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LG 24fps Bombshell

7K views 57 replies 10 participants last post by  PlasmaPZ80U 
#1 ·
I think this deserves a separate thread from other LG threads.


According to LG technical support via phone and email, the LH90 with Real Cinema On and TruMotion Off gives 48fps when viewing 24p input such as Blu-ray disc. Real Cinema and TruMotion Off gives 24fps--yes, that is what I was told by LG technical support. I think that is worth repeating, With Real Cinema and TruMotion Off you get 24fps.


I guess the reviewer at CNET was confused when he said:


"We did appreciate the LG's Real Cinema setting, however, which functioned as advertised to preserve the true frame rate of film as long as the 240Hz function was disabled. We set our Blu-ray player to 1080p/24 output mode, turned the Real Cinema setting on, and fed the LG our favorite test clip for evaluating film cadence, the helicopter flyover of the Intrepid from "I Am Legend." The LH90 showed the proper amount of judder without the slight hitching motion characteristic of 2:3 pull-down, which returned when we set Real Cinema to Off."
http://reviews.cnet.com/flat-panel-t...ml?tag=rvwBody
 
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#3 ·

Quote:
Originally Posted by shaddix /forum/post/18836503


I would never trust LG support over Cnet

Well, the LG LH90 manual does state:


"Makes video clips recorded in film look more natural by eliminating judder effect.

DVD and Blu-ray movies are filmed at 24 frames per second (fps). With LG Real Cinema, every frame is consistently processed 5 times in 1/24 of a second producing 120 fps with TruMotion or 2 times in 1/24 of a second producing 48 fps without TruMotion, thus totally eliminating the judder effect."
 
#5 ·
For what it's worth I do remember reading somewhere that film projectors in movie theaters actually repeat each frame once--I.E. show each frame for 1/48 second twice--to reduce flicker.
 
#6 ·

Quote:
Originally Posted by Steve S /forum/post/18836647


For what it's worth I do remember reading somewhere that film projectors in movie theaters actually repeat each frame once--I.E. show each frame for 1/48 second twice--to reduce flicker.

I was wondering if that's what it was referring too as well, but the manual makes it sound like it actually interpolates 24 frames/second to 48.
 
#8 ·
I see you've posted all throughout the settings thread to no avail. Why don't you try watching some 24fps content with 3:2 pulldown and then with the supposed 48fps mode. The difference between 24fps content on my plasma at 72hz and 60hz is quite subtle. It should be a major, obvious, difference going from 24 to 48 if it really is using frame interpolation.
 
#9 ·

Quote:
Originally Posted by shaddix /forum/post/18836781


I see you've posted all throughout the settings thread to no avail. Why don't you try watching some 24fps content with 3:2 pulldown and then with the supposed 48fps mode. The difference between 24fps content on my plasma at 72hz and 60hz is quite subtle. It should be a major, obvious, difference going from 24 to 48 if it really is using frame interpolation.

What is 3:2? In other words, how am I supposed to setup for both 3:2 and 2:2 and how does that prove 24fps?
 
#11 ·

Quote:
Originally Posted by ambizytl /forum/post/18836810


What is 3:2? In other words, how am I supposed to setup for both 3:2 and 2:2 and how does that prove 24fps?

Turn off both real cinema and trumotion. According to the LG person that will enable 3:2 pulldown. I guess 6:4......? If it's 120hz panel. And that should disable frame interpolation completely. 3:2 pulldown does not look a whole lot different from the actual 24fps cadence. It is noticeable but it is subtle. Then just enable real cinema without trumotion and you should see a very obvious difference if it is actually interpolating to 48fps.

Sometimes I even forget that I'm outputting 60hz to my tv and it takes me 10 minutes to realize that I'm watching 3:2 pulldown.
 
#12 ·

Quote:
Originally Posted by shaddix /forum/post/18836878


Turn off both real cinema and trumotion. According to the LG person that will enable 3:2 pulldown. I guess 6:4......? If it's 120hz panel. And that should disable frame interpolation completely. 3:2 pulldown does not look a whole lot different from the actual 24fps cadence. It is noticeable but it is subtle. Then just enable real cinema without trumotion and you should see a very obvious difference if it is actually interpolating to 48fps.

Sometimes I even forget that I'm outputting 60hz to my tv and it takes me 10 minutes to realize that I'm watching 3:2 pulldown.

I will try that later, but it doesn't make sense. I called Sony and their 24p True Cinema On with MotionFlow Off gives 24fps.
 
#13 ·

Quote:
Originally Posted by shaddix /forum/post/18836878


Turn off both real cinema and trumotion. According to the LG person that will enable 3:2 pulldown. I guess 6:4......? If it's 120hz panel. And that should disable frame interpolation completely. 3:2 pulldown does not look a whole lot different from the actual 24fps cadence. It is noticeable but it is subtle. Then just enable real cinema without trumotion and you should see a very obvious difference if it is actually interpolating to 48fps.

Sometimes I even forget that I'm outputting 60hz to my tv and it takes me 10 minutes to realize that I'm watching 3:2 pulldown.

According to CNET review, Real Cinema Off is worse than Real Cinema On:


"We did appreciate the LG's Real Cinema setting, however, which functioned as advertised to preserve the true frame rate of film as long as the 240Hz function was disabled. We set our Blu-ray player to 1080p/24 output mode, turned the Real Cinema setting on, and fed the LG our favorite test clip for evaluating film cadence, the helicopter flyover of the Intrepid from "I Am Legend." The LH90 showed the proper amount of judder without the slight hitching motion characteristic of 2:3 pull-down, which returned when we set Real Cinema to Off."
http://reviews.cnet.com/flat-panel-t...ml?tag=rvwBody


So what would that tell me by doing what you suggest? If it looks worse with Real Cinema Off, that still doesn't prove On is 24fps with regard to what LG says--if we discard that last statement from the person I spoke to on the phone suggesting 24fps was with Real Cinema Off. She had me hold on while asking about the Real Cinema On but did not when saying Off was 24fps. I think she just wanted to get rid of me at that point.
 
#14 ·
Oh, forgot about that response from LG to someone else saying:


"6. With both Real cinema and TruMotion disabled, does it operate at 60Hz and do 3:2 pulldown?

With both Real cinema and TruMotion disabled, does it operate at? 60Hz? NO and do 3:2 pull down? YES"


Is 3:2 supposed to be 24fps? If that is true, then according to CNET the picture will look worse!
 
#15 ·
3:2 pulldown is 24fps with slightly increased judder. 5:5 is 24fps. 2:2 is also 24fps. The only things that can make it not 24fps is if what that LG person said was true about real cinema: on truemotion: off being 48fps, and with trumotion on it will also no longer be 24fps(higher than 48fps, 120fps?).


Cnet is saying that with real cinema on and trumotion off, its doing 5:5 repeating frames 24fps at 120hz. What LG is saying real cinema on and truemotion off is that it's interpolating and drawing 48 unique frames per second.



3:2 will appear to have the least smooth picture. Then 5:5 24fps with no frame interpolation will be slightly more smooth. Then if LG is correct real cinema on and trumotion off will be much smoother than 24fps because you've doubled the framerate. If Cnet is right then you haven't doubled the framerate and its just repeating frames which is what you want if you don't like frame interpolation.


Doing what I suggested will determine if LG is right or if Cnet is right. If you turn real cinema off and it looks slightly worse, barely noticeable, then Cnet is right. If you turn real cinema off and it looks extremely less smooth, then LG is right.
 
#16 ·

Quote:
Originally Posted by shaddix /forum/post/18837237


3:2 pulldown is 24fps with slightly increased judder. 5:5 is 24fps. 2:2 is also 24fps. The only things that can make it not 24fps is if what that LG person said was true about real cinema: on truemotion: off being 48fps, and with trumotion on it will also no longer be 24fps(higher than 48fps, 120fps?).


Cnet is saying that with real cinema on and trumotion off, its doing 5:5 repeating frames 24fps at 120hz. What LG is saying real cinema on and truemotion off is that it's interpolating and drawing 48 unique frames per second.



3:2 will appear to have the least smooth picture. Then 5:5 24fps with no frame interpolation will be slightly more smooth. Then if LG is correct real cinema on and trumotion off will be much smoother than 24fps because you've doubled the framerate. If Cnet is right then you haven't doubled the framerate and its just repeating frames which is what you want if you don't like frame interpolation.


Doing what I suggested will determine if LG is right or if Cnet is right. If you turn real cinema off and it looks slightly worse, barely noticeable, then Cnet is right. If you turn real cinema off and it looks extremely less smooth, then LG is right.

Where do you see CNET saying with Real Cinema On and TruMotion Off it is 5:5?
 
#17 ·

Quote:
Originally Posted by ambizytl /forum/post/18837610


Where do you see CNET saying with Real Cinema On and TruMotion Off it is 5:5?

With trumotion turned off, the LH90 refreshes at 120hz if I am not mistaken. So the only way that the LH90 can display proper 24fps cadence at 120hz is 5:5. Repeating each frame 5 times, 24 times a second for 120 screen refreshes. Since CNET said that real cinema on and trumotion off it was displaying 24hz properly, it must be displaying 5:5 at 120hz if CNET is correct.
 
#21 ·
Todays 120 HZ LCD displays normaly have 3 ways to handle 24fps content input:

1. Use 3:2 Pulldown to convert it to 60 fps and display each frame twice.

2. Use 3:2 Pulldown to convert it to 60 fps and then use frame interpolation to insert a new frame between each pair of the 60 created 60 fps frames to reduce motion blur and Judder casused by the slow 24 fps capture rate of film cameras.

3. Use 5:5 pulldown to elimnate the frame rate Judder caused by 3:2 pulldown by displaying each recieved frame 5 times.


Different brands of TVs apply differnt names to these modes. Note there is there is not a mode listed above that has no frame rate Judder or film rate capture Judder.

The 240 Hz LCD displays are potentialy capable of eliminating both.
 
#22 ·
That is the general consensus. However, what were confused about is the actual frame rate and what exactly happens when you enable both 24p mode (Real Cinema) and de-judder/frame interpolation (TruMotion). This is how LG responded to ambizytl:
Quote:
With LG Real Cinema, every frame is consistently processed 5 times in 1/24 of a second producing 120 fps with TruMotion or 2 times in 1/24 of a second producing 48 fps without TruMotion, thus totally eliminating the judder effect.

I just went back and read KakimotoRift's analysis HERE and I think he is correct in his resulting framerate calculations when the different modes are enabled.


So to go into more detail in Kaki's post, for 24p sources:

Real Cinema On - TruMotion Off - 5:5 pulldown is applied, so each frame is displayed 5 times, but only 24 individual frames are displayed (so 24fps).


Real Cinema On - TruMotion Low - 5:5 pulldown is applied but double the amount of individual frames are displayed by the motion estimation processing and the intermediate frames that are inserted between the original frames (so 48fps).


Real Cinema On - TruMotion High - 5:5 pulldown is applied, motion estimation processing inserts intermediate frames, then the backlight strobing gives a 240Hz effect essentially inserting another intermediate frame between the original frames (so 96fps).


When Real Cinema is OFF, 3:2 pulldown is applied and TruMotion has the same effect on the frame rate (Off=60fps, Low=120fps, High=240fps).


The frame rate does not have to be a divisible number of 120, but the set always refreshes at 120Hz. The source output rate, however, must be a divisible number of 120, and because 120 is divisible by all NTSC frame rates, the LH90 can handle all sources without any complicated conversions (like 3:2 pulldown).
 
#23 ·

Quote:
Originally Posted by rahzel /forum/post/18838244


That is the general consensus. However, what were confused about is the actual frame rate and what exactly happens when you enable both 24p mode (Real Cinema) and de-judder/frame interpolation (TruMotion). This is how LG responded to ambizytl:



I just went back and read KakimotoRift's analysis HERE and I think he is correct in his resulting framerate calculations when the different modes are enabled.


So to go into more detail in Kaki's post, for 24p sources:
Real Cinema On - TruMotion Off - 5:5 pulldown is applied, so each frame is displayed 5 times, but only 24 individual frames are displayed (so 24fps).


Real Cinema On - TruMotion Low - 5:5 pulldown is applied but double the amount of individual frames are displayed by the motion estimation processing and the intermediate frames that are inserted between the original frames (so 48fps).


Real Cinema On - TruMotion High - 5:5 pulldown is applied, motion estimation processing inserts intermediate frames, then the backlight strobing gives a 240Hz effect essentially inserting another intermediate frame between the original frames (so 96fps).


When Real Cinema is OFF, 3:2 pulldown is applied and TruMotion has the same effect on the frame rate (Off=60fps, Low=120fps, High=240fps).


The frame rate does not have to be a divisible number of 120, but the set always refreshes at 120Hz. The source output rate, however, must be a divisible number of 120, and because 120 is divisible by all NTSC frame rates, the LH90 can handle all sources without any complicated conversions (like 3:2 pulldown).

I don't understand how you can get that in bold when LG claims Real Cinema On and TruMotion Off gives 48fps?
 
#24 ·

Quote:
Originally Posted by ambizytl /forum/post/18839837


I don't understand how you can get that in bold when LG claims Real Cinema On and TruMotion Off gives 48fps?

I don't think LG knows wtf they're talking about. With trumotion off if the panel really does refresh at 120hz, there's no way to display 48 frames per second smoothly. It would have to refresh at 96hz or 144hz.
 
#25 ·

Quote:
Originally Posted by shaddix /forum/post/18839916


I don't think LG knows wtf they're talking about. With trumotion off if the panel really does refresh at 120hz, there's no way to display 48 frames per second smoothly. It would have to refresh at 96hz or 144hz.

I don't know who knows, but when a TV's native refresh rate is 120, is it possible for it to change to 60? From that link above: "*Real Cinema Off uses 3:2 pulldown from Panel Running at 60Hz (Setting Refresh Rate to 60Hz for 24p Material) Degraded 24p"


LG seems to have said the LH90 always refreshes at 120.
 
#26 ·

Quote:
Originally Posted by ambizytl /forum/post/18839976


I don't know who knows, but when a TV's native refresh rate is 120, is it possible for it to change to 60? From that link above: "*Real Cinema Off uses 3:2 pulldown from Panel Running at 60Hz (Setting Refresh Rate to 60Hz for 24p Material) Degraded 24p"


LG seems to have said the LH90 always refreshes at 120.

With Real Cinema off and TruMotion off the TV does what Walford described above:

Quote:
1. Use 3:2 Pulldown to convert it to 60 fps and display each frame twice.

Which I guess you could call 6:4 pulldown
 
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