Please Explain Pulldown?!?

[ObiTrentKenobi]

Hello,
could someone here please explain 3:2 pulldown for me. I've tried reading up on it all over, but I'd like to hear a fresh and realistic layman's version of the technology.

Do I want it, or don't I want it on my HDTV?
Is it an alternative to having true 24p playback?
Does it create a distorted picture?
Does it create flicker?

THEN; tell me how it would help or hurt an HDTV with these specs:
42" LCD 1080p, 60hz, 3:2 pulldown, 2000:1 native contrast, 450cd/m2 brightness, 3-D Y/C comb filter.

[Trix]

Originally Posted by ObiTrentKenobi

Hello,
could someone here please explain 3:2 pulldown for me. I've tried reading up on it all over, but I'd like to hear a fresh and realistic layman's version of the technology.

Do I want it, or don't I want it on my HDTV?
Is it an alternative to having true 24p playback?
Does it create a distorted picture?
Does it create flicker?

THEN; tell me how it would help or hurt an HDTV with these specs:
42" LCD 1080p, 60hz, 3:2 pulldown, 2000:1 native contrast, 450cd/m2 brightness, 3-D Y/C comb filter.

I will TRY to keep this as simple as I can, but, as anyone who knows me can attest, I rarely achieve that. So, please don't hesitate to let me know if I've failed to actually simplify.

1) What is it?
3:2 pulldown, generally speaking, is the process by which 24 fps sources are converted for 60 fps viewing. As the name hints at, you achieve a 3:2 cadence, since 24 does not multiply properly into 60. So, if each number below is a frame, frames 1 to 4 look something like this:

1,1,1,2,2,3,3,3,4,4

So, the first frame is repeated 3 times, then the second is repeated twice, and so on so forth.

2) Do I want it, or don't I want it on my HDTV?
This is a tricky question. Without 3:2 pulldown, sets that cannot display an image at 24 fps would have no way of showing these images. Keep in mind that most sources capable of producing 24 fps sources will not do so unless the set can display it, but essentially, 3:2 pulldown is required, mainly for 24 fps sources.

Also keep in mind that HDTV's are not the only devices that can enable 3:2 pulldown; all blu-ray players outputting 24 fps discs at 60 fps have performed 3:2 pulldown themselves. Further, some AVR, video decoders, and pre/pro's also have the ability to perform 3:2 pulldown themselves.

3) Is it an alternative to having true 24p playback?
As mentionned above, 3:2 pulldown is how one achieves a 60fps cadence for displays that do not supports 24fps. So, it is an alternative for displaying 24 fps blu-ray discs on 60 fps televisions.

4) Does it create a distorted picture?
That depends on your definition of distorted, and on how sensitive your eyes are. The uneven cadence (3:2) creates what is referred to as motion judder, because every other image is presented 1.5 times as long as the other. However, most people will not perceive this, and some people have grown accustomed to the judder, given that 3:2 pulldown has been standard for far longer than 24 fps has been available to the masses.

5) Does it create flicker?
Directly, no. As mentioned above, it is the cause of motion judder, which is perceivable to some people, but not the majority.

6) How does it help or hurt your HDTV?
As mentioned above, your HDTV is only capable of playing material at 60fps. So, the 3:2 pulldown ensures that any 24 fps material that makes it to your HDTV is transformed into 60 fps so that it can be displayed, as opposed to displaying a message telling you that the material cannot be displayed at all. In your case, it can be essential.

Hope that answers all the questions, and rather simply, as you requested. If not, feel free to let me know, either here, or through PM. Also, if anyone has any information to expand on what I've said, feel free to provide it, and educate even me!

[NuSoardGraphite]

Originally Posted by ObiTrentKenobi

Hello,
could someone here please explain 3:2 pulldown for me. I've tried reading up on it all over, but I'd like to hear a fresh and realistic layman's version of the technology.

I'll give it a shot. I'm no expert, but I've done quite a bit of reading on it myself when I was researching how HDTV's work during my tv search.

Do I want it, or don't I want it on my HDTV?

If you purchase a 60hz tv, you have no choice. You're going to have it. If you don't want it, you need to purchase a 120hz (or better) LCD or a Plasma with 72hz or 96hz option.

Is it an alternative to having true 24p playback?

No, it is not an alternative, it is a conversion. If its included in the set, thats because its abolutely necessary.

Does it create a distorted picture?

Distorted picture, no. Jittery picture, maybe. Depends on who you ask (and how good the pulldown in the tv is)

Does it create flicker?

Flicker in the classic sense? No. Thats in interlacing thing.

THEN; tell me how it would help or hurt an HDTV with these specs:
42" LCD 1080p, 60hz, 3:2 pulldown, 2000:1 native contrast, 450cd/m2 brightness, 3-D Y/C comb filter.

It won't hurt it. Since the TV is 60hz, it has to have it.

You see, 3/2 Pulldown is a conversion process that transforms movies that are filmed at 24 frames per second (24p) to 60 frames per second. How they do that is by showing a single frame twice, then the next frame will be shown 3 times. The end result allows the film to be shown at 60 frames per second. The problem with this that 2 frames then 3 frames, then 2 frames then 3 frames is an uneven process and this creates jittery motion in some scenes. Under most circumstances it is not noticeable, but during long sweeping panning shots it becomes apparent.

Also keep in mind that the standard 24 frames per second rate of shooting film is too fricken slow to show proper motion. Films shown at a rate of 24 frames per second show jittery motion naturally. Some critics of 24p claim that it is more jittery than that caused by 3/2 pulldown!

I myself have a 1080p 60hz LCD tv, and I barely notice any jittery motion in panning shots. It is far from distracting. Also many DVD players perform 3/2 pulldown as well, so if the tv is incapable, the DVD player can do it (which is why many Blu ray players have to be set to 1080/24p as opposed to 1080/60 to turn off the pulldown feature) so you can set your Blu Ray player to output 1080/24p and your TV will engage its pulldown feature. Try to figure out if the pulldown in the player is better, or the tv is better and engage that one (in general, the pulldown in the player is probably better, but that will depend on your tv)

The great thing about 120hz is that it performs 5/5 pulldown (it shows each frame from a 24p source 5 times) wich makes for an smooth transition from 24hz to 120hz. If you have a 120hz tv, you are better off setting the player to output in 24p and have your tv engage its 5/5 pulldown which should give you a smooth-like-butter film experience. (note that this is different from frame interpolation and shouldn't be confused with the Soap Opera Effect which derives from such motion enhancement)

All in all, 3/2 pulldown is one of the last things that should even be on your mind when looking for a tv. If you don't want the possibility of jittery panning shots, then go for a 120hz LCD (or 72hz/96hz Plasma), but otherwise don't sweat it. I've found that 3/2 pulldown jitters is an overblown subject and no cause for concern. (or maybe I just picked the right TV. A Samsung LN40A530 for the record)

[NuSoardGraphite]

Originally Posted by Trix

I will TRY to keep this as simple as I can, but, as anyone who knows me can attest, I rarely achieve that. So, please don't hesitate to let me know if I've failed to actually simplify.

1) What is it?
3:2 pulldown, generally speaking, is the process by which 24 fps sources are converted for 60 fps viewing. As the name hints at, you achieve a 3:2 cadence, since 24 does not multiply properly into 60. So, if each number below is a frame, frames 1 to 4 look something like this:

1,1,1,2,2,3,3,3,4,4

So, the first frame is repeated 3 times, then the second is repeated twice, and so on so forth.

2) Do I want it, or don't I want it on my HDTV?
This is a tricky question. Without 3:2 pulldown, sets that cannot display an image at 24 fps would have no way of showing these images. Keep in mind that most sources capable of producing 24 fps sources will not do so unless the set can display it, but essentially, 3:2 pulldown is required, mainly for 24 fps sources.

Also keep in mind that HDTV's are not the only devices that can enable 3:2 pulldown; all blu-ray players outputting 24 fps discs at 60 fps have performed 3:2 pulldown themselves. Further, some AVR, video decoders, and pre/pro's also have the ability to perform 3:2 pulldown themselves.

3) Is it an alternative to having true 24p playback?
As mentionned above, 3:2 pulldown is how one achieves a 60fps cadence for displays that do not supports 24fps. So, it is an alternative for displaying 24 fps blu-ray discs on 60 fps televisions.

4) Does it create a distorted picture?
That depends on your definition of distorted, and on how sensitive your eyes are. The uneven cadence (3:2) creates what is referred to as motion judder, because every other image is presented 1.5 times as long as the other. However, most people will not perceive this, and some people have grown accustomed to the judder, given that 3:2 pulldown has been standard for far longer than 24 fps has been available to the masses.

5) Does it create flicker?
Directly, no. As mentioned above, it is the cause of motion judder, which is perceivable to some people, but not the majority.

6) How does it help or hurt your HDTV?
As mentioned above, your HDTV is only capable of playing material at 60fps. So, the 3:2 pulldown ensures that any 24 fps material that makes it to your HDTV is transformed into 60 fps so that it can be displayed, as opposed to displaying a message telling you that the material cannot be displayed at all. In your case, it can be essential.

Hope that answers all the questions, and rather simply, as you requested. If not, feel free to let me know, either here, or through PM. Also, if anyone has any information to expand on what I've said, feel free to provide it, and educate even me!

You beat me to it!

[Trix]

Originally Posted by NuSoardGraphite

You beat me to it!

That's surprising, because I'm usually the slow typer! I'm just glad we didn't give opposite answers, and really confuse someone....

[Johnny Vinyl]

Very nicely explained...both of you!

John

[NuSoardGraphite]

Originally Posted by Trix

That's surprising, because I'm usually the slow typer! I'm just glad we didn't give opposite answers, and really confuse someone....

Kinda hard to give opposite answers when the answer is that cut-n-dried.

[Big Daddy]

[Trix]

BigDaddy,

Maybe I'm not looking at the diagrams you've posted properly, but, I've long wondered this, and thought I may seek your expertise, or anyone else's, here;

You've posted 1080p24 being transformed into 1080i60 for transport or display, through 3:2 pulldown. Now, maybe I'm just not seeing another step in the sequence, but, when a player outputs a signal at 1080p60, where is it getting its 60 progressive frames from? Or is there no such thing? As far as display, given that 99.9% of modern displays only show progressive images, how do they go from their transformed 1080i60 sequence to displayed 60 (or 120, or 240) progressive frames?

If I'm just missing something obvious, I would appreciate if someone could point me in the right direction. As is evident through my earlier post, I was under the impression that 3:2 pulldown involved tranforming 1080p24 material into 1080p60 material through frame repetition at a 3:2 (or 2:3) cadence. I would appreciate clarity on that if this is not the case.

I am not overly excited to learn something new. And cherish my inner geekiness.

[NuSoardGraphite]

I'm pretty sure thats a problem with interlacing in general. Pulldown just adds one more dimension to the equation. If your TV has a good de-interlacer (or you DVD player, if its a Progressive Scan player) then you'll never notice.

If you have a 1080p tv and your Blu Ray player is outputting in 1080p24, you don't have to worry as the tv won't have to de-interlace. It will use pulldown on full frames rather than fields of frames as with an interlaced format.

So the above explaintion with the pictures is essentially a "worst case scenario" if a tv is doing pulldown on interlaced material, like 1080i or 480i cable programming. I have paused such programming and seen the interlacing (via combing), but unless its paused, I don't notice it. Interlacing artifacts are another matter entirely though.

update: Watching Batman Begins on HD cable right now and Uuugh its damned fugly. It doesn't even look high def. The station is coming in at 1080i/60 but it most certainly doesn't look like it. And it has artifacts and motion blur like crazy. I have the movie on DVD (no not BD, DVD) and it looks 10 times better than this does.

Interlaced formats suck big monkey nuts!

We should start a campaign to rid the world of interlacing! Who's with me?!?!?!?!

[NuSoardGraphite]

UPDATE!

I watched Speed Racer on BD recently. My buddy brought over his PS3 and I busted out the copy of Speed that a co-worker gave me so that I could check it out.

Made sure the PS3 was outputting in 1080p/24 in order to test the Pulldown in my set.

The results: "Holy Pristine Image, Batman!"

It was by far the best looking image I have ever seen. No judder. No motion-blur. At all. And Speed Racer is a very fast-paced movie with a lot of panning scenes as the camera follows the cars along their track.

Pulldown performed spectacularly. No jumps in the frame-rate. Smooth like butter.

Then we watched Aliens vs Predator: Requiem, also on Blu. Again, smooth like butter with no problems whatsoever.

Now I really want a PS3, damnit!