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Keylight 1.2 making my keys look interlaced on non-interlaced footage?

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Aza Allen
Keylight 1.2 making my keys look interlaced on non-interlaced footage?
on Jul 8, 2010 at 1:20:36 am

I have a rather difficult, yet small key, I am trying to pull.

The footage is HVX-200 480 24p footage (minidv)

When I try to do a key with Keylight, the result looks as though it's interlaced? I can not figure out why this is happening.

I have included an image here:

I included a shot with motion blur so you can see it's not interlaced (I shaded the BG transparency color Magenta for clarity)

I am trying to pull a key of the hand against a white wall (I know, it's not ideal)

Can someone help, or provide tips of similar keys you've pulled?

Thanks all,
Aza

Make sure to check out our website http://www.makeyourfriendsuncomfortable.com


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Dave LaRonde
Re: Keylight 1.2 making my keys look interlaced on non-interlaced footage?
on Jul 8, 2010 at 1:09:49 pm

Dude, you didn't remove the pulldown! All SD 24p footage contains pulldown, whether it's 24p or 24pa. AE will remove it for you -- look in the interpret footage settings. But it won't help you pull a really good-looking key.

You REALLY shot yourself in the foot by recording on mini-dv -- it's in the DV codec, which is a right royal pain in the body part of your choice to key.

That camera takes p2 cards to record HD: DVCPro HD, which has MUCH better color resolution, which makes it MUCH easier to pull a good-looking key. I'd shoot it 720 24pn, myself.

Dave LaRonde
Sr. Promotion Producer
KCRG-TV (ABC) Cedar Rapids, IA


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Dave LaRonde
Re: Keylight 1.2 making my keys look interlaced on non-interlaced footage?
on Jul 8, 2010 at 1:47:07 pm

I should also add that it's no big deal AT ALL to put 720 footage into a DV-resolution comp. You just scale and position to taste. I do it all the time. In fact, I use the additional picture size to create zooms and such.

Works like a charm.

Dave LaRonde
Sr. Promotion Producer
KCRG-TV (ABC) Cedar Rapids, IA


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cowcowcowcowcow
Dave LaRonde
Re: Keylight 1.2 making my keys look interlaced on non-interlaced footage?
on Jul 8, 2010 at 3:11:25 pm

[Aza Allen] "I included a shot with motion blur so you can see it's not interlaced (I shaded the BG transparency color Magenta for clarity) "

Uh-huh. So have you figured out what those gray horizontal lines are yet? It's interlacing!
And it's interlaced because you didn't remove the pulldown from the footage!


All -- repeat, ALL -- standard-definition footage contains interlacing, even footage shot progressive-scan.

Oh, you're pulling my leg, Dave, how can that be?

The technical standard for standard-definition TV was established long, long before cameras could do progressive scan. So to comply with the standard, they record the scanned frame as two TV fields. They do the same thing to progressive-scan pictures in high-definition TV too, at 1080 lines. They just give it a fancy name: Progressive Segmented Frame.

In the case of 24p, the cameras have to add pulldown, a scheme of adding additional TV fields to the film frame rate, to spread about 24 frames across about 30 frames.
Sometimes it's the 3:2 pulldown (24p) which has been used to show movies on TV since Days of Yore.
Sometimes it's 2:3:3:2 pulldown (24pa) which exists solely to make it easy for computers to remove said pulldown.

Removing pulldown results in the footage having a frame rate of 23.976 frames/sec. Not 24, not 23.98 (which is just a nickname), but 23.976.

Kapiche?

Dave LaRonde
Sr. Promotion Producer
KCRG-TV (ABC) Cedar Rapids, IA


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Aza Allen
Re: Keylight 1.2 making my keys look interlaced on non-interlaced footage?
on Jul 9, 2010 at 11:06:36 pm

Thank you Dave! I really appreciate the extended reply as well, I like learning as much as possible. I totally forgot about pulldown... I previously knew that, but for some reason I think I assumed, wrongly, that After Effects did that automatically on import. I will remove it. Thanks again, and thanks for putting up with noobs like myself!

Aza

Make sure to check out our website http://www.makeyourfriendsuncomfortable.com


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Dave LaRonde
Re: Keylight 1.2 making my keys look interlaced on non-interlaced footage?
on Jul 10, 2010 at 8:01:45 pm

Aza Allen: "...,thanks for putting up with noobs like myself! "


You're welcome. If you have ANY CHANCE WHATSOEVER to re-shoot at 720p60, you should do so!!!! You would be astounded by the difference between DV's 4-1-1 color resolution and DVCPro HD's 4-2-2 color resolution. The difference is like day and night. And the chroma key is virtually automatic, whereas you're jumping through multiple hoops right now to pull a key.

Lots of pain.... or virtually no pain. The choice is yours.

Dave LaRonde
Sr. Promotion Producer
KCRG-TV (ABC) Cedar Rapids, IA


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