Absurdly High Frame Rate

[Jafloogan]

So, I was standing in Best Buy the other day, and I walked past a high-def TV playing Avatar. Something caught my eye though...it was REMARKABLY smooth, compared to my DVD and compared to what I saw in theaters.

It seemed like the High-Def blu-ray was running at 60-120fps, while my DVD was stuck at 24-30 : /. Is it the TV? The player? Or the the blu-ray? and WHY wasn't it like this in theaters?!

[Colonel Quaritch]

DVD is nowhere near as good at storing video information (that would be the frames) as Bluray. More space = more frames. The cinema uses a film reel; which is limited to a certain speed (although I have no idea what that is). Disregard this post if someone comes along with a smarter/more accurate answer

[electrosphere11]

The tv can make alot of difference in itself. Most tv's play at around 60Hz but the newer ones are able to make 120Hz which is what makes the images flow together so smoothly. That coupled with a blu-ray would be magical lol.

[Vauktu]

The tv can make alot of difference in itself. Most tv's play at around 60Hz but the newer ones are able to make 120Hz which is what makes the images flow together so smoothly. That coupled with a blu-ray would be magical lol.

This is true. Some TVs have 60hz processing while others have 120, and some 240. Though the difference between 120 and 240 is unnoticeable. I bought a plasma TV with 600hz processing and returned it for a projector which has 60hz and haven't noticed much of a difference.

The difference between DVD and Blu-ray is also very big.

[Dreaming Of Pandora]

If you have a Blu-ray player with rewind (or fast-forward) functions of 1/16 then you can see the difference in frame rate quite a lot, there's a lot more FPS on Blu-ray than DVD, more than twice more than standard DVD formats.

[Tìrol]

I think NTSC dvds use 29.something and PAL uses 25 frames

[applejuice]

A bit of theory. Cinema takes advantage of the persistence of vision, it means that our brain will see a series of still pictures presented to our eyes sequentially, fast enough, each changing a bit, as a fluid movement (although, persistence of vision is sort of a myth, vision is much, much, much more complicated). Our brain will usually see fluid movement if that series of still pictures passes before our eyes at a rate >= 24 frames per second (a frame is a complete picture). TV (CRT) uses a different scheme to achieve the same goal. In the theater, each still frame is projected on the screen for a brief period of time then the screen goes dark and then another frame is projected (24 frames per second), TV splits each frame in two fields (odd and even lines) and scans the screen one whole field after another. To make a correct representation, the screen has to be scanned at least two times the minimum rate of frames; this is, each frame = 2 fields, then, if you want to have 24 frames you have to scan the screen at least 48 times, this is an analogy of Nyquist theorem. Now, NTSC decided to have almost 30 frames per second on the screen and PAL is more close to the 24 frames of the cinema, 25 frames per second (as a note, you can now infer why when you record the screen of a cinema theater with your NTSC camera doesn't get you a nice movie but a blurry one, the frame rates are not equal, so you are losing information). Now, new CRTs are capable of a faster scanning (known as Progressive Scan) and can, actually, scan a whole frame each time the beam sweeps the screen (it scans line 1, line 2,..., while the conventional scans line 1, line 3, line 5... and you get a more solid image and artifacts are less noticeable than in conventional scanning). LCDs work a lot like the cinema, they display a complete frame each time the screen refreshes. This is an advantage, the more information you can display, the better. The reason why a theater can't (yet) display a movie with that quality is simple: Storage. For a conventional theater, the reel would be absurdly long (for example, Avatar is about 160 minutes, each frame of film is about 19 mm tall, then we have 24 fps x 60 x 160 = 230400 frames x 19 mm = 4377600 mm = 4377.6 meters or roughly 4.4 kilometers of film, for Imax is at least the double). And if it's a digital theater, well, I have no idea, but a finished minute in the Weta rendering farm takes 18 GB, so for now, it's the price of the technologies required to make that happen what makes a Blu-ray-kind-of theater to be out of scope, by now.

[Tìrol]

Not to mention motion compensation to help fool our eyes.

[Dusso Janladde]

What you're seeing is motion interpolation. 120Hz and 240Hz TVs can do it. Movies are always filmed and projected at 24 FPS, Avatar is no exception. Without motion interpolation, a 120Hz TV will display each frame of the movie 5 times, since 120 divided by 24 is 5. With motion interpolation, the TV will look at the difference between every two frames of the movie and essentially create new frames that go between the real ones. So, instead of showing the same (real) frame 5 times, it will show the real frame then 4 "new" frames that go between it and the next frame.

Does it look good? Depends. It does look FAKE, because it's adding new frames that make the movie look like it's filmed at higher framerate than it really was. The result is, instead of looking like a FILM, it looks like a home video, which is normally filmed at 60 FPS. It's called the "Soap Opera Effect".

Long story short, you should always watch anything at the framerate at which it was recorded. The best way to to make sure the movie looks the way it should is to make sure your Blu-ray player is sending 24 FPS video rather than 60 FPS video to your TV.

[applejuice]

Note how different is Interpolation from Oversampling...