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Old 2nd November 2007, 14:58   #41  |  Link
fjhdavid
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Jdobbs, this thread is also releant for DVD-RB as you use dgdecode.

but let's have this summary (which is OK, according to Kumi and myself tests, and with Wilbert, Jdobbs, Oppo guys and other posts) and works with 709 DVD and 601 DVD:


First CCE does NOT do colorimetry conversion and is expecting nothing as input.

If your original DVD is 709, dgdecode will decode it as 709, and you have to input directly into CCE, and CCE will output 709.
The only warning is to be sure that your original DVD is 709 (and dgdecode seems not sufficient) and check that your DVD player or DVD software player is 709 compliant. Your display must also expect 709.

If your original DVD is 601, dgdecode will decode it as 601, and you have to input DIRECTLY into CCE (without any colormatrix filter) and CCE will output 601.
The only warning is to be sure that your DVD player or DVD software player is 601 compliant (it is true for Oppo and PowerDVD ("original" settings) and that your display is expecting 601.

DVD 601 seems easier to handle because when dgdecode identifies them as 601, you are sure they are 601.

PS: all that was said, is for SD output. For HD ouput the scaler or DVD player scaler has to handle properly the 709 and do the conversion for 601 DVD.

my two cents.
Maybe if you all agree, Jdobbs could do a sticky post from this one?

Last edited by fjhdavid; 2nd November 2007 at 18:07.
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Old 2nd November 2007, 18:28   #42  |  Link
manono
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Sorry, but I can't resist:
Quote:
Maybe if you all agree, Jdobbs could do a sticky post from this one?
Speaking strictly for myself, the last place your post should wind up is as a sticky, as I don't agree with much of anything you said in your post. It's almost as if the posts by others have gone in one ear and right out the other. Maybe there's an English comprehension problem here, I don't know.
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Old 2nd November 2007, 18:45   #43  |  Link
fjhdavid
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maybe my english is not as good as yours, I am sorry about that (but I am sure my french is better....smile)

but remember that the aim of DVD-RB is to do the best DVD possible, and if you are wrong in matrix color, it is a pitty, but one more time if someone can demonstrate something different, I would like to hear (I don't care about document from 1995 or 2007 (becaude jdobbs showed us maybe two contradictory one (post 32)),

I don't have any 709 video so I trust Kuni (post 38), I just said be careful with dgdecode as it seems it say 709 even when there is no header extension written

But about 601 DVD, I am sure that you don't need colormatrix() and I have evidences about that (post 37), I have also evidence that PowerDVD and Oppodigital players are 601 compliant (post 29 part2)

But please be free to sending me a 601 video footage I can check with my PC which show me I am wrong with 601 DVD

Last edited by fjhdavid; 2nd November 2007 at 19:27.
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Old 2nd November 2007, 19:52   #44  |  Link
kumi
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Quote:
be careful with dgdecode as it seems it say 709 even when there is no header extension written
Take a deep breath, and read my last post again. If you feed Rec.601 to CCE, the output will not have the sequence_display_extension() set, as it should. Do you REALLY think CinemaCraft would overlook such a thing? Of course not. CCE expects ONLY Rec.709 input.

It's obvious that CinemaCraft engineers are comfortable with encoding Rec.709 WITHOUT the sequence_display_extension(). Thanks to that, you can easily argue that DGDecode's assumption of Rec.709 coefficients on input streams without explicit flagging is reasonable and correct.
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Old 2nd November 2007, 20:00   #45  |  Link
fjhdavid
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maybe you are right Kuni,

but, to convince me, can you just do a simple test for me:

take a 601 pure red showing RGB = (X,0,0) (or a part of a picture)
convert it with DVD-RB and CCE WITHOUT any colormatrix filter

then read the output and tell us the re-encoded output RGB value

now do the conversion with DVD-RB and CCE and a colormatrix (bt601->bt.709) before encoding as it "should be" if I understood your purpose

then read the output and tell us the re-encoded output RGB value

thanks for your help

Last edited by fjhdavid; 2nd November 2007 at 20:05.
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Old 2nd November 2007, 20:06   #46  |  Link
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Let me respond on two points:

Quote:
as I know that powerDVD is bt.601 compliant and the original video are 601, CCE MUST be 601 compliant to get the same result before and after re-encoding

do you agree?
No. Suppose you original video is 601, and you feed it as YCbCr to CCE. CCE doesn't add the "sequence display extension" field to the resulting MPEG-2 file. Hence IF (*) we follow the MPEG-2 specs, Rec.709 coefficients should be assumed upon display, and the displayed clip has wrong colors.
But assuming that you are correct by your statement that PowerDVD uses Rec.601 upon display, then your encoding will look the same as your original.

About (*), which brings me to the following point:
Quote:
but remember that the aim of DVD-RB is to do the best DVD possible, and if you are wrong in matrix color, it is a pitty, but one more time if someone can demonstrate something different, I would like to hear (I don't care about document from 1995 or 2007 (becaude jdobbs showed us maybe two contradictory one (post 32)),
What we really know is what the DVD-specs say about this. None of us seems to know, and in the AVS forum they are silent about it. The DVD-specs are supposed to be a subset of the MPEG-2 specs, but it wouldn't be the first time if two specs would contradict each other, when they should not.

About your last post:
Quote:
but, to convince me, can you just do a test for me:

take a 601 pure red showing RGB = (X,0,0)
convert it with DVD-RB and CCE WITHOUT any colormatrix filter

then read the output and tell me the RGB value
Such tests are pointless. Your assumption here is that the player/renderer is correctly displaying the video, but at the same time we question *how* it should be displayed.
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Old 2nd November 2007, 20:17   #47  |  Link
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Quote:
Originally Posted by fjhdavid View Post
then read the output and tell us the re-encoded output RGB value
Like Wilbert said, that's meaningless. What coefficients do you choose for the YV12-to-RGB conversion? Rec.709? Rec.601?

Look, it's already proven that CCE does not flag it's output stream, even when it's fed Rec.601 input. This fact alone demolishes your entire argument about how "601" is the "SD standard". I now retire myself from further participation in this thread (it's not going anywhere.)

Last edited by kumi; 2nd November 2007 at 20:19. Reason: I'm done here...
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Old 2nd November 2007, 21:08   #48  |  Link
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Quote:
and dgdecode seems not sufficient
i have to disagree. dgdecode is following the mpeg2 specs and reporting exactly what they say it should when the extension is missing. the only other solution would be a complex mess of decode tests trying to determine minor colour variances etc. hardly practical.

Quote:
The only warning is to be sure that your DVD player or DVD software player is 601 compliant
actually that would be 601 forced as it is ignoring what the mpeg2 specs says it should doing.

Quote:
but, to convince me
and here is the real problem i think. its been shown there is plenty of doubt about what you think it all should mean. i do not think you will be totally happy or convinced no matter what anyone says. so

Quote:
I now retire myself from further participation in this thread (it's not going anywhere.)
i am doing the same. i have other more imprtant things to deal with at the moment.

Quote:
it wouldn't be the first time if two specs would contradict each other, when they should not.
true. also go back and read the quote that i commented "scary huh" to.
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Old 2nd November 2007, 23:56   #49  |  Link
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Wilbert and Jdobbs thanks for your point about my post. I will go further in testing if I can.

Kumi and Dragongodz, I am sorry you lost your time with me.

My purpose was just to try to understand why:

people from PowerDVD and WinDVD assume 601 for DVD SD (powerDVD and winDVD are nb 1 and 2 of PC DVD player)

people like Joe Kane from DVE and guys from getgray are doing wrong DVD calibration tools for SD DVD

why MTK and Cirruslogic, wellknown chip maker are using wrong colormatrix

why, we don't have any info from CCE guys to tell us their specs

I am also wondering how you are playing your DVD with all this people doing wrong bt.601 compliant stuff?
but as you said it is maybe not important...
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Old 3rd November 2007, 00:03   #50  |  Link
Wilbert
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I'm reading "ITU-T Rec.H262 (2000 E)". All the ITU-T docs are available for free since a short while:

http://www.itu.int/rec/T-REC-H.262/en

The relevant quote (page 44) says something different (than the 1995 version):

In the case that sequence_display_extension() is not present in the bitstream or colour_description is zero the matrix
coefficients are assumed to be implicitly defined by the application.


What's that supposed to mean?

Last edited by Wilbert; 4th November 2007 at 13:50.
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Old 3rd November 2007, 00:23   #51  |  Link
jdobbs
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It means "if the sequence_display_extension() isn't there -- your guess is as good as mine." they were just afraid to write that into the spec.

It also says this:

Quote:
NOTE 2 – In applications which may have signals with more than one set of colour primaries, transfer characteristics, and/or matrix coefficients, it is recommended to transmit a sequence display extension with colour_description set to one, and to specify the appropriate values for the colorimetry parameters.
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Old 3rd November 2007, 01:26   #52  |  Link
fjhdavid
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look at this address even if they are talking about SDTV:

(sigmadesigns is also a wellknown decoder chip maker used in a lot of DVD player)

http://www.sigmadesigns.com/public/S...omaticity.html

But for Wilbert an Jdobbs, I read also ITU-T Rec.H262 (2000 E)".
The application should be for example SD (or HD), or SD TV, or HD TV, as the player would recognize by the height and width which application the mpeg2 stream are talking about?
It could be the same with PAL and NTSC as the player would recognize the application with the refresh rate (25hz and 30hz)?

PS: I tested DGindex and it is a 709 compliant DVD player...

Last edited by fjhdavid; 3rd November 2007 at 11:30.
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Old 3rd November 2007, 16:36   #53  |  Link
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Quote:
Originally Posted by Wilbert
In the case that sequence_display_extension() is not present in the bitstream or colour_description is zero the matrix coefficients are assumed to be implicitly defined by the application.
This is a mess, not a standard anymore

BTW, thanks for the ITU link.

Quote:
Originally Posted by Wilbert
Suppose you original video is 601, and you feed it as YCbCr to CCE. CCE doesn't add the "sequence display extension" field to the resulting MPEG-2 file. Hence IF (*) we follow the MPEG-2 specs, Rec.709 coefficients should be assumed upon display, and the displayed clip has wrong colors.
But assuming that you are correct by your statement that PowerDVD uses Rec.601 upon display, then your encoding will look the same as your original.
True, but what if the "sequence display extension" with 601/709 flags is added to the stream.

I just added this header to HCenc to see what happens for different input/output combinations, the next table shows the RGB values for the red, green and blue colorbars using PowerDVD.

Code:
input   output    red                  green               blue
601     601       RGB=187,  0,  0      RGB=  2,187,  2     RGB=  1,  0,187
601     709       RGB=187,  0,  0      RGB=  2,187,  2     RGB=  1,  0,187
709     601       RGB=171,  0,  2      RGB= 17,220,  8     RGB=  1,  0,179
709     709       RGB=171,  0,  2      RGB= 17,220,  8     RGB=  1,  0,179
Seems DVD has its own rules and is not a subset of the MPEG2 standard regarding colorimetry, PowerDVD always outputs 601 regardless if the stream is flagged 601 or 709, the info in the sequence display extension is ignored.

Now lets see how DGIndex handles it:
Code:
input   output    red                  green               blue
601     601       RGB=188,  1,  1      RGB=  3,188,  3     RGB=  1,  1,188
601     709       RGB=204, 19,  0      RGB=  0,160,  0     RGB=  0, 12,195
709     601       RGB=172,  0,  2      RGB= 18,221,  9     RGB=  1,  0,179
709     709       RGB=188,  1,  1      RGB=  4,189,  3     RGB=  0,  1,187
According to the MPEG2 standard this is correct, the info in the sequence display header is read and processed.

What does this mean for DVD-RB using CCE?
IMHO nothing, DVD content already has 601 characteristics, CCE encodes the YUY planes to YV12 planes and doesn't write the sequence display header so DGIndex correctly sees it as 709 but DVD players will ignore it and use 601 for the conversion.
However if you use Colormatrix to convert the DVD from 709 to 601 you will end up with the wrong colorimetry, and DGIndex will still report it as 709...

For those who are interested the testfiles used can be downloaded here
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Old 3rd November 2007, 16:50   #54  |  Link
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So here are the questions, since the standard can't apparently be trusted:

1. Can we assume DVDs with no sequence_display_extension() are Rec.709 or Rec.601?

2. What conversion is DGDECODE doing when it frame serves it to HC or CCE?

3. Why is it that when I do see sequence_display_extension() used on a DVD it is always used to specify Rec.601? It would at least give you the impression that the default is other than Rec.601, wouldn't it?

Since DVD-RB scans the file and creates the D2V file itself, I could very easily make the D2V default to Rec.601 -- but is that right?

Sigh...
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Old 3rd November 2007, 17:32   #55  |  Link
hank315
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As long as nobody here has the DVD specification it's all speculation...

Quote:
1. Can we assume DVDs with no sequence_display_extension() are Rec.709 or Rec.601?
My guess is all DVDs are rec.601, there's too much info on the Inet saying SD is 601.
The testfiles also show wrong colorimetry using 709 as input.

Quote:
2. What conversion is DGDECODE doing when it frame serves it to HC or CCE?
As far as I can see in the code: none.
The sequence display info is only parsed, not processed.

Quote:
3. Why is it that when I do see sequence_display_extension() used on a DVD it is always used to specify Rec.601? It would at least give you the impression that the default is other than Rec.601, wouldn't it?
Sounds logical indeed but PowerDVD (WMP does the same) seems to ignore the settings in the sequence display header completely, outputting the header seems just a waste of bits?
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Old 4th November 2007, 00:27   #56  |  Link
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Quote:
Originally Posted by hank315 View Post
My guess is all DVDs are rec.601,
I agree

Quote:
Originally Posted by hank315 View Post
Sounds logical indeed but PowerDVD (WMP does the same) seems to ignore the settings in the sequence display header completely, outputting the header seems just a waste of bits?
I think you'll find all pc players will do the same,
use 601, ignore headers.

Quote:
Originally Posted by jdobbs View Post
2. What conversion is DGDECODE doing when it frame serves it to HC or CCE?
it does nothing, the encoders do nothing.

Quote:
Originally Posted by jdobbs View Post
3. Why is it that when I do see sequence_display_extension() used on a DVD it is always used to specify Rec.601? It would at least give you the impression that the default is other than Rec.601, wouldn't it?
It gives me the impression that it's an encoder error not setting the display extension. A shortcoming.

btw, restream can add matrix coeffs to a stream,
it sets to I470.
Don't know if there's a tool to set the header coeffs to 709.
I like that Hank added the feature to add the header in a test version of HC,
I'm sure it will make it through to the next HC.

anyway,
i think it's good to know what behaviour to expect with conversions to rgb so basically i gave this answer to the op:

consider 4 sources:

A
Code:
colorbars(720,480)
killaudio()
converttoyv12()
trim(0,120)
Feed to HC/CCE/mencoder, get mpeg2, 601 coeffs used.
No sequence_display_extension present.

B
Take stream A and use restream to add sequence_display_extension with colour,
restream sets matrix coeffs to 'I470'.


C

Code:
colorbars(720,480)
killaudio()
converttoyv12(matrix="rec709")
trim(0,120)
Feed to HC/CCE/mencoder, get mpeg2, 709 coeffs used.
No sequence_display_extension present.

D
the same as C but set matrix coefficients in header to 709.
Like I said I don't know of a tool to do it,
but Hank's colorbar input709to709output stream linked to above fits the bill.

slap the 4 sources on a disk or use them for input to your apps.

Scenario 1:
Mpeg2 is converted to rgb using 601 always.
Source A = Normal (N) ; B = N ; C = Red Push (RP) ; D = RP

Scenario 2:
Mpeg2 is converted to rgb respecting the header,
in the absence of the header 709 is assumed.
A= Green Push (GP) ; B = N ; C = N ; D = N

Scenario 3:
Mpeg2 is converted to rgb respecting the header,
in the absence of the header 601 is assumed.
A = N ; B = N ; C = RP ; D = N

Scenario 4:
Mpeg2 is converted to rgb using 709 always. (nicely hypothetical)
A = GP ; B = GP ; C = N ; D = N


That way you know what's happening on the end part.
and effectively what to do before you get there.

If Scenario 2 is actually the standard,
and is abided to,
then what CCE (and other encoders) does is wrong by not setting
color matrix coeffs in the header,
and I would run them through restream to add a header.

As for knowing what you are working with...
I'd treat dvds with no header as though they are 601.
Of course you can just wing it visually, deciding if you're ok,
or if you've been pushed either red or green,
and revert with colormatrix.

anyway,
that's what I think.

gl
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Old 4th November 2007, 01:43   #57  |  Link
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I am happy that Hawk315 found same results as my post 37 with the RGB values, even if Hawk has been able to do more things than me thanks to its knowledge, and as I said in my post 41: "CCE does NOT do colorimetry conversion and is expecting nothing as input"

As I said many many times in this thread, we don't care about the norm (and maybe we never know if there is a followed norm) but we must be pragmatic:

Even if assuming that 709 DVD were true, NO DVD players on the market (as long as I know) would play the 709 DVD without chromacity error (as DVD players use only two or three different chip decoder that are 601 - see my posts)), and ONLY Dgindex for PC (as I know (see my post 52)) would be able to read the re-encoded 709 DVD!!!

IT IS NOT an EVIDENCE of something, it is a FACT.

Now, everyone can do what he wants but it is a non sense to use a colormatrix (bt 601->bt709) with 601 DVD.

I know my english is bad (someone else, like Manono can write it), but I think we need a sticky post about this subject.

But even if there is nothing more on the subject, lets me thank, one more time, Jdobbs for its work, as I used it everyday.

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Old 4th November 2007, 01:51   #58  |  Link
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Quote:
Originally Posted by fjhdavid View Post
we don't care about the norm (and maybe we never know if there is a norm) but we must be pragmatic:
I agree.


Quote:
NO DVD players on the market (as long as I know) would play the 709 DVD without chromacity error, and ONLY Dgindex for PC (as I know see my post 52) would be able to read the re-encoded 709 DVD!!!

It is not an evidence of something, it is a fact.
I'm not sure why you are so sure about this. Can you explain?



Since the standards are murky, what if we blind test the users on Doom9? Carefully author a DVD with a few test patterns, have users view them, and then answer some questions about their visual impressions. The questions would be designed to determine which of Immersion's four 'Scenarios' is in effect for a particular SAP (see post #56). If enough users participate, we might be able to arrive at some real-world conclusions regarding the desirability of different colorimetry/header combinations.

But... is this type of blind study possible? Or rather, given a test DVD with a few sample clips: does there exist a series of simple-to-answer questions that will tell us which of Immersion's "Scenarios" a given SAP is using?

Last edited by kumi; 4th November 2007 at 01:53.
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Old 4th November 2007, 01:59   #59  |  Link
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Quote:
Originally Posted by jdobbs
2. What conversion is DGDECODE doing when it frame serves it to HC or CCE?
Quote:
Originally Posted by Immersion
it does nothing, the encoders do nothing.
Uhh... it does something as it very obviously decodes it and presents it to the encoder as a picture.
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Old 4th November 2007, 02:05   #60  |  Link
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All the DVD players on the market are using a DVD decoder chip, and major chip manufacturer (MTK, cirruslogic, sigmadesign) are 601 compliant (see my previous posts).

then if 709 DVD was the norm, all this DVD player would play 709 DVD with a chromacity error (independantly from DVD-RB or HC/CCE)....do you think that all these engineers are wrong? I don't know but I doubt...

this is why Hawk and myself said that DVD must be 601 compliant as there is so much info on the net according to this fact.
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