what you’re doing, you can really screw yourself.”
… which is why 30p is so nice. Progressive, with no pulldown worries.
-
I explained the situation to the guy and there was indeed a problem with his footage. So he sent me back a proper 29.97 version, and when I separated the fields for rotoscoping, the problem was gone. Well, almost, there are still a few frames with a ghosting effect, but I’m guessing it’s the motion blur, since the action movements are fast. I should manage.
Thanks for the help, much appreciated.
Pat
Reply to this Discussion! Login or Sign Up