Movies at 60 Hz , how they do that?
May 11, 2015 7:13 PM   Subscribe

My new Sony flatscreen TV seems to have developed the superpower to show movies at 60 frames per second. But since I always thought that the movies were filmed at 24fps, it has me wondering: Are the in-between frames being GENERATED by the TV?

When I saw RETURN OF THE JEDI in a movie theater, it certainly had that 24fps "FILM" look, but if I watch it on my new Sony flatscreen TV, it looks like it could have been filmed with video cameras, has a SOAP OPERA, or NIGHTLY NEWS look of smoothness.

Where the hell they getting all that extra smoothness information?

Is it a magic trick of MPEG code and programming, that is perhaps described in a technical paper somewhere?
posted by shipbreaker to Technology (8 answers total) 6 users marked this as a favorite
Sony brands it as MotionFlow, you can turn it off.
posted by Confess, Fletch at 7:17 PM on May 11, 2015 [4 favorites]

Are the in-between frames being GENERATED by the TV?

Yes. It's basically an advanced, tuned form of tweening. Some tvs have more powerful processors and do it at a higher rate and in higher quality.

Every tv i've ever seen do it does it inconsistently and irritatingly where the smoothness slides in an out because it can't really "read ahead" and know what's about to happen, it just has the previous frame to compare to the current one.

This also introduces input lag, which is generally not super bad but if you kill the effect like this on your tv and toggle back and forth sometimes you can detect the difference.

I plugged my laptop in to my tv, turned on display mirroring, and played some video. There was a DEFINITE amount of lag with any processing on.

Some nicer TVs(ie sony, samsung, etc) have a mode called "clear" in which it's still processing, but it's eliminating stutter from things like 3:2 pulldown or playing 50hz content on a 60/120hz display.

The best reproduction of 24fps content you can get is on a 240hz tv that supports 24p input. I bought one and i fucking love it. With a real 24p source(IE blu ray) and a player that supports 24p output(basically all of them) and a correctly configured display. you just get... 24fps.

Is it a magic trick of MPEG code and programming, that is perhaps described in a technical paper somewhere?

The better brands implementations are sort of a trade secret, it seems. Samsung has "clearmotion" and their clearmotion rates(which go up to stupid high bullshit ratings like 720 or 1280 or whatever frames per second), sony has their reality engine(which i guess is now running "motionflow") or whatever they want to call it now. It usually amounts to some custom silicon, an ARM cpu and a decent GPU of some capacity, and some fancy firmware.

Despite input lag i ended up leaving the "clear" mode turned on with my display, because it really does do a gigantically awesome job of eliminating all the frame-frame-GADUNK-frame-frame-GADUNK of various pulldown rates. Once you see it working correctly to eliminate that without generating a ton of bullshit smoothed frames, you'll probably enjoy it.
posted by emptythought at 7:26 PM on May 11, 2015 [6 favorites]

The term of art on wikipedia is motion interpolation, although it goes by many names. It has nothing to do with the input source and everything to do with the decoder and renderer.

It's commonly known (and googleable as) soap opera effect in that movies and television shows that were shot on film, or in the framerate common to film, will look like soap operas (shot on television cameras) or sporting events.
posted by mikeh at 7:40 PM on May 11, 2015 [2 favorites]

Frame interpolation and pulldown are orthogonal to each other. Good sets can take a 60fps 3:2 film source from television or DVD and losslessly undo the 3:2 to recover the original 24p and display it as such. True 24p input is not necessary.

Crappier sets stick you with the frame interpolation, which is not good for much, IMO, except that it can improve the smearing of high contrast crawls that happens on some LCDs due to the constant backlight. At one time, some sets had strobed backlights, but that feature seems to have gone away.

As far as how interpolation works, it literally calculates the difference between two frames and inserts a new one halfway between, much like MPEG encoding stores only the difference between successive frames to reduce the amount of data needed for storing video.
posted by wierdo at 8:25 PM on May 11, 2015 [1 favorite]

Is this why my friends expensive big screen almost ruined watching "Hard Eight"? Soap opera effect seems like an apt description, you feel like your watching a vhs behind the scenes documentary, it really breaks the suspension of disbelief. Can it be turned off?
posted by Pembquist at 11:10 PM on May 11, 2015

Best answer: See also the c|net article "What is the soap opera effect?" - or perhaps this critical review of the 48fps version of "The Hobbit". Your question "How do they do that?" breaks down into four topics:
1. What is your TV trying to do with the medium.
2. What did the producer of whatever you are watching intended you to see.
3. How does your visual system work.
4. What cultural expectations do you have regarding the look of film and video.
posted by rongorongo at 2:12 AM on May 12, 2015

Almost every picture "feature" on your set that can be turned off, should be turned off. Frame interpolation, noise reduction, white or black boost, etc. Noise reduction is particularly nasty -- a few weeks ago I thought my screen was dying since there was suddenly a ton of "ghosting" in darker scenes and I just assumed my LCD wasn't refreshing as often as it used to. But, no, it turns out I had been farting around with the picture and had somehow turned noise reduction to max and had forgotten to turn it back down again. Boy, was I relieved.

The best reproduction of 24fps content you can get is on a 240hz tv that supports 24p input.

I think you only need 120Hz for this, since 24 is a common denominator of 120 as well as 240? Certainly 24p looks great on my 120Hz screen and I thought it was because each frame was being repeated, cleanly, five times. (Because 24x5=120.)
posted by Mothlight at 8:11 AM on May 12, 2015

This may not be pulldown, or frame interpolation, rather it may be black frame insertion.

An enormous amount of money goes into studying the human response to imagery, and engineering solutions that cope with that behavior. Black frame insertion is one of the seemingly counterintuitive but useful results.
posted by intermod at 2:21 PM on May 12, 2015

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