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Pulldown for 60i contained 24p footage

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David Klein
Pulldown for 60i contained 24p footage
on Aug 27, 2013 at 8:50:12 pm

I'll say it upfront, I am horrible with things like interlacing, fields, and pulldowns...

Notwithstanding, I am ready to learn :) I have some footage shot shot on a Canon Vixa HF S20, and from my understanding, the camera has 3 shooting modes:

60i: Interlaced 60 fps footage. I understand how the interlacing works and how it differs from 30p.
24p: From what I have read, the camera has a 'true' 24 fps mode in which it shoots and encodes actual 24p video.
PF24 and PF30: This is what is giving me trouble, although I do understand roughly how it works (24 or 30 fps encoded to 60i)

Now, I would have preferred to shoot plain 24P, but due to my ignorance on the shooting day, I now have a folder full of PF24 footage, and I have to make do with it.

I drag this footage (.MTS, PF24) into after effects, and my objective via interpretation is to end up with progressive 24 fps footage, but as of yet it seems to elude me. AE auto-interprets to 29.97, upper field first footage, and the frames appear ok, but it's 29.97, not 24 fps. If I set the fps to 24 and leave the other settings the same, in a 24 fps comp the footage appears jerky. Unless necessary I won't go into details of any of the other myriads of interpretation combinations I've tried, I would just appreciate suggestions on how to properly interpret this footage, and whether or not a method works I can provide details and 'debug' from there. (I know I need pulldown somewhere in there, but I don't know where and with most combinations I have tried I end up with interlaced footage in my comp)

Sorry for the long post, I'd appreciate any help possible.

Sincerely,
A desperate filmmaker


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Keith Slavin
Re: Pulldown for 60i contained 24p footage
on Aug 27, 2013 at 10:34:05 pm

Hi David,

It seems like you need to apply 2:3 pulldown in your AE.
If you cannot get your footage to look right, you may want to check out our fast, file based, GPU accelerated standards conversion/transcoding services at http://isovideo.com/services.php, based on our award-winning Viarte server. We have automatic 3:2 pulldown detection in 60i to deal with the exact situation you are facing.
We would provide you with a speedy free test if your are interested. If your footage is not very long, we may do the whole conversion for you without any charge!

Best regards,
Keith


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David Klein
Re: Pulldown for 60i contained 24p footage
on Aug 27, 2013 at 11:52:43 pm

I have several gigabytes of footage and a slow internet connection, so any web-based conversion service is kind of out of the question. Thanks anyway, though...I've bookmarked the website for potential future use.


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Keith Slavin
Re: Pulldown for 60i contained 24p footage
on Aug 28, 2013 at 1:01:46 am

Actually, we are not really web-based standards conversion services yet. For any large amount of data transfer, we still need overnight shipping via a USB3 disk drive. For any short clip tests, we could upload from the web.

Best


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Walter Soyka
Re: Pulldown for 60i contained 24p footage
on Aug 28, 2013 at 1:13:56 am

[David Klein] "I drag this footage (.MTS, PF24) into after effects, and my objective via interpretation is to end up with progressive 24 fps footage, but as of yet it seems to elude me. AE auto-interprets to 29.97, upper field first footage, and the frames appear ok, but it's 29.97, not 24 fps."

Technically, the footage IS 29.97 frames per second -- that is, 23.976 frames per second with pulldown applied so the 24p footage fits in a 30 fps wrapper.

To remove the pulldown, you'll have to choose one of the pulldown removal options in the interpret footage window, right underneath the "separate fields" option. There are two buttons below that: Guess 24p pulldown (which will attempt to guess the correct cadence to remove a 3:2 pulldown), and Guess 24PA pulldown (which will attempt to guess the correct cadence to remove a 4:2 pulldown).

See more here: Remove 3:2 or 24Pa pulldown from video [link]

Walter Soyka
Principal & Designer at Keen Live
Motion Graphics, Widescreen Events, Presentation Design, and Consulting
RenderBreak Blog - What I'm thinking when my workstation's thinking
Creative Cow Forum Host: Live & Stage Events


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David Klein
Re: Pulldown for 60i contained 24p footage
on Aug 28, 2013 at 1:36:16 pm

Well, I fooled around with the pulldown options a bit, and it seems that WSSWWW works just fine. My only question is this (And maybe this is just a result of the pulldown): The video plays fine in a 23.976 comp (The interpreter says it has an effective fps of 23.976), but some frames seem to have some very slight interlacing artifacts if I look closely around the edges of motion. Without any pulldown and just using Upper field first, (although the framerate is not right), all the frames seem pretty clean. However, with the pulldown removal, some frames have a slight 'residue' of interlacing. Is this an unavoidable fact of pulldown, or is there something else I can do? The best quality option is greyed out as well...


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Walter Soyka
Re: Pulldown for 60i contained 24p footage
on Aug 28, 2013 at 2:28:33 pm

[David Klein] "The video plays fine in a 23.976 comp (The interpreter says it has an effective fps of 23.976)..."

Once the pulldown removal is active, the clip is treated as if it were 23.976 progressive material.


[David Klein] "... but some frames seem to have some very slight interlacing artifacts if I look closely around the edges of motion. Without any pulldown and just using Upper field first, (although the framerate is not right), all the frames seem pretty clean. However, with the pulldown removal, some frames have a slight 'residue' of interlacing. Is this an unavoidable fact of pulldown, or is there something else I can do? The best quality option is greyed out as well..."

A screenshot would help, but my guess is that this is an artifact of compression from your camera.

Pulldown can be perfectly removed from a pristine source, but if there's any bleed or contamination due to compression across the fields or lines in the image, traces of the interlacing/pulldown may remain. This does not occur with advanced pulldown (2:3:3:2), since there is only one blended frame and since that frame can be discarded because it is redundant.

Better to shoot true 24p next time, or with advanced pulldown, or at 29.97, whichever your camera allows.

Walter Soyka
Principal & Designer at Keen Live
Motion Graphics, Widescreen Events, Presentation Design, and Consulting
RenderBreak Blog - What I'm thinking when my workstation's thinking
Creative Cow Forum Host: Live & Stage Events


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David Klein
Re: Pulldown for 60i contained 24p footage
on Aug 28, 2013 at 4:59:13 pm

[Walter Soyka] "Once the pulldown removal is active, the clip is treated as if it were 23.976 progressive material."

I understand this, it's seems to be a fairly logical concept.


[Walter Soyka] "
Better to shoot true 24p next time, or with advanced pulldown, or at 29.97, whichever your camera allows."


So...either use true 24p, enable the advanced pulldown method (if available), or just shoot at 30fps (29.97)?


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