How do modern 60 Hz TVs handle 24p outside of 2:3 pulldown?

[Shalashaska]

I've been reading quite a bit on this subject and I can't get a straight answer anywhere. Some are saying modern TVs have no problem with changing their refresh rate and display 24p video just fine, others are saying there's no way to display 24p video on a 60 Hz TV without 2:3 pulldown because it's not a multiple of 60. If the latter is true, why was 24p such a big deal with Blu-ray if 120 Hz TVs are only being largely introduced now?

Guys, honestly, what's the answer here? I live in Europe, and my TV can output in both 50 Hz and 60 Hz, so shouldn't it be able to do 24 Hz also?

[richieb1971]

Your question doesn't make much sense to me.

But effectively your TV will only refresh at 50 or 60 cycles per second (hz).

What you plug into it (Blu ray, games consoles) are the technologies which allow 24p playback. This works as you say with a 3:2 pulldown (or 2:3 pulldown) algorithm which splits between -

Odd frames - 2 x 12
Even frames - 3 x 12

Gives total frames = 60

If your TV was only 50hz, that wouldn't work. Because 24p doesn't fit into 50hz, the historical way of getting round this is to speed up the film to 25p. The pitch of the sound will go up, but its only 1 frame per second so not many people notice the difference. It does shorten the movie though by approximately 4 to 6 minutes.

[Shalashaska]

Originally Posted by richieb1971

Your question doesn't make much sense to me.

But effectively your TV will only refresh at 50 or 60 cycles per second (hz).

What you plug into it (Blu ray, games consoles) are the technologies which allow 24p playback. This works as you say with a 3:2 pulldown (or 2:3 pulldown) algorithm which splits between -

Odd frames - 2 x 12
Even frames - 3 x 12

Gives total frames = 60

If your TV was only 50hz, that wouldn't work. Because 24p doesn't fit into 50hz, the historical way of getting round this is to speed up the film to 25p. The pitch of the sound will go up, but its only 1 frame per second so not many people notice the difference. It does shorten the movie though by approximately 4 to 6 minutes.

Thanks. That's what I originally thought, but this website says many recent TVs (even some 60 Hz displays) can "change the panel refresh rate on demand, enabling non-multiple frame rates. The 3:2 pull down problem is mostly a legacy one. In your case, the TV just sends a frame rate of 24 fps to the panel and displays it as is."

I can't get a straight answer anywhere. Since my TV can change its refresh rate on demand between 50 Hz and 60 Hz though, shouldn't it be able to do 24 Hz? When I plug my laptop into the TV with a HDMI cable, it shows 24 Hz as an option.

[richieb1971]

I read quite a bit on that website you linked but it talks mostly of telecine judder and nothing to do with compatibility issues.

Telecine judder occurs mostly when the camera pans left or right in 24p. I see it in the source material even at the cinema so going through the 3:2 pulldown process is going to add more judder.

A 120hz TV will give the best representation of 24p since it does not require 3:2 pulldown. It just displays each frame 5 times. If your TV is 120hz and you use HDMI, the handshake the Blu ray player does with display unit will work out how to display 24p. Either 3:2 pulldown, or output 24p natively in a 120hz (x5) mode.

[HDTV1080P]

99% of the movies shot on film and digital videotape is at a native frame rate of 24 or sometimes called 24Hz. High-end DLP projectors will display movies at 24fps with no flicker issues since the quality of the light engine can handle all the way down to 0fps without any flicker issues. Film projectors and flat panel screens have limitations in their technology that prevents them from using native 24fps. For example in a commercial movie theater projector there would be a unwatchable flicker issue if the film projector showed the movie at 24fps. Therefore film projectors use a minimum of 48fps on the screen by repeating each frame twice. 100% of all film projectors use 48fps or higher to get rid of the unwatchable 24fps flicker issue. Flat panel screens like the classic Pioneer plasmas from 2006-2008 use 50Hz,60Hz,and 72Hz. The old Pioneer plasmas will accept a 1080p/24 signal and triple flash the image on the screen at 72Hz with a flicker free experience.

Flat panel screens have a unwatchable flicker problem at 24Hz if someone were to every make one that displays 24fps, and a flicker problem at 48Hz. No flat panel screen every made will use 24Hz on the screen since there would be a flicker problem, also all rare 48Hz flat panel displays have been discontinued do to flicker problems. A flat panel screen needs a minimum of 72Hz in order to show 24fps material without a flicker problem and without 3:2 pulldown judder (60Hz is used on most older flat panel screens when displaying 24fps material) , and that is why LCD screens use 120Hz, 240Hz, or higher multiplies of 24fps and 60fps.

For those that can afford it the best of the best for movie watching is a DLP projector that offers excellent motion quality with the ability to display images on the screen at 24fps with no flicker problems. Only one projector is needed for 24fps in a 2-D setup. A IMAX setup uses two DLP projectors.

[Shalashaska]

Originally Posted by HDTV1080P

99% of the movies shot on film and digital videotape is at a native frame rate of 24 or sometimes called 24Hz. High-end DLP projectors will display movies at 24fps with no flicker issues since the quality of the light engine can handle all the way down to 0fps without any flicker issues. Film projectors and flat panel screens have limitations in their technology that prevents them from using native 24fps. For example in a commercial movie theater projector there would be a unwatchable flicker issue if the film projector showed the movie at 24fps. Therefore film projectors use a minimum of 48fps on the screen by repeating each frame twice. 100% of all film projectors use 48fps or higher to get rid of the unwatchable 24fps flicker issue. Flat panel screens like the classic Pioneer plasmas from 2006-2008 use 50Hz,60Hz,and 72Hz. The old Pioneer plasmas will accept a 1080p/24 signal and triple flash the image on the screen at 72Hz with a flicker free experience.

Flat panel screens have a unwatchable flicker problem at 24Hz if someone were to every make one that displays 24fps, and a flicker problem at 48Hz. No flat panel screen every made will use 24Hz on the screen since there would be a flicker problem, also all rare 48Hz flat panel displays have been discontinued do to flicker problems. A flat panel screen needs a minimum of 72Hz in order to show 24fps material without a flicker problem and without 3:2 pulldown judder (60Hz is used on most older flat panel screens when displaying 24fps material) , and that is why LCD screens use 120Hz, 240Hz, or higher multiplies of 24fps and 60fps.

For those that can afford it the best of the best for movie watching is a DLP projector that offers excellent motion quality with the ability to display images on the screen at 24fps with no flicker problems. Only one projector is needed for 24fps in a 2-D setup. A IMAX setup uses two DLP projectors.

That's understandable, thanks. For some reason, there seems to be less judder when I output 24 Hz and let the TV handle the telecine process. I would've assumed my Blu-ray player would've done a better job.

In terms of PAL video and 50 Hz, does that mean there should be little or no flicker/judder with R2 DVDs? When I watch one of my 50 Hz/25 FPS DVDs, panning shots don't seem to have any judder and there's no visible flicker either. Why is there a lot flicker with 48 Hz/24 FPS video but not 50 Hz/25 FPS?

[joie]

Originally Posted by Shalashaska

That's understandable, thanks. For some reason, there seems to be less judder when I output 24 Hz and let the TV handle the telecine process. I would've assumed my Blu-ray player would've done a better job.

In terms of PAL video and 50 Hz, does that mean there should be little or no flicker/judder with R2 DVDs? When I watch one of my 50 Hz/25 FPS DVDs, panning shots don't seem to have any judder and there's no visible flicker either. Why is there a lot flicker with 48 Hz/24 FPS video but not 50 Hz/25 FPS?

Horizontal panning "judder" can be caused by a camera operator doing a horizontal pan too fast, at a rate that bakes the judder into the film/video. It's either done deliberately or out of ignorance.

edit: maybe 50-Hz operators are more knowledgeable -- ha ha

[Shalashaska]

Originally Posted by joie

Horizontal panning "judder" can be caused by a camera operator doing a horizontal pan too fast, at a rate that bakes the judder into the film/video. It's either done deliberately or out of ignorance.

edit: maybe 50-Hz operators are more knowledgeable -- ha ha

That seems to be a result of 3:2 pulldown more than framerate though, right?

[joie]

Originally Posted by Shalashaska

That seems to be a result of 3:2 pulldown more than framerate though, right?

No, not always. It can result from panning the camera too fast. One example is a pan (vertical?) in a panoramic shot of Casablanca at the beginning of that movie. The camera was moved too fast.

edit: here is a link from the makers of the RED digital camera:
http://www.red.com/learn/red-101/camera-panning-speed

[HDTV1080P]

Originally Posted by Shalashaska

That's understandable, thanks. For some reason, there seems to be less judder when I output 24 Hz and let the TV handle the telecine process. I would've assumed my Blu-ray player would've done a better job.

In terms of PAL video and 50 Hz, does that mean there should be little or no flicker/judder with R2 DVDs? When I watch one of my 50 Hz/25 FPS DVDs, panning shots don't seem to have any judder and there's no visible flicker either. Why is there a lot flicker with 48 Hz/24 FPS video but not 50 Hz/25 FPS?

Flat panel screens have a unwatchable flicker at 24fps, 25fps, and 30fps (native screen output at 30Hz and below casues flicker issues because of quality issues with consumer grade flat panel screens). Some rare older flat panel screens would receive a 1080p/24 signal and then double flash 24fps material at 48fps, however there were consumers complaining about flicker at 48fps, so all flat panel manufactories stopped offering the 48Hz feature (The 48hz feature was offered on one model of Sony LCD flat panel many years ago and several old Panasonic plasmas).

25fps material is double flashed to 50Hz on the old Pioneer plasmas and some International flat panel screens. 50Hz does not have flicker issues unless the display is poor quality and the brightness is turned up very high. 1080i 30fps material is double flashed to 60Hz on flat panel screens that are native 60Hz.


So in summary since native 24Hz is never used on flat panel screens, you will never experience the unwatchable flicker issue since that output is locked out (Only DLP projectors and commercial grade LCOS projectors offer native 24fps output with no flicker). When it comes to 48Hz that feature is now only offered on DLP projectors since flat panel screens have either a slight flicker or unwatchable flicker when 48Hz is used. 50Hz and 60Hz in general are high enough frame rates that no visible flicker appears most of the time.

In the future the ideal flat panel screen technology could be created where the flat panel screen operates like a DLP projector and offers 24Hz output with no flicker.However that might never happen since to make flat panels with the same quality motion that DLP projectors have might add several thousands of dollars to the cost of the flat panel screens. Most LCD flat panel screens in the year 2017 for the North America market are frame locked to 60Hz, or 120Hz, or 240Hz. Basically every flat panel screen that uses 120Hz is always going to display everything at 120Hz. The same goes with 60Hz LCD screens, everything is displayed at 60Hz.

Older flat panel screens like the Pioneer plasmas used 50Hz, 60Hz, and 72Hz. Gone are the days when one can purchase a flat panel screen that has variable fps output.

[Shalashaska]

Originally Posted by HDTV1080P

Flat panel screens have a unwatchable flicker at 24fps, 25fps, and 30fps (native screen output at 30Hz and below casues flicker issues because of quality issues with consumer grade flat panel screens). Some rare older flat panel screens would receive a 1080p/24 signal and then double flash 24fps material at 48fps, however there were consumers complaining about flicker at 48fps, so all flat panel manufactories stopped offering the 48Hz feature (The 48hz feature was offered on one model of Sony LCD flat panel many years ago and several old Panasonic plasmas).

25fps material is double flashed to 50Hz on the old Pioneer plasmas and some International flat panel screens. 50Hz does not have flicker issues unless the display is poor quality and the brightness is turned up very high. 1080i 30fps material is double flashed to 60Hz on flat panel screens that are native 60Hz.


So in summary since native 24Hz is never used on flat panel screens, you will never experience the unwatchable flicker issue since that output is locked out (Only DLP projectors and commercial grade LCOS projectors offer native 24fps output with no flicker). When it comes to 48Hz that feature is now only offered on DLP projectors since flat panel screens have either a slight flicker or unwatchable flicker when 48Hz is used. 50Hz and 60Hz in general are high enough frame rates that no visible flicker appears most of the time.

In the future the ideal flat panel screen technology could be created where the flat panel screen operates like a DLP projector and offers 24Hz output with no flicker.However that might never happen since to make flat panels with the same quality motion that DLP projectors have might add several thousands of dollars to the cost of the flat panel screens. Most LCD flat panel screens in the year 2017 for the North America market are frame locked to 60Hz, or 120Hz, or 240Hz. Basically every flat panel screen that uses 120Hz is always going to display everything at 120Hz. The same goes with 60Hz LCD screens, everything is displayed at 60Hz.

Older flat panel screens like the Pioneer plasmas used 50Hz, 60Hz, and 72Hz. Gone are the days when one can purchase a flat panel screen that has variable fps output.

I see. Thanks very much, I appreciate your help.

One more thing. Would you have any knowledge as to why some LCD PC monitors (or all, not really sure) are able to change their refresh rate on demand? Also, that article I posted earlier must be BS, right? Or maybe I'm just interpreting it wrong?

[joie]

Originally Posted by HDTV1080P

Flat panel screens have a unwatchable flicker at 24fps, 25fps, and 30fps (native screen output at 30Hz and below casues flicker issues because of quality issues with consumer grade flat panel screens). Some rare older flat panel screens would receive a 1080p/24 signal and then double flash 24fps material at 48fps, however there were consumers complaining about flicker at 48fps, so all flat panel manufactories stopped offering the 48Hz feature (The 48hz feature was offered on one model of Sony LCD flat panel many years ago and several old Panasonic plasmas).

25fps material is double flashed to 50Hz on the old Pioneer plasmas and some International flat panel screens. 50Hz does not have flicker issues unless the display is poor quality and the brightness is turned up very high. 1080i 30fps material is double flashed to 60Hz on flat panel screens that are native 60Hz.


So in summary since native 24Hz is never used on flat panel screens, you will never experience the unwatchable flicker issue since that output is locked out (Only DLP projectors and commercial grade LCOS projectors offer native 24fps output with no flicker). When it comes to 48Hz that feature is now only offered on DLP projectors since flat panel screens have either a slight flicker or unwatchable flicker when 48Hz is used. 50Hz and 60Hz in general are high enough frame rates that no visible flicker appears most of the time.

In the future the ideal flat panel screen technology could be created where the flat panel screen operates like a DLP projector and offers 24Hz output with no flicker.However that might never happen since to make flat panels with the same quality motion that DLP projectors have might add several thousands of dollars to the cost of the flat panel screens. Most LCD flat panel screens in the year 2017 for the North America market are frame locked to 60Hz, or 120Hz, or 240Hz. Basically every flat panel screen that uses 120Hz is always going to display everything at 120Hz. The same goes with 60Hz LCD screens, everything is displayed at 60Hz.

Older flat panel screens like the Pioneer plasmas used 50Hz, 60Hz, and 72Hz. Gone are the days when one can purchase a flat panel screen that has variable fps output.

For a long time theatrical projectors have double or triple flashed 24 fps film to achieve a pseudo 48 or 72 Hz rate. I think they may use a shutter to do that.

[HDTV1080P]

Originally Posted by Shalashaska

I see. Thanks very much, I appreciate your help.

One more thing. Would you have any knowledge as to why some LCD PC monitors (or all, not really sure) are able to change their refresh rate on demand? Also, that article I posted earlier must be BS, right? Or maybe I'm just interpreting it wrong?

CRT computer monitors can change their refresh rate and also some LCD computer monitors can also. However most LCD computer monitors operate at 60Hz or higher to avoid the flicker issue. In fact I have never seen a computer monitor operate below 50Hz. For example when the graphics card for a desktop computer outputs 24Hz the computer monitor that accepts 24Hz uses 3:2 pulldown and displays the image on the screen at 60Hz (60fps).