is CCE bt.601 or bt.709?

[fjhdavid]

Dear all,

If there are CCE programers or DVD specialist

I would like to know if CCE is expecting Bt.601 coeff or Bt.709 coeff for input/output?

its seems that the answer is bt.709, but it is just to be sure as we have no direct info from CCE guys

thanks
Francois

PS: there is already a thread open in DVD-RB forum

[45tripp]

but it is just to be sure as we have no direct info from CCE guys


company reps are notorious for spewing bull...


I would like to know if CCE is expecting Bt.601 coeff or Bt.709 coeff for input/output?

The simple answer would be: it expects nothing.

With rgb input, the conversion to yuy2 is done with 601 coeffs.
With yuy2, what you input is what you'll get for output.

Now, if input is decoded to rgb with different coeffs to what output is, that's mostly dependent on the app doing the yv12->rgb conversion.

My opinion is that most SD, if not all, is and should be handled with 601 coeffs.

I think it's a matter of knowing what behaviour to expect when you get converted to rgb.
I think not setting color matrix coefficients in the header is a mistake.
I also think assuming 709 coefficients in the absence of the header is also a mistake despite what the paper says.

anyway,
consider 4 sources:

A
colorbars(720,480)
killaudio()
trim(0,120)

Feed rgb to CCE, 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
colorbars(720,480)
killaudio()
converttoyuy2(matrix="rec709")
trim(0,120)

Feed to CCE, get mpeg2, 709 coeffs used.
No sequence_display_extension present.

D
the same as C but set matrix coefficients in header to 709.
I don't know of a tool to do it,
but Hank produced a colorbar stream with an HC version he made
for 709 input to 709 output. The es is linked to in the dvdrebuilder thread you mention.

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,
assuming the material prior to getting to you when going through
yuy2<->rgb conversions was doing so with 601 coeffs.
And I do assume that.

gl

[fjhdavid]

thanks for your answer.

I was at the origin of a thread in DVD-RB forum where you also answer.

I completely agree with you as I tested different case with PowerDVD and DGindex for 601 flagged DVD.

I also think that all DVD are 601 even if there are unflagged and even if the norm say they must be 709 (the norm is a mess for this point)

awfully DGindex follows the norm and is 709 compliant and then shows chromacity error on this unflagged DVD. PowerDVD doesn't care about the display extention header and assumes that everything which is SD is 601 (as many DVD standalone players...)

to summarize, but correct me if I am wrong, colormatrix (bt.601 ->bt.709) and others conversion filters are USELESS and MUST NOT be used as they are source of chromacity error.

[45tripp]

awfully DGindex follows the norm and is 709 compliant and then shows chromacity error on this unflagged DVD.
I don't think it awful, it's mostly informational and had good basis.
Although, the info can misleed (and has).
An 'assumed' notification might be nice.


to summarize, but correct me if I am wrong, colormatrix (bt.601 ->bt.709) and others conversion filters are USELESS and MUST NOT be used as they are source of chromacity error.
Useless is a strong word,
most things find use.
I can't know what each piece of equipment and player does...
If one happens to assume 709 for unflagged content,
or abide to some other scenario?
Then you should incorporate some conversion and/or flagging
to your work flow.

I do think though that the crushing majority of content is 601
and should stay so,
that most players will use 601.

gl