Interlacing and 654x480

M

mr_goodbomb

Active member
I imported a project's worth of footage into a 30fps timeline, while the video was shot in 24p. Interlacing issues followed, and I have discussed it on several forums, and unless I intend to re-edit (I didn't notice the issue until after the project was edited), which I don't, there isn't much to be done to fix it. It doesn't seem to be something normal "deinterlacing" will fix without a lot of ghosting, etc.

However, I sent some footage out to an editor, exported as an animation file to do some visual effects on. I can compare the original footage to the footage her added effects to in AE, and notice two differences.

The finished clip is 654x480 rather than the original 640x480 (DVX footage shot with widescreen bars)
and the interlacing issue appears to be resolved.

I asked what he had done, and he said he had just rendered it as animation, just as I had.

Here's a still.
15mli8l.png



Any ideas on how I might fix the interlacing issue as he did with the entire film, and on whether or not the difference between 640 and the edited 654 will cause issue, and if so, how to resolve it?

Thanks.
 
Actually, the DVX records 720x480 with a pixel aspect ratio of .9091, which is (roughly) equivalent to 655x480 with square pixels -- in terms of frame size.

If you want to get rid of interlacing altogether, shoot 24pA, remove pulldown on capture, and then edit on a 23.98 timeline. You will not see any interlacing at all.
 
Thank you for the response. The shot on the right is the original footage exported out by me as an animation file, which is 640x480, original size off the camera. The left is the editor's alteration, though he didn't specifically or intentionally alter the size or deinterlace, and it's 654x480, and you can see it is not interlaced.

I appreciate the advice, but since I shot all this content in 24p, I'm stuck, and having edited in a 30fps timeline, I'm just trying to figure out what he did to fix it, as everything I've tried hasn't seemed to work.
 
But the camera doesn't record 640x480. No NTSC DV camera does. If those two represent the same frame, the one on the right has the sides chopped off.

The editor probably removed pulldown in AE by using Interpret Footage. You can try removing 2:3 pulldown (reverse telecine) in Cinema Tools, but there's really no way to do it on the FCP timeline.
 
Ok, allow me to correct myself, then. The original footage exported from my system reads as 720x480 (640x480). The files I'm getting back are 720x480 (654x480). I'm trying to understand why, and if it's going to be the problem. You can look at the images and see the sides aren't "chopped off," it's the original footage, so unless content can somehow be ADDED to the original footage, or it's there and exists but not displayed due to some settings, then that doesn't make sese. The 2nd export, a modified version of the original, appears to be stretched slightly, though the editor didn't do anything intentionally to make this happen.

He didn't do anything intentionally to alter the interlace issue, either. He didn't seem to believe he himself had removed the pulldown. He may have unintentionally, I ask him to check his export settings. That said, would removing pulldown fix the issue of 24p footage causing problems in a 30fps timeline? You may or may not be thinking of and discussing a different but related topic.
 
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Dude.

You seem to have a habit of telling people who are trying to help you that what they're telling you is wrong, and from the threads I've participated in, it hasn't been. If you would like continued help, I would put a check on that, else no one's ever going to bother.

If the footage he returned to you doesn't have interlacing, then there are two possibilities, and only two: the footage was deinterlaced, or the pulldown was removed. You said it wasn't deinterlaced, so it leaves only the other possibility. But if he returned it to you as 29.97, and it doesn't show interlacing, then it was deinterlaced. There is no other possibility.

One thing you may be able to do, as I said, was use Cinema Tools to do a reverse telecine. You can try exporting as NTSC DV and running it on the exported file. This may or may not be effective depending on your editing points; some sections may be more effective than others. However, if the underlying footage is 24p, then this is the ideal way to go if it works.

The frame on the left has more picture than the frame on the right. That is verified by simply looking at it. No, it will not affect any issues relating to interlacing, but the fact remains, there's more picture.

Keep in mind with all of this that getting rid of the interlacing is going to impact your footage negatively in at least some ways -- that can't be avoided. You will lose some vertical resolution; you'll probably see ghosting here and there. You may see some choppy movement. There will be no totally clean transition; that's just the mathematics of it.
 
I'm not disagreeing with you. What I'm saying is, he didn't do anything deliberately that he knows of, so unless it's automatically set to remove pulldown when exporting in AE...

And I'm trying to understand if the issues brought about when dropping 24p footage into a 30fps timeline is JUST interlacing, and nothing more, and removing pulldown will fix that (with, yes, ghosting as a result). I understand that doing so in FCP isn't as easy as it seems to be on any other system, which is why I haven't got to play with it and see if it remedies the visual problems with this footage. Whatever he did (incidentally, as even he can't seem to explain why his exports look this way) seems to have repaired it.

I'm not telling you you're wrong, I'm telling you we may be talking about different things. If the ONLY issue with dropping 24p footage into a 30fps timeline is the interlacing, which would be resolved by removing pulldown, then what we're talking about is one in the same, and I appreciate the clarification.
 
OK, let's back it up and go step by step.

First, the frame size discrepancy doesn't affect anything.

Second, as you've pointed out, the reason you have interlacing in your footage is because you shot 24p standard and are editing in a 29.97 timeline. This is normal behavior.

Third, you were asking how to get rid of the interlacing. There are two possibilities: remove the 2:3 pulldown in Cinema Tools (reverse telecince), which will (should) give you straight, progressive 23.976 files. These files should be proper in every respect. Or, deinterlace, which is not the same thing. This can give you the equivalent of 30p files, but then you'll have the problems of resolution loss, ghosting, choppy motion, etc. 24p simply does not convert well to 30p.

I have been pushing you toward the first option, because going to 23.976 is the better play. 24p footage shouldn't be cut on a 29.97 timeline, not least because of the problem you're seeing here. But, because FCP won't remove standard 2:3 pulldown automatically, obviously, you did. So, that being what it is -- you may, as I said, still be able to render out as NTSC DV and use Cinema Tools to do the reverse telecine and get 23.976 progressive files. No interlacing, no ghosting, no added choppiness.

Now, if what you're really asking is how to render out to 29.97 with no interlacing, then deinterlacing, not pulldown removal, is your only way to go. That's not the path I would recommend.

Obviously, in the future, your best bet is to shoot 24pA, remove pulldown on capture, and edit on a 23.98 timeline.
 
So the difference in size, when putting the two sizes into one project, won't matter? That's good to know. I'm not sure I understand why, but it's reassuring.

At this point, the 24p files, rendered from a 30fps timeline, are with the color timing editor, who's on a PC. He's going to remove pulldown from there, I guess. It's funny, I asked about this same issue at CreativeCow when it first happened, and they essentially told me, after importing to a 30fps timeline, there was nothing that could be done, I was screwed, and stuck with that mistake. Thanks for the info.
 
From the numbers you gave, they are the same size. They're both 720x480. The only difference appears to be the pixel aspect ratio.

As I said earlier, the reverse telecine may work -- but if you have edits in points which disrupt the pulldown cadence, then you may see sections with problems. But there is the possibility that it may work out fine.
 
The deinterlacing is being done on a PC in Vegas. He said he'd look into pulldown removal, but he intended to use some Vegas approach to it, I forget what it was called, but it wasn't related to pulldown.
 
Well, Vegas has the same two options -- deinterlacing or pulldown removal. Vegas can remove 2:3 pulldown manually from DV, so if that works, it's the better option.
 
Possibly, though there's also the possibility that they will have to be re-rendered as AVI DV (though this shouldn't affect quality at all if the MOVs are DV). If you can render out DV AVIs for him, it would be better, though.
 
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