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Fairground Mirrors

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Jordan Copeland
Fairground Mirrors
on Dec 15, 2008 at 9:09:44 pm

Hello all,

I'm a freelance editor who's just taken the plunge into directing - ironically, the directing was a breeze but I'm having problems with Post. I'm at the very last stage - synching up my graded picture with my mixed soundtrack - and the picture is suddenly distorting strangely, with different parts of the image moving independently of each other. I'm stumped by this, hope someone can help...

It's a documentary, shot DV NTSC on a DVX100. Edited in London, sent mini-DV tape to LA for grading. The colorist put it on a digibeta tape, worked his magic, then put the end result onto another digi which he sent back to me. I took the tape into a dub-house to get it digitized (to 8-bit Uncompressed QT), and now when I watch the movie from the hard-drive, I get what seems to be some kind of interlacing issue, but not like any I've seen before.

When played in Quicktime, it just looks interlaced for two frames out of five. But in FCP though it doesn't look interlaced, I do get a weird warbling effect - the image divides into seven or eight horizontal bands, which move independently of each other, giving a sort of fairground-mirror effect, again for two frames out of five. Static talking-heads shots look fine - the more movement in the shot, the more pronounced the problem. Here's a before and after - it's a blurry handheld shot, but it illustrates the problem quite well:

On the left is is how it looked when I finished editing, on the right is the newly digitized, graded version.

Photobucket

So my question is: First off, what's causing the problem? I'm guessing it must be something to do with the pulldown process (of which shamefully I have only a basic understanding), but how come it hasn't been a problem until now? Is the problem likely to have been introduced when I first laid-off to mini-DV tape, or when the colorist put it on digibeta, or when the dub-house digitized it back onto my hard-drive?

And secondly, crucially: CAN I FIX THIS IN FCP? Or do I have to pay to get it digitized again? Or does the colorist have to send me a new tape?

Any ideas or explanations would be much appreciated.
Thanks,
Jordan

Tech Specs: FCP 6.0.5, OSX 10.4.11 on a MacPro with 2 x 3GHz Quad-Core Intel Xeon, memory: 5GB 667 MHz DDR2 FB-DIMM. The film was shot as DV NTSC on a DVX100, partly in 24P and partly in 24PA, edited in FCP (obviously), exported to mini-DV, graded on a DaVinci of some kind, and put onto digibeta. The dub house (in London) knew it was NTSC, but their decks are probably usually set up for PAL. The file they put on my LaCie Rugged hard-drive is Uncompressed Quicktime 8-bit 4:2:2, 29.97fps, pixel aspect NTSC - CCIR 601, field dominance Lower (Even), frame size 720 x 480. The film is an observational documentary about a troupe of bellydancers touring with Lollapalooza.



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Darren Laberee
Re: Fairground Mirrors
on Dec 15, 2008 at 10:43:58 pm

The problem in the right side window is the footage was scaled, before it was de-interlaced. You get the same with any video that has been manipulated without seperating fields. Ask first about the edit in london, whether they changed standards at all, or if it is only some shots, possibly those images were scaled as a progressive image, and not as interlaced.

You might find that if only some of the shots are like this it could be the 24P/24PA causing trouble, as that would match the cadence of 2:3 pulldown removal being applied incorrectly.

Good Luck
Darren Laberee

Darren Laberee
Riddle Films Inc.
Toronto Canada
416-778-4973


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Jordan Copeland
Re: Fairground Mirrors
on Dec 16, 2008 at 3:06:47 am

Hi Darren - thanks a lot for your prompt reply. I'm now concerned that the frame I've chosen is misleading - not all the footage looks this bad, only the shots with a lot of movement. It is happening throughout the film, but in shots with only a little movement the problem is barely noticeable - you can tell that something's a bit odd but you don't get this very clear separation (as in this freeze-frame) unless there's a lot of movement. Would a scaling issue limit its symptoms in this way, or would it be more universally applied?

Also - I feel like the fact that Quicktime plays the movie fine must be important. If this is a standards conversion issue or a scaling issue or a pulldown issue, why does it look fine (just plain old interlaced) in QT but not in FCP? Can you think of any particular settings I could tweak or transcoding I could attempt?

Many thanks,

Jordan



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Stace Carter
Re: Fairground Mirrors
on Dec 16, 2008 at 2:30:31 pm

I'd check the movie properties in the QT player (CMD+I) and make sure they match your sequence settings.



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