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24/30/60 fps comparison

post #1 of 82
Thread Starter 

Post update: some dead links removed 07-07-13.

 

A shot history of frame rates:

(link)

 

 

 

 

This video shows what happens when frames are repeated symmetrically (30fps @ 60Hz), vs not being repeated at all (60fps @ 60Hz). 120hz TVs and their controversial "soap opera" look fall in this last category. See if you can tell a difference.


(link)





Original file on Vimeo (taken with an Aiptek Action HD 720p-60 camcorder with high shutter speed).


Edited by borf - 8/10/13 at 10:27am
post #2 of 82
I'll take a look at these later on tomorrow.
post #3 of 82
Thank you borf!
My computer is too slow, unfortunately. But it's very easy to download and play.
post #4 of 82
Just got a chance to check these out. I guess that is the definition of judder.

Edit: Oh and by the way the downloading was fantastic, I got up over 600KBps.
post #5 of 82
Thread Starter 
Ok file size was greatly reduced. They should d/l faster and play a lot smoother. I am liking MediaFire a lot.
post #6 of 82
Wow, the 24 vs 60 looks jarring.

It should be added movies intentionally add motion blur to their films so 24fps does not look as bad as in that video.

Thanks for the video, anyone wanting to know how framerate matter or whatnot should definitely reference your post.
post #7 of 82
Thread Starter 
Quote:
Originally Posted by wtfer View Post

Wow, the 24 vs 60 looks jarring.

It should be added movies intentionally add motion blur to their films so 24fps does not look as bad as in that video.

Ok movie with added motion blur comming up.
I wanted to try that anyway.
post #8 of 82
24fps...oh my eyes, my eyes!
post #9 of 82
Thread Starter 

Blurry 24 - Someone else made this video but it shows how blur can smooth out low juddery frame rates (with a loss in detail)
Smooth 60fps also shown with no detail loss. Enjoy.

(link)


Edited by borf - 7/7/13 at 10:54am
post #10 of 82
Thread Starter 

Might as well add the "wagon wheel effect" - If you noticed the taxi cab's wheels going backwards you saw "the wagon wheel effect" - another problem with shooting at low frame rates.
 




Ever watch a western where the coach wheels go backwards.
Ever see the same watching car spokes at night under a 60hz street lamp.
(It won't happen during the day unless you get spinning rims )
In these cases the "frame rate" (street light frequency or camera shutter) is matching the object's frequency of motion.

"frequency of motion" being - the frequency at which stuff repeats when moving, like fence posts, bricks, wheel spokes ect.
Nature is pretty random so it happens mostly when moving past human constructs and urban scenes imo.

Cinematographers use a simple rule to avoid the "wagon wheel effect" and try to go by it:
Keep a frame rate at least twice that of any "frequencies" in the scene.


I wanted to see if the theory held up. According to the theory anything moving at a frequency of 24hz should come to a complete stop (in a 24fps movie).
In other words the camera should capture the object in exactly the same spot every time, if the shutter is in sync with the object.
(keep in mind the objects are still moving though - here's what happened. ).

(LINK)

Neat-o...and once again blur comes to the rescue when watching the next clip:

(LINK)

The "blur-it-away" principle is used to hide all kinds of video artifacts - from noise reduction techniques to de-interlacing. Its like spreading food around your plate to make it look like you ate something. Blur reduces overall quality and as in the case of low frame rates, there are usually better ways imo.


Edited by borf - 7/7/13 at 10:51am
post #11 of 82
Since this is forum has science in its name, there's an alternative way of thinking about frame rates, shutter speed and motion blur.

The frame rate is the temporal sampling of the image. If the temporal signature of the motion you're trying to capture is significantly higher than your frame rate, you end up with temporal aliasing, which manifests as strobing (wheels going backwards etc.).

Basic sampling theory says the highest temporal frequency you can actually render at 24 fps is motion on the order of 12 Hz. So either you make sure you don't shoot anything moving faster than 12 Hz, or you use a temporal low-pass filter. That is to say, you decrease the shutter speed and allow more motion blur.

If you shoot 24p content with a high shutter - you are simply begging for strobing effects. This is what occurs in computer games, since they tend not to render motion blur. While it is actually possible to render motion blur for computer games, it requires at least as much horsepower as rendering out higher frame rates.

In short, 24p without motion blur is just dumb.
post #12 of 82
Thread Starter 
Quote:
Originally Posted by -Spiff- View Post

So either you make sure you don't shoot anything moving faster than 12 Hz, or you use a temporal low-pass filter. That is to say, you decrease the shutter speed and allow more motion blur.

Yep..the other option is to raise the frame rate, which was the point there. Sample-and-hold blur, judder, and the "wagon wheel effect" all fall under the broad term temporal aliasing. They can be avoided simply by raising the temporal frame rate in an appropriate way.

edit - The wagon wheel effect can be mostly avoided but never completely - depends on the frequency.
post #13 of 82
Thread Starter 

Speaking of low frame rates,

This sample and hold boot camp video mentions the 800lb gorilla in the room - Mr. low frame-rates.
It was a load of fun making it (most of the time)..





high-res 84meg

can also be seen on VIMEO (better quality than youtube)


Edited by borf - 7/7/13 at 11:02am
post #14 of 82
When I set my monitor to 72hz, 60fps still looks smooth, while 24fps looks like crap. I would have thought that reverse would have been true. Why is this?
post #15 of 82
Quote:
Originally Posted by borf View Post

Speaking of low frame rates,

This sample and hold boot camp video mentions the 800lb gorilla in the room - Mr. low frame-rates.
It was a load of fun making it (most of the time)..

high-res 84meg

can also be seen on VIMEO (better quality than youtube)

Thanks for that video, Borf. It should be an effective way of getting the message across for those who don't like to read pages of text.
post #16 of 82
Thread Starter 
Quote:
Originally Posted by joikd View Post

When I set my monitor to 72hz, 60fps still looks smooth, while 24fps looks like crap. I would have thought that reverse would have been true. Why is this?

I think i know why you thought that but 60fps is a higher frame rate than 24fps - so there is less judder/blur/flicker.

I guess you were looking for the "magic number" - 72hz isn't really a "magic number" because at 24fps you still have repeat frames (3 repeats per frame). repeats cause judder & blur which destroy motion resolution (especially at lower frame rates). unsymmetrical repetitions are even worse - and again worse at low frame rates. The 30 vs 60 fps video above should be about identical to 24@72hz - compare to the 60fps side.

the only true "majic number" is the one that matches your refresh rate.

Quote:
Originally Posted by tqn View Post

Thanks for that video, Borf. It should be an effective way of getting the message across for those who don't like to read pages of text.

hope its understandable thanks.
post #17 of 82
Wow!

The difference between 60fps and 24fps is very noticable. 60fps looks so lifelike whereas 24fps is so choppy. Until I got my first Pioneer Kuro I hadn't noticed judder so much but now it really bothers me from time to time.
post #18 of 82
this means i should stop watching movies in 24p right?
post #19 of 82
Well, I think most movies are 24fps, so we're kind of stuck.
post #20 of 82
I still don't understand why we are still embracing 24p. It was a limitation of using film and distribution of it waaaaaaaaaaaay back decades ago. I really really hate the fact that we have made significant improvements to image resolution, color resolution, and sound resolution, but we completely ignore motion resolution. WTF?

I wish to see the end of 24p video. It is just not acceptable!
post #21 of 82
Thread Starter 
xb1032's post underscored the point....

Advancements in Current and future displays (including Oled/Sed/Fed) are limited by current frame rates - no matter how good PQ gets it will always be smothered in the sea of blur, judder & flicker any time the picture moves and displays are about moving pictures 95% of the time. Oled will have no better motion resolution than current dispalys. If you think any display can fix what is a basic lack of information i think you are asking it to do the impossible. 120hz is a nice attempt but will always have some drawbacks (artifacts, lag ect) - it can only do so much.

I also see display blaming for frame rate issues - so next time you notice blur, judder, flicker, tbe or lag on your brand new expensive set you should take it up with the 800lb gorilla. Displays are perfectly capable of eliminating all these problems today given the correct source.

Will it be changed - I don't think any time soon and maybe never, but folks should be aware the implications.
post #22 of 82
Exactly... it needs to start at the source. Hollywood needs to quit the 24p charade and evolve to higher motion fidelity.
post #23 of 82
Quote:


I still don't understand why we are still embracing 24p. It was a limitation of using film and distribution of it waaaaaaaaaaaay back decades ago. I really really hate the fact that we have made significant improvements to image resolution, color resolution, and sound resolution, but we completely ignore motion resolution. WTF?

I wish to see the end of 24p video. It is just not acceptable!



Not really. 24fps is/was a limitation only as far as theatrical releases are concerned.

Television productions could have been filmed at 30fps for decades, yet virutally all dramatic television shows have been, and continue to be, shot at 24fps.
post #24 of 82
Any idea when the evolution to a higher fps will take place?
post #25 of 82
Quote:
Originally Posted by joikd View Post

When I set my monitor to 72hz, 60fps still looks smooth, while 24fps looks like crap. I would have thought that reverse would have been true. Why is this?

It's is due to the shutter speed and the camera

Movies are filmed at shutter speed between 24-48 to 1, which creates natural blur. That's why they don't look as awful as the clip.

On the other hand, 60i/p is too high. It has unnatural appearance to it.

The sweet-spot for natural motion around 48p with motion blur. Unfortunately, it hasn't been standardized...yet and only IMAX is using that format.

PS: Moving picture based on frame rate will not appear fully natural because our eyes are based on frame-less capture, which can be simulated by updating individual pixels rather than the entire frame. It is still in its early stages, but remarkable advancements have been made in recent years.

If you'd like more, search frameless rendering in google.
post #26 of 82
Forgot to add, Frameless Rendering can save vast about of bandwidth in both video (capture-storage-display) and video games (render-display).

PS: As most gamers would tell you, even 60p is not enough for PC gaming due to the:

1. Lack of motion blur
2. Input method

On the other hand, rendering visually intensive games at 120p+ requires a lot of bandwidth between the GPU and the memory (not to mention the GPU itself). But most of that processing cycle and bandwidth are wasted because the GPU continues to render 120 frames every second (even when the motion is stationary). Frameless rendering will completely solve this problem and give developers to focus more on visuals.
post #27 of 82
Very interesting thread. i alway thought 24p was suppose to be better than 60hz. why does everybody talk about 24p like its something special when obviously its not? pioneer talks about having true 24p, if its inferior why? i guess thats why they double it to 72hz?

Im also to surprised to see that the problem is not our displays, its the movies. why the hell are they still shooting in 24p?

What a fracking turn of events this is on my knowledge of this subject.
post #28 of 82
Quote:
pioneer talks about having true 24p, if its inferior why?

Because a 24fps movie shown on a 60Hz display will suffer from pulldown judder. 24fps pulldown judder is elimated with 72/96/120Hz, etc displays.

It has nothing to do with 24fps inherently looking better than 60fps.
post #29 of 82
This is a very interesting thread so for the layman who doesn't understand all of this stuff, what really matters?

New panels are touting 24fps and higher 120 and 240 hz ratings. But do you really need the 24fps feature if the panel has 120hz (as an example, the Panasonic V10 vs. S1 series). What's best for BR movie watching? Standard Digital Cable Hi-Def Viewing and Standard Def Viewing? how about gaming?

Don't get me wrong, I enjoy my TV and am looking to purchase another, but am having a hard time trying to decide based on some of the latest and great creature features that the new panels have. Most everything is coming out 1080p so that's a given, and the more high end panels are a minimum of 120hz but this new 24fps feature is still confusing. Is it worth it or just hype?

I tend to replace my TV's every few years so spending a bunch on the latest end all be all panel may not be worth it if the technology that is being broadcast isn't matching up with what the panel can do(in that the panel's technology is far better than what can be shown on it). Given that flat panels are supposed to be replaced by design more often (like every 5 years from what I've read) unlike our older CRT's, what's the best setup for a non-gamer or a gamer?


Thanks in advance!!
post #30 of 82
A very basic explanation follows...

Traditional TVs operate at 60Hz, or 60fps. Film is shot at a rate of 24fps. Nearly all movies and many television shows are shot at this rate.

When displaying 24fps material, a 60Hz TV needs to fit 24 frames into 60 so that it can display them. This is generally accomplished by repeating a frame twice, then the next frame three times, until you get to 60 (2:3:2:3, etc). The process then repeats for the next two frames, and repeats again for as long as you're watching the material. This process is referred to as 3:2 pulldown and creates "judder" as the frames are being displayed in an uneven fashion.

With, say, 120Hz, each frame is simply repeated five times, or 5:5:5, etc. This eliminates pulldown judder as the frames are being output evenly. This is also true of displays that can operate at 48Hz, 72Hz, 96Hz, or any multiple of 24.
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