3:2, 5:5, 3:3 Pulldown questions - AVS Forum
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post #1 of 39 Old 01-12-2008, 06:48 AM - Thread Starter
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Ok, I posted a similar question over in my Ultimate Noob Thread, but his applies to new 120hz LCDs a little.

I know the 120hz LCDs are doing 3:2 pulldown and doubling to 120, but still, the possibility for 5:5 is there, so here's some issues I'm having understanding this.
I read some people mention you can't compare 3:2 pulldown to telecine. That they're two different things. From what I'm gathering I don't see how they are? Also, I know from reading that having a refresh rate of 72hz or 120hz would in theory allow 3:3 and 5:5 pulldown respectively. Now, I don't see how this would relieve jittering, because this is how I see it.

24fps movie
72hz refresh rate display
24fps source is interlaced
Let's take the first four frames of the original movie source as an example

FRAME A
FRAME B
FRAME C
FRAME D

With 3:2 your, field/frame structure looks like this, correct:

Field1-A
Field2-A

NEXT FRAME

Field1-A
Field2-B

NEXT FRAME

Field1-B
Field2-A

Next Frame

And so on


The problem with juttering is that two consecutive frames (of every five) contains information from two different frames from the original.

Now with 3:3 (72hz), wouldn't it look like this?

Frame1

Field1-A
Field2-A

Next Frame

Field1-A
Field2-B

Next Frame

Field1-B
Field2-B

Next Frame
Field1-A
Field 2-A

Next Frame

Field1-A
Field 2-B

And so on


So does the juttering result because two CONSECUTIVE frames contain different information and not ANY frame? If so then I see why 3:3 (or 5:5) works, because there's never any two consecutive frames that are made up of mix-matched material...correct?

Now, I also read that's there's a correct and incorrect way for a display/player to do 3:2. I would assume the player (or display) must first take the 108-p24 signal and INTERLACE it, correct? Then the 3:2 pattern is down throughout the fields...then (if your display is 1080p or 760p), it must then DEINTERLACE it for final viewing? Seems like a lot of steps. Would this be the incorrect way of doing it? Would the right way be to use a line doubler and reverse the the 3:2 process to get a progressive frame?
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post #2 of 39 Old 01-12-2008, 07:00 AM
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Here's several videos that cover the topics: http://www.hqv.com/technology.cfm

The two that apply to your questions are de-interlacing and film cadence. There are some 120Hz TVs that accept 24p and with motion interpolation off, do 5:5.

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post #3 of 39 Old 01-12-2008, 07:08 AM
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I really hope Samsung's new 650/750 series lcds do 5:5 pulldown because the 71 series doesn't.
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post #4 of 39 Old 01-12-2008, 07:30 AM - Thread Starter
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Quote:
Originally Posted by wtr_wkr View Post

Here's several videos that cover the topics: http://www.hqv.com/technology.cfm

The two that apply to your questions are de-interlacing and film cadence. There are some 120Hz TVs that accept 24p and with motion interpolation off, do 5:5.

Thanks, good links (although written a bit with advertising in mind by hqv). Now, here's a question. Movies shot in 24fps are left on the HD-DVD and Blue-ray at 24fps, or are they converted over with a 3:2 to the DVD? So what I'm asking is, the difference between deinterlacing and reverse pulldown is that if a signal was SHOT interlaced like CBS HD broadcasts, deinterlacing is use and the fields will always differ from each other slightly (if there was motion). If the source was SHOT in film (or if it was shot progressive, which I want to ask, are any movie studios, broadcast stations SHOOTING with progressive cameras?), then the fields can be reconstructed since the two fields won't have differing information?

If that's true, then why are people complaining about the 3:2 pulldown jitters on 1080p24 movies? Since those movies were shot on film, wouldn't the fields be the same and isn't this the "reverse 3:2 pulldown" technique where the third repeating field is dropped and converted back to a progressive frame? I am MORE confused now
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post #5 of 39 Old 01-12-2008, 12:42 PM
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What is the confusion?

Deinterlacing is for interlaced video, most commonly live broadcasts, and is relatively rare on HD/BD discs. It takes two half-frames shot at slightly different intervals and makes a best guess as to how to piece them together to make a single frame to put on your screen.

Inverse telecine (you can call it reverse 3:2 pulldown for NTSC material) restores hard telecined sources exactly to their original progressive frames. (For soft telecined material, this isn't even necessary, since the actual frames are stored in their original form and the telecine flags can simply be ignored.)

Judder is a result of frames being repeated unevenly, for example in 3:2 pulldown, since the target frame rate is not equal to an exact multiple of the source frame rate. That's why you don't get PAL (25 fps) judder on a 50 Hz, and also why 120 Hz is so desirable for films and NTSC video.

And yes, progressive HD video is becoming increasingly common; video does not necessarily equal interlaced.
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post #6 of 39 Old 01-12-2008, 01:27 PM - Thread Starter
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Originally Posted by nm88 View Post

What is the confusion?

Deinterlacing is for interlaced video, most commonly live broadcasts, and is relatively rare on HD/BD discs. It takes two half-frames shot at slightly different intervals and makes a best guess as to how to piece them together to make a single frame to put on your screen.

Inverse telecine (you can call it reverse 3:2 pulldown for NTSC material) restores hard telecined sources exactly to their original progressive frames. (For soft telecined material, this isn't even necessary, since the actual frames are stored in their original form and the telecine flags can simply be ignored.)

Judder is a result of frames being repeated unevenly, for example in 3:2 pulldown, since the target frame rate is not equal to an exact multiple of the source frame rate. That's why you don't get PAL (25 fps) judder on a 50 Hz, and also why 120 Hz is so desirable for films and NTSC video.

And yes, progressive HD video is becoming increasingly common; video does not necessarily equal interlaced.

The confusion is from me thinking about it too hard I suppose. All 1080p24 BR and HD-DVD were telecined to be put on that format (because, again, those movies were SHOT with film) correct? So all a 1080p display does is reverse 3:2 pulldown? Which is essentially dropping the third field that's a repeat of the first, to create a frame, then just repeating frame 1 three times, frame 2 twice, frame 3 three times, and so on? The actual interlacing was the telecined step when the 24fps film was encoded on to the disc then right? I read that with MPEG-2 the third field (A1,A2,A3) isn't even encoded right?

Why, though, was I reading that there's a correct and incorrect way of deinterlacing and/or doing the 3:2 pulldown?
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post #7 of 39 Old 01-12-2008, 02:38 PM
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Quote:
Originally Posted by MGH-PA View Post

All 1080p24 BR and HD-DVD were telecined to be put on that format (because, again, those movies were SHOT with film) correct? So all a 1080p display does is reverse 3:2 pulldown?

If they're hard telecined (i.e., telecined during the mastering process and stored as separate fields), then yes, either the player (if using 1080p/24 output) or 1080p display is reversing the process to show you the original progressive frames.

And while I'm not sure about the technical details, I'd assume that if they're soft telecined (i.e., stored as a progressive stream with flags to tell the player how to telecine), a 1080p/24 player can just ignore the flags and play the progressive stream. If it's a 1080i player, then it will telecine, and the 1080p display will reverse it.

Either way, you end up with the original progressive frames, so you shouldn't worry too much about it.
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Originally Posted by MGH-PA View Post

Why, though, was I reading that there's a correct and incorrect way of deinterlacing and/or doing the 3:2 pulldown?

Don't confuse deinterlacing and inverse telecine; although they both involve combining fields, they are two completely different things.

Deinterlacing is a lossy, speculative process, and there are competing algorithms with varying levels of quality. Some methods are more sophisticated and look better than others, but there really isn't an "incorrect" method.

Inverse telecine is a very simple and exact process that should exactly restore the progressive frames. The main problem here is the small number of badly encoded/flagged discs which screw up the pattern and cause artifacts.
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post #8 of 39 Old 01-12-2008, 03:06 PM - Thread Starter
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Quote:
Originally Posted by nm88 View Post

If they're hard telecined (i.e., telecined during the mastering process and stored as separate fields), then yes, either the player (if using 1080p/24 output) or 1080p display is reversing the process to show you the original progressive frames.

And while I'm not sure about the technical details, I'd assume that if they're soft telecined (i.e., stored as a progressive stream with flags to tell the player how to telecine), a 1080p/24 player can just ignore the flags and play the progressive stream. If it's a 1080i player, then it will telecine, and the 1080p display will reverse it.

Either way, you end up with the original progressive frames, so you shouldn't worry too much about it.Don't confuse deinterlacing and inverse telecine; although they both involve combining fields, they are two completely different things.

Deinterlacing is a lossy, speculative process, and there are competing algorithms with varying levels of quality. Some methods are more sophisticated and look better than others, but there really isn't an "incorrect" method.

Inverse telecine is a very simple and exact process that should exactly restore the progressive frames. The main problem here is the small number of badly encoded/flagged discs which screw up the pattern and cause artifacts.

Thanks for the response! Very helpful. So really, either way, you end up with progressive frames like you said. The jittery motion some experience is only due to the fact that each frame can't be repeated the same amount of times with a 3:2 pulldown (on a 60hz display).
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post #9 of 39 Old 01-12-2008, 03:32 PM
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3:2 pulldown is an accomodation to past technical limitations that in all cases degrades the image. In the high def, digital world we are now in, hopefully 3:2 pulldown will be given a timely death and never be spoken of again.
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post #10 of 39 Old 01-12-2008, 03:33 PM
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Quote:
Originally Posted by keell View Post

I really hope Samsung's new 650/750 series lcds do 5:5 pulldown because the 71 series doesn't.

The 71 does do 5:5 pull down when you turn off certain motion settings or one of the picture modes. They explain it in one of the 71 series threads
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post #11 of 39 Old 01-12-2008, 08:14 PM
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Quote:
Originally Posted by MGH-PA View Post

... a signal was SHOT interlaced like CBS HD broadcasts...

This is over 2years old: "CBS executives said that they are putting a lot of programming in the can shot in 1080P/24 and that all the new cameras they were buying were 1920X1080P60."

Let's make this simple. (A) Film is 24p. (1) SD DVD is 480/60i, which can be inverse telecined to create the original 24p. On the typical TV, it is simply de-interlaced (either well or poor) and displayed (2) HD DVD is 1080/24p, which can be displayed on the typical 60Hz TV by doing 3:2. Some TVs can do 5:5. (Note, initial BD that did 24p used Broadcom's chip to convert to 60i and then converted it back to 24p.)

Broadcast video is either 1080/60i (made using 60p cameras) or 720/60p. 60i is unfortunate.

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Originally Posted by NMJack View Post

3:2 pulldown is an accomodation to past technical limitations that in all cases degrades the image. In the high def, digital world we are now in, hopefully 3:2 pulldown will be given a timely death and never be spoken of again.

Yes, but not in my life time. If you do enough reading, you may find that 24fps is also a big problem.

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post #12 of 39 Old 01-12-2008, 08:25 PM
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Quote:
Originally Posted by wtr_wkr View Post


Yes, but not in my life time. If you do enough reading, you may find that 24fps is also a big problem.

I guess I'll need some more info on that. You're suggesting that the native film format forever is a "big problem?" Odd....
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post #13 of 39 Old 01-12-2008, 09:14 PM - Thread Starter
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Originally Posted by wtr_wkr View Post

This is over 2years old: "CBS executives said that they are putting a lot of programming in the can shot in 1080P/24 and that all the new cameras they were buying were 1920X1080P60."

Let's make this simple. (A) Film is 24p. (1) SD DVD is 480/60i, which can be inverse telecined to create the original 24p. On the typical TV, it is simply de-interlaced (either well or poor) and displayed (2) HD DVD is 1080/24p, which can be displayed on the typical 60Hz TV by doing 3:2. Some TVs can do 5:5. (Note, initial BD that did 24p used Broadcom's chip to convert to 60i and then converted it back to 24p.)

Broadcast video is either 1080/60i (made using 60p cameras) or 720/60p. 60i is unfortunate.




Yes, but not in my life time. If you do enough reading, you may find that 24fps is also a big problem.

Thanks, I found a few threads stating that CBS/ESPN cameras captured at 30fps, so that was confusing me. I guess my problem with understanding this was the contradictory things I was reading on here.

Now, are HD-DVDs and Blu-ray more often than not hard-telecined or soft-telecined?
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post #14 of 39 Old 01-12-2008, 11:25 PM
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Quote:
Originally Posted by NMJack View Post

3:2 pulldown is an accomodation to past technical limitations that in all cases degrades the image.

If done properly, without errors, it won't degrade the image.
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post #15 of 39 Old 01-13-2008, 07:46 AM
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Quote:
Originally Posted by NMJack View Post

I guess I'll need some more info on that. You're suggesting that the native film format forever is a "big problem?" Odd....

You do see jerky motion at a movie theater don't you?

Here's an example of a theater that converted to solely DLP Digital Cinema projection using the Christie 2000 series and DOREMI computer storage. (Source withheld by request.)

Transformers weighed in at a very healthy 263GB for 2hr. and 30mins.
Pirates of the Caribbean: At World's End looked amazing with a size around 280GB. (And yes, they are compressed.)

Digital Cinema encodes are 2190x800 for Scope (2.39:1) and 1980x1080 for Flat (1.85:1).

Was anyone expecting to see BD specs?

Here's an experience regarding motion at a digital theater with, needless to say, NO 3:2 judder:

Quote from Foursix:
BTW....I saw Bourne Supremacy last night in the state of the art theater and it had so much motion judder it was almost unwatchable in some fast scenes. Almost made me motion sick. There is nothing any TV will be able to fix what is intrinsic to the source material such as this. 24P is just to slow for fast action.

And Nismor2's opinion:
Well i believe some theater use 48hz or 72hz for 24hz films. The thing about American cinema these days is that the zoom in the camera for action sequences to hide the fact that the choreography sucks. Those frantic shots make my head hurt. I was watching Mission imposible 3 and the panning shots and action sequences were just too frantic it was just annoying. HD can bring up front some film issues that we didnt notice before. I was also paying attention to a Nascar race while focusing on the wall sings to see if they blur and the CRT was bluring them too. Ive never notice this before or cared to pay attention to it. If you look for it you will see it.

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post #16 of 39 Old 01-13-2008, 08:35 AM
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Quote:
Originally Posted by nm88 View Post

If done properly, without errors, it won't degrade the image.

My point was that artificially showing every other frame for 50% longer in all cases is a degradation to the native image. I'll stand by that assessment.
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post #17 of 39 Old 01-13-2008, 08:44 AM
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Quote:
Originally Posted by wtr_wkr View Post

Digital Cinema encodes are 2190x800 for Scope (2.39:1) and 1980x1080 for Flat (1.85:1).

Was anyone expecting to see BD specs?

Here's an experience regarding motion at a digital theater with, needless to say, NO 3:2 judder:

Quote from Foursix:
BTW....I saw Bourne Supremacy last night in the state of the art theater and it had so much motion judder it was almost unwatchable in some fast scenes. Almost made me motion sick. There is nothing any TV will be able to fix what is intrinsic to the source material such as this. 24P is just to slow for fast action.

Bourne Supremacy utilized a lot of hand held camera scnenes with an excessive amount of panning. I read where that is a method some film makers use to trick the viewer into thinking that an action movie has even more action than it really does. Needless to say, it gave me motion sickness just watching it on my 142" PJ screen. To your point though, as Hollywood starts generating native material at faster frame rates, I'll be all over players and displays that are capable of retaining the native signal. In general, I'm just not a fan of any player or display that forces us away from the native image (i.e. 3:2 pulldown, undesired scaling, etc.). I don't mind them as options, but it's time that those of us who want to retain the native image stored on HD media are able to do so without being forced into the top end models. I may wind up buying a 120Hz panel just to see what all the buzz about interpolation really amounts to, but would prefer to have 24fps on the lower end models.
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post #18 of 39 Old 01-13-2008, 12:01 PM
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Quote:
Originally Posted by NMJack View Post

My point was that artificially showing every other frame for 50% longer in all cases is a degradation to the native image. I'll stand by that assessment.

Ok. But that has nothing to do with 3:2 pulldown, but rather the refresh rate of the display, particularly the 60 Hz electricity-based standard we've been stuck with since the 1930s.

You could display progressive film frames, with no pulldown, and you will still have the same judder if your display is 60 Hz.
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post #19 of 39 Old 01-13-2008, 12:09 PM
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Quote:
Originally Posted by NMJack View Post

Bourne Supremacy utilized a lot of hand held camera scnenes with an excessive amount of panning. I read where that is a method some film makers use to trick the viewer into thinking that an action movie has even more action than it really does.

The "Saving Private Ryan" look, where they run the cameras at a high shutter speed (like 1/250 instead of the normal 1/48) to nearly eliminate motion blur (and give us more of a slide show) and hand-hold the cameras so the image is shaky.

This technique has been so overdone lately, and it just becomes nauseating.
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To your point though, as Hollywood starts generating native material at faster frame rates,

That's not going to happen any time soon.
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post #20 of 39 Old 01-13-2008, 01:51 PM
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"My point was that artificially showing every other frame for 50% longer in all cases is a degradation to the native image. I'll stand by that assessment."

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Originally Posted by nm88 View Post

Ok. But that has nothing to do with 3:2 pulldown,

Actually, in the progressive realm (i.e. 1080p/24 HD-DVD and BD), that is the exact definition of 3:2 pulldown. Maybe you're thinking of the field duplication that occurs when dealing with an interlaced signal?
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post #21 of 39 Old 01-13-2008, 01:51 PM
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This technique has been so overdone lately, and it just becomes nauseating.

Literally!
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post #22 of 39 Old 01-13-2008, 03:02 PM
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Quote:
Originally Posted by NMJack View Post

Actually, in the progressive realm (i.e. 1080p/24 HD-DVD and BD), that is the exact definition of 3:2 pulldown. Maybe you're thinking of the field duplication that occurs when dealing with an interlaced signal?

It's a question of terminology.

3:2 pulldown, a telecine process, means converting 24 progressive film frames to 59.94 fields (half-frames) that are compatible with standard interlaced NTSC displays. It follows a specific pattern which you can read about here.

Repeating progressive frames to match the frame rate of the display is not 3:2 pulldown.
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post #23 of 39 Old 01-13-2008, 04:10 PM
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Quote:
Originally Posted by nm88 View Post

It's a question of terminology.

3:2 pulldown, a telecine process, means converting 24 progressive film frames to 59.94 fields (half-frames) that are compatible with standard interlaced NTSC displays. It follows a specific pattern which you can read about here.

Repeating progressive frames to match the frame rate of the display is not 3:2 pulldown.

Really What is then, if not 2:3 pulldown?
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post #24 of 39 Old 01-13-2008, 04:12 PM
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"The process of converting 24 frame/s material to 29.97 frame/s is known as 2:3 pulldown"

From your link.
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post #25 of 39 Old 01-13-2008, 04:33 PM
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Quote:
Originally Posted by nm88 View Post

It's a question of terminology.

I'll accept that, but realize that terminology in the AV realm is not always 100% consistent. Whatever we call it, I don't want my display to screw up the 1080p/24 source material on HD-DVD and BD media through any kind of scaling, frame rate conversion, etc. All I ask for is that each original frame of film be displayed exactly as the original, in the correct sequence, at the correct rate. It is beyond me why the CE manufacturers can't just latch onto this concept and market their wares accordingly.

To my original point, any display that doesn't or can't present the 1080p/24 material at its original (or even multiple of) frequency is messing up the image for no good reason. Who's with me on this?
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post #26 of 39 Old 01-13-2008, 07:53 PM
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Originally Posted by NMJack View Post

All I ask for is that each original frame of film be displayed exactly as the original, in the correct sequence, at the correct rate. It is beyond me why the CE manufacturers can't just latch onto this concept and market their wares accordingly.

1) It costs money.

2) Most people are too stupid, inattentive, or apathetic to notice or care about judder.

J6P just wants the the screen filled with sports in blinding torch mode. And he's the one who's buying the overwhelming majority of the sets and paying for all the R&D.
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any display that doesn't or can't present the 1080p/24 material at its original (or even multiple of) frequency is messing up the image for no good reason.

There is a good reason. The set has to support 60 Hz, and it costs money to support other custom refresh rates (without internal conversion).

The LCD manufacturers have to thrown in that silly interpolation gimmick just to sell 120 Hz to J6P.
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post #27 of 39 Old 01-13-2008, 07:53 PM
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Quote:
Originally Posted by tower101 View Post

"The process of converting 24 frame/s material to 29.97 frame/s is known as 2:3 pulldown"
From your link.

Yes, 29.97 interlaced frames. You have to read more than one sentence.
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post #28 of 39 Old 01-14-2008, 09:27 AM
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Then what is it called?? You might want to read a bit more.

From you link

"In 59.94 frame/s progressive formats such as 480p60 and 720p60, entire frames (rather than fields) are repeated in a 2-3 pattern, accomplishing the frame rate conversion without interlacing and its associated artifacts."

Most call that 2:3 again what do you call it?
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post #29 of 39 Old 01-14-2008, 09:37 AM
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Oh and don't tell the "stupid, inattentive, or apathetic " people but guess what its also Called a telecine process.
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post #30 of 39 Old 01-14-2008, 12:53 PM
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Quote:
Originally Posted by tower101 View Post

"In 59.94 frame/s progressive formats such as 480p60 and 720p60, entire frames (rather than fields) are repeated in a 2-3 pattern, accomplishing the frame rate conversion without interlacing and its associated artifacts."

Read the sentence before it. The interlaced version is called 3:2 (or 2:3) pulldown.

Again, it is just a matter of terminology, so we know what process is being referred to.

When a display states that it performs reverse 3:2 pulldown/inverse telecine/"film mode"/etc., it means from an interlaced source. It does not simply mean it will repeat frames to match its internal refresh rate, as that feature is taken as a given so long as the input frame rate is supported.
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