What causes judder and what can be done about it?

[drstew12]

What causes judder? Is it inherent to the video on the disc (movie) or are the blu-ray player and HDTV to blame? Can the settings on either or both improve matters? Are there some blu-ray players and HDTVs that reduce this significantly?

[Cornucopia]

There are (at least) 2 very different things which people tend to confuse when talking about this:
1. Motion flicker from footage shot and/or displayed at too low of a framerate (should most times be just called "flicker")
2. Stuttering from non-steady motion (should be the thing called "judder"). This most often occurs with telecine pulldown.

Here's 2 pictures showing normal, steady motion (and steady framerate to display the motion), and unsteady/juddered motion (or the same steady motion shown with unsteady framerate).
Both generally get to the same goal points and the cumulative/overall average rate is still the same, but one has very little (or none) variation in the linear change where the other is decidedly non-linear.

1. Steady motion



2. Unsteady/Judder motion


The thing about telecine is that it uses 3:2 (or 2:3) pulldown, and CREATES this kind of non-steady motion. To some, this is very noticeable, and just compounds the jerkiness quality that people may already notice about lower framerate presentations (24p - cinema, or 25/29.97/30p video).

Since film is 24p (almost always), and your video display IS NOT, there has to be some type of conversion of the framerate. Unless you are fortunate to have gotten a modern 120Hz/240Hz display which has the feature of directly displaying 5 flashes of 24Hz = 120Hz (or 10 flashes = 240Hz), you are stuck with using telecine or motion interpolation of some kind (which has it's own set of problems).

Scott

edit: note also that telecine to interlaced video rates (50i/59.94i/60i) is inherently less juddery than telecine to progressive rates (25p/29.97p/30p) because the interlacing "imitates" a higher framerate (aka a smaller "step-size").

[jagabo]

When 24 fps film is displayed on a 60 Hz TV or monitor film frames are repeated 2 or 3 times, alternating between the two. So the first frame is repeated for 2/60 second, the next for 3/60 second, the next for 2/60 second, etc. This unequal duration of the frames (which where all supposed to be displayed for 2.5/60 the second) causes judder.

https://forum.videohelp.com/threads/307004-Best-framerate-conversion-%28eg-23-97-to-30-...=1#post1888926

[edDV]

... Is it inherent to the video on the disc (movie) or are the blu-ray player and HDTV to blame?

"NTSC" DVD/Blu-Ray discs can be encoded with hard telecine (as if recorded directly off a TV broadcast) but most movies and TV series discs are encoded progressive.

The DVD/Blu-Ray player has settings to match various displays. When playing a "progressive" disc, players can output the following

29.97 telecine (over composite, component or HDMI)
59.95 progressive with 2:3 frame repeats (component or HDMI)
23.976 progressive (some Blu-Ray players over HDMI only)

So called (60Hz) HDTV sets will display 59.94 progressive directly with the 2:3 judder. For 29.97 telecine, they will first inverse telecine to 23.976p, then frame repeat 2:3 to 59.94 fps.

The "120 Hz" HDTV sets will remove the 2:3 frame repeats from 59.94 inputs resulting in 23.976 film rate. Then these frames are repeated 5x to 119.88 fps free of judder. The same is done following inverse telecine or from direct "24p" inputs from some Blu-Ray players.

Can the settings on either or both improve matters? Are there some blu-ray players and HDTVs that reduce this significantly?

The conversion is done during input processing at the HDTV. As far as judder is concerned, it really doesn't matter whether the player outputs telecine, 2:3 progressive or "24p". The HDTV will process each to the native display frame rate. "60Hz" models will show judder, "120Hz" models won't.

[gaelsano]

To add to edDV's great info (I've been stalking his/her posts on this forum for a while--what an expert), make sure the 120Hz set you have (if you have it) has motion interpolation turned off. It takes frame #1/24 and frame #2/24 and makes them new frame #1/120 and new frame #6/120 and then makes up new frame #2/120, #3/120, #4/120 and #5/120. This causes odd motion like someone get sucked into a black hole (slow then really quick and smooth) or creates a wipe effect when the camera cuts and other screwy things.

For cinema-like viewing you need to make sure motion enhancement is off. The most accurate is 72Hz (each frame shown 3 times) but I haven't seen it before.

[spiritgumm]

sorry to bump up this old thread, but I have questions about telecine judder. I notice a slight hesitancy on retail dvds that have a pattern of 2:2:2:4. Some viewers also noticed it, some others didnt. Why is that? I dont think I can adjust the playback on my bluray or HDTV. I re-encoded one dvd (ivtc'ed and re-encoded with HCenc which added pulldown), and it looked fine.

I ripped samples using DGindex with and without "honor pulldown flags." The dvds with 2224 pattern always showed that pattern. That means it was hard telecined, right?
The 2:3 pattern dvd played progressive without honoring pulldown flags, so that sounds like it's really 24 fps with pulldown flag.
Is there a way to get my setup to play the 2224 dvd smoothly? And why is this an issue between retail dvds and equipment? Should I complain to the dvd company?
judder.m2v

[jagabo]

I notice a slight hesitancy on retail dvds that have a pattern of 2:2:2:4. Some viewers also noticed it, some others didnt. Why is that?

Once trained anyone can see it. Find a long, smooth, medium speed panning shot. That's where it's most obvious. There will be six little jerks every second as one out of every 4 frames is displayed for twice as long as the others.

Is there a way to get my setup to play the 2224 dvd smoothly?

Some players and TVs can detect the pattern and "correct" for it. The HQV Benchmark tests for it:

http://www.anandtech.com/show/4380/discrete-htpc-gpus-shootout/4

If your equipment doesn't handle it there's not much you can do other than buy new equipment or reencode the video.

[spiritgumm]

hi jagabo,
unfortunately I wasnt trained to see the judder - just cursed to see it.
I pointed out the scene I uploaded to someone with the dvd, but they still said they didnt see it. I can see the judder in the sample on my PC.
Part of my question is why this is an issue. I dont think my equipment is that old. Why do companies do this? Should I mention it to the dvd company?

[jagabo]

Part of my question is why this is an issue.

Because you have to get from 24 fps film to 60 fps video one way or another. Some will do it one way, some another. Both 3:2 judder and 2:2:2:4 jerkiness are visible. It's possible your friend's player or TV detected 2:2:2:4 and corrected it. Some do some don't.

[spiritgumm]

I wonder if it's a per-case issue for some reason? Surely I've gotten dvds that used that pattern but didnt notice. I recall one dvd for sure in 2010, but I might have had the same HDTV.
To specify, this is an issue with the recent Columbia Noir Vol. IV (5 dvd box set), from TCM Shop. The video also appears to have noticeable aliasing (or jaggies), although I dont know if it's related to the telecine.
I dont notice the judder with 2:3 (just looks blurry).

[manono]

The video also appears to have noticeable aliasing (or jaggies), although I dont know if it's related to the telecine.

It looks to me like they took a hard telecine source and poorly deinterlaced it, creating both the aliasing and the dupes every five frames.

[spiritgumm]

tangential question related to 2224 telecine judder. I made a side-by-side clip (attached below) of the original 29.97 fps video I described with decimated 24 fps version. When I play it, the 24 fps side ends sooner, I guess because a media player is playing the whole video at 29.97. I assumed the combo clip (from avisynth/vdub) would play normally since each side is the same runtime. Aside from adding 3:2 telecine to the decimated clip, is there a way to match up the 29.97 with 24 fps?
The problem happens on all 5 movies in the recent "Columbia Noir Vol. IV" set from TCM.
29vs24.avi

[sanlyn]

All digital TV's are not as talented as others when it come to motion handling and interpreting various pulldown schemes. My SONY LCD and Samsung plasma seem to do a decent job, provided they're fed by a competent player (and all players aren't talented, either). You can't judge a TV's or player's performance by looking at it them in a showroom. There are too many hookup variables involved, not to mention those showroom videos that are designed to mask many display problems. And that doesn't even count the effects of showroom lighting. Finding a TV or player with competent motion handling (and none are perfect, no matter what the salesmen say) is a lottery. I consult the reviews of advanced critics who seem to be cognizant of motion problems. Those critiques are often difficult to find.

One of the more enlightening displays IO once saw was a showroom demo set up with a 60" Sharp that had the screen split in half: left side = 120Hz motion comp, right side = "normal". They both looked alike, but with blurry soap-opera effect on the 120Hz motion side.

[poisondeathray]

tangential question related to 2224 telecine judder. I made a side-by-side clip (attached below) of the original 29.97 fps video I described with decimated 24 fps version. When I play it, the 24 fps side ends sooner, I guess because a media player is playing the whole video at 29.97. I assumed the combo clip (from avisynth/vdub) would play normally since each side is the same runtime. Aside from adding 3:2 telecine to the decimated clip, is there a way to match up the 29.97 with 24 fps?
The problem happens on all 5 movies in the recent "Columbia Noir Vol. IV" set from TCM.
29vs24.avi

Your comparison is flawed because the 24fps version is running at 29.97 in your "side by side" . You have repeated frames at the end . You're essentially playing the 24fps "faster"

The frames will match up (temporally in terms of timecodes of each frame - very close within a few ms) with a 29.97 pulldown version vs. a 23.976 pulldown removed version

[spiritgumm]

Your comparison is flawed because the 24fps version is running at 29.97 in your "side by side" . You have repeated frames at the end . You're essentially playing the 24fps "faster"

yes, I believe I said that. My question was how to make them play correctly together (without adding telecine to the decimated clip). Probably impossible.

[jagabo]

My question was how to make them play correctly together (without adding telecine to the decimated clip). Probably impossible.

You can't of course. That's why movies are telecined in the first place. They don't do it just for fun.

[poisondeathray]

Your comparison is flawed because the 24fps version is running at 29.97 in your "side by side" . You have repeated frames at the end . You're essentially playing the 24fps "faster"

yes, I believe I said that. My question was how to make them play correctly together (without adding telecine to the decimated clip). Probably impossible.

Yes it's impossible without adding back some frames (duplicates, blends , interpolated, whatever) - essentially you add back the same or similar frames that you decimated

A video can only run at one speed . You can't have portions of frames that run at different speeds

[spiritgumm]

you guys work miracles, so I thought I'd ask anyway.

[efiste2]

Just to add my humble words. Many American TV series on DVD suffer terribly from this, usually the less popular ones, I Have seasons of shows like Hunter,Hardcastle & Mcormick etc etc they all judder......

[jagabo]

Everything shot on film shows judder when broadcast for TV.