120Hz HDTVs: The Secret to Making Movies Look as Smooth as Butter

Illustration for article titled 120Hz HDTVs: The Secret to Making Movies Look as Smooth as Butter

Click to viewWhile the rest of the world is gawking at 108-inch LCDs and quad-resolution pixel counts, I'll let you in on a little secret: 120Hz HDTVs are going to help movies look better than ever on the little screen in your living room.


Here's how.

Film is 24 frames per second. That standard was the approximation of what was defined in the early 20th century by hand crank cameras. And just about every movie disc you can buy is encoded in this format. We're not just talking DVD. We're talking about HD DVD and Blu-ray, too.

The problem is, most TVs run at 30 frames per second. Fitting that 24-frame content onto a 30-frame screen isn't that easy; the math just doesn't compute cleanly. You can't divide 24 by 30 without filling in the gaps with some junk. That junk causes stuttering in the video. This is a jerky-looking phenomenon that's particularly noticeable when the camera pans across a scene. The conversion is better known by film and TV wonks as 2:3 pulldown. It spreads out 24 frames into 30 by placing one frame on the screen three times and the next one after that two times, and repeating this pattern ad infinitum.

How does this relate to an 120Hz HDTV showing frames at 120 frames per second? A bit of simple math tells you that 120 is a multiple of 24, because 24 x 5 = 120. So one of the claims of the purveyors of these sped-up monitors is that they can natively reproduce 24p programming, namely, just about every film has ever been shot.

These new HDTVs avoid this awkward 3:2 pulldown process altogether by changing their frame rate to something that's a multiple of 24 by using either frame doubling or interpolation (also called "tweening"). Then, their playback can be as close to native 24fps playback as you can get. That's why 72Hz (24 x 3 = 72) and 120Hz refresh rates are gaining traction. Native 24p playback: Yeah, sounds good. But how will it be implemented and which manufacturers are involved? And who does it best?

Next in our series: Which TVs and disc players are in on this nascent 72Hz/120Hz phenomenon, and which method of frame expansion does each use? Is this going to cost a lot? How much better will it look? Here's part 2.




An interesting question. The answer is not so obvious. I will try to keep the answer simple since so many people have headaches from the rest of this thread :)

Recently (within the past 5 years) there have been a number of tests done with film rates other than 24, at the end of the day it was decided that 24fps will continue to be thes standard for some time to come.

The "24fps is just fine" camp believes that 24fps video is a frame rate that allows you to engage with the film with a certain level of psychological detatchment. In other words, it is a high enough frame rate to be viewable comfortably without asking you to completely engage with the content. The low frame rate allows you a certain sense of disbelief, you always know that what you are watching is not real and therefore you accept it as entertainment, not reality. Frame rates higher than 24fps (48hz, 60hz, etc) are found to be too engaging for the average viewer. The high frame rate allows for better motion portrayal and a greater sense of realism. Too real as it turns out. People responded to a much greater degree to scenes shot in 60fps than in 24fps.

The other more obvious reasons that 24fps will continue to dominate.

- The equipment (projectors)in the theaters is all designed around 24fps.

- Film nerds get all touchy feely about 24fps and film in general so they are not going to give it up (Director of Photography, directors, etc)

- Cost. Its simply much cheaper to do effects and processing when there is only 24frames per second to deal with. Film costs center around feet of film, less frames equals lower production costs.

- Its a differentiator (albeit a disappearing one) between film and video

- Film nerds

- Film nerds

- Film nerds

The better question would be. Why are we still shooting on film? (- film nerds)