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24p pulldown removal from incorrectly encoded files

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Mike Celona
24p pulldown removal from incorrectly encoded files
on Jan 7, 2010 at 11:04:58 pm

Today a major corporate client gave me a hard drive containing footage shot in several different countries throughout the world, all of which was delivered as anamorphic 16:9 NTSC 29.97 Quicktime Animation files. Since my client and I do not have a direct line of communication with the people who produced the footage I cannot confirm what program/equipment it was captured with, what camera(s) were used or whether it was reencoded and conformed to the specs mentioned above after initial capture (I'm inclined to believe that it was).

Despite the ambiguity, everything went fine with the rest of the footage until I got to a series of clips from Malaysia that appear to have been shot in 24p because they created the recognizable judder effect when dropped into a 29.97 timeline. Having experienced this issue on an earlier project I attempted to convert the files with both Compressor and After Effects using multiple settings until I stumbled upon the correct one as suggested by earlier Cow posts but had no luck. I also dropped the footage into 24fps and 23.98fps timelines but all that did was shift the redundant frames to another position in the cadence. Finally, I opened the source files in a standalone Quicktime player outside of FCP and found that the judder was present there as well.

Question: If these files had been reencoded by a third party with an incorrect cadence and the distortion is now part of the new image, is there any way to correct this short of manually removing the redundant fames and beating the crap out of the image with a deinterlacing filter or should I tell my client that the footage isn't usable?

On a side note, I have also seen people write about using Cinema Tools as yet another way to remove pulldown but since I have never worked with film transfers and am unfamiliar with that program I couldn't quite make sense of it at first glance and would prefer to give myself a crash course some other time unless someone feels that it can do something in this scenario that these other programs can't.

Thanks,

Mike Celona
Maslin Digital
Rochester, NY


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Matt Lyon
Re: 24p pulldown removal from incorrectly encoded files
on Jan 8, 2010 at 7:16:23 pm

Mike,

Cinema tools offers you some more advanced controls for pull down removal, but it is designed for telecine transfers (eg. AA/BB/BC/CD/DD cadence), not 24P video material, so AFAIK, it only works on material with "mixed frame" cadence patterns.

If you are 100% sure that the material is 24P, then Cinema Tools probably won't help you. Try opening a clip in cinema tools and step frame through the shot and see if you can tell what the cadence pattern is by eye. Cinema tools also has the advantage of displaying both fields simultaneously (which FCP will only do if the viewer is set to 100%).

You can study the various pulldown patterns in the "reverse telecine" screen to help give you an idea of what to look for when stepping through the video. But like I said, these only apply to interlaced material.

Could the problem in the footage be one with field dominance?

Matt Lyon
Editor
Toronto


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Mike Celona
Re: 24p pulldown removal from incorrectly encoded files
on Jan 8, 2010 at 7:50:05 pm

Hi Matt,

Thanks for the clarification regarding Cinema Tools, a program that I know very little about. As I mentioned, I have no way to contact the people who produced the source media and I believe that they may have reencoded the footage with the wrong settings. I tried shifting field dominances during my systematic attempt to stumble upon the right conversion settings in After Effects and Compressor but that didn't do much.

Anyways, it turned out to be a moot point since today my client decided not to use those shots for creative reasons but I would still like to get to the bottom of this just so that I know how to deal with problems like it going forward. I guess I'll start by familiarizing myself with Cinema Tools now that I have a reason to do so.

Thanks again,

Mike


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Bill Lenz
Re: 24p pulldown removal from incorrectly encoded files
on Mar 22, 2010 at 8:05:05 pm

I need to fix broken cadence from standard def. video, 29.97 fps. The original video source was film at 23.97 fps and editing in an online room caused broken cadence. Although it is possible to remove the pull down scene by scene, a device or application that can identify the cadence automatically, and provide either a correct cadence at 29.97 fps, or provide clean frames at 23.97 fps. would be greatly appreciated.
Bill Lenz


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