60i to 24p, how to avoid judders

Ros wrote on 8/20/2005, 2:40 PM
Is there a way to avoid judders or flickering when panning. Interlaced video always looks good but when I convert to 24p in order to get a film look, it is just annoying. I did try to convert to 30p, which seems a little better and also tried DVfilmmaker demo, but I am never totally satisfied with the final result.

I noticed the new JVC GY-HD100u has a Smooth motion function, is that what I should move up to eventually in order to get a nice 24p film look?


I am presently shooting NTSC 29.97i 720 x 480 video on a SONY pd170.

Robert

Comments

farss wrote on 8/20/2005, 2:55 PM
Have you tried adding motion blur?
24fps has a restrictions on panning rates etc, if you don't watch them I believe all sorts of wierd things can go wrong.
Bob.
John_Cline wrote on 8/20/2005, 4:40 PM
Robert,

60i video has a temporal resolution of 60 images per second, 24p has less than half that, it only has 40% of the temporal resolution of 60i. 24p is going to "judder" during pans and there is really no satisfactory way around it. Yes, motion blur will mitigate the problem somewhat, but that will simply blur the picture during periods of fast motion.

In my opinion, 24 frames per second is actually the least important aspect of achieving the "film look." Film has a different color response than video and it's more about getting the video image to look more like film. It also helps if you light your video using film style techniques.

I spewed my opinions on the subject in more detail in this thread:

http://www.sonymediasoftware.com/forums/ShowMessage.asp?ForumID=4&MessageID=285294

John
Paul_Holmes wrote on 8/20/2005, 7:28 PM
With Vegas 6 I don't get the "judders" in most situations when I convert 60i to 24p. In brightly lit situations where my atuomatic shutter speed ends up high I do get them.

If you can set your camera's shutter speed to 1/60th or, in my case, use neutral density filters in bright situations Vegas 6 does an incredible job of making 24p look natural and undistracting. I upgraded from Vegas 4 and experienced a "Wow!" factor in the difference.

Personally I use 24p and widescreen for all my family films, so that along with music and VASST film looks I can achieve a fun dramatic feel to what could be just mundane movies.

If you're a professional, like John Cline (although I'm not, I've been involved with a couple more serious projects with a VX2000) you have to understand your audience and decide whether you want that more immediate live look of 60i (with the VX2000 I did -- it was a church service), or the more dramatic look of say an Indie film.

P.S. It's interesting to see, though that the widescreen look itself is getting more popular. You see it simulated all the time in commercials and recently I was surprised to see it on one of my favorite religious programs, Joel Osteen's Lakewood Church weekly broadcast. He and his church recently moved into the Compaq Center in Houston and to inaugurate that they gave the video a new widescreen look. At first I found it a little strange but then I realized that, metaphorically it made sense, since they're now in a huge arena and the widescreen look compliments that.
Jessariah67 wrote on 8/21/2005, 10:10 AM
I recently completed a film that was shot 60i and converted to 24p. With two exceptions, there was no "jitter" (in Vegas 6). If you watch closely, you can see picture studder on native 24p or film. I haven't shot native 24p, but from what I've seen in conversion (and what I've read), it's just a different approach to camera movement. Shooting 60i with this in mind will probably make the 24p conversion smoother.

Personally, I have to disagree with 24p not being important to achieve "film look." It's just my opinion, but you can do anything you want to 60i and it will still "look like video." Personally, my eyes can't get past the crispness of interlaced picture, and that's an instant deal breaker for me when watching a "movie."
Paul_Holmes wrote on 8/21/2005, 3:49 PM
Another thing about video is that it doesn't handle high contrast as well as film. Whites tend to get overblown and blacks can lose all detail. I was recently reading up on the Canon XL2 and it has all kinds of interesting ways of dealing with that to create a more film-like look at the shooting level. The tutorial on the camera went through the major differences between film and video and how the Canon allowed you to overcome a lot of those barriers. I'd love to see the same features in a lower-priced camera.
Ros wrote on 8/22/2005, 9:34 AM
Thanks to all for your input !
I guess I will do more experimenting. A lot of stuff I shoot is handheld with a shoulder brace, it is a little more unstable than a steadycam but that could explain part of the judders, the camera is constantly moving.
Yes, I do believe there is more than converting to 24p in order to achive a film look, but I do believe deinterlacing is a good start either 24p or 30p.

Also Paul, would you have a copy or link to that XL2 tutorial? I'd love to read that! You also mentionned that you shoot widescreen, do you view it on a 4:3 or 16:9 tv? Are you getting more res on widescreen or it is only adding black bands at the top or bottom. Has you can see, I have never experimented on widescreen yet.

Thaks,
Robert
Paul_Holmes wrote on 8/22/2005, 7:18 PM
Robert, here's the link

The link takes you to their main page. Right now you'll find them advertising a 35 minute streaming video explaining the XL2 in detail. I only got through about half of it but was fascinated by not only the camera (which is way out of my league) but all the information provided on how film and video differs and how the XL2 overcomes much of that.

I shoot all my family videos with an older Sony TRV-315 digital 8 in widescreen. I switched over to widescreen about 15 movies ago because I'm trying to create that more dramatic filmic look. The improvement in the look of my movies with Vegas 6, VASST's Celluloid movie looks, and looks I've been able to improvise working off Celluloid's FX is astonishing. There's no comparison to the smoothness and ambience of the videos on my latest 6 movie DVD compared to the last 7 movie DVD.

To answer your question, however, I film and edit in 16X9. On my 14inch 4X3 Sony "monitor" (just a flat-screen TV) the 16X9's are cut off on the top and the bottom. However if played on a friend's widescreen TV, they fill the screen with no black bars. (DVD players simply need to be programmed to know what kind of TV you're watching the DVD on and if it's 4X3 the player knows to display widescreen with black bars -- if you've told the player you've got a 16X9 TV, it will display widescreen movies without black bars).

P.S. It's amazing how many people have their DVD players set for the wrong TV!

(Edit) One other great thing about 24p -- If you use the variable rate setting to create the mpg (8000/6000) and use AC3 in DVD Architect you can cram about 1 hour and 40 minutes of high quality video on one DVD. My latest DVD has 1 hour and 35 minutes.
David Jimerson wrote on 9/15/2005, 12:23 PM
I agree that converting to 24p is not the only step in achieving a film look, but the least important? Hardly. I think I was able at NAB to demonstrate what happens when you do everything else but don't convert to 24p . . . you end up with something which looks like cinematic video.

As for the judder, if your intent is to convert to 24p for a film look, you need to be thinking about that as you shoot. Shooting film -- and shooting 24p -- requires handling the camera differently than when shooting in 60i, precisely because of the difference in motion samples per second, 24p having only 40% of the temporal information that 60i does. Shooting 24p, you need to have sloooow pans, especially at longer focal lengths, slower zooms, and a general mindfulness of the motion characteristics. You can get away with a lot more shooting in 60i because it's very, very close to the "refresh rate" of the human eye, and it looks real.

When you convert to 24p from 60i, you're going to end up with the same motion artifacts that you would if you had shot in 24p originally. So, shoot in 60i as if you're shooting in 24p, and you'll get a much, much smoother transfer.

Also, keep in mind that many of the camera movements and techniques that we've come to consider "cinematic" were developed around the use of 24fps film, to get the MOST out of it. If you're using the techniques well-suited for 24p/24fps film, you've already gone a long way toward a film look before you ever get into post.
johnmeyer wrote on 9/15/2005, 7:22 PM
If you pan quickly, you are going to get judder at 24p, whether you shoot that way natively, or whether you convert from 60i. It's just the nature of how the eye reacts to 24 progressive pictures per second.
FrigidNDEditing wrote on 9/15/2005, 9:39 PM
(Didn't read any of the other posts)

probably heard this already, but - film uses subtractive coloring, Digital Video uses Additive color - 24P is only a small portion of the equation.

7 second pans is the answer (more or less)

If you wanna move faster have something for the eye to follow across the scene - it's just the way things are, when you do 24P.

i have to say, however - that I enjoy the look of 24P in combat sequences - I like to see the jump of the arms and legs etc... - it just makes me feel like it's more emphasis with the action.

That's just me though. :)