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60hz 120hz 240hz *Explained*

post #1 of 84
Thread Starter 
To the experts on AVS Forum...

This is a question.

TV's advertise 120hz & 240hz a lot now. I was taught that 1080i is broadcast in 30hz and 720p in 60hz.


?How can a TV view a 1080i picture that is broadcast in 30hz viewable in 240hz?


I have seen a 240hz LCD Samsung and I could tell a big difference.

Thanks in advance.
-Bill
post #2 of 84
these TV's duplicate frames and when motion enhancers are turned on they manipulate the duplicate frames by predicting motion in the video image and adjusting parts of the image accordingly

if you shut off the motion enhancer (AMP on samsungs, motionflow on sonys etc.) these TV's are effectively the same as a 60hz TV so in other words, the 120/240hz is just an enabler for motion enhancers to do their work to make things look smoother and more fluid on the screen
post #3 of 84
If you turn off the motion enhancement, it doesn't revert back to 60hz though? If not, I would think the image should look a tad more smooth with the doubling of frames from the 120hz. Is this the case?
post #4 of 84
Quote:
Originally Posted by Tsantsa View Post

If you turn off the motion enhancement, it doesn't revert back to 60hz though? If not, I would think the image should look a tad more smooth with the doubling of frames from the 120hz. Is this the case?

no not really because LCD's are sample and hold type displays if an image displayed does not change it stays the same on the display until it does, technically the display itself has no "refresh rate" the timing component before the display does and has to convert signals to drive the display
post #5 of 84
Quote:
Originally Posted by Tsantsa View Post

If you turn off the motion enhancement, it doesn't revert back to 60hz though? If not, I would think the image should look a tad more smooth with the doubling of frames from the 120hz. Is this the case?

Motion enhancement takes two real incoming frames, interpolates (guesses) what an intermediate frame would look like if it actually existed, and inserts that between the two real frames.

Turning it off makes the set just repeat each incoming frame twice with no alteration to convert 60 incoming frames to 120 displayed on the screen. Since there's no alteration the net effect is the same as a 60 hz set. Showing one frame twice, each time for 1/120th of a second each time is the same as showing that same frame once, each time for 1/60th of a second.

There are two uses for 120/240 hz sets over 60hz sets

1-frame interpolation to supposedly give smoother motion but also makes film sources look like video (soap opera effect) and can introduce weird "swimmy" look.

2-Blu Ray discs are encoded at 24fps. This does not divide evenly into 60hz so the player will convert to 60fps, so not all frames repeated the same number of times, hence judder.
24 does divide evenly into 120 or 240, BD player can be set to output at the disc's native 24 fps, each frame will be repeated the same number of times.
There's still judder but it's the exact same judder one sees in a movie theater with a projector running at 24fps, the standard for projection of motion picture film. I still go to the movies occasionally and can't tell the difference between this judder and the judder I see on my 60hz television.
post #6 of 84
Quote:
Originally Posted by Tsantsa View Post

If you turn off the motion enhancement, it doesn't revert back to 60hz though? If not, I would think the image should look a tad more smooth with the doubling of frames from the 120hz. Is this the case?

Since the response time of the LCD panels on current generation HDTVs with 120Hz is significantly less then 1/60th of a second there is apparently no benefit to displaying 60fps content twice when "motion flow" is turned off.
post #7 of 84
Thanks for the info gentlemen! I had been watching a recent episode of HD Nation on rev3 the other day and Robert Heron made some comment about something similar. I can't remember exactly but he had said if options were disable within a 120hz tv, it would still be a 120hz tv. Or something to that effect. I was confused so when I saw this thread, I popped in to ask.
post #8 of 84
Quote:
Originally Posted by frito View Post

no not really because LCD's are sample and hold type displays if an image displayed does not change it stays the same on the display until it does, technically the display itself has no "refresh rate" the timing component before the display does and has to convert signals to drive the display

Makes you wonder why we need 3:2,2:3,2:2,4:4,5:5,10:10 pull down. LCD's should be able to display film content at exactly 24fps. =P

Oh well, that's marketing for you. Always assuming consumers are idiots.
post #9 of 84
Quote:
Originally Posted by Quad5Ny View Post

Makes you wonder why we need 3:2,2:3,2:2,4:4,5:5,10:10 pull down. LCD's should be able to display film content at exactly 24fps. =P

Oh well, that's marketing for you. Always assuming consumers are idiots.

Many 120/240Hz LCDs with the motion processing off, do display a 24p input at exactly 24 original frames per second.

24fps without frame interpolation would be too slow. Motion would appear jerky.

Even though film is 24fps, movie theater projectors convert it to 48fps or 72fps showing duplicate frames by shuttering each frame twice or three times.
post #10 of 84
Thank the holy Jesus for this thread.

I have been trying to prove to stubborn people that there is no difference between a 60hz and a 120hz and 240hz set when their motion enhancement settings are off.

A 60hz TV and a 120hz/240hz ALL have the same lines of motion resolution when the motion enhancement settings are off. Nothing is smoother since repeating the same frame twice or four times is the same as displaying it once.

I've been telling them that asides from true 24fps playback, all the sets behave exactly the same as a 60hz.

It's ONLY when you turn on the motion enhancement that you get some real benefit of 120hz/240hz. This is especially so for those TV's like the Samsung B750 that separate blur reduction and dejudder. So if you want a TV that won't add the soap opera effect but add the blur reduction qualities of 120hz and 240hz, buy a set that can separate them and allow you to turn them on/off independently.

All this means is that the people who buy 120hz/240hz without ever using motion enhancement (at LEAST blur reduction), are throwing money away when they could've easily just got a beastly 60hz set. The only thing they are getting is correct 1080p/24 playback.
post #11 of 84
Quote:
Originally Posted by Quad5Ny View Post

Makes you wonder why we need 3:2,2:3,2:2,4:4,5:5,10:10 pull down. LCD's should be able to display film content at exactly 24fps. =P

Oh well, that's marketing for you. Always assuming consumers are idiots.

How many hudreds of $ more are you willing to pay for a LCD HDTV in the US that can display multiple frame rates?
I am not willing to spend a dime.
Maybe you don't remember that Multiscan rate PC monitors cost twice as much as standard TVs with size screens sevreal years ago
post #12 of 84
Well with the ability to separate blur reduction and dejudder, TV's that can display multiple frames allows for higher motion resolutions = less blur.

For example:

60hz: 300-400 lines of motion resolution.

120hz: 600

240hz: 800-1000

2009 plasmas: All 1080 lines.

So with a 240hz TV, you can get near plasma like motion handling. This IMHO is only truly worth it if you can get it without the soap opera effect, which TVs like the Samsung B750 does correctly.
post #13 of 84
yeah and actually there are some 60hz sets that have motion enhancement, my sony 32xbr6 is 60hz and has 60hz motionflow that does give movies a mild soap opera effect when turned on 120hz motionflow works alot better though
post #14 of 84
So to avoid the soap opera effect for someone who watches blu-ray (24p) and plays games on the pc (can I really get 240hz from my pc to output to the samsung), which samsung led would you guys recommend?
post #15 of 84
Quote:
Originally Posted by Beeper View Post

Because 24fps would be too slow. Motion would appear jerky.

Even though film is 24fps, movie theater projectors convert it to 48fps or 72fps by showing duplicate frames or shuttering each frame twice.

Cinema projectors use a double shutter 48Hz to reduce visible flicker not improve motion.
You can only improve motion if you add motion information (temporal data), and that requires more REAL frames per second.

Normal LCD's cant flicker because there is no blanking between frames so 24Hz is not a problem as far as flicker is concerned.
post #16 of 84
Quote:
Originally Posted by walford View Post

How many hudreds of $ more are you willing to pay for a LCD HDTV in the US that can display multiple frame rates?
I am not willing to spend a dime.
Maybe you don't remember that Multiscan rate PC monitors cost twice as much as standard TVs with size screens sevreal years ago

The problem is there is no such thing as a high end 60 hz set anymore. People forget they are not just spending money for higher hertz but for better picture quality in general. Take the samsung series for example. The 60 hz 5 series has noticeably lower picture quality than the 120 hz 6 series (color, contrast ratio, black level etc.). There is nothing in between.
post #17 of 84
Quote:
Originally Posted by ymarker View Post

So to avoid the soap opera effect for someone who watches blu-ray (24p) and plays games on the pc (can I really get 240hz from my pc to output to the samsung), which samsung led would you guys recommend?

no your PC will only beable to output 24 or 60 hz at 1920 x 1080 to any LCD TV

the samsungs are generally not the best for gaming because of excess input lag, most people dont notice it much in game mode (motion enhancer will be off in this mode) but FPS games can make it more apparent esp if played online

Sharps tend to be the most consistant and fastest with input lag mostly because they all use IPS panels that are faster than PVA panels with input lag, but lack the same level of picture quality and black levels of samsung/sony's PVA panels, LG also uses IPS panels but lately they have been switching many models to PVA panels and the input lag is like samsungs at around 40-60 ms in game modes

if you turn on a motion enhancer the lag will jump over 100 ms and you will notice it alot on most any type of game and with mouse cursor movements
post #18 of 84
Quote:
Originally Posted by Beeper View Post

Even though film is 24fps, movie theater projectors convert it to 48fps or 72fps by showing duplicate frames or shuttering each frame twice.

Heh, you learn something every day. =P

Quote:
Originally Posted by Shin CZ View Post

I've been telling them that asides from true 24fps playback, all the sets behave exactly the same as a 60hz.

It's ONLY when you turn on the motion enhancement that you get some real benefit of 120hz/240hz. This is especially so for those TV's like the Samsung B750 that separate blur reduction and dejudder. So if you want a TV that won't add the soap opera effect but add the blur reduction qualities of 120hz and 240hz, buy a set that can separate them and allow you to turn them on/off independently.

All this means is that the people who buy 120hz/240hz without ever using motion enhancement (at LEAST blur reduction), are throwing money away when they could've easily just got a beastly 60hz set. The only thing they are getting is correct 1080p/24 playback.

You forget that company's put better panels into the higher end models, and have better quality control for things like flashlighting.

Honestly I think blur reduction is a bad idea it effects the natural motion blur that was part of the film. Pause a frame from a movie and you will see its blurred depending on the amount of motion. It has to do with how long the shutter on the film camera was open, the ISO sensitivity of the film and some other stuff. When you interpolate frames together you loose that effect, which is why it ends up looking like a soap opera. It effects lip syncing too depending on how 120/240hz is implemented or in Samsung's case the strength of the blur reduction/judder reduction setting.

Some 60hz sets can do 48hz (or 2:2 pull-down). That way you still get correct 24fps playback.

Quote:
Originally Posted by walford View Post

How many hudreds of $ more are you willing to pay for a LCD HDTV in the US that can display multiple frame rates?
I am not willing to spend a dime.
Maybe you don't remember that Multiscan rate PC monitors cost twice as much as standard TVs with size screens sevreal years ago

Most US TV's can do 24hz 30hz 60hz(interlaced) and 60hz. The only thing were missing is 50hz.

My first monitor was a Philips 107S1 which I bought in 1999 (I was 12), so I don't really remember. =P

Quote:
Originally Posted by Shin CZ View Post

Well with the ability to separate blur reduction and dejudder, TV's that can display multiple frames allows for higher motion resolutions = less blur.

For example:

60hz: 300-400 lines of motion resolution.

120hz: 600

240hz: 800-1000

2009 plasmas: All 1080 lines.

So with a 240hz TV, you can get near plasma like motion handling. This IMHO is only truly worth it if you can get it without the soap opera effect, which TVs like the Samsung B750 does correctly.

I'm not sure what you mean by lines of motion. The TV is suppose to display whatever the source material has(pixel for pixel and frame for frame).

I think what people are calling 'Motion Resolution' is being confused with Response Time. When you turn on the motion enhancement feature of LCD's not only does it interpolate frames, it also gives it longer to analyze the motion and figure out a better way to 'Overdrive' the pixels therefor decreasing the response time.

You also get the extra frames from the interpolation going on, but I don't think that's why your seeing better motion resolution.

I get the soap opera effect on my B750 with the latest firmware. I don't think there is any way to avoid it with this type of image processing.

---
LCD overdriving is achieved by analyzing the motion beforehand and deciding which pixels on the screen to supply a increased voltage to. Therefor increasing response time.

This sounds like a really excellent idea on paper, but in practice the extra time required for motion analysis adds input lag.
---

By the way, anything over about 65fps the human mind can't process, and LCD's don't flicker...so it makes you wonder what the heck the point of 120/240hz is. If it accepted a 120hz input then it would be good for use with 3D shutter glasses, but manufactures are stupid.

Quote:
Originally Posted by ymarker View Post

So to avoid the soap opera effect for someone who watches blu-ray (24p) and plays games on the pc (can I really get 240hz from my pc to output to the samsung), which samsung led would you guys recommend?

1.) No current Samsung actually supports 240hz input. They all take whats input; 24,30,50,60,72, or 85hz and convert it to 240hz using image processing(The tv will only accept 72-85hz in lower resolutions such as 800x600).

2.) Stay away from Samsung's current LED back lit displays, almost all of them have very noticeable flashlighting.

Quote:
Originally Posted by Owen View Post

Normal LCD's cant flicker because there is no blanking between frames so 24Hz is not a problem as far as flicker is concerned.

I wonder what 24fps would look like on a LCD without any pull-down(1:1).

Quote:
Originally Posted by gbmannc View Post

The problem is there is no such thing as a high end 60 hz set anymore. People forget they are not just spending money for higher hertz but for better picture quality in general. Take the samsung series for example. The 60 hz 5 series has noticeably lower picture quality than the 120 hz 6 series (color, contrast ratio, black level etc.). There is nothing in between.

I wonder if going into the service menu and changing my model number to a 5 series number would disable 120/240hz. Maybe I'll try it next time I'm feeling risky.

Quote:
Originally Posted by frito View Post

no your PC will only beable to output 24 or 60 hz at 1920 x 1080 to any LCD TV

the samsungs are generally not the best for gaming because of excess input lag, most people dont notice it much in game mode (motion enhancer will be off in this mode) but FPS games can make it more apparent esp if played online

Sharps tend to be the most consistant and fastest with input lag mostly because they all use IPS panels that are faster than PVA panels with input lag, but lack the same level of picture quality and black levels of samsung/sony's PVA panels, LG also uses IPS panels but lately they have been switching many models to PVA panels and the input lag is like samsungs at around 40-60 ms in game modes

if you turn on a motion enhancer the lag will jump over 100 ms and you will notice it alot on most any type of game and with mouse cursor movements

You can do 30hz 60hz and 60hz interlaced and 72-85hz in low resolutions(and 50hz if your in a PAL region).

From what I've read in the forums Sharps don't calibrate very well. The Panasonic LCD's with IPS-Provectus are also really good.

According the the audio lag offset in the service menu Samsung's have a 40ms input lag in game mode. And my own tests showed 47ms. So I would say 40-47.

In normal mode the service menu audio lag offset is 89ms and my tests showed 92-109ms.

--------

Also some sets don't actually do 120/240hz. Instead they use a scanning backlight to simulate the effect(just another thing to keep in mind).

--------


Does anyone have a high fps digicam? I'm really interested on seeing what 120/240hz sets look like with the effect off/on.
post #19 of 84
Quote:
Originally Posted by Quad5Ny View Post

You can do 30hz 60hz and 60hz interlaced and 72-85hz in low resolutions(and 50hz if your in a PAL region).

From what I've read in the forums Sharps don't calibrate very well. The Panasonic LCD's with IPS-Provectus are also really good.

According the the audio lag offset in the service menu Samsung's have a 40ms input lag in game mode. And my own tests showed 47ms. So I would say 40-47.

In normal mode the service menu audio lag offset is 89ms and my tests showed 92-109ms.

i use a sony 32xbr6 as my main PC monitor at 1920 x 1080 (1080p) the only signal the TV will accept is 24 or 60, 24hz btw is complete comedy to see on a PC the cursor n such lag around the screen so bad its horrid

your lag numbers sound right for most samsungs, word is the newer models have a bit more lag as well say 10-20 ms more, my sony tested at 30-47 ms lag vs a CRT using the timer and camera method, i've tested it extensively and have a thread on here with the results of the tests and the images, i game on it regularly and its fast enough for me to not notice the lag

Quote:


Also some sets don't actually do 120/240hz. Instead they use a scanning backlight to simulate the effect(just another thing to keep in mind).

no 120hz set worth buying does this, many of the new 240hz sets however are just 120hz with a scanning backlight to simulate 240hz- pretty much a gimmick imho
post #20 of 84
Wait so which company got it right?
post #21 of 84
Oops I'm a bit of a idiot sometimes. I should have said the latest Samsung's support those refresh rates.


Which newer models? The LED backlit ones?

I did my lag tests on a B750.


Quote:
Originally Posted by sweetmisery View Post

Wait so which company got it right?

Got what right?
post #22 of 84
Quote:
Originally Posted by frito View Post

no 120hz set worth buying does this, many of the new 240hz sets however are just 120hz with a scanning backlight to simulate 240hz- pretty much a gimmick imho

Perhaps not.

Scanning the backlight, or flipping it on and off rapidly, helps deal with the sample on hold issue inherent to LCD's. It's a way of making them behave more like a plasma or CRT, at least as far as our brains are concerned.
post #23 of 84
Thread Starter 
Excellent info everyone...

Thank you.

I reposted on accident because of the internet connection @ McDonalds LOL
post #24 of 84
Quote:
Originally Posted by sweetmisery View Post

Wait so which company got it right?

See the following link about 240Hz models from different vendors:

http://reviews.cnet.com/8301-18438_7-10243372-82.html
post #25 of 84
Quote:
Originally Posted by Owen View Post

Normal LCD's cant flicker because there is no blanking between frames so 24Hz is not a problem as far as flicker is concerned.

They can insert black frames instead of interpolated frames. They can flicker the backlight.
post #26 of 84
Quote:
Originally Posted by Quad5Ny View Post

I wonder what 24fps would look like on a LCD without any pull-down(1:1).

LCDs are sample and hold displays. If the frame doesn't change, the picture on the screen doesn't change. The display can repeat the same frame as many times as it wants in a given period of time, but the picture still doesn't change, or flicker, or blank (unless the display is designed to flicker or blank) during that period. Turn AMP off on a Samsung on a 1080p24 source, and 1:1 is exactly what you are getting.

Raw 24p isn't exactly pretty. Even theaters don't feed you that.
post #27 of 84
Also some sets don't actually do 120/240hz. Instead they use a scanning backlight to simulate the effect...

Quote:
Originally Posted by frito View Post

no 120hz set worth buying does this, many of the new 240hz sets however are just 120hz with a scanning backlight to simulate 240hz- pretty much a gimmick imho

Many would beg to differ with yho.

CNET tested the Toshiba SV670U which is 120Hz with a scanning backlight.
CNET stated that the observed motion resolution was comparable to other (Sony Samsung) actual 240Hz models at 800 to 1000 lines of resolution.

It's actually a cleaner "gimmick" to reduce LCD blur than frame interpolation which introduces artifacts.
post #28 of 84
I'm under the impression that you only get motion artifacts with the dejudder processing in 120hz and 240hz sets. As stated before, Samsung and a few other companies allow you to separate dejudder from anti-blur. There is no interpolation artifacts AT ALL when I set my 240hz Sammy with Blur Reduction at any setting. It's when I turn on Dejudder that I get artifacts.
post #29 of 84
Quote:
Originally Posted by Shin CZ View Post

I'm under the impression that you only get motion artifacts with the dejudder processing in 120hz and 240hz sets. As stated before, Samsung and a few other companies allow you to separate dejudder from anti-blur. There is no interpolation artifacts AT ALL when I set my 240hz Sammy with Blur Reduction at any setting. It's when I turn on Dejudder that I get artifacts.

Any type of frame interpolation opens up the door for possible artifacts.
post #30 of 84
Quote:
Originally Posted by Shin CZ View Post

It's ONLY when you turn on the motion enhancement that you get some real benefit of 120hz/240hz. This is especially so for those TV's like the Samsung B750 that separate blur reduction and dejudder. So if you want a TV that won't add the soap opera effect but add the blur reduction qualities of 120hz and 240hz, buy a set that can separate them and allow you to turn them on/off independently.

What's a decent recommended setting for this?

Blur Reduction = x?
Judder Reduction = x?

Thanks.
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