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Vector Paint, and Interlacing question (mask is shaky)
Hi folks,
I’m a little stumped here. Been using AE since 3.1 (on and off)
I’m making a moving mask, that followes a lady walking across screen.
Here is what I’ve done.I used Vector paint, to “rotoscope” about 120 frames, masking out the area around the walking lady.
RAM preview in AE shows a fairly decent moving mask, at least good enough for what I need.I have interpreted the footage as Lower Field first (correct for what we are working with)
Preserve edges is checked.I render for FCP, using Field Render, Lower Field First.
When imported into FCP, the mask jumps around… a lot.. not like inches, but a few pixels. Enough to look crappy.
So I went back to AE, exported with Field Render OFF, imported back into FCP, and the mask is fine. Just like it looked in AE.
BUT, not the image is jumpy. Not like I have the wrong field order, but let’s see… how to explain it..
Almost like I tried to apply some film look to it.Right now I’m working with Uncompressed 4:2:2 Dbeta, FCP HD and AE 6.5
I’m sure it’s something simple, but I’m missing it.
Anything stand out from what I’ve described?
Thanks for your help, I need to fix this fast..
Bryan
Chattanooga, TN -
3 Replies
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Sounds like there is so much motion in the video that you really need to paint on all the fields and not just the lower fields.
You can do that by doubling the framerate in the composition settings – it will show you each field in the interlaced video. It means twice the amount of paint work though…
Bar3nd
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Short answer:
double the comp’s framerate, then animate the mask.
Long answer:
You’re animating the mask in 25 (or 30) fps but the footage is interlaced.
So you’re seeing only half of the motion that’s happening in the clip.But, when you render to fields: all the interlaced motion is re-introduced in the clip: this is the normal way to work, because it saves you the head-ache of seeing all those damn interlace comb-y lines in the comp.
Now for the tricky part:
You’ve been animating your mask probably every Frame or so, but when you’re rendering to fields, there’s a step in time inbetween those two keyframes: the 2nd field. You defined no mask there, and since your mask keyframes don’t have “Hold Keyframe” toggled on: you’ll see an interpolated mask inbetween.
Your reflex to render out without frames solves this, but introduces what you called the film look: less definition in the motion, because of no interlacing.
how do you get the best of both worlds ?
Interpret the footage with the correct Field-order
Open up the comp settings and double the framerate. Do 50 for Pal, or 59,94 for NTSC, or 48 for Cinema you get the picture.
Now check you mask every frame, or at least inbetween those keyframes you allready created.
When you go to an even-numbered frame, you’ll actually see the second field.When you render, switch the comp’s framerate back to normal, or override the framerate in the rendersettings, and enable fields.
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Thanks Barend, and Filip
Yes, that does make sence. It might not be as much work as the first time, but you never know.
dang… all these years, and I still don’t know everything! =)I guess this will apply to everytime i do something with a moving mask huh.
Thanks again for the quick answers.
Bryan
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