bt.709 and CCE [Archive]

fjhdavid

29th October 2007, 01:29

DVD-RB inputs YUY2 into CCE, then it means that it will input the "DVD orginal color matrix" and it tells only that, it could be rec.601 or rec.709

BUT, where did you read that CCE output Bt.709? because if it's true, we don't need "colormatrix avisynth filter" anymore.....

I think CCE doesn't write any color matrix in its header and by default, we are thinking it is bt.709

but the DVD compliant color matrix has always been rec.601 as DVD is only SD

anyway, give a try with getgray calibration disc (which is 601), and you will see if CCE output bt.601 or bt.709

jdobbs

29th October 2007, 04:18

Here's some text from the Colormatrix documentation (my boldfacing):

There are several ways to convert a YUV stream to RGB. The most well known one, uses Rec.601 coefficients. It is for example used in the color conversion routines of AviSynth, VirtualDub and XviD/DivX. When playing back a XviD/DivX the stream is converted to RGB using Rec.601 coefficients. The main issue is that sometimes other coefficients are used for the YUV to RGB conversion (the other two are Rec.709 coefficients and FCC coefficients). A problem arises if a stream is encoded using one set of coefficients (Rec.709 coefficients for many dvd streams for example), and somewhere in the reencoding-processing-playback chain a different set of coefficients is assumed (Rec.601 coefficients for the XviD/DivX decoder or FCC coefficients for TMPGEnc/QuEnc or Rec.709 coefficients for CCE). You will get a slightly color distortion, which looks like a change in brightness (it's not really a change in brightness, the colors are just slightly off).

How do you know what set of coefficients are using when encoding a MPEG-2 stream? Sometimes the coefficients are stored in the header of the MPEG-2 file (the "matrix coefficients" field in the "sequence display extension"). Newer versions of GSpot will be able to read this part of the header, but also DGDecode (with Mpeg2source(info=1)) can be used to view them. If this extension field is not present in the header of the MPEG-2 file, the specs say we are supposed to use the default Rec.709 coefficients (0.2126, 0.7152, 0.0722). The Colormatrix filter is applied before the encoding.

CCE's site spells out that it outputs in MPEG-2 in accordance with ISO/IEC13818-2, ITU-T Rec.H262 (MP@ML only). CCE doesn't add a sequence_display_extension.

The specification for 13818-2 spec page 53 states:

"In the case that sequence_display_extension() is not present in the bitstream or colour_description is zero
the chromaticity is assumed to be that corresponding to colour_primaries having the value 1."

and

the value 1:

"1 Recommendation ITU-R BT.709"

If CCE were not outputting in Rec.709, and was not setting the sequence_display_extension(), it would be writing a non-compliant stream... which I highly doubt.

In writing/testing DVD-RB I can assure you that the vast majority of DVD (SD) movies either don't have sequence_display_extension present or have it with a matrix coefficients value set to "1" -- meaning it uses Rec.709. The exceptions I see on a common basis are seen in menus and extras and video from television -- which often are Rec.601 -- and have sequence_display_extension present with a value of "6".

fjhdavid

29th October 2007, 10:27

I think we are facing a real problem.

I completely agree with you that in mpeg2 stream if no header is present, it is bt.709 assumed and that CCE output doesn't exhibit any color matrix header (but maybe it is a mistake!)

BUT, all the DVD spec says that DVD MUST be bt.601 compliant because they are SD (I found many place on the WEB and datasheet where it is written)

In addition, a lot of DVD player use bt.601 (I asked OPPO developper and Philips and if you read the DVD re-encoded by CCE in this case, you will face a problem)

last, if you look at the page 51 and 52 of the CCE owner guide it is written that RGB to YCB is bt.601-5 compliant and the equation gives coeff 601)
this link:
http://forum.doom9.org/showthread.php?s=&threadid=53770
tends to say the same things that CCE is expecting bt.601 as input , so you must not use any colormatrix conversion before input in CCE...

maybe a mail to CCE will answer our question?

PS: a lot of PAL DVD commercial are also bt.601...and getgray which is a wellknow calibration DVD is bt.601 also (I asked its author)

dragongodz

29th October 2007, 12:19

(but maybe it is a mistake!)

do you realise how long CCE has been around and used by professionals ? i think someone would have noticed before now if this was the case.

BUT, all the DVD spec says that DVD MUST be bt.601 compliant because they are SD (I found many place on the WEB and datasheet where it is written)

please give links that say this.

In addition, a lot of DVD player use bt.601 (I asked OPPO developper and Philips

use how ? if they are looking at a dvd with no sequence_display_extension and saying that means its 601 then they are the ones that have it wrong. jdobbs post already showed that.

if you look at the page 51 and 52 of the CCE owner guide it is written that RGB to YCB is bt.601-5 compliant and the equation gives coeff 601
this link:
http://forum.doom9.org/showthread.php?s=&threadid=53770
tends to say the same things that CCE is expecting bt.601 as input

sorry but no it does not. it is specifically talking about the conversion of RGB input to YCbCr when done by CCE and the luminance range of the conversion. it does not specify what the output is etc.

a lot of PAL DVD commercial are also bt.601

do you mean commercial PAL dvds ? if so i call B.S. to that. i tested that already and the vast majority are 709, NOT 601. i even found 1 that used 420m.

fjhdavid

29th October 2007, 13:15

a link to DVD player from oppo:

http://www.avsforum.com/avs-vb/showthread.php?t=760726&pp=30&page=144
(response 4308, 4317 and 4320)
and

http://www.avsforum.com/avs-vb/showthread.php?t=760726&pp=30&page=145
(response 4324)

look to neuromancer post which is working in oppo

you can also go to getgray site where it is explained that SD DVD MUST be bt.601

for the CCE owner guide manual:
it is said: if you enter the CCE encoder with a RGB signal, it will convert it according to bt.601, then it means that we must NOT use the colormatrix filter if the dvd is bt.601 before entering and that we have to use a bt.709 to bt.601 conversion for a dvd bt.709...(i said that because I use a green correction avisynth filter)

THEN why would CCE use bt.601 for input and then bt.709 to output (double conversion)? wouldn't it have been easier to leave everything in bt.709 from the input to the output (especially if all DVD were bt.709)?

in addition, I don't prefer bt.601 over bt.709 (you will see in the link I provided that I am a strong advocate of bt.709.....), I just want to know, because I have a lot of DVD which are bt.601 and you have one that are bt.709....

maybe if you own CCE, a quick mail should answer the question...

Wilbert

29th October 2007, 20:11

a link to DVD player from oppo:

http://www.avsforum.com/avs-vb/showthread.php?t=760726&pp=30&page=144
(response 4308, 4317 and 4320)
Not convincing:

response 4308:
DVD is YCbCr 4:2:0 BT.601 IIRC.
No evidence here.

response 4317:
"main level (ML) - A range of proscribed picture parameters defined by the MPEG-2 video standard, with maximum resolution equivalent to ITU-R BT.601 (720 x 576 x 30)."
I'm not sure what this statement means here (which parameters are they referring to?). In any case it is referring to that maximum resolution 720 x 576 x 30. Does it also refer to which coefficients are used? I don't know. Perhaps others know or can look it up?

response 4320:
DVDs are encoded like Neuromancer said. Upconverted SD DVDs should be output with 709 because when a TV sees a 720p, 1080i or 1080p signal it assumes its HDTV standard which uses REC 709.
More statements without evidence.

response 4324:
The MTK solution decodes at BT.601. Once this signal is sent to the Faroudja chipset, the Faroudja chipset will then sample it at the native BT.601 (480p) or convert it to BT.709 (720p, 1080i, 1080p).

This chipset will then output the resulting signal to the one which is most appropriate to the native decoding of your display.
Well ok, this chipset works that way. The main question still remains, why ????

or the CCE owner guide manual:
it is said: if you enter the CCE encoder with a RGB signal, it will convert it according to bt.601, then it means that we must NOT use the colormatrix filter if the dvd is bt.601 before entering
This can be either true and false. It all depends on how the final YCbCr->RGB conversion is done upon display. If it's done correctly (ie using Rec.709, at least that's my opinion and many others in this thread), then their statement is false.

I've added a reply in that thread. Let's wait if they come up with any credible evidence.

45tripp

30th October 2007, 02:02

Is there a tool to insert color matrix coefficients into the mpeg2 header?

I know you can strip the color coefficients with restream,
but what about addition?

ty

dragongodz

30th October 2007, 04:37

because I have a lot of DVD which are bt.601 and you have one that are bt.709

actually what i said is i have many that are 709 and i have 1 that is 420M. of the ones i checked i found exactly 0 to be 601.

a link to

i asked for links to show the dvd specs say dvds MUST be 601 as you claimed. none of those links do that. opinions do not count as fact.

dragongodz

30th October 2007, 05:19

maybe this will help

http://www.dvddemystified.com/dvdfaq.html#3.4

Pictures are subsampled from 4:2:2 ITU-R BT.601 down to 4:2:0 before encoding, allocating an average of 12 bits/pixel in Y'CbCr format.

note it doesnt say its subsampled TO bt.601 Y'CbCr. so for RGB or 4:2:2 footage then it would appear to expect bt.601 to sample down. now if CCE is only going to encode to bt.709 surely it knows to sample down to the correct Y'CbCr to do so.

fjhdavid

30th October 2007, 10:00

Ok, I am sure we will find the answer, but remember, DVD-RB is a tool to re-encode DVD in order to play them with a PC or with a DVD player.

For the DVD player, the MTK pre-processor is used in a lot of products (the output of the MTK chip is then going to a faroudja or an anchorbay or an HQV chip for de-interlacing or scaling, and then for scaling they use bt.709 for 720p and 1080p as it is specified in the HD spec but not SD)

and the fact is that MTK is 601 compliant!

so even if CCE is bt.709, you won't read correctly your DVD in a lot of commercial or standalone player....as today, this is a fact, and it should be better to ask CCE guys to be bt.601 compliant!

this a problem, don't you think? do you think that CCE guys don't know the fact about MTK is 601? so why would they go to bt.709?...surprising if it is true

guys from DVE essential and Getgray told me also that DVD is bt.601 and they are (at least for DVE) wellknown in the DVD calibration tool (and i am sure they bought the DVD specs even if it is 5000 dollars)

dragongodz

30th October 2007, 14:44

The MTK solution decodes at BT.601. Once this signal is sent to the Faroudja chipset, the Faroudja chipset will then sample it at the native BT.601 (480p) or convert it to BT.709 (720p, 1080i, 1080p).

and the fact is that MTK is 601 compliant!

is it decoding using bt.601 though or is it decoding to bt.601(thus a conversion if not bt.601 already) ? the second would be basically a reverse of the bt.601 RGB conversion i mentioned earlier.

guys from DVE essential and Getgray told me also that DVD is bt.601

you will have to excuse me for having more faith in the evidence of all the commercial dvds out there and real viewable specs ,such as the mpeg2 13818-2, than just the word of these people. especially when you said
BUT, all the DVD spec says that DVD MUST be bt.601 compliant because they are SD (I found many place on the WEB and datasheet where it is written)

now if you could get someone from a major studio or such to say categorically that dvd must be encoded USING bt.601, not just in RGB colour conversion, then you may have something.

fjhdavid

30th October 2007, 15:30

maybe you are right, guys from MTK and Joe Kane from DVE are wrong...but let me have a doubt about that....

DVE is used by professional calibrator and studio broadcaster to calibrate their SD and HD stuff (and DVE is available in two different disc, one for SD in bt.601 and the second for HD in bt.709)

MTK is used in philips, Oppo ...

Cirrus Logic (an another wellknown and wide used DVD player decoder chip also use bt.601)

but have a look to:
http://www.pinnaclesys.com/files/MainPage/Professional/TopTabItems/products/dc1000/WhitePapers/DC1000-DVD1000MPEG2whitepaper.pdf

Page 4 and page 15

and
http://www.dvddemystified.com/dvdfaq.html#1.1

section 3.4

but, I have an idea: I will re-encode tonight a DVD bt.601 and look with DGindex if CCE write something in the header. If it writes bt.601, it means that CCE simply use the matrix color of the original DVD and dosen't change it...
Then for your DVD bt.709, CCE will write nothing as it is bt.709 by default....

an another point is that you refer to 13818-2, but which version? 1995, 1996, 2000 with 2002 correction included or with 2007 corection...
if it is the 1995 version, DVD didn't exist at this time, and I am not able to download the other versions

dragongodz

30th October 2007, 17:39

MTK is used in philips, Oppo ...

Cirrus Logic (an another wellknown and wide used DVD player decoder chip also use bt.601)

which doesnt answer the question i asked at all.

Page 4 and page 15

which only talks about resolution. so no proof there that output must be bt.601 colormetry.

section 3.4

so you missed i already posted a link to that and commented on it ?

I will re-encode tonight a DVD bt.601 and look with DGindex if CCE write something in the header. If it writes bt.601, it means that CCE simply use the matrix color of the original DVD and dosen't change it...

and what if it does convert it to bt.709 and then doesnt write the header, so should be assumed bt.709 per mpeg2 specs, what then ?

fjhdavid

30th October 2007, 18:06

if the CCE re-encoded DVD show a bt.601 with DGindex, it means that there is no bt.709 in CCE !

(you didn't answer to my question about the 13818-2 version)

Wilbert

30th October 2007, 18:43

if the CCE re-encoded DVD show a bt.601 with DGindex, it means that there is no bt.709 in CCE !
It doesn't. Other people have checked that.

an another point is that you refer to 13818-2, but which version? 1995, 1996, 2000 with 2002 correction included or with 2007 corection...
if it is the 1995 version, DVD didn't exist at this time, and I am not able to download the other versions
That's a good point. Mine is "ISO/IEC 13818-2: 1995 (E)". Do you have a more recent one?

kumi

30th October 2007, 19:02

By the way, if the OP's goal is to see if his player is correctly displaying CCE-encoded video, why doesn't he simply encode 2 clips in CCE:

A) SMTPE colorbars, Rec.709
B) SMTPE colorbars, Rec.601

...then burn them to DVD and examine the output on his standalone player. Colorspace conversions using the wrong set of coefficients (Rec.709 vs. Rec.601, or vice-versa) are easy to spot, aren't they?

jdobbs

30th October 2007, 20:39

if the CCE re-encoded DVD show a bt.601 with DGindex, it means that there is no bt.709 in CCE !

(you didn't answer to my question about the 13818-2 version)DGIndex won't show Rec.601 unless there is a sequence_display_extension() calling it out. If it is missing, DGIndex assumes Rec.709 (as it should).

fjhdavid

30th October 2007, 23:57

Ok, I did some experiment tonight and results add nothing more (Wilbert and JDobbs are right):

I took a bt.601 film and dgindex stated it is "bt.601 colorimetry" (the header is written)

I did a CCE re-encode and dgindex stated it is "bt.709 colorimetry" (the header is written?)

what does it mean exactly? I don't know but it seems that there are three possibilities:

1- DGdecode use a bt.601 matrix to decode and CCE apply a sort of colormatrix (bt.601 -> bt.709) before re-encoding

2- DGdecode use a bt.709 matrix to decode and CCE keep it

3- DGdecode use a bt.601 to decode, CCE use a bt.601 to re-encode but doesn't write the header and DGindex assumes it is bt.709

what is your opinion?

For Wilbert I also have the "ISO/IEC 13818-2: 1995 (E)" as you have to pay for the others.

For Kumi, I don't know if it is easy to see if the two pictures are not projected side by side
but I will try to find something to re-encode and try to detect color shift on the PC

second part of the night:

I took mires from calibration tools (gray at 20%, 40%, 60%) which are bt.601

I do a convertToRGB (bt.601)
I do a RGBAdjust in order to add red only on the red channel
I do a convertToYUY2 (bt.709)

I do a re-encode with CCE
I play the re-encoded DVD with Cyberlink PowerDVD and take a photo

and there is a problem, the others channels (green and blue) had changed

I think that if PowerDVD uses bt.709, we wouldn't see any change in the green and blue channels?

manono

31st October 2007, 01:40

If you'd like to see what happens to the colors if you do it wrong, scroll down to the bottom of this page, start hitting the "Next" button, and study the color changes:

http://www.sigmadesigns.com/public/Support/chromaticity.html

For you (and me) starting with some form of a Rec.601 DVD and using CCE, but without the ColorMatrix filter applied correctly, I think the results you'll get will be the BT.601 encoding, BT.709 decoding. Someone correct me if I'm wrong on that. The differences in the first set of pics are hard to make out, The differences become more obvious with later sets in the sequence.

dragongodz

31st October 2007, 11:29

a thought about this statement

The MTK solution decodes at BT.601. Once this signal is sent to the Faroudja chipset, the Faroudja chipset will then sample it at the native BT.601 (480p) or convert it to BT.709 (720p, 1080i, 1080p).

now bt.601 specs are limited to SD resolutions and BT.709 added HD resolutions. so would that above statement be just saying that the MTK just decodes to SD resolution and then the Faroudja will convert it to the required resolution for your output ?

if so, and that what it does appear to be really saying to me, then that is all just about resolutions. it has nothing to do with colormetry at all.

so saying

MTK is 601 compliant!

can be true but does not cover the question being asked, that of colormetry. really there needs to be some specifity to these questions and answers or they can be construed to mean more than they actually say.

fjhdavid

31st October 2007, 21:17

I do my best!

which dvd player are you using?

because if CCE is bt.709 and dvd players as said by Oppo guys are bt.601 (and they know how they built their players at least), do you think that you get the solution?

secondly, I don't own CCE but if you do, can you post a mail to CCE guys, it would be grateful for all of us and we will have definitively the answer

thanks

jdobbs

31st October 2007, 21:46

That seems a little awkward. It's saying:

"Hi. Your documentation says you are ISO/IEC13818-2, ITU-T Rec.H262 compliant. I have no reason to doubt you, but are you really compliant?"

I trust their documentation and their product and if I were going to question it I'd need some reason... and I really don't see one in all this discussion. I am certain that Rec.709 is the most common matrix in use on standard definition DVDs and that it is within the DVD standard -- why would I suspect that the output of a high-end product like CCE, in a profile designed for DVDs, would be anything other than Rec.709 when a scan of the M2V files says that it is?

fjhdavid

31st October 2007, 23:13

the reason should be that one of the major DVD player manufacturer, like Oppo (which get many rewards) or guys from DVE like Joe Kane which are also high end product are saying that DVD is SD and should follow the bt.601colorimetry (and MTK and Cirruslogic manufacturers are saying the same)

remember also that CCE itself in their owner guide mentions bt.601 and don't speak even one time of bt.709

and also that we are, here, refering to a document ISO that was written in 1995 when the DVD didn't even exist

but anyway:

If CCE guys says "of course we are bt.601", then we will have learn something
and if they say "of course we are not", Oppo and DVE guys have learn something

isn't it the aim of our quest?
but if everybody is completely sure....you didn't show me evidences...

dragongodz

31st October 2007, 23:26

dvd players as said by Oppo guys are bt.601

but that was my point, that could just mean 601 resolution limit. the statement does not say it decodes using 601 colormetry irrelevant of what the mpeg streams information says(or doesnt say). you would need to get that information from them, from an actual tech not a PR guy, and then it may have relevance.

fjhdavid

31st October 2007, 23:32

me and Wilbert asked Neuromancer which is working in Oppo and I also asked them directly with their support team because I own a DVD player from Oppo and they are talking of bt.601 colorimetry compliancy

and what about Joe Kane? its DVE disc are used by professional broadcaster...you can go to DVE essential site

http://www.videoessentials.com/

IMPORTANT info:

PowerDVD (everybody knows PowerDVD), uses also bt.601 colorimetry to decode DVD. If you have it, go on this site and download the 75% red bt.601 and the 75% red bt.709....take a photo of each and look with photoshop...

http://www.w6rz.net/

but maybe guy from cyberlink (PowerDVD manufacturer) also doesn't know their job for 6 or 7 years

if you can't read your DVD on PC with PowerDVD and with DVD player from Oppo, where will you read your DVD bt.709?

Mtz

1st November 2007, 00:20

What I think: bt.609 is for SD and bt.709 is for HD.
(Update, 1/23/2007) As I mentioned last week, OPPO has been working on a firmware update to allow control of the colorspace setting. That work has led to a new beta firmware (not yet official). You can find the firmware on the 981HD's support page. This beta should only be necessary if you are encountering an uncorrectable "green push" (green tint to all video), as the problem may be due to the display improperly using the BT.601 color conversion matrix (intended for SD video, YCbCr sources) instead of the BT.709 color conversion matrix that should be used with HD sources. Manually selecting "RGB" will instruct the 981HD to apply BT.601 even at HD resolutions. If you are having no problems and elect to install this firmware, you should select "Auto" from the options of Auto, RGB, and YCbCr 4:4:4 on the General Setup Page of the setup menu.
Source: http://www.prillaman.net/oppo981_review.html

The problem with Oppo maybe is because of the Faroudja chipset for HD upscaling which needs bt.709, not the MTK chipset:
Adding the color space selection menu allows the user to specify which color space to use. This feature may potentially be used to work around some color accuracy issue with certain TVs. For example, the HDTV specification requires the use of BT.709 color conversion matrix for YCbCr signal in high definition, and the DV-981HD correctly implemented this requirement. However there are some TVs on the market incorrectly applies the BT.601 color conversion matrix, which is intended for SD YCbCr signal, to HD signals. When this incorrect color conversion matrix is applied by the TV, it will result in so called "green push" - green becomes too saturated or the image has a green tint. By selecting the RGB color space, a user can avoid the TVs color conversion matrix and work around this problem."

To achieve desired color reproduction on a LCD TV is a complex task, particularly under competitive cost constraints. As color reproduction devices, LCDs have unique problems that require careful characterization and calibration. For media display applications, LCD TVs are demanded to handle various video encoding standards and viewing environments. Color management tools are a system-wide solution, aiming to provide a common protocol for accurate color reproduction among various imaging devices. In this workshop, we will review (1) color imaging science as applied to display devices; (2) video color encoding and interface standards, such as NTSC, EBU, ITU-R BT.709, sRGB, xvYCC, and HDMI
Hsien-Che Lee received his B.S. from National Taiwan University, M.S. from the Ohio State University, and Ph.D. from Purdue University. He now works as a full-time consultant to MediaTek Inc., Hsin-Chu, Taiwan.
Source: http://www.di.nctu.edu.tw/IDMC07/PresentationsWL.htm

enjoy,
Mtz

mc2man

1st November 2007, 01:09

I also have an oppo DV-981HD which at the moment is mainly used for pal titles. It plays both cce backups and orig. .601,.701's fine. The colormatrix dll only affects whether a backup is accurate to a .601 source. Proper playback is an issue between the player and display. I think your comparing apples to oranges.
a simple view can be found here
http://www.gadgetbench.com/colormatrixerrors/

oppo did offer a firmware update as in mtz's post several weeks ago

jdobbs

1st November 2007, 02:01

Interestingly I found this link (http://www.bjpace.com.cn/data/tec/tec-DVB/DVB%20BlueBooks%20Standards/Specifications%20and%20Standards/mpeg/dvb-mpeg/A001r5.pdf) that contradicts the specification quotes in earlier posts.
It's the "Implementation Guidelines for the use of MPEG-2 Systems, Video and Audio in Satellite, Cable and Terrestrial Broadcasting Applications DVB DOCUMENT A001 rev 5 June 1999"

It says:

Within 25Hz SDTV bitstreams, if the sequence_display_extension() is not present in the
bitstream or colour_description is zero, the chromaticity shall be implicitly defined to be
that corresponding to colour_primaries having the value 5, the transfer characteristics
shall be implicitly defined to be those corresponding to transfer_characterstics having the
value 5 and the matrix coefficients shall be implicitly defined to be those corresponding
matrix_coefficients having the value 5. This set of parameter values corresponds signals
compliance with ITU-R Recommendation BT.470-3 System B,G,I. The value "5", of course, is the equivalent of Rec.601... so the most I can say is "WTF? Will the prevailing standard please stand up?" Of course this document is talking about Digital Video Broadcasting Standards -- but you'd think MPEG-2 would be MPEG-2, wouldn't you?

Mug Funky

1st November 2007, 04:34

FWIW, it's possible that oppo, MTK etc are simply outputting 601 (which would make sense as it applies to analog component as well as digital IIRC), and just making sure colorimetry is handled correctly on input. if the DVD is flagged as 709, then the decoder will presumably know what to do with it to get a 601 output.

dragongodz

1st November 2007, 06:08

it's possible that oppo, MTK etc are simply outputting 601 (which would make sense as it applies to analog component as well as digital IIRC), and just making sure colorimetry is handled correctly on input. if the DVD is flagged as 709, then the decoder will presumably know what to do with it to get a 601 output.

well i asked on the first page

s it decoding using bt.601 though or is it decoding to bt.601(thus a conversion if not bt.601 already) ?

meaning the matrix was detected and as you say decoder TO 601.

me and Wilbert asked Neuromancer which is working in Oppo and I also asked them directly with their support team because I own a DVD player from Oppo and they are talking of bt.601 colorimetry compliancy

well i saw you asked and the response of

The MTK solution decodes at BT.601. Once this signal is sent to the Faroudja chipset, the Faroudja chipset will then sample it at the native BT.601 (480p) or convert it to BT.709 (720p, 1080i, 1080p).

doesnt say it ignores what colormetery is in the stream at all. decodes at ? at ? as i said that can mean the resolution. that is really no answer at all.

Of course this document is talking about Digital Video Broadcasting Standards -- but you'd think MPEG-2 would be MPEG-2, wouldn't you?

yes and no. they are doing is limiting what parts of the mpeg2 specs they use. just as dvd has limits to what frame rates and resolutions are usable etc. its when they decide to go against the mpeg2 specs altogether that it becomes a "WTF?" moment. such as when they say when the header is not present use BT.470-3.
though you have to remember that that is a limitation they have built in. if dvd had such a limit why does professional hardware and software encoders not enforce it ? why do the majority of dvds use bt.709 ? doesnt make sense to me.

dragongodz

1st November 2007, 06:22

refering to a document ISO that was written in 1995 when the DVD didn't even exist

from here
http://en.wikipedia.org/wiki/DVD_authoring

DVD authoring software must conform to the specifications set by the DVD Forum group in 1995.

here is something else interesting from that page

The DVD specifications were written in Japanese and then translated to English for use in America with prose that often rivals the complexity of legal documents. To this day, many companies interpret various parts of the specifications in different ways. This is the reason DVD players from different manufacturers do not always conform to the same rules – each developer understands the specifications in a slightly different way.

scary huh.

fjhdavid

1st November 2007, 12:30

as I asked before, we are all intrested in first place with CCE (input and output)

please ask CCE guys, and we will know for sure which color matrix they implemented for DVD re-encoding (independently from the norm...if one does exist...)

then we will be able to find the best prameters for our players (PC or standalone DVD player) and display (plasma, videoprojector...)

fjhdavid

2nd November 2007, 01:20

sorry for this second post but I think I have the answer to our question: CCE is 601 input and 601 output

the evidence:

I took a video sequence with a perfect 75% red from two different calibration disc which are 601.

I read it with powerDVD and took a picture. the RGB value is as supposed (189,0,0) (189 is 75% of 255 and in the same time this is an evidence that PowerDVD is 601).

then I did a CCE re-encoding with NO colormatrix filter

then I read it with PowerDVD, took the picture and look at the value which is still (189,0,0)

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?

PS: I made the same process with, in addition a colormatrix (Bt.601->bt.709) before re-encoding and this time the RGB showed (171,0,0)

I made also the same experiment with 75% green and 75% blue which confirm

kumi

2nd November 2007, 03:11

PowerDVD could be mangling your video in all sorts of creative ways. To judge CCE's behaviour, you need to control all intermediary colorspace conversions.

First, let's see what the SMPTE color bars are supposed to look like. Use this script: ColorBars(720,480,"YV12").ConvertToRGB24(), and you get:
http://img523.imageshack.us/img523/2532/smptecolorbarsuo4.th.png (http://img523.imageshack.us/img523/2532/smptecolorbarsuo4.png)

OK? Now encode that Rec.601 clip into CCE. If you convert the CCE output clip to RGB24 using Rec.709 coefficients, it looks wrong:
http://img219.imageshack.us/img219/2195/rec601torgbwithrec709ix8.th.png (http://img219.imageshack.us/img219/2195/rec601torgbwithrec709ix8.png)

On the other hand, if you convert the CCE output clip to RGB24 using Rec.601 coeffiecients, the colorbars look right:
http://img151.imageshack.us/img151/1698/rec601torgbwithrec601hu3.th.png (http://img151.imageshack.us/img151/1698/rec601torgbwithrec601hu3.png)

Conclusion? Rec.601 input is not converted to Rec.709 internally by CCE, yet the CCE output clip is (according to DGDecode) flagged as Rec.709.

Now let's feed CCE a SMPTE colorbars clip encoded with Rec.709 coefficients. You can get this with colorbars(720,480,"YV12").ColorMatrix(mode="Rec.601->Rec.709", clamp=false).

Convert the CCE output clip to RGB24 using Rec.709 coefficients, and it looks right:
http://img48.imageshack.us/img48/8062/rec709torgbwithrec709hb3.th.png (http://img48.imageshack.us/img48/8062/rec709torgbwithrec709hb3.png)

But convert the CCE output clip to RGB24 using Rec.601 coefficients, and it looks wrong:
http://img48.imageshack.us/img48/7002/rec709torgbwithrec601ix3.th.png (http://img48.imageshack.us/img48/7002/rec709torgbwithrec601ix3.png)

Conclusion? Rec.709 input is not converted to Rec.601 internally by CCE, and the CCE output clip is AGAIN (according to DGDecode) flagged as Rec.709.

See? CCE requires Rec.709 input coefficients. Anything else will be incorrectly flagged.

fjhdavid

2nd November 2007, 11:45

You said exactly the same thing than me in the first conclusion of your post and you give a second evidence of what I said; but you omit that DGdecode always give rec.709 when the header is not written and it doesn't mean that it is rec.709 (it is also the purpose of the main discussion of this thread) and CCE dosn't write anything in the header

PowerDVD is very good as you select "original" in the settings.
I tested it with many calibration disc and it gives exactly what was expected: it is 601 compliant

look back to my post and give me the evidence that I am wrong somewhere as my evidence is pure logic

PS: I didn't say that CCE convert anything from rec 601/709 to rec709/601 (I would be surprised if it does)
I just say CCE give correct results when feed by rec.601 and output using a player 601 compliant, it is sufficient for me....not for you?

jdobbs

2nd November 2007, 11:54

I think kumi's post makes good sense. What it says is that CCE doesn't do any internal conversion at all -- it simply encodes what was given to it. So by feeding Rec.709 into it you get Rec.709 output -- and that's the only way to make it meet the 13818-2 callout without insertion of a sequence_display_extension(). It also means that by default all the existing commercial DVDs (that are marked as Rec.709 based upon 13818-2) are being correctly encoded -- without the need for ColorMatrix() -- as has been previously stated.

Either way, this is a CCE discussion and should probably be moved to the CCE forum -- as I'm sure it really has nothing to do with DVD-RB itself -- as interesting as it is.

fjhdavid

2nd November 2007, 14:58

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?

manono

2nd November 2007, 18:28

Sorry, but I can't resist:
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.

fjhdavid

2nd November 2007, 18:45

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

kumi

2nd November 2007, 19:52

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.

fjhdavid

2nd November 2007, 20:00

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

Wilbert

2nd November 2007, 20:06

Let me respond on two points:

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:
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:
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.

kumi

2nd November 2007, 20:17

then read the output and tell us the re-encoded output RGB valueLike 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.)

dragongodz

2nd November 2007, 21:08

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.

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.

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

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.

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. :)

fjhdavid

2nd November 2007, 23:56

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...