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Weird Interlacing Issue with AE Render

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David FrankWeird Interlacing Issue with AE Render
by on Jul 8, 2010 at 11:21:30 pm

I am doing some effects to a timelapse clip from an EX1 in AE and when I render it out and bring it into final cut, I am getting some weird interlacing issues. The footage is 1080i50 XDCAM EX footage. My comp is setup for HDTV 1080 25 preset. I have an idea that it has something to do with field dominance, but I've rendered out with the "BEST SETTINGS" preset which has no field dominance and then modified it to render out upper field first. I am having the issue with both. The Output Module i am using is Prores 444 25p. Field dominance is upper on the original clip obviously.

It looks like this:

http://www.flickr.com/photos/wuntrikpony/4775232285/


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Dave LaRondeRe: Weird Interlacing Issue with AE Render
by on Jul 9, 2010 at 1:37:59 pm

[David Frank] "...The footage is 1080i50 XDCAM EX footage. My comp is setup for HDTV 1080 25 preset. I have an idea that it has something to do with field dominance..."

...and you'd be right. But first, you should know that the term is actually called Field ORDER. FCP and Apple use the term incorrectly.
Field dominance is a totally different property of a television signal than field order, having to do with signals syncing correctly in video switchers.

If you didn't shoot progressive-scan, you should interpret your footage in AE as Upper Field First, and you should render as upper field first. That will take care of problem #1.

You didn't know you had a problem #2, did you? If you don't have the latest version of AE you've got a problem, and I bet you don't have it. The problem is your footage. Read on:

Dave's Stock Answer #1:

If the footage you imported into AE is any kind of the following -- footage in an HDV acquisition codec, MPEG1, MPEG2, AVCHD, mp4, mts, m2t, H.261 or H.264 -- you need to convert it to a different codec.

These kinds of footage use temporal, or interframe compression. They have keyframes at regular intervals, containing complete frame information. However, the frames in between do NOT have complete information. Interframe codecs toss out duplicated information.

In order to maintain peak rendering efficiency, AE needs complete information for each and every frame. But because these kinds of footage contain only partial information, AE freaks out, resulting in a wide variety of problems.

I'm a Mac guy, so I like to convert to Quicktime movies in the Animation or PNG codecs; both are lossless. I'll use Apple's Compressor, Adobe Media Encoder or Quicktime Pro to do it.


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


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David FrankRe: Weird Interlacing Issue with AE Render
by on Jul 9, 2010 at 7:41:37 pm

Thanks Dave! Changing the interpretation to upper and then making sure the render settings and output module both were Upper first did the trick.

I appreciate you giving me the right lingo. I had used field dominance/order interchangeably, until now.

I have no idea you needed to interpret the footage in AE. Does it always assume there is no field order? When I went into the interpret footage window, I had to change it to upper field. Weird that it doesn't figure that on it's own.

The footage is in Quicktime format with the XDCAM EX VBR codec. It seems silly that I would need to convert it to animation codec(which is enormous) to get proper renders from FCP. What is the reason? And does CS5 fix it?


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Dave LaRondeRe: Weird Interlacing Issue with AE Render
by on Jul 9, 2010 at 7:59:40 pm

[David Frank] "And does CS5 fix it?"

You're not going to like this answer. It's "maybe". Okay, I'll change that to "probably".

Back in April, Todd Kopriva from Adobe went to the NAB convention in Las Vegas to demo AE 10. While he was there, he played a game of "Let's Break AE" with all comers. People brought him all kinds of interframe-compressed footage, and AE didn't even hiccup when using it. That's a far different result than you'd get in AE 9. So AE 10 seems to work much better with such footage.

Did Todd try out EVERY different kind of interframe compression known to man? I don't think so.

Did he keep a list of the ones he DID try? Probably not, because his real job was to show off the new AE to potential customers, not to test the software.

Fair enough answer?

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


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