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Last Update: 2012 Jan 16

SUMMARY

Do you need a TV that is 4:4:4 Chroma Capable?


Do you only use your TV for watching TV/movies and playing console video games? Then NO, you do not need a 4:4:4 capable TV.


Do you use your TV as a PC monitor or play PC video games? Then YES, it is strongly recommended you use a 4:4:4 capable TV.


For a list of TVs that can or cannot do 4:4:4, see post #2 in this thread.

INTRODUCTION


Using TVs as PC monitors is becoming increasingly popular. In my opinion, the two biggest factors that makes a TV a good PC monitor is 1) low input lag, and 2) 4:4:4 chroma support. Unfortunately, both capabilities are never published in TV specifications, so the only way to get a definitive answer is through testing.


Thanks to frito and his “Input lag wars!” thread, input lag awareness and discussion is widely available. Lately, there has been a lot of 4:4:4 discussion within frito’s input lag wars thread, but it’s beginning to “pollute” that thread’s original intent. So to clean things up a bit, this thread was created to establish a centralized thread for 4:4:4 chroma discussions.

THREAD PURPOSE


I anticipate this thread to be akin to frito’s input lag thread, but with emphasis on 4:4:4 chroma discussion instead. The first few posts will consist of three components:
  • Overall background on chroma subsampling. This will describe *what* chroma subsampling is all about and describe some use cases where 4:4:4 chroma support is preferred.
  • A FAQ for answering the most common questions regarding 4:4:4 capability, testing, and troubleshooting.
  • And finally, a list of TVs with proven 4:4:4 capability. See post #2. (Note: I’ll keep the list up-to-date as long as I can).
After that, as long as its 4:4:4 related, anything goes. Also, by no means am I the authoritative source on all chroma subsampling matters. I’m still learning as I go. So if you find a mistake, or think of something else that needs to be included here, please let me know. Other than that, let the fun begin!


BACKGROUND

B1) What is Chroma Subsampling?


Wikipedia explains chroma subsampling very well, so I’ll defer you to there: link .


In summary… Chroma subsampling is a process where color information (a.k.a., chrominance or chroma) is sacrificed in order to reduce bandwidth. Why sacrifice color information? It’s because of the limitations of our eyes. The human eye has poor color acuity for detecting color details -- especially on a moving object.


Chroma subsampling sounds like an awful idea, but think it in terms of individual pixels (which is the level where subsampling works its magic). Let’s say you have a column of bright-red pixels and another adjacent column of dark-red pixels. With subsampling, you’ll end up with two columns of bright-red pixels instead. Unless you sit 1 cm away from your TV and have the eyes of a hawk, it’s highly unlikely you can detect the difference. Compound the fact that typical video footage is a series of different images being displayed at a rate of 24/30/60 fps, subsampling becomes imperceptible to the human eye.

B2) What does “4:4:4” (or 4:2:2 or 4:2:0, etc) mean?


Again, Wikipedia explains this very well with illustrative examples: link . For more technical descriptions, check out these pages: link1 , link2 , link3 .


For you audio-visual learners, this youtube video explains the nomenclature very well too: link .


To sum it up, 4:4:4 means no subsampling is used at all -- so your image is displayed in its purest form. Anything less than 4:4:4 means original color information is lost.



B3) I want to “future-proof / feature-proof” my TV as much as possible, do I still need 4:4:4?


Unless you have future plans on using your TV as a PC monitor, you still do not need a TV with 4:4:4 capability. Why? Because all commercial video footage (OTA TV, Cable, Satellite, Blurays, DVDs, Camcorders, etc) is already subsampled at the recording source. So there’s no point owning a 4:4:4 TV if you don’t have any 4:4:4 material.


In regards to modern game consoles like the Xbox360 and Playstation3, they *should* be able to produce 4:4:4 material (they’re essentially computers, after all). However, I have yet to find anything definitive on this topic. But for the sake of argument, let’s assume game consoles are 4:4:4 capable. With games updating at a rate of 30/60 fps, detecting pixel differences between 4:4:4 and non-4:4:4 under normal viewing conditions is impossible. So 4:4:4 or non-4:4:4 on game consoles becomes irrelevant.

B4) Why do TV / Movie studios do chroma subsampling?


For the most part, it’s because of modern limitations in data storage capacity and transmission bandwidth.


For example, all blurays are subsampled down to 4:2:0 at the mastering studio (this is according to official bluray spec). As a result, most bluray titles have an average video bitrate of 25 Mbps. Assuming a 2 hour movie, you need a storage medium that can hold ~22.5 GBytes; which a bluray disc can do no problem. Now lets do 4:4:4 (no subsampling) on that same 2 hour movie. Going from 4:2:0 to 4:4:4 quadruples the amount of information required. So that 25 Mbps becomes 100 Mbps, and 22.5 GBytes becomes 90 GBytes; not even a dual-layer bluray disc can hold that much data.


If a bluray disc can’t hold it, don’t expect satellite/cable/fiber to transmit this kind of data either.


Note: the numbers used in this example are under review; will update when straightened out

B5) Is a TV with 4:4:4 capability *REALLY* that important for a PC monitor?


This is a really delicate matter, as results will vary vastly across different TV brands, TV models, manufacturing variances, anti-glare coating, lighting conditions, your own vision acuity, etc.


The general consensus is that without 4:4:4 capability, only red/orange/yellow colored text will be blurry. However, in my personal experience, *everything* looks blurry and slightly off without 4:4:4. Picture quality is obviously subjective, but based on my A/B test (A = LG LD450 with 4:4:4, B = LG LD450 without 4:4:4), there is a clear night-and-day difference between the two.


Describing quality differences through words is difficult, so I will let pictures do the talking instead. Here are some A/B comparisons between 4:4:4 and non-4:4:4. All pictures were taken under identical conditions without any post-manipulation (except a resize function).
  • Test 1: Windows Gadget Network Meter (reference image: link )
    • Light-blue and green text on black background - result
    • White and orange text on black background - result
    • Light-blue text on black background - result
  • Test 2: CNN Home Page (reference image: link )
    • White text on red background - result
    • “Real life” image - result
    • Black text on white background - result
  • Test 3: Chowhound Home Page (reference image: link )
    • Black text on yellow background - result
    • Bolded red text on white background - result
    • Regular red text on white background - result
  • Test 4: Hardforums Forum Page (reference image: link )
    • Text graphic (White text w/ black shadow on orange background) - result
    • Underlined bold orange text on dark gray background - result
    • Underlined regular orange text on dark gray background - result
From the examples, you can clearly see quality differences (except for the “real life” image). The differences are even more pronounced in-person. So is 4:4:4 a necessity? I certainly think so, especially when it comes to text.

TESTING AND TECHNICAL

T1) How do I know if my TV is 4:4:4 capable? -OR- How do I test for 4:4:4 capability?


Unfortunately, 4:4:4 capability is never listed in the spec sheets. So the only way to determine 4:4:4 capability is to test it yourself.


There are three ways of determining 4:4:4 capability: one is the quick-and-dirty / red-magenta method, the second is the Belle-Nuit method, and the third is the bspvette86 method.
  • Quick-and-Dirty Method (a.k.a., Red-Magenta Method): Open the image found here: link . Make sure you’re at 100% zoom, and pay special attention to the Red and Magenta columns. On a 4:4:4 TV, the “Red” and “Magenta” text will be nice and sharp just like the text in the other columns. On a non-4:4:4 TV, the “Red” and “Magenta” text will be noticeably fuzzy, but the text in the other columns will be nice and sharp.
  • Belle-Nuit Method: Open the image found here: link . Make sure you’re at 100% zoom, and pay special attention to the area with the red/cyan columns (to the left of the “20”). On a 4:4:4 TV, each red/cyan columns will be perfectly 1 pixel wide. On a non-4:4:4 TV, the red/cyan columns will have alternating thickness – some would be 1 pixel wide while others would be 2-3 pixels wide. Note: for the Bell-Nuit test, you may need a magnifying glass or macro lens to see the pixel widths clearly.
  • bspvette86 Test: Forum member bspvette86 has created his own 4:4:4 test pattern, and you can find it here: link . On a 4:4:4 TV, every horizontal and vertical line is exactly one pixel in height and width, respectively. On a non-4:4:4 TV, pixels will appear faded and/or duplicated -- this is most noticeable with the red, blue, and magenta lines. Note: for the bspvette86 test, you may need a magnifying glass or macro lens to see the pixel widths clearly.
To give you an idea of what 4:4:4 and non-4:4:4 results should look like, check out these three examples: link1 , link2 , and link3 .

T2) My TV is said to be 4:4:4 capable, but its failing the 4:4:4 tests, what’s going on?


The easiest fix is to use a DVI->HDMI cable to connect your PC to your TV. In some rare cases though, a DVI->HDMI connection will still cause 4:4:4 to fail. Additional details on this will be discussed in question T3.


For some TVs, you have to set specific TV settings to enable 4:4:4 capability. These include things like switching to special picture modes (i.e., “Game” or “PC” mode) or relabeling your input ports. If your TV has these types of settings, give it a try and see if it passes the 4:4:4 tests.


For the TVs that have already been tested and require these special tweaks, I’ll be sure to note them in the 4:4:4 TV list.

T3) I’m using a DVI->HDMI cable, but I’m still failing 4:4:4, what’s going on?


Unfortunately, I don’t have a technical explanation why this happens to some people. The popular theory is that during the EDID exchange between video card and TV, the HDMI audio extensions becomes enabled over DVI. When HDMI audio extensions are enabled, *something* causes 4:4:4 to fail. I have no idea if this is a TV issue, or a video card issue, or a HDMI issue, or an EDID specification issue, or a combination.


The good news though, there is a fix that has a high success of getting 4:4:4 working again over a DVI->HDMI connection. This fix is commonly known as the EDID Override fix or the Disable HDMI Audio fix, which will be described in [the next question].

T4) What is the EDID Override fix? -OR- What is the Disable HDMI Audio fix?


The EDID Override fix (a.k.a., Disable HDMI Audio fix) disables the HDMI audio extensions after the initial EDID exchange takes place. I don’t know the technical details on why this fix works, it just does.


So how do you install the EDID Override fix? The Internet is littered with mini- How To’s, but the two that I’ve found to be the easiest to understand (even for those not technically savvy) are:Note1: Both walkthroughs achieve the same result, they just have different approaches. So go with whichever one you think easier. I personally prefer the currysauce way.


Note2: Both walkthroughs are written for nvidia video cards, but it’s the same for amd/ati video cards too.

T5) Is there an EDID Override fix for Linux PCs?


Yes, there is. Check this out: link .

T6) I want to use a HDMI->HDMI cable (because I want HDMI audio), can I still get 4:4:4?


From my experience and observations, the answer is no. As mentioned previously, *something* relating to HDMI audio extensions causes 4:4:4 to fail. Only by disabling the HDMI audio extensions (via a DVI->HDMI cable and/or EDID Override) will 4:4:4 become enabled.


There was some detailed discussion about this issue in the LG LD450 thread between galneon and a few others (starting at post #800 and ending at post #878), but nothing was ever conclusively determined.


If anyone has insights to this matter, then please let us know. If we can isolate the problem and develop a fix, then a lot of folks would benefit from it.


Note: with some 2011 TVs (ex., Sony HX729 and Samsung D6000), 4:4:4 is available even if HDMI audio is enabled. Hopefully this will become the norm and we'll see more 4:4:4 + HDMI audio TVs in the future.

T7) I want to take a chance on an untested TV. Are there features/indicators that will increase my probability of finding a 4:4:4 capable TV?


Generally, TVs with fancy features like 120+ Hz frame interpolation and dynamic image processing will not be 4:4:4 capable. These TVs are designed to manipulate the image, and therefore may be “hard-coded” with features that prevent 4:4:4 rendering. So go for the TVs that are minimalistic as possible (in other words, the cheap TVs).


I want to reiterate that this is only a rule-of-thumb. There does exist feature rich TVs that are indeed 4:4:4 capable. One prime example is the Sony EX720 series.

OTHER LINKS OF INTEREST


Here's a few other threads about 4:4:4 I've found. Most are inactive now, but still good sources of archival data. Special thanks to each thread's respective author.


- LCD Televisions with 4:4:4 Subsampling and low Input Lag (still active)

- input lag wars! (there's a lot of 4:4:4 info sprinkled throughout, but please keep 4:4:4 discussions in this thread and not over there)

- 4:4:4 Chroma Sampling - Questions

- 4:4:4 Chroma needed for HDTV as a computer monitor?

- Who can name a Panasonic TV that achieves full chroma resolution (4:4:4)?
 

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Discussion Starter #2
Last Update: 2012 Mar 11


Note1: A different size of the same model should theoretically have the same PASS/FAIL result.

Note2: If you find a mistake in the list, let me know.

4:4:4 PASS/FAIL Television List


For the "Proof" column, P = photographic evidence and A = anecdotal evidence. P evidence trumps A evidence.

YearBrandModel4:4:4ProofNotes
2007LG37LB5DPASSA1None
2007LG47SL90PASSP1None
2008SamsungLN40A650PASSA1PC mode required
2008SamsungLN46A950PASSA1PC mode required
2010InsigniaNS-32E570A11PASSP1a / P1bNone
2010LG32LD450PASSP1None
2010LG42LD450PASSP1None
2010LG42LD520FAILA1 , P1None
2010LG??LD550FAILA1None
2010LG??LE5400PASSA1 , A2None
2010PanasonicTC-L42U25FAILP1None
2010RCA40LA45RQFAILP1None
2010SamsungLN40C630FAILP1None
2010SamsungLN??C650PASSA1Set input port label to PC
2010SharpLC-40D68UTFAILP1None
2010SharpLC-46LE810UNFAILP1None
2010Sony32EX500FAILP1 , P2Only EU/UK version (w/ Bravia Engine 3) supports 4:4:4
2010Sony32EX700PASSA1Graphics mode required
2010Sony46NX711PASSA1Game mode required
2010Sony??HX909PASSA1 , A2 , P1Game mode or PC mode required
2010Toshiba40G300UFAILP1None
2010VizioM260MVPASSP1None
2010VizioXVT473SVFAILP1None
2011DynexCX-32L230A12PASSP1a / P1b / P1cService menu has advanced tweaking options (RGB Gain/Offset, Sharpness, etc); info here - link
2011JVCJLC37BC3000FAILP1None
2011LG32LK450PASSP1None
2011LG42LK450PASSA1, P1 , P2 , P3Both S-IPS and VA panels pass 4:4:4
2011LG47LV5500FAILA1None
2011LG47LW5300FAILA1None
2011PanasonicTC-L32U3FAILA1 , P1None
2011Philips47PFL4606H/12PASSA1PC mode required
2011SamsungLE32D550FAILP1European version of the LN32D550
2011SamsungLN32D550PASSP1 , P2Set input port label to PC/DVI; Will only pass belle-nuit test if Black Level = Low.
2011SamsungUE40D5000PASSP1PC mode required
2011SamsungUN32D6000PASSP1Set input port label to PC. Also supports 4:4:4 + HDMI audio through a HDMI->HDMI connection.
2011Sony32EX720PASSP1Game mode or Graphics mode required
2011Sony32EX723PASSP1a / P1bGame mode or Graphics mode required
2011Sony46HX729PASSP1Graphics mode required. Also supports 4:4:4 + HDMI audio through a HDMI->HDMI connection
2011Sony55BX520PASSA1Game mode or Graphics mode required. Also supports 4:4:4 + HDMI audio through a HDMI->HDMI connection
2011WestinghouseVR-3225PASSA1 , P1None
2011WestinghouseVR-3280PASSP1None
2011WestinghouseVR-3730PASSA1None
2011iSymphonyLC32iF90FAILP1None

The following table is for plasma televisions. I won't spend too much time researching this table, but I'll update it with any info that comes across my way.

YearBrandModel4:4:4ProofNotes
2008PioneerPDP-5020FDPASSA1PC mode required
2011PanasonicTC-P50ST30FAILP1None
 

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Quote:
Originally Posted by thepoohcontinuum /forum/post/21386798


post reserved #2

Nice job so far. Certainly has made a few things clearer to me. Looking forward to the next installment.
 

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Let me begin the list: LG 47LW5300 - 4 2 2 is the best I can get. I'm using DVI to HDMI cable.

And let's get some thing straight, sometimes full chroma is important in games as well. For example I like to play flight simulator games like FSX and reading small gauges is important, but guess what? They're hard to read when color is subsampled. Anyhow, just looking at the desktop with subsampled chroma is an eyesore, especially on gorgeous 40-50 inch screen and that's good enough reason to keep this going, at least for me. Thanks for starting it.
 

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I think you made a mistake in your data rate calculations. If I remember correctly (and I could be wrong, it's been few yrs since I study this) you only need 3 values for each pixel: value for R, G, B and from that you can calculate luma, or you can have luma and B and G, from that you can calculate R. So from your 8 pixel example you need 8*3=24 bytes for full RGB signal and you need 8+2=10 bytes for chroma 4 2 0. So now your original 25 GB subsampled movie would become 60GB full RGB version, not 100GB, or whatever the original file size you used in your sample (file size *2.4). The difference should be 1/3 with chroma 422. So the file is bigger but I think not as much as you stated.
 

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Discussion Starter #7

Quote:
Originally Posted by pete4 /forum/post/21387478


I think you made a mistake in your data rate calculations. If I remember correctly (and I could be wrong, it's been few yrs since I study this) you only need 3 values for each pixel: value for R, G, B and from that you can calculate luma, or you can have luma and B and G, from that you can calculate R. So from your 8 pixel example you need 8*3=24 bytes for full RGB signal and you need 8+2=10 bytes for chroma 4 2 0. So now your original 25 GB subsampled movie would become 60GB full RGB version, not 100GB, or whatever the original file size you used in your sample (file size *2.4). The difference should be 1/3 with chroma 422. So the file is bigger but I think not as much as you stated.

Somewhere online, I read a brief statement that said going from 4:2:0 to 4:4:4 meant quadrupling the bandwidth. Although admittedly, your explanation sounds much more plausible. Let me read a bit more on it and I'll update accordingly. Thanks for the heads up!
 

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Come to think of it no matter how you send the data, 1/4 data rate with chroma 420 has to be wrong. Color info alone is 4 times higher in 4 4 4 than in 4 2 0, right? But in each case full luma (black and white info) is send as well. So when you add luma and chroma together the ratio has to be less than 4 times.
 

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As far as I know that only means TV can receive that data format, it doesn't mean it will display it without downsampling. My video card tells me it sends YCbCr 4 4 4 or RGB 4 4 4, but screen shows 4 2 2. BTW on mine RGB looks better, but still dowsampled.

Quote:
Originally Posted by mcantu1 /forum/post/21388003


how about checking the EDID for 4:4:4? mine says, 'Supports YCbCr 4:4:4..... Yes'
 

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First of all, thanks for great thread.

AFAIK, PC mode for HDMI input means RGB and all the others mean YCbCr. And "PC monitor" means RGB I'd guess.

Here is a question:

T8) What if I have 2 separated connections from one ATI card:

- DVI - HDMI: TV (not a "proper" DVI-HDMI adaptor w/o sound. Picture only)

- HDMI - HDMI: AVR (sound only)

?

OK, I'll check later by myself, but can't promise a pics.
 

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PC "mode" or input on a TV usually means it will interpret video data as "PC video levels", e.g. 0 is black and 254 is white. Depending on the TV it may or may not accept YCbCr since RGB is what PCs use. If it does accept YCbCr, then it still probably expects PC video levels.


larry
 

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For my LG LCD "PC" means RGB and High Black level gives 0-255, Low Black level gives 16-235.
 

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Quote:
Originally Posted by Qaq /forum/post/21388435


T8) What if I have 2 separated connections from one ATI card:

- DVI - HDMI: TV (not a "proper" DVI-HDMI adaptor w/o sound. Picture only)

- HDMI - HDMI: AVR (sound only)

?

OK, I'll check later by myself, but can't promise a pics.

A) 4:4:4 (at least Red & Magenta are OK). TV in PC mode. Sorry, can't make a pics (batteries are low).
 

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Discussion Starter #15

Quote:
Originally Posted by mcantu1 /forum/post/21388003


how about checking the EDID for 4:4:4? mine says, 'Supports YCbCr 4:4:4..... Yes'

As pete4 mentioned, this is an unreliable method for checking 4:4:4 capability. The Panasonic E3/U3 reports the same "Supports YCbCr 4:4:4..... Yes", but its been said by a few folks that it doesn't truly support 4:4:4.
 

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By the way :

Quote:
Unfortunately, I don’t have a technical explanation why this happens to some people. The popular theory is that during the EDID exchange between video card and TV, the HDMI audio extensions becomes enabled (even though DVI is incapable of audio)

I have LK450, DVI-HDMI cable, Nvidia video adapter. Nvidia Control Panel shows "Connector : HDMI-HDMI" and there's audio. Of course, as expected, 4:4:4 is disabled. With EDID override audio is disabled and 4:4:4 is enabled.
 

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Quote:
Originally Posted by JoshZH /forum/post/21390164


By the way :


I have LK450, DVI-HDMI cable, Nvidia video adapter. Nvidia Control Panel shows "Connector : HDMI-HDMI" and there's audio. Of course, as expected, 4:4:4 is disabled. With EDID override audio is disabled and 4:4:4 is enabled.

Is that nvidia video adapter some sort of nvidia-proprietary adapter that overlays audio over a DVI interface/signal? Because I don't think DVI officially supports audio.
 

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Quote:
Originally Posted by thepoohcontinuum /forum/post/21390282


Is that nvidia video adapter some sort of nvidia-proprietary adapter that overlays audio over a DVI interface/signal? Because I don't think DVI officially supports audio.

It's GTX 400 series.


Did a quick google search :

Quote:
Note that some graphics cards now are spitting out audio over the DVI connection. I have a GTX 460 which comes with audio drivers, connected with a simple DVI to HDMI cable, and I've got sound on both a TV and monitor via this setup.
http://www.cnet.com.au/does-dvi-carr...-339270821.htm


So i'm not alone.
 

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ATI does it too. DVI not supposed to support audio, but somehow ATI does it. I don't remember anymore if all you need is DVI to HDMI cable, or you need special adapter from ATI (DVI to HDMI) and then HDMI to HDMI cable. I may need to figure this out soon since my older TV had DVI port with RCA sound, the new one has only HDMI.

The ATI port itself seems standard DVI.
Quote:
Originally Posted by thepoohcontinuum /forum/post/21390282


Is that nvidia video adapter some sort of nvidia-proprietary adapter that overlays audio over a DVI interface/signal? Because I don't think DVI officially supports audio.
 
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