White Level - Can't see moving bars - Page 4

I think you had 1 or 2 good points there Chris its all about keeping an open mind "Verses" A closed mind .....

While I get the point of a good technical discussion, the stakes just aren't high enough warrant this much emotion. One discussion in the AVS forum is not going to change the nomenclature everyone uses to describe this condition. Call it clipping. Call it a "run out". As long as we all understand the condition we mean we can have productive conversations here.

Anybody would have to admit that this statement is absurd. I have been following this thread (if nothing else for the drama) and this statement can't possibly help your case.


I hate to tell you this, but having tbrunet agree with you is not a good thing. He basically trolls Chris because Chris has proven his ideas wrong in the past. As abrasive as Chris is, he normally doesn't get into discussion without knowing ahead of time that he is correct... I have to give him that much.

There has been review as in "Don't you think it is odd to say a passive device can clip?" and "Can you think of any other passive devices that are said to clip?" Yes, and no, respectively, are the general responses (paraphrased). But when the question is posed "Do you think it's possible to get people to stop using "clipping" in reference to a passive device like a light valve controlled video display?" The typical answer boils down to "too much inertia".

Considering you and Chris are obviously unable to even comprehend what actually define IRE..

Chris's Source Settings Guide
http://www.avsforum.com/avs-vb/showt...89#post4969789
“An IRE simply a representation of volts”

That statement by Chris is false:
Now apparently Chris can't even grasp how simple passive devices fundamentally operate

According to Greg Rogers you don't even comprehend the "definition" IRE units. I've corrected your misunderstanding in the past and still your Source Settings Guide is wrong!

Your attempt at correcting Doug use of technical terminology is literally the preverbal:

"Pot calling the Kettle black"

How exactly are you using the second quote to disprove the first?

Even gregr, who you use so often to point out that we know nothing about IRE, disagrees with your use of terminology.

http://www.avsforum.com/avs-vb/showt...6#post13491136

I swear you make half of this crap up just to try to get a rise from people.

IRE are not simply “Volts”, but rather a relative linear scale representing percent (%) luminance from the blanking level to reference white.

Actually Greg is spot on about the nature of IRE's and you btw are trying to cloud the issue. You and Greg did not grasp that I was referring to "ANY" hypothetical (%) IRE value. In retro I see how it was misinterpreted, but the following quote by Greg supports my position 100%..pun intended

IRE can simply be unnecessarily confusing when the source is always typical video material, for example http://www.avsforum.com/avs-vb/showt...6#post14173946 For the purpose of this forum, many people have no real need to ever be introduced to the IRE term because a black to white percentage reference with less ambiguity regarding video levels can be used. For the purpose of communication, sometimes simple definitions like "Clip (v) Forcing a signal to a certain maximum (or minimum) level, so as to avoid excursion above (or below) that level" can be beneficial so that there is a clear reference to what is being discussed.

In an analog video system, IRE is "simply" a measure of voltage.

You can apply IRE to just about anything you want, but in the context of analog video signals (which is the context of the Source Settings Guide), IRE is "simply volts."

I don't know why I even bother with this. All you are going to do is take a bunch of quotes out of context and twist them to your liking.

Since theres no digital video formats in the consumer domain that contain or encode (7.5%) setup, the digital "%" level and the IRE value will be the same.

How does that quote not also support the position that "IRE is simply volts" for an analog system. All it basically says is that you can determine what 75 IRE represents if you are given all of the other contextual information that is needed.

Avia labels black 7.5 IRE, not 0 IRE. Depending on how the end-user uses a calibration disk, black could be said to be output at either 7.5 IRE or 0 IRE. That does not match what you said, so how is that not generally confusing?

Strictly speaking the information is actually YCbCr, but for simple understanding no one labels things that way. Of course everything I've brought up so far can be altogether avoided if black is defined as 0% and white as 100%. The latter percentages are simply far simpler to communicate to an end-user than getting into either what IRE or YCbCr mean. This is the same point I was making with Doug's attemps at a more complex definition of clipping, for the purpose of this forum it's simply not necessarily important to have all that information and a simple definition works for the task at hand.


You're so full of it, but I think you're amusing none-the-less. Like I said the information is YCbCr and understanding IRE brings nothing to the table for a general end-user calibration. As you've said in some contexts 0 IRE matches 0%, but when it comes to outputting from a player 0% is less ambiguous because black can vary when using the IRE term. So with percentage you have a defined level if you know the source, but with IRE you have to know how things are output which introduces uncertainty. Like I've offered before, if I'm dead wrong then by all means please enlighten me as to how IRE is so "profound".

The disc (lable) is broken by design!

From Tektronix Standards:
"Eventually the IRE (later to be the IEEE) established a unit of measure for video signals. This "IRE unit'' was defined as 1% of the video range from blanking to peak white, without reference to the actual signal voltage."

Note theres no reference to pedestal or setup amplitude.

(Y)Luminance or (Y')Luma, it makes no difference, the IRE measure is relative one.

Not exactly, because with default settings most players don't output an analog signal at 0 IRE. While I personally don't use connections like component, some people still do so there are cases where the Avia disk is correctly labeled in the way IRE has been commonly used. If they were to instead use 0 IRE for labeling then there would be cases that the player would output a commonly defined 7.5 IRE level for black even though the disk reads 0 IRE. In your championing of IRE I still fail to see how setup doesn't come into play, but in contrast that item never arises if using percentages from black to white. I think you're again fighting for a losing cause, but I did read through everything Doug wrote.

Do you know what the definition of an IRE is?

From Tektronix Standards:
Eventually the IRE (later to be the IEEE) established a unit of measure for video signals. This "IRE unit'' was defined as 1% of the video range from blanking to peak white, without reference to the actual signal voltage.

Guys, let it go. You will never convince thomas of anything. Greg Rogers and Guy Kuo tried to explain some very basic things to him, and he accuses them of not knowing what they're talking about either.

All engaging him will do is drag a thread into the mud and get it closed.

You can add him to your ignore list instead:
http://www.avsforum.com/avs-vb/profi...nore&u=7507853

This part I bolded scares me. Is he teaching students his ideas?

Or maybe he just meant he works in the custodial arts as a hydro-ceramic engineer!?

See another term that has to be defined - blanking. Okay, so blanking is 0v in an analog output. So if the player outputs an analog signal with a setup of 7.5 IRE, then black is 7.5 IRE. That matches Avia, but again you said that Avia's label was broken by design and black should be 0 IRE. Well then if black was labeled zero IRE, but black was at 7.5 IRE then the label would no longer be corrent. My best guess is that by your logic this situation about how one IRE label would always be incorrect in certain situations depending on the end-user must be why IRE is so "profound."

No, blanking on those shinny disc you call DVDs is equal to black level.

Setup was necessary for the real world limitations of terrestrial broadcast transmitters. Whether or not your DVD player adds setup is irrelelvant with respect to the encoded signal amplitude.

0IRE = DIGITAL 16 (8-bit) = 0% Stim

100IRE = DIGITAL 235 (8-bit) = 100% Stim

EDIT/
Note to self: Maybe Guy Kuo should take some notes on the subject matter

Since when is a display a passive device? Since when is an LCD a passive device?

A passive device would be like a screen. That won't clip anything, and you're right that it won't because it is passive. We haven't been discussing passive devices. We've been discussing electronics, specifically displays and their behavior. And nothing we've discussed is passive.

Unless you're talking about the hughes-JVC ILA displays from way back that were CRT-driven, I'm not sure how in any way you could characterize anything we've discussed as passive. There's nothing passive about it.

IRE, as exactly defined by your quote, ultimately depends on how the information is output. If the player adds setup in an analog situation, then the black level in IRE terms changes. In percentage terms black level remains the same when the player adds setup, but when the player adds setup once again very clearly the IRE changes. So the percentage label is always correct by definition, and with IRE the label is either correct or incorrect depending on how the player used. By a very strict definition of the media as what is being labeled, sure black is at 0 IRE, but when a definition breaks down in use its counter-productive to use the strict version when a simpler one works for the ultimate task at hand. Like I said if the most strict definition was beneficial, then you might as well have all calibration disks labeled with YCbCr because that's actually what they contain.

What a given player does will not reverse engineer itself onto the calibration disc nor "change" the encoded levels.

During production its possible to raise the encoded (image) master pedestal (1%, 4%, 7.5%, 20%, ect) above the blanking level, this release for example has that relative IRE level effectively embedded into the media.

Avia is mistaken when they produced a disc with a 7.5% lable when in reality 7.5% setup was NOT encoded.

LOL

If one can encode 75 IRE then the same is true for 7.5 IRE

Some players do use the IRE term for their analog black level settings. So it's unnecessarily confusing for most people to ever learn how the player might typically have black at 7.5 IRE and the media could be said to have black at 0 IRE. That just brings up questions like - well if the media is at 0 IRE shouldn't I use the 0 IRE setting on the player? Then you have to explain about NTSC levels, and how after using NTSC levels that if the disk was labeled by how you want then even though that's not the NTSC standard that the output doesn't match the disk's labels. Like I said, ultimately from a simple-to-understand perspective if the player adds setup then black could be said to be at 7.5 IRE from the player. The first Avia disk came before digital consumer connections, so this sort of labeling a typical analog output was reasonable from a practical general-end-user perspective even if it's not a strictly by-the-book match.

What some players do or whats confusing for most people is irrelevant to the fundamentally correct technical "definition" of the unit in question.

The same level of detail is true with respect to Doug Blackburn's succinct explanation regarding engineering terminology.

I couldn't disagree more. Avia is a company and I seriously doubt they're not-for-profit. Their ultimate bottom-line is to produce and sell a product. If the product is too confusing for the target audience then that goes against their #1 intent of producing and moving a product. I'm not thrilled by how they use the term saturation differently than TomHuffman's guide, but they do define their term so I figure they probably give further details on their labels somewhere.



I don't think Doug ever offered a succinct definition, but again likewise with as basic question as what was asked to start this thread Doug's definition offers no value to someone asking such a question.

Not only did Doug give a clear definition, but he walked you through step by step how the LCD fundamentally operates and one artifact in particular. If you managed to miss this, that in itself is quite revealing!