15.2 C
New York
Friday, April 12, 2024

I Use Motion Smoothing on My TV—and Maybe You Should Too

For years, new TVs have come with a feature called frame interpolation, or motion smoothing, enabled by default. By creating new frames in between the ones encoded in the movie, it makes motion clearer. But it also imparts an almost artificial look, as if the movie were shot like a soap opera on cheap video. So cinephiles—including many here at Wired—have raged against this feature for years, to the point that it's become a meme starring Tom Cruise. As a tech writer who reviews TVs, I've kept my feelings mostly under wraps, but it's time to come clean: I actually use motion smoothing at home.

Before you break out the pitchforks and tiki torches, hear me out: It's not as bad as it sounds. I still hate the way it looks out-of-the-box on most TVs. I use it on its lowest setting and only on TVs that can actually do the job well. In other words, I wouldn't say Tom Cruise was 100 percent right about motion smoothing—but maybe that he's 80 percent right.

If you buy something using links in our stories, we may earn a commission. This helps support our journalism. Learn moreLearn moreLearn more.

Modern TVs Aren't Very Good at Producing Clear Motion

When early filmmakers were shooting the first motion pictures, they tried a variety of frame rates, eventually settling on 24 frames per second. This wasn't some magic number that created a certain "filmic" effect, like we think of it today—it was, in part, a cost-saving measure. Film stock doesn't grow on trees.

It's enough to give the illusion of motion, but it isn't really continuous, says Daniel O'Keeffe, who does in-depth display testing at RTINGS.com. He uses the example of a tennis ball flying through the air: "If you were watching the game in person, you could track the ball smoothly and it may always appear in the center of your vision. This results in clear, smooth motion."

But on film, you aren't actually seeing motion—you're seeing a series of still images shown at a rate of 24 per second. This isn't a huge problem in a movie theater, where typical projectors use a shutter to black out the screen in between frames. During these blackout periods, he says, "Your eyes 'fill in' the intermediate image due to a phenomenon called persistence of vision." This makes the motion appear smooth, despite its relatively low frame rate. Old CRT and plasma-based displays had inherent flicker that resulted in a similar effect.

But modern LCDs use what's called sample and hold: They draw the image super fast, then hold it there until the next frame. (You can see it in action in this video from The Slow Mo Guys). So your eye attempts to track an object moving across the screen, but that object isn't always where your eye expects it to be. It's still held in its previous position, and there's no black flicker to give your eyes a chance to "fill in" the missing information. So the image appears to stutter and blur, especially in shots that pan across the scene too quickly. You can see a more visual representation of this in RTINGS' video series on motion, embedded below.

Some people don't notice or care about this stutter. Other people, like me, are more sensitive to it and find it uncomfortable to watch. Certain TVs are more prone to it, too, depending on their response time—their ability to shift colors quickly. Cheaper TVs with low response times stutter less, instead causing a moving trail behind objects. TVs with fast response times—like high-end LCDs and especially OLEDs—have less of a ghosting trail but will stutter more. Neither is really ideal, and neither will give you motion as clear as a CRT or plasma display would. So dweebs like me can't watch a movie on modern sets without silently cursing under their breath about how the movie looks like a slow, messy flip book.

(A quick note for the TV nerds: I'm talking about 24 frame-per-second stutter here, not the telecene judder produced by using 3:2 pulldown to fit 24 frames into a 60-Hz refresh rate. That's an entirely different phenomenon, though many people conflate the two. You can fix telecine judder by using a streaming box capable of outputting 24 Hz properly, like the Apple TV 4K or Roku Ultra (here's our guide to picking the best Roku). Not all streaming services will support proper 24-Hz playback, though, so a TV that can reverse this pulldown process is also helpful.)

Motion Interpolation Is the Best Solution—Used Sparingly

So here we come to the crux of my dilemma. Twenty-four frames per second is not an ideal frame rate for modern displays, but it's what we're all used to, and it doesn't seem to be going away soon.

Sample-and-hold displays are sticking around for now too, but the latest models attempt to combat these motion issues with two primary features: black frame insertion and the dreaded motion interpolation. I won't get into the nitty-gritty of black frame insertion too much, but RTINGS has a great explainer on how it works and what some of its downsides are. On most TVs, it dims the picture significantly and causes a flicker that some people find uncomfortable—not to mention image duplications that can mar the image.

Which brings us back to frame interpolation, aka motion smoothing. And yes, its default settings are usually far too dramatic. But I've found that lower settings are less offensive. A bit of interpolation adds just enough information to "clean up" the picture during moving scenes, giving you a clearer, less stuttery image without making it look like an episode of Days of Our Lives.

That said, finding this balance can vary from TV to TV, and some brands do it better than others. Remember, the TV is taking frames from your movie and guessing how frames in between them should look—which can result in artifacts, or glitches, in the picture when it guesses wrong. O'Keefe says these artifacts are more common on higher interpolation settings, but it depends on the TV, its interpolation algorithm, and its processing power—and, to an extent, on how much you notice them to begin with.

In my experience, no one does it better than Sony, who has a reputation among A/V enthusiasts for having the best motion processing. This is, in big part, due to their Cinemotion feature, which has been present on Sony TVs for many years. The company tells me this feature uses de-telecining (to reverse that 3:2 pulldown judder) and tiny amounts of frame interpolation to present 24-fps content the way you expect to see it, rather than the way modern sample-and-hold displays show it in its purest form. Most people probably don't even realize this is happening, especially since Sony's main Motionflow interpolation feature is separate from the more subtle Cinemotion setting: Even if you turn Motionflow's Smoothness down to zero, there's still a bit of interpolation happening in the background with Cinemotion on.

But part of Sony's reputation is also due to its fantastic processing algorithms, which can interpolate frames with fewer artifacts than competing brands. And ultimately, it's why I bought a Sony TV after many years of motion-induced frustration—no other brand could hit that sweet spot quite as well without side effects. Their current flagships, the X950H LED and A8H OLED, use their most advanced processing hardware, and having had personal experience with both, they're the models I'd recommend looking at if you want the best motion on a modern TV. But you can try it on your current set, too—you just need to play with the settings.

Each brand calls its interpolation feature something different, and the settings can even vary between models from the same brand. But if you dig into the options, you'll almost certainly find it under Motion. Samsung calls it Auto Motion Plus, for example, while LG calls it TruMotion. Vizio just calls it Smooth Motion Effect, and TCL calls it Action Smoothing. Bump it up by one or two notches, give yourself time to get used to the subtle differences, and see what you think—you'll also find the black frame insertion feature in that menu, if your TV has one, and you can use them in conjunction with one another if your TV has a good implementation.

Sony's motion settings are a tad more complicated than other brands, but I've found that turning Cinemotion off, with Motionflow's Smoothness and Clearness both set to 1—the lowest settings for interpolation and black frame insertion—produces the best motion to my eyes. These three settings all interact with one another differently, so you may have to try different combinations to see what you like best.

Exceptions to the Rule

So I'm sorry, Mr. Cruise: I watched Mission: Impossible Fallout with motion smoothing turned on. (It was still awesome, by the way). But, while it's ultimately personal preference, there are still times when I recommend disabling it entirely.

First and foremost, you should always turn off motion processing when gaming. Because the TV has to know the next frame to generate interpolated motion, O'Keefe says, having it turned on will inherently introduce input lag. So you'll get smoother motion, but the controls won't be as responsive, making those boss battles more difficult. (That's why your TV has a Game Mode, which turns off motion interpolation alongside lots of other behind-the-scenes processing.)

In addition, he says, motion smoothing can be hit or miss for sports. While a lot of people like the added clearness it provides, it can also produce more artifacts in fast-paced play—like a hockey puck disappearing during slap shots.

I've also found certain movies to be more affected by interpolation than others, especially on certain TVs. On my old LG OLED, for example, even low levels of interpolation introduced noticeable soap opera effect on films like Captain America: Civil War, which have scenes that use a strobing effect to minimize motion blur. Other movies, like Spider-Man: Into the Spider-Verse, use clever frame-rate tricks in their animation to tell the story, and interpolation can interfere with that. So you may want to set up a few different settings profiles you can flip between at will.

Ultimately, though, it's all up to you. I'm not here to tell you that motion interpolation on its highest setting is a crime against cinema, nor that pure 24 Hz is a motion-sickness-inducing atrocity. As always, there's a tug-of-war between accuracy and preference, and you're free to do whatever you want with your TV. But if you're picky about motion like me, you might find this solution creates a happy balance that's easier on the eyes. Just don't throw me in the TV-reviewer stockade.

Related Articles

Latest Articles