[opendtv] Re: Call for Presentations HPA Tech Retreat 2010 - 21:9

  • From: john.meehan@xxxxxxxxxxx
  • To: opendtv@xxxxxxxxxxxxx
  • Date: Wed, 16 Sep 2009 07:17:23 -0500 (CDT)

Hello Jeroen,
 
A question about the Philips 21:9 set and subtitles on Blu-Ray disks - as you've probably seen, subtitle placement varies from one disk to the other - the two lines of text sometimes appear over the active picture, or are split, with the upper line over active picture and the lower line over the black letterbox area.
 
This seems to be entirely an authoring choice, and the viewer is not given the ability to move the subtitles within the player (I've heard that this is "not allowed" according to the standard. Not sure if it's precluded, or just an oversight).
 
The "split" subtitle placement currently causes problems in home theaters set up for anamorphic projection - the second line is cut off when full vertical stretch is used. And unless I'm mistaken, this subtitle placement can be problematic on the new 21:9 set as well...
 
I think there have been discussions in the Blu-Ray group to address this issue. Are you familiar with this?
 
Regards
 
John   
----- Original Message -----
Sent: Wednesday, September 09, 2009 8:05 AM
Subject: [opendtv] Who's going to IBC ? and Call for Presentations HPA Tech Retreat 2010

Hello,

 

I was wondering who of the readers of Open DTV might be going to the IBC 2009 ?

I'll be there next Friday 11 September, most of the day.

I remember meeting some of you in Amsterdam a couple of years ago, when there was

an IBC dinner afterwards. I wouldn't mind shaking a few hands.

 

Most of our AT lab people are coming too, and we're having a group dinner in "l'Express"

(Utrechtsestraat 29) at 18h. I know that Mark Schubin will be in Amsterdam, but only

from Saturday. He has something to look forward to, but I won't tell you what.

 

Then, Mark has issued a "call for presentations" for the HPA Tech Retreat 2010.

I might convince my management to send me next year (I had to cancel this year),

and I might do so by proposing to present a paper, maybe about (application aspects of

our) 21:9 aspect ratio TV. Do I hear any encouragements ?  ;-)

 

Groeten,

-- Jeroen

 

 

  Jeroen H. Stessen

  Specialist Picture Quality

 

  Philips Consumer Lifestyle

  Advanced Technology  (Eindhoven) 

  High Tech Campus 37 - room 8.042

  5656 AE Eindhoven - Nederland

 

 

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Sep 16, 2009 07:26:49 AM, opendtv@xxxxxxxxxxxxx wrote:

Hello,

Kilroy Hughes @ Microsoft wrote:

Ø  I reviewed the deck and am newly inspired to advocate allowing xvYCC (negative coefficient encoding in Y’CbCr).

I prefer if you say: (encoding of negative R'G'B' values in Y'CbCr). But let's not forget

that xvYCC can (and probably will) also encode larger-than-unity values of R'G'B'.

BTW, if Y'CbCr stay within 16..235(240) and add only the previously illegal

combinations of legal Y'CbCr values then (I think) the standard is called sYCC.

Ø  Any recommendation on how to correctly represent that in H.264 encoded content?

I'm not sure what you mean, or if I did that I would know the answer, but I think that

it makes no difference to the (video) content, only to the metadata that describes the

way the content is encoded. Is that what you meant ? In that case I can only refer you

to the HDMI 1.3 and 1.4 specs, where they have tackled the same problem. I think

that there are similar references in MPEG-2. It's all in the metadata.

The only purpose for the "this is wide gamut" metadata bit that I can think of is for

switching between gamut extension (for standard gamut content) and gamut mapping

(for wide gamut content). And this is not even very essential to have.

I think that even in the absence of any metadata, xvYCC would still work quite well.

Of course you do need information about the R'G'B'<->Y'CbCr matrix (Rec.601

for SD, Rec.709 for HD), but that applies also to standard YCC.

Ø  It looks like Transfer Characteristics = 11 signals IEC 6966-2-4; and Primaries and Matrix Coefficients are the same as Rec 709 (VUI value = 1).

Ø  Some inaccuracy there, but Transfer Characteristics different from Rec 709 should encourage some guessing as to what real primaries were encoded.

True, basically you just need a few bits to signal that a wide-gamut standard has been

used, and perhaps distinguish between a few variations. Nothing of it is essential IMO.

On top of that, HDMI also allows to send "Gamut Boundary Metadata", which can

describe very accurately what the source gamut is. This can be simplified to the

original color primaries, i.e. the source gamut is an RGB cube with primaries that are

different from Rec.709 (a.k.a. sRGB). But it is also possible to encode an irregular 3D

shape in all its detail. I think that very few people really ever want to use this, so I don't

know if this will ever be picked up by broadcasters or receivers. It's optional anyway.

The real camera primaries themselves do not matter, of course, since they have been

replaced by (color space converted to) the Rec.709 (sRGB) primaries for xvYCC

encoding. The color space that is actually used will be smaller than an RGB cube, it

is described by a 2D contour like the "Pointer color set" or the 3D "Munsell cascade"

variant. Knowing the edges of the source gamut is supposed to help you with tuning

of the gamut mapping or gamut extension.

Note that HDMI 1.4 distinguishes a few of the professional (photo) color spaces,

meaning that the data is referred to the actual (non-standard) color primaries. This

avoids the conversion to the Rec.709 referred xvYCC color space, and permits a

single conversion to the target (display) color space. There is no compatibility with

Rec.709 standard displays, but if the target refuses to accept it then the source will

have to convert the data to an acceptable format (xvYCC or even standard gamut).

I suppose that these color spaces were added for connecting professional cameras

directly to a display (via HDMI), and transfer the image data as in the JPEG files.

Groeten,

-- Jeroen

  Jeroen H. Stessen

  Specialist Picture Quality

  Philips Consumer Lifestyle

  Advanced Technology  (Eindhoven) 

  High Tech Campus 37 - room 8.042

  5656 AE Eindhoven - Nederland

 



The information contained in this message may be confidential and legally protected under applicable law. The message is intended solely for the addressee(s). If you are not the intended recipient, you are hereby notified that any use, forwarding, dissemination, or reproduction of this message is strictly prohibited and may be unlawful. If you are not the intended recipient, please contact the sender by return e-mail and destroy all copies of the original message.
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