TV panel refresh rate confusion - help! - AVS Forum
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post #1 of 6 Old 02-14-2013, 03:04 AM - Thread Starter
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I recently purchased a TV, and I've been trying to figure out what its native refresh rate is. The brief specs on the manufacturer's website at http://www.furrion.com/audio-visual/televisions/led/FEFS55L1D/ state: "Max. resolution 1920 x 1080 @ 120Hz FHD"

However, someone on another forum opened theirs up, and the sticker on the actual panel reveals that it is one of these: http://www.panelook.com/LC550EUN-SEM1_LG%20Display_55_LCM_overview_14500.html

This website states that the panel has a 60Hz refresh rate, but if you hover your mouse over the '?' icon next to that, there is a small popup that states the following info:
Quote:
120Hz (60HZ Input) : Embedded MEMC Circuit
120Hz+120Hz : 120Hz Panel+120Hz Backlight
240Hz (60HZ Input) : Embedded MEMC Circuit

Does anyone know what this means, and if indeed the TV/panel can/does refresh at 120Hz or not?
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post #2 of 6 Old 02-14-2013, 03:22 AM - Thread Starter
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I should add that what lead me to trying to determine the TV's refresh rate is that I was wondering if it handed 24p content. Although 24p support isn't mentioned in the official specs, I've read that 120Hz panels are good for displaying 24p video because 120 is divisible by 24. In other words, each frame can be shown 5 times, so the 'judder' effect causes by frame 'pulldown' can be avoided.

I have a 'WDTV Live Streaming' media player box (connected via HDMI) which I use to play media files, and in its video output settings, you can either let it use the 'auto' settings (which I *think* it determines by polling whichever output device it's connected to, to find out which video modes it supports), or you can manually specify the video mode from a whole array of resolutions and refresh rates. One of the options is '1080p 24Hz', but when I set it to this format, the box displays a message saying "the connected TV does not support this resolution". It does, however, support 1080i/p @ 50/60Hz when I try setting those formats manually.

So am I right in assuming that 24p is not supported by my TV?
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post #3 of 6 Old 02-14-2013, 05:39 AM
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I guess there are two questions here :

1. What refresh rate is your panel operating at.
2. What formats does your TV accept via HDMI.

2. is more important than 1. I gues for you (as if you can't feed 24p in, whether your panel refreshes at 120Hz or 60Hz is not an issue?)

If your WDTV Live gives an unsupported resolution error at 24Hz, that suggests that the TV is signalling via EDID (the signal from the display that tells sources what refresh rates, resolutions, colour spaces and audio formats it supports) that it doesn't support 24p. There are ways, on PCs, of forcing graphics drivers to ignore EDID (or to use an EDID you edit yourself) to absolutely check this, and you could try another source like a Blu-ray player to double check?

However if your TV doesn't accept 24p input that's not a good sign.

That said some displays will accept a 60Hz input, detect the 3:2 pull-down of a 24Hz source at 60Hz, and then run this at 120/240Hz with 5:5 or 10:10 - but I suspect the only way of seeing this is to look for 3:2 artefacts - or the lack of them. However I'm not sure whether any that do this don't have 24p inputs as well. Because I'm based in Europe where 3:2 is far less of an issue (24p content is run at 25p with 2:2 pulldown and 4% speedup instead) it's not something I know that much about.

I had a look at the panel site - and as you say you get 60Hz as the headline figure and then some extra 120Hz info on the (?) logo. I'm not expert enough to know how that reads I'm afraid.

I have a 4-5 year old Sony Bravia 40W4000 display that appears to run at 48/50/60Hz changing its refresh rate based on the 24/50/60Hz input format. Because the LCD is constantly backlit you don't have the flicker issues at 48Hz you'd have with Plasma or CRT. (As the refresh is modulating a constant backlight, rather than the refresh generating light)
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post #4 of 6 Old 02-14-2013, 05:53 AM - Thread Starter
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Quote:
Originally Posted by sneals2000 View Post

I guess there are two questions here :

1. What refresh rate is your panel operating at.
2. What formats does your TV accept via HDMI.

2. is more important than 1. I gues for you (as if you can't feed 24p in, whether your panel refreshes at 120Hz or 60Hz is not an issue?)

Cheers for the info. To answer your questions:

1. It _seems_ to operate at both 50 and 60hz (see below)

2. When I turn on or switch to a different input on the TV (i.e. my Sky HD, or WDTV boxes), the TV displays the signal details briefly on the screen. It correctly reports both interlaced and progressive signals at both 50 and 60hz (i.e. the Sky HD box signal is reported as "1080i@50hz", and the WDTV as "1080p@60hz" when I have them each set as such in their respective setup options). It also accepts 720p and lower @ 50/60hz too.
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post #5 of 6 Old 02-14-2013, 06:00 AM - Thread Starter
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Quote:
Originally Posted by sneals2000 View Post


That said some displays will accept a 60Hz input, detect the 3:2 pull-down of a 24Hz source at 60Hz, and then run this at 120/240Hz with 5:5 or 10:10 - but I suspect the only way of seeing this is to look for 3:2 artefacts - or the lack of them. However I'm not sure whether any that do this don't have 24p inputs as well. Because I'm based in Europe where 3:2 is far less of an issue (24p content is run at 25p with 2:2 pulldown and 4% speedup instead) it's not something I know that much about.

The impression that I get from this TV (given its price and the relative lack of options in the settings menu) is that the electronics driving the panel are very basic, so I doubt that it would be smart enough to detect a 24hz source in a 60hz "pulldowned" signal frown.gif

PS: I'm in the UK, which also presents another potential issue: TV is 50hz, so I'm hoping that this TV/panel isn't fixed to 60hz, and switches to 50hz when a 50hz input is detected, rather than run strictly at 60hz and employ some sort of pulldown...
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post #6 of 6 Old 02-14-2013, 09:38 AM
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Quote:
Originally Posted by pashtun View Post

The impression that I get from this TV (given its price and the relative lack of options in the settings menu) is that the electronics driving the panel are very basic, so I doubt that it would be smart enough to detect a 24hz source in a 60hz "pulldowned" signal frown.gif

PS: I'm in the UK, which also presents another potential issue: TV is 50hz, so I'm hoping that this TV/panel isn't fixed to 60hz, and switches to 50hz when a 50hz input is detected, rather than run strictly at 60hz and employ some sort of pulldown...

Very easy to check. Watch Sky News or BBC News Channel and see whether the ticker judders. The ticker should have nice smooth linear motion, and not appear to jump or jerk. If the 50Hz video is displayed at 60Hz then you'll get slightly jerky motion.

If the TV was sold in the UK I suspect it will be 50/60Hz refresh (though some early plasmas were fixed at 60Hz and looked horrible with standard TV...) Suspect you are right about the processing... If you can borrow a Blu-ray player or PS3 you could try those to check it isn't a 'funny' with the WDTV Live and 24p though.
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