Why use interlacing ?

We shoot with DVCpro50 at 24p.
A few questions.

1. Is there anytime that there is an advantage, or a time when you have to use field dominance ?
Interlaced footage looks like crap. Stills look horrible in an interlaced timeline - why ever use it ?
It seems I can just switch the field dominance from "lower/even" to "none" and everything looks 10 times better on computer and NTSC monitor.

2. Is there anytime that there is a disadvantage to removing the pulldown and editing in 24fps. It looks 10 times better without the screwd up "B/C & C/D" frames if you leave it in and edit at 29.97fps.

3. is there any advantage or quality enhancement by removing the pulldown in "Shake" rather than letting FCP do it while capturing. And after removing, should your sequence timeline be set to 24fps or 23.98fps and why ?

4. Have G5, OSX 10.4.8, AJA IO hooked up to NTSC monitor, and can't view 24fps timeline on external NTSC monitor - only frames when parked - is that because these monitors will only accept 29.97 field dominated footage ?

Interlace is video compression as designed in 1952. Let's cram 60 pictures per second through a television channel that can only handle 30. Poof. Interlace. First send lines 1, 3, 5, and 7, and then go back and fill in 2, 4, 6, etc. In pictures taken from nature, you literally can't tell. Computer graphics fall apart immediately because they can exist on one field only and tend to jump, crawl, or flicker. Not so grass and trees. Grass and trees look just fine.

When they went color, they did it in a way that would let you keep your old black and white TV. In order to do that, they had to give up 30 and 60. To transmit the color signals, they had to slow down the rates a little which gave you 29.97....(the number never comes out even), and 59.94....

The National Television Systems Committee decided this. NTSC.

23.976 is an even 3/5 of 59.94. If you ever want to get back and forth between a 24 frame show and NTSC television, the show should actually be 23.976 for the least visible damage. The process of conversion is either 3:2 or 2:3:3:2. This is called "pulldown" from the dance that telecine film projectors do to perform the conversion.

23.976 is frequently abbreviated 23.98.

It is strongly suggested that you do all the work on the show at 23.98 and pull down to NTSC later. As you found out, trying to actually edit a mixed show at 29.97 is a nightmare and doesn't always look all that good either.

Koz

<<<4. Have G5, OSX 10.4.8, AJA IO hooked up to NTSC monitor, and can't view 24fps timeline on external NTSC monitor - only frames when parked - is that because these monitors will only accept 29.97 field dominated footage ?>>>


I didn't catch them all. An AJA Io is a Standard Definition device. 24/23.98 is a High Definition Standard.

I think our Kona2 card will try to convert--almost anything--on the fly to a local NTSC monitor.

Koz

I'm the editor - they shoot with a SPX900 in 24p - if you don't remove the pulldown, frames 3 & 4 out of the 5 frame cycle combined with the interlacing gives really bad results. So out of curiosity I switched the sequence dominance setting from "lower/even" to "none" - at this point is it still treated as interlaced or if it is set to "none" is it now progressive, like when you are editing in 24 and the field dominance window is greyed out. I would think that this would look jittery on a TV because the field order isn't right - but it doesn't - I can make DVD, VHS(not sure why), and monitor on NTSC external monitor - and the only difference is that the stills look incredibly better - there's no banding and stair stepping on the shoulders- on either the computer monitor or the NTSC monitor. And with it set to "lower/even" the bigger the computer or TV screen the worse it looks - but with it set to "none" the stills just get softer as you view them on bigger screens as if the right amount of gaussian blur was being added automatically - Isn't that wht you want ?

So that was why I ask "why use interlace" if you have a choice?

Also - what is the difference between "standard pulldown" and "advanced pulldown" ?
- Curios how they call it pulldown in both directions - when adding the extra frame to go from 23.98 to 59.94 shouldn't it be called "pull up" ?

<<<So that was why I ask "why use interlace" if you have a choice? >>>

Don't. It's far easier and with smoother results to cut in progressive. More accurately, cut in the show's native framerate, not a framerate somebody made up in post.

By the way, I suspect there's more magic happening there than you think. If you didn't intentionally remove the pulldown, then it's still there and can cause problems.

<<<Also - what is the difference between "standard pulldown" and "advanced pulldown" ? >>>

One is a lot more advanced than the other. Just kidding.

3:2 is the time-honored 3/5 method where they make up the framerate difference by splitting television fields. Its claim to fame is that it looks really good, but it doesn't convert in and out of 30 easily. Advanced is only advanced in that you can convert in and out of 30 very easily, but it doesn't look as good. That's why 3:2 didn't vanish in a puff of light. It still looks the best.

<<<shouldn't it be called "pull up">>>

Yes. That's why they call it "pull up." The metaphor of watching the film motion inside a projector falls apart when you do that, but everybody knows what you're talking about.

Koz

Thanks for your insight.
I found this article that seems to suggest that "advanced pulldown" is more capable of recovering the 4 original true frames where as 3:2 will have a generationalized 3rd frame because it has to be rebuilt from the B/C & C/D (4th & 5th) frames of the video.

Yes. That's why recovering from old 3:2 is such a pain in the butt. The newer cameras all deliver 3:2:2:3 which looks good enough to cut by, reverses back to 24-ish just fine and then, if you feel the need, you can *still* perform old 3:2 for great looking NTSC delivery.

Koz

I think FCP can only remove Advanced pulldown anyways.
I just got Shake - I think maybe it can do the traditional 3:2

Thanks again - makes more sense now.

Yes Shake can remove 3:2 pulldown.

Derek

"I think FCP can only remove Advanced pulldown anyways."

This is not quite correct. If the material was shot in normal 24p recording at 29.97 pulldown is added in the camera. 3:2 pulldown is handled automatically in FCP. The pulldown is added to allow 29.97 editing and display on a 29.97 frame rate system. You don't need to remove it unless you're going back to film. In which case it would be better to shoot 24pa in the first place. Pulldown removal can be done using Cinema Tools. That's what it's for, when you're doing film out.