24p Output for no stutter?

D

DrMario

Member
I just shot some 720/24P footage with my HVX-200, ran it through the Serious Magic HD decoder so I could work with it in AE7, since my Matrox Axio won't deal with MXFs yet.

Anyway, I started an AE project with the DVCPROHD 720/23.976 settings:

DVCPRO HD720/23.976
960 x 720
Pixel Aspect: 1.33

So after dropping the video in there, I exported out as a Windows Media file (720 24p). When I watch the wmv file or preview the file in AE, the motion (a truck driving by) looks stuttery.

I know this is an issue when playing back a 24p clip in a 29.97-based timeline, but why would I see it if everything is set to 24fps? Any help would be appreciated, as I am a 60i video guy trying to get more into the "film look" of 24p, please pardon my ignorance.

Thanks.
 
24p stutters. Film stutters. It's part and parcel of dealing with a low sampling rate. With video you have 60 samples per second, with film (and 24p video) you only have 24 samples. In terms of motion resolution, think of film as 24 dots per inch and video as 60 dots per inch -- which will look smoother? Video, of course.

But 24p works and looks like film. Examine a similar shot in a movie or on film and you'll see it stutters exactly the same way.
 
But motion in film, while a touch blurred, doesn't look like this. I can't imagine anyone who shot 24p would live with motion like I'm seeing in this clip.

I mean, I've seen your juggling clips on the boot camp DVD (some shot in variable frame rates) but one shot in 24fps and the motion looks smooth. Would it make any difference if I shot in "film camera" mode instead of "video camera" mode? Maybe if I slowed the shutter to 1/24 in stead of 1/48? Do I need to remove 3:2 pulldown?

I just feel like I'm not doing something correctly. Maybe your next DVD should be "Shooting in 24p and 24pN for Dummies". I'll take the first copy.
 
Did you shoot 24p or 24pN???
Make sure the serious magic decoder
properties were set correctly.
If you shot 24p then have After Effects
interpret the footage....
On fields and pulldown try
Remove Pulldown On
Guess 3:2 pulldown.......
 
I am not shure if making some adjustments in the settings would make things more smooth but I do know that you have to move and pan the camera SLOWLY just like a film camera. Barry commented on another thread that the rule of thumb for the speed of panning shots should be no faster than 7 seconds for an object to pass from one side of the screen to another.

Filming has to be so much more controlled to get good results as opposed to the typical run and gun shooting you can do with video cameras.
 
OK, I tried the pulldown settings as villeluna (and ville, I was shooting in 24p NOT 24pN, sorry should have clarified) suggested and still stuttery. I tried to change the frame rate to see if that helped...no good. I wish I could post the wmv here so you all could look at it. Anyone willing to give me their email address and I'll email it and you can take a look and see what's up?

I do understand that pans and tilts need to be slow when shooting in this mode, but the camera was static and the truck passes in front of the lens.

Anyone know of a comprehensive step-by-step website or resource that explains how to get from 24p (HD or SD) to 29.97 video in an easy fashion, if that exists?
 
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Might be a stupid question, but what are your computer specs?

but the camera was static and the truck passes in front of the lens.
Click to expand...

Oh didn't see this.

Try this:

How close are you to the truck, pan with the truck as it passes and see if the studders dissapears.

Welcome to the world of 24p dude.
 
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I would say I'm about 15ft from the truck. I'll try the pan next time.

I know I've seen 24p finished footage with motion that didn't look as stuttery as what I have here. Maybe when Matrox gets it's act together and releases Axio 2.5 I'll have better luck.
 
Barry is absolutely correct. Stutter is a function of the frame rate and the relative motion of the objects within the frame. This same characteristic would be present regardless of the type of system used to acquire the image.

It is simply the nature of a sampling system. What makes this characteristic acceptable and actually desirable is the skill of the shooter, not the system itself.

You can certainly trade off stutter for more motion blur by using a slower shutter, but you can't completely eliminate it unless both the camera and the subjects move really slowly across the frame (like 20 seconds minimum edge to edge).
 
How about changing the shutter angle from 180 degrees to 200 degrees?

I thought I read somewhere that this could make a difference. I am not sure though.
 
Changing the shutter angle is another way of saying change the shutter speed. A change from a 180 degree shutter to a 200 degree one isn't going to make much difference.

With a 24 fps rate a 180 degree shutter is 180/360 * 1/24 = 1/48th of a second

24 fps and a 200 degree shutter is 200/360 * 1/24 = 1/43.2 of a second

Something like a 270 degree shutter (1/32 of a second) is going to give a much stronger effect.
 
khmuse said:
Changing the shutter angle is another way of saying change the shutter speed. A change from a 180 degree shutter to a 200 degree one isn't going to make much difference.

With a 24 fps rate a 180 degree shutter is 180/360 * 1/24 = 1/48th of a second

24 fps and a 200 degree shutter is 200/360 * 1/24 = 1/43.2 of a second

Something like a 270 degree shutter (1/32 of a second) is going to give a much stronger effect.
Click to expand...

Thanks for the eplanation. I have always been a little confused by the shutter degree/shutter angle relationship.
 
Just got the new Axio 2.5 update that allows me to import the mxf files directly AND start a Premiere project with the correct 24p timebase.

And NOW I see what acceptable stutter looks like. And yes, it is very acceptable. When I started this threat, the footage looked nowhere near as smooth as it does now.

Still, appreciate all the help. Thanks again.
 
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