60i Footage Interlace Problems

[Providmike]

I did interpret with lower field first. And it’s still interlaced. Thats the problem.

[Steve Roberts]

If you shot at 60i (29.97), then you should interpret lower first and bring into a 29.97 timeline in Premiere and AE.

You should only use a 23.976 timeline (23.98 in FCP) if the footage had pulldown added in telecine, was shot at 24p in a camcorder, or 24Pa in a camcorder. In that case, you’d interpret and remove pulldown. But this is only for this situation. You can’t just make something that was shot at 29.97 (with no pulldown) into 23.976 without using a plugin like Twixtor to generate the intermediate frames.

So. Did you shoot 24P on a camcorder?

[Providmike]

Its shot 60i

If use lower fields then building’s lines are extremely interlaced but if I turn off fields or use upper field then my subject walking is extremely ( lower portion of the screen ) and building is perfect.

[Kevin Camp]

you may need to give us your workflow, from the original footage format (dv, dvcpro, beta), to the capture setting, to the export setting and the specifics fo what ae thinks the footage settings are.

you say ‘shot 60i’… we assume you are talking about 30i, which would be an interlaced frame with a frame rate for 29.97. is this correct?

you mentioned you captured to dv… was it dv tape you captured from? what did you export out of premiere, dv, lossless…? high compression settings and compressing and recompressing can start to muddy up interlacing, and that may create problems.

in ae, if the footage is interpretted without separate fields and you step through it frame by frame, you are seeing interlacing wherever there is movement, right?

explain your shot a little more… you said the building looks clean when separate fields is off, but the guy walking is interlaced. is camera locked down for the shot, no pan or other movement? by your footage’s field description i would assume this to be correct. did you try to separtate fields (lower) with preserve edges checked? this can often help.

remember, deinterlacing footage that was shot as interlaced (not 24p witha pulldown added) will involve interpolation by the software, and may not be perfect. you may end up maksing out a deinterlaced guy walking over an interlaced building to get the best results.

if you can get the interlacing problems worked out, and you have 30i (29.97, interlaced)you can slow your footage down by deinterlacing, but interpretting the footage as half of what your comp’s frame rate is. so if you want to slow 30i footage by half, interpret footage as separate fields (possibly, with preserve edges), but set the frame rate to 14.94 then drop that into a comp that is 29.97… 30i to 24p (23.976): do the same, but set the footage to 11.988 and put that into a comp that is 23.976.

you can go slower, as steve mentioned, you will need to use time remap or timewarp or a third party effect (like twixtor) to generate the extra frames.

Kevin Camp
Designer – KCPQ, KMYQ & KRCW

[Steve Roberts]

Per second,
60i means 60 fields,
30i means 30 fields,
60p means 60 frames,
30p means 30 frames…
… by convention.

So “60i” is the term for 29.97fps interlaced. 🙂

Back to topic: oftentimes, AE’s field separation goofs up complex inorganic objects somewhat, so they do look better left interlaced. However, if you need to separate, I’ve found that RE:vision FieldsKit does a better job for those subjects, set to “fields blend”.

Hope that helps …

[Kevin Camp]

i suppose you are right… i mean, you can’t argue with steve roberts 😉

but i’ve never worked with anything that used a field rate… it just seems that saying 30 (29.97) interlaced frames per second would be less confusing than bringign in another number for field rate…. but there are so many confusing things with video standards.

Kevin Camp
Designer – KCPQ, KMYQ & KRCW

[Steve Roberts]

[moldyboot] “i mean, you can’t argue with steve roberts ;)”

Well, you can try … 😉

Confusion in video standards? Impossible! That’s why they call them standards! They’re , um, standard! 😉

“Interlacing: it’s a feature!”

[Darby Edelen]

Although I wanted to at first, there’s really no way to argue with the fact that interlaced 29.97 footage isn’t 29.97 (30) frames per second but rather 59.94 (60) fields per second. Each field was captured 1/60th of a second after the last, so no two fields correspond to the same moment in time. They’re all unique!… Just like every single one of us… sorry for the Mr. Rogers moment (;

Darby Edelen
DVD Menu Artist
Left Coast Digital
Aptos, CA

[Steve Roberts]

Now *that’s* the argument!

Each field is *unique*, and there are 60 unique fields per second. Hence, 60i.

Well said.

[Kevin Camp]

that’s good, i don’t know what i’d do with half my day if i could be here at the cow.

Kevin Camp
Designer – KCPQ, KMYQ & KRCW