Hey everybody - I wanted some thoughts on this. For the past 4 years, I've been toying with native 24p filming, and in the end I always back away and shoot in 30p because of the extreme judder and strobing, especially when panning high-contrast vertical elements, at 24p. Nothing new there. For years, I've read on message boards the discussions on this, which usually amount to "set shudder speed to twice the frame rate," "don't move the camera," "it's because you have a huge depth of field with video," or, simply, "24p is for cinematographers and not amateurs, and I don't know why people are so stuck on shooting at that frame rate anyway." Perhaps true, but none of those answers have ever really been satisfactory. Then, something hit me. A movie projector has a flicker rate of twice the speed of film, or 1/48 second. This is because when set to 1/24, there's an unacceptable amount of judder. When watching film, we see each frame twice before the next is advanced So, I tried rendering my 24p footage at 50p and 60p. Bingo. It looks "like a movie." Could I accomplish the same thing by adjusting my monitor refresh rate, or the like? Maybe. But this is easy, and seems to be universal, working across all of my devices. I wanted to throw it out there not for professionals, who probably have far more expensive ways of dealing with viewing and projecting 24p footage, but because amateurs always complain about their kid's birthday party being all juddery and strobe-like, and this could really help them as an easy solution to get the effect they're looking for. Thoughts?
An interesting 24p Judder solution...
- Thread starter CTLiotta
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A couple things: Are you saying you normally set your shutter to 1/24 for 24p shooting? Should be 1/48 (or closest equivalent) for normal motion blur cadence.
Also, I've always heard it's all about movement speed. . .there's some kind of formula for how fast/slow the camera needs to move across a certain distance to avoid issues (i.e. when panning or dollying and vertical objects are in frame), likewise for actors or objects crossing frame.
In addition, there's always the pulldown issue. . .I shoot and post so little 24p that I'm way out of the loop and don't even know if it applies these days, but are you taking your 24p footage through the proper post process so that it
ends up looking the way it's supposed to? Some cams have different 24p modes that require different sequence/timeline settings in post to be handled properly. Make sure you're setting all that up right when you edit. Sometimes it looks terrible straight off the cam until the proper processing is applied down the line.
Also, I've always heard it's all about movement speed. . .there's some kind of formula for how fast/slow the camera needs to move across a certain distance to avoid issues (i.e. when panning or dollying and vertical objects are in frame), likewise for actors or objects crossing frame.
In addition, there's always the pulldown issue. . .I shoot and post so little 24p that I'm way out of the loop and don't even know if it applies these days, but are you taking your 24p footage through the proper post process so that it
ends up looking the way it's supposed to? Some cams have different 24p modes that require different sequence/timeline settings in post to be handled properly. Make sure you're setting all that up right when you edit. Sometimes it looks terrible straight off the cam until the proper processing is applied down the line.
Thanks, Josh. At a minimum, I use a shutter speed of 48 when shooting in 24p. You're correct about panning - I forget the rule, too (x number of seconds from the right end of the frame to the left, or somesuch). I don't think about it, but rather pan very slowly. I think I have the pulldown issue accounted for, as I shoot in native 24 these days, and edit with a program that can handle 24p native. No issue there, happily.
If I can find the time, I'll post two examples- one with the judder when 24p renders at 24p, and the other where it's smooth when 24p renders at 60p.
If I can find the time, I'll post two examples- one with the judder when 24p renders at 24p, and the other where it's smooth when 24p renders at 60p.
Sounds like you've heard some really idiotic things on some message boards
:None of that is true, at all.
As to what you tried:
Rendering your footage out to 60p (or 50p) doesn't affect the motion (and thus, the motion judder); it simply inserts a pulldown and the 24 frames are shown for the same length of time they would have been at native 24 fps. Everything still moves 24 times per second, not 60.
If it "looks like a movie," then it's because objects move 24 times per second. If objects moved 60 times per second, it would look "live."
The way to get smooth motion with 24 fps is to make your camera motion slow. If you mess that up while you're shooting, you're not going to be able to do anything about it in post.
Also, I wonder if you're confusing two concepts -- motion judder, which you seemed to be referring to, and flicker, which is what the projector tries to eliminate. Showing the same frame twice for 1/48th of a second does not eliminate any motion judder. It's exactly the same as showing a frame continuously for 1/24th a second. The motion judder comes from moving objects being too far apart from picture to picture to make a smooth motion. This isn't alleviated by showing the same frame twice; the "jump" of moving objects from one frame to the next is still going to be there.
You're quite right. In simple terms, show each frame 2 or three times, like a film projector does, and 24fps looks smoother. You also need to take into account that there has to be an equal number of interspersed black "fields", so your minimum display rate for this to work is 96fps. Microsoft did a demo of this technique a few years back. It actually looks more like film than any other "filmic" method, e.g large sensor, proper lighting, 10 degree shutter, etc... Unfortunately at this time there's no way to view at that rate in a standard monitor. Only way I know is to reverse telecine and use a film projector. It's why movies shot on video and distributed on film look like film.
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24 fps material in a 60 (i or p) stream does show each frame 2 or 3 times. That doesn't eliminate the motion judder generated by improper 24 fps camera motion.
Movies shot on video and distributed on film look like film, to the extent they do, because they're on film. Movies shot at a video frame rate of 60 (i or p) and then distributed on 24 fps film move like 24 fps film and not like 60 because they've been converted to 24 fps.
Movies shot on video and distributed on film look like film, to the extent they do, because they're on film. Movies shot at a video frame rate of 60 (i or p) and then distributed on 24 fps film move like 24 fps film and not like 60 because they've been converted to 24 fps.
starcentral
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What's warped are the LCD/LED TV's that enhance the motion to actually look like LIVE TV. It is so messed up to watch, big blockbuster hollywood movies look like the next episode of "Cornation Street".
:undecided
:undecided
That's just wrong. Some people love it because they prefer the look of live TV, though.
starcentral
Veteran
What's really wrong is that it's the DEFAULT on so many TV's, really bothersome.
What I want to know is how they actually go about getting a 60i look from 24p !?!?
What I want to know is how they actually go about getting a 60i look from 24p !?!?
Some kind of hardware interpolation, apparently. Can't do it with any software I'm aware of.
Yes, but they are shown as a continuous stream - there's no "strobe effect" so that each image appears discreetly after an equal period of black. It's possible that this provides some sort of congruence with brain wave patterns and is responsible for "the magic of film" perceived by some people. There's nothing inherently "magical" about film as a medium. Consumer video cameras today shoot the same DOR and DR as pre 1970's color film.
I'm not entirely sure what you're trying to argue. You certainly could insert black frames after every 24p frame (it wouldn't even be that hard to script it), but I can't imagine how that would make the motion "smoother." I can see how it would make it more flickery, like a cheaper or older film projector, but I don't see how that would be desirable.
As for the "magic" of film, I don't think anyone's said anything about that. I've talked about the motion of 24 fps film, but that's a frame rate and motion issue having nothing to do with dynamic range, depth of field, or anything like that.