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White Level - Can't see moving bars - Page 8

post #211 of 261
Greg thanks for quoting (Table in Figure 2) Michael Robin like I requested. Seems you now use the adjective "erroneous" to describe his mathematical prowess. Greg whats apparent IS you don't actually comprehend how a Multi-Standard digital waveform monitor aligns with a 0-700mV graticule.

According to Michael I’m spot on about the 700mV p-p amplitude correlation between nominal (16-235) Y' for ITU-R BT.601 8-bit video. NO? Please quote the section where I'm misrepresenting the BE Mag article!

Can you suggest just one manufacturer of Digital waveform monitors that will NOT show a RGB or Y,CB,CR industry standard color bar signal that’s not 700mV p-p.

Thanks in advance.
post #212 of 261
Do you really not understand the major conflict here? You said:

Quote:


601 mapping specifies that video black (0mV) is assigned a value of 16, and video white (700mV) a value of 235

That statement is flat-out false because of the word specifies and the mV terms. Rec 601 does not use those mV terms. If you take out the mV items the statement is true, with the understanding that you're talking about digital decimal values. Not everyone in a forum titled "display calibration" only deals with the one specific context you seemingly believe applies to every context.
post #213 of 261
Quote:
Originally Posted by alluringreality View Post

If you take out the mV items the statement is true, with the understanding that you're talking about digital decimal values.

I've already thrown down my gauntlet above (Post 211). I've specified decimal" probably ten times already.. so give that up. I won't even waste my time and quote myself.. the un-edited evidence is documented in the thread.

Alluringreality,

The now infamous (Figure 2) in the Broadcast Engineering article, Michael Robin clearly notes DECMIAL & HEX. There's no getting around both mathematical expressions which validate the fact (SD) ITU-R BT.601 or (HD) ITU-R BT.709

"defines the 8-bit Y' decimal value 235 = 700mV"
post #214 of 261
Quote:
Originally Posted by tbrunet View Post

the fact (SD) ITU-R BT.601 or (HD) ITU-R BT.709

"defines the 8-bit Y' decimal value 235 = 700mV"

As far as I know the ' refers to gamma adjustment, which doesn't apply to digital values in those standards. I really have no idea how it's so difficult to get that the quoted portion is false due to the inclusion of the mV term and lack of definition for that term within the quoted standards. Yes it's possible to define how 700mV can be equal to digital 235, but Rec 601 doesn't do that.


Quote:


I won’t even waste my time and quote myself..

Outstanding, quoting tbrunet is something we can definitely agree on.
post #215 of 261
Quote:
Originally Posted by alluringreality View Post

Yes it's possible to define how 700mV can be equal to digital 235, but Rec 601 doesn't do that.

This does and the ITU-R BT.601 standard does as well:http://broadcastengineering.com/mag/..._video_basics/

"The mathematical expressions defining the ITU-R 601 & ITU-R 709 signal is given in Table 1. In both standards, the color-difference scaling factors were chosen to ensure that the signal amplitudes for a 100/0/100/0 color bars signal equal 0.7 V p-p."

Can either you are Greg go on the record and state one way or the other that Michael Robin the author of Digital Video Fundamentals is WRONG?

i.e. rather standard color bars (mV amplitude) should actually measure 1V p-p on my Digital Multi standard component Y,CB,CR or RGB WAVEFORM MONITOR?

Send questions and comments to: michael_robin@primediabusiness.com
post #216 of 261
Quote:
Originally Posted by tbrunet View Post

Can either you are Greg go on the record and state one way or the other that Michael Robin the author of Digital Video Fundamentals is WRONG?

I'll state that I have not and don't plan on commenting on Michael Robin's article. My comments were around your representation of Rec 601. The major item is that Rec 601 is generally based around gamma corrected signals from black to white of 0 to 1, which is relevant for example in its definition for quantization of Y from E'y. Certainly there are ways to get around this item and use different analog levels, normalizing component levels is one example, but characterizing Rec 601 as using 0 to 0.7V is just misleading. Anway, gregr said basically the same thing here http://www.avsforum.com/avs-vb/showt...5#post14287905 For what it's worth, the article does say "normalized (700mV p-p)" a few times.
post #217 of 261
It’s also apparent you don’t comprehend that the (') symbol represents gamma corrected (E) voltage. Your Berkeley ITU Rec 601 pdf uses the same (coefficients) mathematical expression to define ITU-R BT.601 thats in the BE Mag article..
http://inst.eecs.berkeley.edu/~cs150...nts/ITU601.PDF

2.4 Construction of Y,CR ,CB via quantization of , E’R, E’G, E’B

http://broadcastengineering.com/mag/..._video_basics/

And Michael’s Table 1
Quote:


Component digital signal characteristics of the ITU-R BT.601 and ITU-R BT.709 standards. Click here to see an enlarged diagram.

Is the same expression and coefficients look it up for yourself!
post #218 of 261
More specifically, your Berkeley ITU link Page 6
Quote:


Definition of the digital signals Y,CR,CB, from the primary (analogue) signals E'R , E'G and E'B

Quote:
Originally Posted by alluringreality View Post

As far as I know the ' refers to gamma adjustment, which doesn't apply to digital values in those standards..

..but characterizing Rec 601 as using 0 to 0.7V is just misleading

Please explain these statements?
post #219 of 261
Quote:
Originally Posted by tbrunet View Post

It’s also apparent you don’t comprehend the that a prime symbol correlates with gamma corrected (E) voltage.

I have no idea what this means or how it helps to advance productive discussion. It seems to me that in "8-bit Y' decimal value 235" the prime shouldn't be there, that's the point of what I said there.


Quote:


Your Berkeley ITU Rec 601 pdf uses the same (coefficients) mathematical expression to define the ITU-R BT.601 thats in the BE Mag article..
Michael’s Table 1

the same expression and coefficients look it up for yourself!

This is correct. That's why it's important to understand the range that Rec 601 works with. The main key of what I commented previously is normilization, which is one way for how the 0-0.7V signal can fit with the 0 to 1 range Rec 601 uses. If you were to directly use the 0-0.7V range then by section 2.3 Quantization the digital values wouldn't fit the intended range. For example if you plug 0.7 as white without normilization it results in a digital value of 169. Instead if you normailze a 0-0.7V signal you get 0-1 which then puts white at 235 by the quantization equation. Of course there are other ways to get the output to fit with the input, but this is probably the acutal method used considering his use of the term normalized.
post #220 of 261
Quote:
Originally Posted by alluringreality View Post

I have no idea what this means or how it helps to advance productive discussion. .

..but characterizing Rec 601 as using 0 to 0.7V is just misleading.

Oh please! It should have read..

"its apparent you don't comprehend the (') prime symbol represents gamma corrected (E) voltage"

1)Which SDTV or DVD or HDTV standard (8-bit) 100/0/100/0 color bar signal is not coded as 16-235?

2)Which 100/0/100/0 color bar signal will NOT measure as .7V p-p on 100% of the industry standard component RGB or YCBCR waveform monitors?

Have you ever heard of a component waveform monitor ever measuring a standard reference signal.. and have it indicate 1V p-p?
post #221 of 261
Quote:
Originally Posted by tbrunet View Post

Have you ever heard of a component waveform monitor ever measuring a standard reference signal.. and have it indicate 1V p-p?

Rec 601 doesn't necessarily refer to a 1V p-p like some of my earlier comments, but gregr had it right. While Rec 601 does say "e.g. 1.0 V maximum levels" at one point, generally it avoids any scale and is speaking of normalized values. In the case of a 0-0.7V black to white signal, I would think a normalized white would be 0.7V/0.7V=1. Based on reading Rec 601 and how Michael Robin's Table 1 matches Rec 601, I would have to guess that it's intended to be implicitly understood the values for Table 1 are normalized rather than actual 0-700mV considering how Rec 601 defines equations for quantization using those same terms.
post #222 of 261
Quote:
Originally Posted by alluringreality View Post

..but gregr had it right..

I beg to differ on many levels i.e. I asked Greg explicitly from the very beginning, probably ten times in three different threads.. the same rhetorical question:

Greg I need to color correct a given standard DVD production to be released. I would like to measure the YCBCR video black level. Are you saying I can't because it's digital and volts are not involved?
Quote:
Digital levels are not in volts. That's pretty damn elementary.

..The book (co-authored by Michael Robin) simply lists a few of the analog component video standards that prove you are wrong, as I have been telling you.

Quote: Michael Robin
Digital video is best defined as a means of describing the continuous analog video waveform as a stream of digital numbers.

Now I have to move on and do other things. Unless you are willing to post information that can directly disprove my position that all NTSC/PAL DVD, SDTV, HDTV (ITU-R 601 or R 709) 8-bit or 10-bit digital video, with nominal digital excursion Blanking - Peak Level actually represents a YCBCR/RGB .7V p-p analog waveform.
post #223 of 261
Quote:
Originally Posted by tbrunet View Post

disprove my position that all NTSC/PAL DVD, SDTV, HDTV (ITU-R 601 or R 709) 8-bit or 10-bit digital video, with nominal digital excursion Blanking - Peak Level actually represents a YCBCR/RGB .7V p-p analog waveform.

All you have to do is to look at Rec 601 for example to disprove such a statement; the 0-0.7V p-p you use is not the one and only available relationship. I could say the digital information represents 0-1V p-p with just as much validity. The reason for such a claim is that Rec 601 defines a relationship between normalized signals and the digital information. It's possible to take the normalized signal and equate it to any number of different analog voltage levels. It's possible to also relate the normalized levels to the 0-0.7V p-p you use, but that is not the only available relationship. What I'm saying is explicitly defined in Rec 601, and nowhere does it refer to 700mV.

Quote:


Digital video is best defined as a means of describing the continuous analog video waveform as a stream of digital numbers.

This is fine, but Rec 601 describes a normalized signal as a stream of digital numbers, rather than explicitly 0-0.7V p-p in relation to digital values. Because the standard uses normalized levels, it can relate to any number of different actual p-p levels. All of this has already been discussed in different ways, and yet somehow you still seem to contend that the one relationship your scope uses applies to all situations. Yes it is possible to define a step by step relationship for how 0-0.7V could relate to the digital information, but Rec 601 by itself does not define any such an explicit relationship of how only 0-0.7V would relate to 16-235. Please do not again refer me to Michael Robin's Figure 2, because it seems clear enough that you don't understand how it is that relationship comes about and that it doesn't apply to all situations.
post #224 of 261
Quote:
Originally Posted by alluringreality View Post

All you have to do is to look at Rec 601 for example to disprove such a statement; the 0-0.7V p-p you use is not the one and only available relationship..

It IS whats being encoded and NOT A 1V p-p video waveform.. please show me a link that depicts said 1V p-p defined event. Should be easy if it actually exist.

I've shown you the standard ITU-R BT.601 or ITU-R BT.709. With the accepted nominal .7V p-p waveform which correlates to the original master No sync allowed!
post #225 of 261
This is so silly, but here's an example of normilization of two different values.

350mV from a 0-700mV signal would be 350mV/700mV=0.5
500mV from a 0-1000mV signal would be 500mV/1000mV=0.5

In the case of the 350mV or the 500mV, the relevant information for Rec 601 (0.5) is exactly the same.
post #226 of 261
If you don't mind I would like a valid reference, if it exist there is a pic of said waveform. Also an explanation of how you truncated the 188.97mV extra excursion beyond 1-254, yet appear to recover it magically?

According to “Digital Video Fundamentals"

Nominal luma (Y') excursion is:

254 (decimal) +763.13mV
1 (decimal) -47.9mv

Total = 811.03mV

Please tell me how you can “encode” 1000mV in the ITU-R 8-bit payload?
post #227 of 261
Quote:
Originally Posted by tbrunet View Post

If you don't mind I would like a a valid reference

I've already given my reference for discussion http://inst.eecs.berkeley.edu/~cs150...nts/ITU601.PDF


Quote:


254 (decimal) +763.13mV
1 (decimal) -47.9mv?

There is no such universal definition like this quote that applies to every situation, which is the whole point of contention. The quoted statement is true in certain situations, but to say that it is the one and only relationship is false. In fact Rec 601 expects so many relationships that in the "Definition of the digital signals Y, CR, CB, from the primary (analogue) signals" section it even says "The method is given as an example, and in practice other methods of construction from these primary signals or other analogue or digital signals may produce identical results." So not only might Rec 601 be used for analog signals, but right there it says that it could be used also with a digital signal. Look, the long and short of all of this misunderstanding is that there is no universally fixed relationship such as the above quote based wholly on Rec 601 in the case of DVD.


Quote:


Please tell me how you can encode 1000mV in the ITU-R 8-bit payload?

Do you understand the 5th or 6th grade math example of normilization? The result of the division, the normalized level, is what the quantization equations in Rec 601 are based around. The quantization equation examples are not based on a fixed mV signal.
post #228 of 261
Quote:
Originally Posted by alluringreality View Post

There is no such universal definition like this quote that applies to every situation, which is the whole point of contention. .

alluringreality,

I'm going to break this down for you, ala 5th grade math

Let say we agree on a standard like the Rec 601 standard. This time we will call it SMPTE RP155. It's an audio standard:

-20dBFS = +4dBu = 0VU = 1.23V (RMS)

Please explain how one can encode i.e. 14 Volts (RMS)?..when

0dBFS = 12.28 Volts (RMS)
post #229 of 261
Quote:
Originally Posted by tbrunet View Post

Let say we agree on a standard like the Rec 601 standard. This time we will call it SMPTE RP155.

The suggestion of using a comparison is only another level of abstraction. The reason I am wholly focused on Rec 601 is to limit abstraction and try to be as specific as possible. I want you to focus on what exactly is stated, rather than what you believe is stated. That way maybe you can see that Rec 601 does not explicitly define for digital 235 being one certain peak white voltage.

Quote:
Originally Posted by tbrunet View Post

-20dBFS = +4dBu = 0VU = 1.23V (RMS)

This is a good example of one of my points, Rec 601 generally does not use terms like V. Insead Rec 601 defines quantization of a normalized input to digital levels. Because it works with normalized levels, there is no reference to specific V levels.
post #230 of 261
Quote:
Originally Posted by alluringreality View Post

...there is no reference to specific V levels.

Bull

Using an agreed upon standard to digitally sample a given ANALOG WAVEFORM, the amplitude is defined by said mathematical expression.

If one can measure it in the analog domain, then inturn when it's decoded using the SAME Y'CBCR math. the AMPLITUDE is the same. The digital part is transparent.

Capish
post #231 of 261
Quote:
Originally Posted by tbrunet View Post

Can I do something to make that reading higher???

No, you've already stated the representation your scope uses. Unless your scope allows for different settings for how to represent the digital information, then you'll continue to look at the information the way your scope represents it. To say that what your scope shows is somehow universal and a particular digital value always equals a specific intended mV reading regardless of all other conditions, that's what I am diagreeing with. Just because your scope represents digital information a certain way, in general it's false to take that representation and to make a universal claim that somehow digital 235 is always supposed to be equal to 700mV and digital 16 is 0mV regardless of any other factors.
post #232 of 261
Here's a link:

http://www.broadcast.harris.com/prod...p?sku=VSM_3901

The product can be configured for the different analog component standards. Look at the specifications at the bottom of the page.

Y Signal Level 700 mV or 714 mV (switchable, +/- 1 dB adjustable)
Pb, Pr Signal Level 934 mV (Betacam) or 700 mV (SMPTE) or 648 mV (MII)

Ron
post #233 of 261
Quote:
Originally Posted by dr1394 View Post

Here's a link:

Ron

Is this an example of ITU-R BT.601.


This is my 25+ year career that we are talking about

I don't care if your DVD player can't match exactly what been encoded. I'm not only telling alluringreality and Greg, but yourself included for the last time. My SCOPE (aka WF monitor) is CALIBRATED! I am using the defined ITU-R standard RGB/YCBCR mode of operation. Every time I call up a standard 100/0/100/0 color bar signal. It will measure .7V p-p or else the encoded signal is NOT nominal 16-235.

What do you think Ron, is my WF monitor calibrated?
post #234 of 261
Quote:
Originally Posted by tbrunet View Post

Unless you are willing to post information that can directly disprove my position that all NTSC/PAL DVD, SDTV, HDTV (ITU-R 601 or R 709) 8-bit or 10-bit digital video, with nominal digital excursion Blanking - Peak Level actually represents a YCBCR/RGB .7V p-p analog waveform.

I'm sure you know Harris Broadcast Communications is a world leader in SD/HD Broadcast equipment. Here is a link (http://www.broadcast.harris.com/prod...p?sku=VSM_3901) to the Harris VSM-3901 which converts 10-bit SDI digital video to analog YPbPr video. See the specifications on that page. It produces Betacam, SMPTE, or MII analog YPbPr output levels, just as I have told you (and shown you on page 121 of the very book that you cited as your reference). It converts SDI digital video to Y signals with 700 mV OR 714 mV levels. Note also that the Pb, Pr signal levels are selectable (934 mV, 700 mV, or 648 mV) for Betacam, SMPTE, or MII standards. There are many other similar professional/broadcast products that disprove your position that Rec. 601 digital video only represents 700 mV YCbCr levels. As I've also told you in the past, some DVD players were built to output Betacam levels (714 mV).

You have repeatedly said that Rec. 601 specifies 700mV analog YPbPr levels. You were given a link to a pdf of Rec. 601. You can not cite anywhere in Rec. 601 that 700mV is even mentioned. Yet you continue to post this assertion even when you now have Rec. 601 to read yourself.

There are people that come to the AVS Forum to learn about video. There are particularly people that come to this section, the Display Calibration section, that want/need to learn accurate information about video. The AVS Forum loses the great value it has as an information resource and a learning tool if someone repeatedly posts incorrect information. If I were a moderator I would have deleted this thread long ago.
post #235 of 261
Quote:
Originally Posted by dr1394 View Post

Here's a link:

http://www.broadcast.harris.com/prod...p?sku=VSM_3901 ...

Ron

Ron, I was typing and posted my reference to the VSM_3901 before I saw your post about the VSM_3901. Amazing. I didn't mean to repeat your example.
post #236 of 261
Greg Rogers is going on the record to say I can't measure the black level that I'm encoding onto a DVD because it's DIGITAL. He must first tell me what format it is going to be output in to determine what I'm doing to the signal?

MY SD-HD SDI Multi Standard waveform monitor is not calibrated to measure the ITU-R BT.601 video signal.


BTW Harris Broadcast Communications, I've had 120U transmitter training at their Quincy headquarters.
post #237 of 261
Quote:
Originally Posted by gregr View Post

Ron, I was typing and posted my reference to the VSM_3901 before I saw your post about the VSM_3901. Amazing. I didn't mean to repeat your example.

It's actually pretty cool. Great minds think alike!

Ron
post #238 of 261
Quote:
Originally Posted by tbrunet View Post

Greg Rogers is going on the record to say I can't measure the black level that I'm encoding onto a DVD because it's DIGITAL. He must first tell me what format it is going to be output in to determine what I'm doing to the signal?

That is not exactly what I said, so if you use my name provide exact quotes of what I said (in context). Nevertheless, it is true that you can't take the analog output of DVD player and determine what the digital signal levels on the DVD are unless you specify the standard used to convert from digital to analog output. That is obvious. You will obviously get different analog output levels from a DVD player that outputs Betacam levels or MII levels, rather than CEA 770.2 levels. Rec. 601 does not specify a specific digital to analog conversion.
post #239 of 261
Quote:
Originally Posted by gregr View Post

That is not exactly what I said, so if you use my name provide exact quotes of what I said (in context). Nevertheless, it is true that you can't take the analog output of DVD player and determine what the digital signal levels on the DVD are...

Quote:
Originally Posted by tbrunet View Post

Greg I need to color correct a given standard DVD production to be released. I would like to measure the YCBCR encoded (video) black level. Are you saying I can't because it's digital and volts are not involved?

Quote:
Originally Posted by gregr View Post

Digital levels are not in volts.That's pretty damn elementary.

..The book simply lists a few of the analog component video standards that prove you are wrong, as I have been telling you.

Then you went in detail to explain the Panasoinc MII standard or Sony Betacam standard'. What do they have to do with my job of mastering DVD content i.e. the blanking standard or how my video image relative black level and white level are measured?
post #240 of 261
Quote:
Originally Posted by tbrunet View Post

Quote:
Originally Posted by gregr View Post

That is not exactly what I said, so if you use my name provide exact quotes of what I said (in context). Nevertheless, it is true that you can't take the analog output of DVD player and determine what the digital signal levels on the DVD are...

That is a perfect example of completely distorting what I said by quoting part of a sentence without the complete context of the sentence. You left off the rest of the sentence ... "unless you specify the standard used to convert from digital to analog output." Do you comprehend the crucial meaning of the word "unless"? That as they say, was the last straw. I will no longer respond to your posts. If you distort what I have said I will refer those posts to the moderator.
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