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Mastered in 4K Blu-rays announced by Sony

Phil Hinton

Editor
Staff member
Optimized for 4K Ultra HD TVs! Well so they claim…

If there is one company who will be at the front of the pack when 4K content becomes a reality for consumers, it will be Sony. The company have the means and resources due to their ownership of a film studio, post production houses and mastering facilities, not to mention their consumer electronics experience, to make sure they have a complete 4K eco system in place. So, it's a little surprising that Sony have announced a line of Blu-ray releases which at face value, seem like a marketing initiative rather than offering anything new. We have to say our curiosity was certainly piqued by their latest announcement.

Sony have recently announced two waves of BD releases with the tag line, <i>Mastered in 4K</i>. But this is usually the case for most new releases out of Hollywood where the Blu-ray, such as Universals Schindler's List is encoded to disc from a 4K scanned master, but done so at the BDA specifications of Rec.709 for colour & 8 bit video. Blu-ray discs have to meet the BDA standard to carry the BD badge and be called Blu-ray. As far as we are aware there has been no change in the BDA specification to allow wider colour gamuts or higher than 8bit video. Yet part of the message coming from Sony is that wider colour gamut appears to be one of the features of these new remastered discs. Intriguing stuff.

AVForums members will remember that with DVD Sony did something similar called <i>Superbit</i> where they released DVDs with a claimed higher bit rate for better quality images. These fell by the wayside not long after the release of Blu-ray but they did have fans amongst the home cinema community. It would appear that the <i>Mastered in 4K</i> Blu-rays are in line with the old superbit idea, but we have a few questions for Sony on this one.

As they cannot break the BDA specifications for Blu-ray discs, and Sony were founding partners of the BDA, how are they offering wider colour gamuts on these discs? The press information released so far indicates that the discs are for owners of the Triluminos & 4K TVs to tide them over until native 4K content is available. Yet the discs will also play on normal BD specified equipment, which indicates they are sticking to the BDA spec. So, are they encoding these discs with meta data so they speak to the new Triluminos sets to unlock a wider gamut that fits? That might be technically possible but it also adds yet more questions to what the new discs are supposed to achieve. Some information suggests using x.v.Colour encoding, but as far as we know, that also doesn't fit with the BDA specs. And, the x.v.Colour specifications are Rec.709 colour and D65 white - the same as Blu-ray. The x.v.Colour format does allow some encoding of wider saturation according to some white papers, so this also might make some sense in what Sony is proposing, but it is all rather confusing at this stage, given the limited information Sony has released so far.

So, the cynics out there may say it is purely a marketing drive by Sony with these Blu-ray discs and when you hear comments of the 4K TVs retrieving the extra detail of the 4K mastered disc, at this point we would tend to side with the cynic in us - at the moment anyway. We are all ears Sony and open to a briefing on the technical merits of these releases.

The first wave of discs <i>Mastered in 4K</i> will include Taxi Driver, The Other Guy and Ghostbusters, along with 12 other titles. We also understand that these releases have been confirmed for the UK later this year.
 

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kbfern

Distinguished Member
As you say Phil marketing hype.:) a bit like JVC did with their e-shift although I do accept that is a worthwhile addition but when they put 4k on the boxes it was a bit naughty.
 

vaktmestern

Banned
Think a vs test of those 4k remasterd movies vs the regular bd upscaled to 4k is in order :lesson:
 

The Eggman72

Established Member
hmm the blu isnt the greatest transfer so curious to see how it fares in 4k.
 

Dan201

Prominent Member
Often the quality of transfers to bluray vary from region to region. Perhaps they will just pay more attention to the transfer making sure its 100%. It might make the movie look like its improved past Bluray specs when in realisty the original release didn't take full advantage of the format to begin with.
 

vism

Prominent Member
I really hate it when the industry does things like this.

They are pointlessly confusing the consumer by using the 4k tag on a 1080p Blu-ray.

GIVE IT A REST SONY!
 

figoagogo

Distinguished Member
Superbit Part 2 - sham.
 

Mr.D

Distinguished Member
Here is the film pipe. See if any of you can spot where the Emperor's new clothes come in.

4k film mastering workflow for BD.

35mm film negative scanned on a usually native 6k scanner either 1:1 pixel mapped on the CCD sensor or downscaled on the fly from the full 6k scan to 4k.

Colorspace 10bit log "cineon" usually written out as dpx files these days.
4096x3112 for 4k fullap.

This gets graded into video colorspace; can be done a number of ways for example.

Rec.709 calibrated monitor/projector for reference and the log material is graded subjectively to the preferred look straight to video. This is usually how a legacy film is graded for mastering to BD or dvd.

Some people prefer to grade towards a print target using a correctional 3d LUT on a monitor of known baseline (can be rec.709 or sRGB or even linear). this is more analagous to how a first run feature is graded as you target print and then bake the equivalent correctional LUT in to get you the video versions.

There are lots of variations on this including targeting a P3 (DCI) type baseline and correcting from that or even targeting a linear 32bit float delivery and correcting from that for the various deliverable versions. (last one is a bit more recent)

Either way is transparent when it finally gets to rec.709 , 4:2:0 component 8bit 1080p compressed video. ie you won't be able to infer exactly what has happened upstream from this as the process has got too lossy by that stage.

thats 4k here comes 2k workflow.

Exactly the same except it either comes off the same 6k scanner having been downsampled either on the fly or later from 4k to 2k.

Here is the point 2k film masters have been initially scanned as 4k or greater for about the past 15 years. The only difference between 4k and 2k mastering with regard to BD type deliverables is WHERE the downsample happened in the chain.

The end difference when its on the BD assuming both chains were executed according to standard methodology would be negligible to the point of being a subpixel difference.

Things like the difference between scanning on a pin registered northlight vs a pinch roller registered Spirit datacine ( made by Sony I hasten to add) would be more evident. I would even suggest I'd rather have a 2k scan off a Northlight as a starting point that a 4k scan off a spirit.

Now thats before we get into other mysterious things that happen with regard to the so called "1080p" video you find on BD.

If we assume that a 2k film scan of a fullap 35mm film frame is 2048x1556 then there are a couple of ways of optimising its conversion to 1080p before we reach for 4k.

rule 1.

Maintain pixel to pixel relationship to the original scan;


CROP don't resize the 2048 to 1920. This entails cropping off 68 pixels either side of the 2048 rather than downsizing the 2048 to 1920.
You can then miss out entirely a sub-pixel filtering stage which will likley save you from sacrificing HALF the real resolution in the image of the original 2k.

Film gates in cameras , scanners and the markings that the DOP is referencing through the viewfinder are not usually maintained to tolerances higher than the 2048 to 1920 crop represents anyway AND the scanner usually scans about 20 pixels around the film frame which is unexposed negative anyway;

Upshot ...you won't miss it , its not diluting the directors intent and you will benefit from a massive improvement in real resolution. [/B]

Sounds perfectly simple doesn't it? Now lets ask how often is this done.

Answer (from my investigations ) NEVER.

I've compared original 2k and 4k log scans to the 1080p versions found on BD (I can do this because these are films I worked on and had the material to hand ).

What I see is unexplained , illogical and unecessary subpixel rescales and repositions on the 1080p relative to the 2k and 4k original film frames. We are not talking creative reracking here but arbitrary inconsistent ( sometimes even consistent) rescales that don't make any sense relative to the original scan. The repositioning look like errors and or sloppiness to me rather tan deliberate action. The rescale and repo is often not even centred on the centre of the actual image.

The effect of this is to render most 1080p BDs the equivalent of 1k let alone 2k or 4k. For example if I take the 2048x1556 scan and downsample to 1024x778 it looks sharper than the 1080p blu ray version that also includes me simulating the 4:2:0 component color downsample and eyeballing in the end video grade.

So upshot is that 4k mastering from a BD delivery perspective is baloney and there are other ways to deliver a better end visual result that just rely on care and attention.

However these things are not marketable as something new and shiny , at least not as marketable as a bigger number.
 

vaktmestern

Banned
Thought sony at ces 2013 did say the 4k bds will upscale more easy on they tvs
 

Greg Hook

Moderator & Reviewer
The industry really doesn't help themselves does it? We've endured no end of people saying things like 'I can't tell the difference between DVD and Blu-ray, or HD and SD, then we will now have people saying they can't see a difference between 4K and non 4K, when in fact it isn't 4K anyway. :(

Better mastering , not anything to do with the 4k nomenclature.

Indeed. The original Blu looked awful anyway. So this is probably how it should have looked.
 

Dan201

Prominent Member
Im looking forward to 4k but this just makes me wish they would get the most out of 1080p before moving on.
 

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