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Old August 16th, 2005, 05:15 PM   #1
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Weird One... interlaced 24p off Panny SDX900?

Hey all:

Okay, I'm not sure what I'm looking at, so I figured I'd post and ask the question.

I've been asked to do some work on footage shot on a Panasonic SDX900. It was apparently shot at 24fps, according to the owner.

When I get it, FCP identifies it as 23.98 fps footage... but it is interlaced!

Looking at the footage frame by frame in QuickTime shows a duplicated frame every 4th frame (as in the cadence goes 1-2-3-3-4-5-6-6-etc.). Looking at this in Combustion frame by frame with fields set to "none" (i.e. deinterlaced) then it shows interlacing "combing." QuickTime "info" reports this as a 24fps (rounding) clip... but the timecode embedded in it clearly goes: "00-01-02-03-05-06-07-08-10-11-12-13-15-16-17-18-20-21-22-23-25-26-27-28-00"

I've tried every method of pulldown removal Combustion and FCP have available to them to no avail. Each pulldown combination shows interlacing.

BUT... when I set the footage to "interlaced, lower field first" then it comes out looking beautiful... at 23.98 fps!!! Bizzare!

So, the big question is, is this a problem that needs fixed before final? My gut reaction says that this is a huge mistake that needs to be fixed in post, but going through each and every clip (there are hundreds...) and running them through Combustion to simply mark them as "interlaced, lower field first" and put them into a non-interlaced project and render them will take me many many days.

Any idea what I've got here? Better still, how to FIX it?
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Last edited by Doug Bischoff; August 16th, 2005 at 05:15 PM. Reason: Typos
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Old August 16th, 2005, 05:58 PM   #2
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More Info

The plot thickens.

Apparently there are clips from the same shoot, same tape, but different takes which do not have this problem.

I'm at a loss here: it's almost an even split 50/50 on which clips have interlacing and which don't. All of them have the skipping timecode phenomenon, and there doesn't appear to be any rhyme or reason as to which ones have the problem and which don't!

Anybody got ideas? Is there a camera setting someone may have been jostling or inadvertently setting? Or did this somehow happen at capture? DVCPRO50-NTSC.
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Old August 17th, 2005, 02:20 AM   #3
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Quote:
Originally Posted by Doug Bischoff
Hey all:

Okay, I'm not sure what I'm looking at, so I figured I'd post and ask the question.

I've been asked to do some work on footage shot on a Panasonic SDX900. It was apparently shot at 24fps, according to the owner.

When I get it, FCP identifies it as 23.98 fps footage... but it is interlaced!

Looking at the footage frame by frame in QuickTime shows a duplicated frame every 4th frame (as in the cadence goes 1-2-3-3-4-5-6-6-etc.). Looking at this in Combustion frame by frame with fields set to "none" (i.e. deinterlaced) then it shows interlacing "combing." QuickTime "info" reports this as a 24fps (rounding) clip... but the timecode embedded in it clearly goes: "00-01-02-03-05-06-07-08-10-11-12-13-15-16-17-18-20-21-22-23-25-26-27-28-00"

I've tried every method of pulldown removal Combustion and FCP have available to them to no avail. Each pulldown combination shows interlacing.

BUT... when I set the footage to "interlaced, lower field first" then it comes out looking beautiful... at 23.98 fps!!! Bizzare!

So, the big question is, is this a problem that needs fixed before final? My gut reaction says that this is a huge mistake that needs to be fixed in post, but going through each and every clip (there are hundreds...) and running them through Combustion to simply mark them as "interlaced, lower field first" and put them into a non-interlaced project and render them will take me many many days.

Any idea what I've got here? Better still, how to FIX it?

Doug,

From your description, the pull-down has already been applied for you. It will be interlaced coming out of the camera. FCP can detect that the footage needs this during capture.

Pulldown removal does not remove interlacing. If you want that, you'll have to de-interlace the footage using lower field first. This will cost you some resolution, but you'll be editing 24 fps progressive footage if you do. If you don't remove the interlace, leave the sequence timeline set to 59.97.

The best place to get the information you are needing in this instance is from http://www.adamwilt.com/24p/index.html#24pRecording where you will find a very good text and graphic tutorial on 24p and how it is reconstructed from 60i footage.

regards,

-gb-
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Old August 18th, 2005, 05:48 AM   #4
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Hmm...

Quote:
Originally Posted by Greg Boston
Pulldown removal does not remove interlacing.
Hmmm... something doesn't sound quite right to me. I normally use a Panasonic DVX-100A and routinely shoot 24PA, so removing advanced pulldown is routine for me. When that pulldown is removed I end up with a 23.98fps non-interlaced file.

Is the pulldown from the SDX900 somehow different? It was my understanding that the act of removing pulldown reconstructed progressive scan, 24fps (or thereabouts...) frames out of the interlacing scheme of the original 29.97 NTSC/DV footage. By default, then, no interlacing would remain.

Thanks for the suggestions,
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Old August 19th, 2005, 07:09 AM   #5
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True about 24pa mode, Doug. That does use a 23.98 timeline and FCP has the advanced pulldown removal tool for 24pa. Since the SDX900 has essentially the same shooting modes as the DVX100, I would think one of them would be recognizable to you. Was the footage possibly altered by another NLE before you got it?

-gb-
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