Welcome to Doom9's Forum, THE in-place to be for everyone interested in DVD conversion.

Before you start posting please read the forum rules. By posting to this forum you agree to abide by the rules.

 

Go Back   Doom9's Forum > Video Encoding > MPEG-4 AVC / H.264

Reply
 
Thread Tools Search this Thread Display Modes
Old 26th June 2013, 20:31   #21  |  Link
paradoxical
Guest
 
Posts: n/a
Quote:
Originally Posted by benwaggoner View Post
So how does it work then? The extended primaries get truncated or something? Or is it some kind of an enhancement layer? Multiple encodes?
I don't think anyone has analyzed a stream yet to know exactly. I assume it's some form of custom signaling or metadata that their players can read and is ignored by others. There's no way it can be multiple encodes when the other point of these discs are to increase the average bitrate.
  Reply With Quote
Old 26th June 2013, 20:33   #22  |  Link
paradoxical
Guest
 
Posts: n/a
To add from here:

Quote:
Other Blu-rays have been sourced from a 4K master, so what’s the big deal with these? A few things. First, the video bitrate has been upped considerably to ensure a solid, artifact-free picture: The new, Mastered in 4K Spider-Man maintains a steady 35 Mbps, as compared with the high-20 Mbps bitrate typical with other discs, including the 2012 Spider-Man Blu-ray. (Unfortunately, the increased video data rate means there’s no space for extra stuff like features and commentary tracks.) Second, Mastered in 4K discs incorporate something Sony calls Expanded Color, which otherwise goes by the name x.v.Color or xvYCC. To briefly sum up, discs with x.v.Color incorporate data describing colors outside the standard Rec.709 HDTV color space. When a Mastered in 4K disc is played on an x.v.Color-compatible BD player (according to Sony, only its own player line plus the PlayStation 3 can reliably be called compatible) and displayed on a TV capable of x.v.Color reproduction — Sony’s new W900A series HDTVs (look for my review in the June/July/August issue of Sound&Vision) and XBR-X900A Series 4K Ultra HD TVs, for example — you get the option to view this expanded range. And displaying it shouldn't involve any shift in the TV’s color points — the disc simply instructs the TV to “retrieve” those extra colors without distorting the set’s overall color balance.
There's not a whole lot of specifics though from what I've seen.
  Reply With Quote
Old 26th June 2013, 21:43   #23  |  Link
benwaggoner
Moderator
 
Join Date: Jan 2006
Location: Portland, OR
Posts: 4,736
Quote:
Originally Posted by paradoxical View Post
To add from There's not a whole lot of specifics though from what I've seen.
There really aren't.

The only obvious way I see for them to do what they're doing would be to have a stock Rec. 709 encode and then some kind of enhancement later that added the (relatively small delta) of xvYCC data. Since it's mostly in chroma, that wouldn't be that many samples and they can be quantized quite coarsely. Perhaps using something like Scalable Video coding. I'd think the PS3 would likely have the horsepower to do something like this.

I am now very intrigued by this!

Also, other than Sony BD players, are there any known devices capable of xvYCC playout? It seems support is way more common in TV than it is in any way to play back the content. Can decoders internal to the TVs do the right thing with xvYCC bitstream?
__________________
Ben Waggoner
Principal Video Specialist, Amazon Prime Video

My Compression Book
benwaggoner is offline   Reply With Quote
Old 26th June 2013, 23:00   #24  |  Link
IanB
Avisynth Developer
 
Join Date: Jan 2003
Location: Melbourne, Australia
Posts: 3,167
From what I understand Sony use the 1-15 and 241-254 chroma values to represent higher saturation colours. When you do the normal YUV->RGB translation you can end up with normalised colour values less then 0.0 or greater than 1.0, normal decoders clamp these values, advanced decoders map these values into a wider gamut colour space. The luma range is still 16-235.
IanB is offline   Reply With Quote
Old 26th June 2013, 23:14   #25  |  Link
benwaggoner
Moderator
 
Join Date: Jan 2006
Location: Portland, OR
Posts: 4,736
Quote:
Originally Posted by IanB View Post
From what I understand Sony use the 1-15 and 241-254 chroma values to represent higher saturation colours. When you do the normal YUV->RGB translation you can end up with normalised colour values less then 0.0 or greater than 1.0, normal decoders clamp these values, advanced decoders map these values into a wider gamut colour space. The luma range is still 16-235.
That makes sense. But if chroma is getting clamped at those values, I worry we'll see posterization of chroma levels when the extended colors get clamped. A gradient of "very red" could turn into a flat area of just red without any detail. If there is some texture in the luma channel that might mask things, but still. It seems like it would be hard to make a "best of both worlds" encode like this.
__________________
Ben Waggoner
Principal Video Specialist, Amazon Prime Video

My Compression Book
benwaggoner is offline   Reply With Quote
Old 27th June 2013, 01:25   #26  |  Link
IanB
Avisynth Developer
 
Join Date: Jan 2003
Location: Melbourne, Australia
Posts: 3,167
The out of gamut high saturation colours considered here would have been clamped in normal processing anyway, either by the source camera and/or the display device. The system just gives the opportunity to not clamp the very saturated colours when a high gamut source and display are available.
IanB is offline   Reply With Quote
Old 1st July 2013, 21:26   #27  |  Link
benwaggoner
Moderator
 
Join Date: Jan 2006
Location: Portland, OR
Posts: 4,736
Quote:
Originally Posted by IanB View Post
The out of gamut high saturation colours considered here would have been clamped in normal processing anyway, either by the source camera and/or the display device. The system just gives the opportunity to not clamp the very saturated colours when a high gamut source and display are available.
But if you allow out of range colors that will get clamped on some devices, it seems inevitable that you'll get posterization when it does wind up getting clamped.
__________________
Ben Waggoner
Principal Video Specialist, Amazon Prime Video

My Compression Book
benwaggoner is offline   Reply With Quote
Old 2nd July 2013, 00:18   #28  |  Link
IanB
Avisynth Developer
 
Join Date: Jan 2003
Location: Melbourne, Australia
Posts: 3,167
Yes, intuitively I agree there should be some sort of saturation posterization effect but how do you characterise and witness it.

We are talking about saturation getting clamped here, not luminance or hue. And saturation restriction happens with our simple trichromatic eyes.

The clamping happens in the YUV to RGB translation where you end up with normalised RGB values less then 0.0 or greater than 1.0 I tried an experiment using Limiter(0, 255, 31, 226) to knock another 15 off the normal chroma range and I cannot see any difference, which just probably means I do not have samples that sufficiently use the high saturation part of the existing gamut and/or a display that is not already more saturation challenged than the clamp.

I guess an extreme test case might involve some pure monochromatic light sources like sodium lamps, lasers, etc and a display version of the same. But our eyes cannot see spectrally pure colours as spectrally pure.
IanB is offline   Reply With Quote
Old 2nd July 2013, 02:52   #29  |  Link
benwaggoner
Moderator
 
Join Date: Jan 2006
Location: Portland, OR
Posts: 4,736
Quote:
Originally Posted by IanB View Post
The clamping happens in the YUV to RGB translation where you end up with normalised RGB values less then 0.0 or greater than 1.0 I tried an experiment using Limiter(0, 255, 31, 226) to knock another 15 off the normal chroma range and I cannot see any difference, which just probably means I do not have samples that sufficiently use the high saturation part of the existing gamut and/or a display that is not already more saturation challenged than the clamp.
Yeah. Begging the question of whether xvYCC actually provides any viewer value for most real-world content. How different is the master, really, and for what content?
__________________
Ben Waggoner
Principal Video Specialist, Amazon Prime Video

My Compression Book
benwaggoner is offline   Reply With Quote
Old 2nd July 2013, 05:28   #30  |  Link
ChiDragon
Registered User
 
ChiDragon's Avatar
 
Join Date: Sep 2005
Location: Vancouver
Posts: 600
When I compared the new "Mastered in 4K" BD of the 2002 Spider-Man movie to the old disc, I found that there were more instances of >240 chroma on the previous release than the xvYCC one.

It would be nice if they included some test content to verify the effects of the gamut expansion on your TV. There is a hidden video file but it's just a long, slow pan across a still image with no apparent usefulness.
ChiDragon is offline   Reply With Quote
Old 2nd July 2013, 17:18   #31  |  Link
benwaggoner
Moderator
 
Join Date: Jan 2006
Location: Portland, OR
Posts: 4,736
Quote:
Originally Posted by ChiDragon View Post
When I compared the new "Mastered in 4K" BD of the 2002 Spider-Man movie to the old disc, I found that there were more instances of >240 chroma on the previous release than the xvYCC one.
Huh.

Are there any discs that are known for particularly good use of xvYCC? Or even noticeable use?
__________________
Ben Waggoner
Principal Video Specialist, Amazon Prime Video

My Compression Book
benwaggoner is offline   Reply With Quote
Old 2nd July 2013, 17:28   #32  |  Link
SeeMoreDigital
Life's clearer in 4K UHD
 
SeeMoreDigital's Avatar
 
Join Date: Jun 2003
Location: Notts, UK
Posts: 12,217
Quote:
Originally Posted by benwaggoner View Post
Huh.

Are there any discs that are known for particularly good use of xvYCC? Or even noticeable use?
I'd go further...

I would like to know if there's anybody on this forum who has a 'xvYCC supporting' Sony Blu-ray player and TV? Because without these two supporting devices, nobody is going to 'see' any noticeable difference!
__________________
| I've been testing hardware media playback devices and software A/V encoders and decoders since 2001 | My Network Layout & A/V Gear |
SeeMoreDigital is offline   Reply With Quote
Old 19th July 2013, 19:30   #33  |  Link
benwaggoner
Moderator
 
Join Date: Jan 2006
Location: Portland, OR
Posts: 4,736
Well, I've made myself a Rec. 2020 H.264 High 10 encode via x264!

Anyone have any idea what players actually know about Rec. 2020? I've got a Quadro K4000 plugged into a Dell U3011 30-bit display via DisplayPort, so I can render out 10-bit images via both DirectX and OpenGL. Dell claims it has a 120% gamut range based on the CIE1976 (83%) and CIE1931 (72%) test standards.

But what should be able to do the right thing here?
__________________
Ben Waggoner
Principal Video Specialist, Amazon Prime Video

My Compression Book
benwaggoner is offline   Reply With Quote
Old 19th July 2013, 20:39   #34  |  Link
vivan
/人 ◕ ‿‿ ◕ 人\
 
Join Date: May 2011
Location: Russia
Posts: 643
madVR
vivan is offline   Reply With Quote
Old 19th July 2013, 20:52   #35  |  Link
mp3dom
Registered User
 
Join Date: Jul 2003
Location: Italy
Posts: 1,135
Since the topic also mentions greater color depth, I would like to point out the Panasonic "Master Grade Video Coding". There are not a lot of infos about it, but seems that the hint is to use the bluray MVC structure to use the base view as the standard image, and the dependent view for increase the bit depth of the video. Panasonic players with MGVC support should be able to 'merge' the MVC and outputs a 2D video with up to 12bit informations. Also, this method allows to fully use the 60 Mbps of the bluray 3D specs.
Here some explanation (JP)
mp3dom is offline   Reply With Quote
Old 19th July 2013, 22:15   #36  |  Link
sneaker_ger
Registered User
 
Join Date: Dec 2002
Posts: 5,565
Quote:
Originally Posted by vivan View Post
madVR
madVR does not support output higher than 8 bit - just input. (Plus it only outputs RGB).

Last edited by sneaker_ger; 19th July 2013 at 22:21.
sneaker_ger is offline   Reply With Quote
Old 19th July 2013, 22:33   #37  |  Link
vivan
/人 ◕ ‿‿ ◕ 人\
 
Join Date: May 2011
Location: Russia
Posts: 643
Quote:
Originally Posted by sneaker_ger View Post
madVR does not support output higher than 8 bit - just input. (Plus it only outputs RGB).
But it does support Rec. 2020. I doubt that any other renderer supports it. So it's better than nothing, right?
vivan is offline   Reply With Quote
Old 20th July 2013, 00:30   #38  |  Link
benwaggoner
Moderator
 
Join Date: Jan 2006
Location: Portland, OR
Posts: 4,736
Also, what's the proper --colormatrix setting for 10-bit Rec. 2020 (without expanded luma range)?

Using --colorprim bt2020 --transfer bt2020-10 are obvious, but I can't find any documentation on the difference between bt2020c and bt2020nc
__________________
Ben Waggoner
Principal Video Specialist, Amazon Prime Video

My Compression Book
benwaggoner is offline   Reply With Quote
Old 20th July 2013, 01:49   #39  |  Link
drmpeg
Registered User
 
Join Date: Jan 2003
Location: Silicon Valley
Posts: 455
Quote:
Originally Posted by benwaggoner View Post
Also, what's the proper --colormatrix setting for 10-bit Rec. 2020 (without expanded luma range)?

Using --colorprim bt2020 --transfer bt2020-10 are obvious, but I can't find any documentation on the difference between bt2020c and bt2020nc
bt2020c = constant luminance

bt2020nc = non-constant luminance

So for your example, bt2020nc would be correct.

Ron
__________________
HD MPEG-2 Test Patterns http://www.w6rz.net
drmpeg is offline   Reply With Quote
Old 20th July 2013, 02:53   #40  |  Link
benwaggoner
Moderator
 
Join Date: Jan 2006
Location: Portland, OR
Posts: 4,736
Quote:
Originally Posted by drmpeg View Post
bt2020c = constant luminance

bt2020nc = non-constant luminance

So for your example, bt2020nc would be correct.
Why? I would have thought that "non-constant" would refer to the 12-bit mode with high dynamic range luma, which has a different, steeper gamma for high values.
__________________
Ben Waggoner
Principal Video Specialist, Amazon Prime Video

My Compression Book
benwaggoner is offline   Reply With Quote
Reply

Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump


All times are GMT +1. The time now is 03:35.


Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2024, vBulletin Solutions Inc.