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-   -   BMCC 4K is Quad HD not 4K (https://www.dvinfo.net/forum/blackmagic-cinema-camera/517958-bmcc-4k-quad-hd-not-4k.html)

Bruce Schultz July 26th, 2013 10:23 AM

BMCC 4K is Quad HD not 4K
 
Someone can correct me if I'm wrong about this, but yesterday at the Burbank show I grilled several of the top techs from BMD and they revealed to me that all BMD 4K enabled products (BM Cinema 4K, Hypershuttle Pro, etc) only process in 4:2:2 color space and at 3840 x 2160 not 4096 x 2160.

This is Quad HD and not 4K resolution.

I have no beef with this, as I feel there will be a broadcast market for Ultra/Quad HD, but many potential (cinema) users would be surprised as I was to find out that you are not shooting legitimate 4K with the BMCC 4K camera. The 6G SDI output only outputs 3840 x 2160 also, so no 4K love there either, and no support for 4:4:4 raw at all on that camera either internally or via the 6G SDI. As of yesterday, their 4K camera is only recording 4:2:2 Pro Res HQ. I could not determine if/when the Cinema DNG recording capability is enabled in firmware if that would be legit 4K resolution or not.

I still like the 4K camera and feel that it is a great, inexpensive camera tool for TV broadcast work in Ultra/Quad HD, but I would be hesitant to promote it to any clients expecting cinema 4K resolution footage.

Anyone with a different take on this, please correct me or chime in.

Daniel Epstein July 26th, 2013 10:58 AM

re: BMCC 4K is Quad HD not 4K
 
Are they Square Pixels? Frankly being this close to 4096 and matching the 2160 seems like no big deal. The 4:2:2 issue might be more significant but hey what are they competing against. I remember when HDCAM was 1440 x1080 etc. Of course it might be good to know the technical reason they have a sensor that size.

Charles Papert July 26th, 2013 11:33 AM

Re: BMCC 4K is Ultra HD not
 
That is a difference of 300 lines of resolution. I would love to see anyone who would consider that an issue to have to pick between unlabeled Quad and 4K versions of the same footage projected on any size screen. And if anyone is that much of a stickler, they shouldn't be shooting with a prosumer camera to begin with, one with a form factor that was not designed for professional use.

It's becoming something of a cliche to bring this up as a comparison, but Skyfall was shot at 2.8K and it's hard to argue with the results.

John Nantz July 26th, 2013 11:51 AM

re: BMCC 4K is Quad HD not 4K
 
Just to clarify Bruce's issue, it is not whether the 3840 x 2160 provides a quality image but it is whether 3840 is 4K - or not. This is an important issue if one tells a client that you're shooting 4K but in fact it isn't.

To say one is shooting 4K when it isn't is misrepresenting the product and/or the work.

Its like "close but no cigar." Or you're pregnant or you aren't.

Can't remember the quote from Bill Clinton about dear Monika or I would use it.

Anyway, that's how I read it. What about 4K-ish?

On another note .... a couple years ago I was talking to someone who was shooting in 1440CBR and saving the files to the camera's SD card. He thought the files were 1440 but they weren't, they were SD. BUT they looked great and it wasn't until digging into the camera specs that this was discovered.

Charles Papert July 26th, 2013 12:14 PM

re: BMCC 4K is Quad HD not 4K
 
I see your point--in theory. In real life, it's nothing like being pregnant or not. It's more like being 8.5 months pregnant vs 9 months.

I was initially excited when the last build of the Alexa allowed for internal 2K recording vs HD, but when I did the calculations I saw that it would increase resolution by 6% (the same difference as between Quad and 4K). I have done blowups of 10, even 15% that are undetectable even projected. This should be even less of an issue with double the resolution.

This is splitting hairs and clients who are only budgeting for the use of a $4000 camera should absolutely not be making that kind of distinction. They insist on true 4K, they should be prepared to pony up real money. They are lucky to be getting anything over 1080 (and most likely, they don't even know the difference, they are just spouting rhetoric anyway).

As a point of comparison, I shot a feature coming out on which I was told by the producers that shooting Arriraw on the Alexa was out of the question, ProRes4444 was good enough. This was obviously not a limitation that prevented it from getting a substantial theatrical release and no-one has ever had a concern with the way it looks.

Bruce Schultz July 26th, 2013 12:45 PM

re: BMCC 4K is Quad HD not 4K
 
Is or is it not 4K is what I am musing about. For $4000 this is a great tool for broadcasters & UHD quality archiving of footage. But if I misrepresent it as true 4K then I'm misinforming my client (in my case many times its major studios) then thats not a good or fully honest policy.

I agree that the 256 lines are not distinguishable on blowup to 4096, but one quick look at inspector gives the game away.

Still I like the camera and will probably add one to my kit.

Charles Papert July 26th, 2013 12:53 PM

re: BMCC 4K is Quad HD not 4K
 
If one has to turn camera originals over without processing, that would be the case, for better or worse. I can't see why edited deliverables couldn't be uprezzed 6% to 4K from Quad though.

Bruce, have you already experienced this? Clients making a distinction between the two? Or for that matter--a distinction between 1080 and 2K?

Chris Hurd July 26th, 2013 01:14 PM

re: BMCC 4K is Quad HD not 4K
 
Just to avoid any potential confusion, I have edited the title of this thread...

from: BMCC 4K is Ultra HD not 4K

to: BMCC 4K is Quad HD not 4K

The potential point of confusion being the fact that 4K *is* Ultra HD, by definition.

I guess the real question at stake here is whether or not Quad HD counts as Ultra HD.

I'll have to agree with Charles here. Is there any other word that better characterizes the difference between 3840 and 4K (or for that matter, 1080 and 2K) than "negligible?"

Bruce Schultz July 26th, 2013 01:26 PM

Re: BMCC 4K is Quad HD not 4K
 
Quote:

Originally Posted by Charles Papert (Post 1806214)
Bruce, have you already experienced this? Clients making a distinction between the two? Or for that matter--a distinction between 1080 and 2K?

No not yet. But I would rue the day when Sony or WB post production calls to ask why they now have to blow up the footage

Its all theoretical at this point, but you know how anal post people can be at times and they can bury you when you are not there to explain.

I' ve always found brutal honesty to be the best policy at all times in this regard.

PS. Skyfall yes but remember Avatar, Hugo were both only 1080 & in 3D

Bruce Schultz July 26th, 2013 01:35 PM

Re: BMCC 4K is Quad HD not 4K
 
Quote:

Originally Posted by Chris Hurd (Post 1806215)
I'll have to agree with Charles here. Is there any other word that better characterizes the difference between 3840 and 4K (or for that matter, 1080 and 2K) than "negligible?"

No argument from me on that. Purely academic, but still 256 lines & a necessary blowup to conform to a 4096 timeline in post. Someone is bound to bitch at some point, don't want to be on that receiving end.

And let's not overlook the 422 vs 444 issue either. Might not be a big problem in normal production but definitely would be a big issue in any compositing or VFX work.

So I say again, honesty is still the best policy here.

Charles Papert July 26th, 2013 01:36 PM

Re: BMCC 4K is Quad HD not 4K
 
Agreed on the anal thing! (although that phrase gives me pause for some reason)

Preaching to the choir with me on 1080p--I've certainly worked on plenty of features and episodic that have originated in that format. I didn't fight hard when I was shut down on the Arriraw request. In truth, the Codex recorders would have killed us. Now that it is available internally on the Alexa, I'm sure I'll be more likely to fight the good fight down the road.

Bruce, please update this thread when your first set of 4K specs comes down the road. I'd be curious to see what the studio requests are.

Brian Drysdale July 26th, 2013 01:38 PM

Re: BMCC 4K is Quad HD not 4K
 
HD cameras are used for 2k cinema release and have been for many years, there's no real difference.

David Heath July 26th, 2013 03:47 PM

Re: BMCC 4K is Quad HD not 4K
 
Quote:

Originally Posted by Chris Hurd (Post 1806215)
I'll have to agree with Charles here. Is there any other word that better characterizes the difference between 3840 and 4K (or for that matter, 1080 and 2K) than "negligible?"

Unfortunately, as has been the case so often in the past, usage of nomenclature gets blurred, to the extent where it starts to cause confusion.

The key point is that the difference between 3840 and 4096 systems is far, far less one of "a bit of resolution", far more one of ASPECT RATIO. Quad HD is exactly that, and hence (like HD) it maintains the 16:9 aspect ratio that is considered the TV norm. It can also be expressed as 1.78:1.

The 4096 system has a wider aspect ratio - about 1.9:1, which is roughly the traditional norm in the projected cinema.

It's worth looking at Wikipedia which makes it a bit clearer - 4K resolution - Wikipedia, the free encyclopedia . Hence, both 3840x2160 and 4096x2160 can accurately be described as "4k" - but the former is primarily intended for TV displays, the latter for the cinema.

If something is shot 4096x2160, then making a quad-HD version is simple - just crop off either side to make the 3840x2160/quad-HD version. But the other way round is not so good. You have to crop vertically (to change 1.78:1 to 1.9:1) - but then additionally have to scale the frame up to 4096x2160.

Finally, as if that wasn't confusing enough, then the 4:4:4 and 4:2:2 aspects are a complete red herring. Leaving aside top end cameras like the F65, nearly all 4k cameras at the moment have a 4k sensor - 4096 (or 3840)x2160 photosites with a Bayer filter. That will inevitably mean that luminance resolution after deBayering will be only about 80% of the sensor dimensions, and chroma resolution 50%. (Think about it - the red and blue photosite patterns are only 1920x1080 in isolation. There is no way the sensor can give "4:4:4", even if that's the recording system.)

Brian Rhodes July 26th, 2013 04:11 PM

Re: BMCC 4K is Quad HD not 4K
 
Quote:

Originally Posted by Chris Hurd (Post 1806215)
Just to avoid any potential confusion, I have edited the title of this thread...

from: BMCC 4K is Ultra HD not 4K

to: BMCC 4K is Quad HD not 4K

The potential point of confusion being the fact that 4K *is* Ultra HD, by definition.

I guess the real question at stake here is whether or not Quad HD counts as Ultra HD.

I'll have to agree with Charles here. Is there any other word that better characterizes the difference between 3840 and 4K (or for that matter, 1080 and 2K) than "negligible?"


I have the Sony 84 inch 4K TV Sony specs. the TV 4K Ultra High Definition (3,840 x 2,160) resolution.
LG 4k TVs are the same resoulution Ultra HD 4K Resolution (3840 x 2160p).

So the 4K TVs are not really 4K? Quad HD

Chris Hurd July 26th, 2013 04:17 PM

Re: BMCC 4K is Quad HD not 4K
 
Quote:

Originally Posted by David Heath (Post 1806236)
The key point is that the difference between 3840 and 4096 systems is far, far less one of "a bit of resolution", far more one of ASPECT RATIO.

I really need to add a "like" button, and a "thanks" function!


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