How does UHD BD compare to the files used by proper digital movie theaters?

[bhampton]

Does anyone know by the numbers how UHD BD compares with the files used in movie theaters?

I have heard many theaters get encrypted hard drives containing movie releases.

I have also heard (but I do not know for sure) that digital movie theater projectors are 4K.

UHD BD claims theater quality sound and video at home and seems to deliver. I wonder if actual theaters still have higher bit rates. I know some theaters have higher frame rates.

-Brian

[koberulz]

It's completely different in every way.

[benricci]

It's a mixture of 2K and 4K screens (we'll leave IMAX out of it for now), with a lot of theaters actually using 2K setups, not 4K (keep in mind, this is still high enough quality for a super-huge theatre screen).

Digital Cinemas, as opposed to home video formats, get files up to 250 Mb/s (many films reaching up to 150GB in file size, if I remember correctly) which is a higher bitrate than home formats like UHD and normal blu-ray. So there's going to be less compression employed at the cinema than at home, though your ability to actually perceive those differences depends on a lot of factors.

I'm sure there are those with more expert knowledge than me, but that's the general gist of it. They're not just popping in a UHD disc and pressing play, if that's what you were wondering. it's an entirely different setup.

You can go down the rabbit hole and get lost in lots of tech specs here: https://en.wikipedia.org/wiki/Digital_Cinema_Package

[meremortal]

Originally Posted by benricci

It's a mixture of 2K and 4K screens (we'll leave IMAX out of it for now), with a lot of theaters actually using 2K setups, not 4K (keep in mind, this is still high enough quality for a super-huge theatre screen).

Digital Cinemas, as opposed to home video formats, get files up to 250 Mb/s (many films reaching up to 150GB in file size, if I remember correctly) which is a higher bitrate than home formats like UHD and normal blu-ray. So there's going to be less compression employed at the cinema than at home, though your ability to actually perceive those differences depends on a lot of factors.

I'm sure there are those with more expert knowledge than me, but that's the general gist of it. They're not just popping in a UHD disc and pressing play, if that's what you were wondering. it's an entirely different setup.

You can go down the rabbit hole and get lost in lots of tech specs here: https://en.wikipedia.org/wiki/Digital_Cinema_Package

Bolded part certainly is worth noting. I've seen movies at arthouse theaters where they just used the blu ray as the source from what looked like a computer or htpc kind of setup since I've seen a media player and scrolling mouse projected onto the screen at times. And they looked pretty good to me even on a huge cinema screen in 1080p. I've sat close to the front rows, towards the middle, or in the back rows and pretty much anywhere has looked pretty nice on a theater screen. If blu ray can look great in a cinema, then I'd like to see some uhds in that setting for comparison.

[Fjodor2000]

Originally Posted by benricci

Digital Cinemas, as opposed to home video formats, get files up to 250 Mb/s (many films reaching up to 150GB in file size, if I remember correctly) which is a higher bitrate than home formats like UHD and normal blu-ray. So there's going to be less compression employed at the cinema than at home

DCP is just a series of JPEG 2000 images, and simply speaking the encoder looks for similarities within a single frame when compressing. H.264/265 as is used on BD/UHD on the other hand look for similarities in a number of subsequent frames, and can use that to compress more efficiently. If there is not much differences between subsequent frames (i.e. typically little movement & low noise), this will result in much better compression. DCP vs H264/265 are completely different encoders, and this was just one example where they differ.

So it's apples vs oranges as others also has mentioned. You cannot look only at the bitrate when comparing.

[Geoff D]

Basically, it's all so different that it's not worth trying to compare them on file sizes alone.

[silentbob]

I haven’t worked at a greater in 7 years. Basically lost my job because we went all digital. Still, yeah they came on HDD but more were heading forward with Digital Downloads. When we had 2-4 Theaters each print had to loaded onto each theatre HDD and build the print in a drag and drop sort of way. Input your 4 ques for the theatre lighting and you have yourself a print. We were all 2k projectors but 2-4 of them were capable of being upgraded to show 4K (if I remember correctly) Good chunk of your Theaters are more then likely just 2K projectors. The gentleman who trained me installed a few and said he really didn’t notice much if any difference. He also help setup the first IMAX theatre in Toronto at Ontario Place all them years ago. We’re buying glass tube audio components from local HiFi stores he said before normal audio setups happened. My theatre used Christie Projectors (2040 and 3020 I believe were the model numbers) Like you mention as well, yes they are encrypted. Depending on the studio the digital key to unlock your print were usually good 2-3 weeks before needing another digital key after that to continue playing the film. I think Sony was the only distributor we had that allowed their prints to stay unlock for 3-4months. They ranged in film size from 74GB to well over 100GB for the 3D Avatar like films.

[avs commenter]

It’s only convenient to compare bitrate and file size when comparing HT digital vs physical

[Geoff D]

Originally Posted by avs commenter

It’s only convenient to compare bitrate and file size when comparing HT digital vs physical

...because they use the same masters, chroma subsampling, compression schemes etc. It's more or less 'like for like' when it comes to the underlying standards, unlike digital cinema vs home cinema

[avs commenter]

Originally Posted by Geoff D

...because they use the same masters, chroma subsampling, compression schemes etc. It's more or less 'like for like' when it comes to the underlying standards, unlike digital cinema vs home cinema

So we’re done with bitrate? These will be the new buzzwords?

[Geoff D]

Originally Posted by avs commenter

So we’re done with bitrate? These will be the new buzzwords?

I'm not saying that bitrate doesn't matter when it comes to your digital vs physical example, I'm saying it's pretty much the ONLY thing that matters when comparing consumer digital vs consumer physical because so many of the other parameters are going to be the same.

But trying to compare home formats to D-Cinema is pretty much about everything BUT bitrate as so much else is different between them before you even get to the question of bitrate. To some people those "new buzzwords" have been known about, e.g. https://forum.blu-ray.com/showthread...0#post16523538

[s_har]

Originally Posted by avs commenter

It’s only convenient to compare bitrate and file size when comparing HT digital vs physical

Comparing bitrate when it comes to streaming VS physical is a comparison that makes more sense though.
They are both HEVC encodes (theaters use a different file format entirely so a direct comparison in bitrate doesn’t make sense).
On top of that streaming and physical are both watched under the exact same circumstances in our homes using the same displays, viewing distance etc so those are basically an apples to apples comparison, which theatrical is not, imo.

[Phil92]

Originally Posted by bhampton

UHD BD claims theater quality sound and video at home and seems to deliver. I wonder if actual theaters still have higher bit rates. I know some theaters have higher frame rates.

-Brian

DVDs and Blu-rays said the same thing once upon a time.

In short, it’s not comparable at all.

[brian9229]

Some theaters download the files from satellites, through whatever studio.

[professorwho]

Originally Posted by brian9229

Some theaters download the files from satellites, through whatever studio.

I've experienced that several times. Mostly with regards to Fathom Events limited runs of classic films and anime titles. It's pretty easy to tell if it was downloaded from a satellite with a low bitrate DCP, as the artifacting can get REALLY bad (anime films have a ton of banding, but the worst had to be when I saw King Kong- the amount of macroblocking was insane!).

[Dubstar]

Originally Posted by professorwho

I've experienced that several times. Mostly with regards to Fathom Events limited runs of classic films and anime titles. It's pretty easy to tell if it was downloaded from a satellite with a low bitrate DCP, as the artifacting can get REALLY bad (anime films have a ton of banding, but the worst had to be when I saw King Kong- the amount of macroblocking was insane!).

the couple of times I saw Fathom Event's satellite feeds were downright shit.

[WBMakeVMarsMovieNOW]

Originally Posted by Dubstar

the couple of times I saw Fathom Event's satellite feeds were downright shit.

do the satellite feed ones at your theater seem to have faded out gray black level?

i'm still not sure if my theater is just not properly converting from satellite black to theatrical projector black level or whether it's fathom mussing that up

on the plus side, the largest non-IMAX/Dolby screen at my theater is the one that has the DishTV Fathom capability so at least those are insured to be a on giant screen which is pretty impressive

[David M]

Originally Posted by professorwho

I've experienced that several times. Mostly with regards to Fathom Events limited runs of classic films and anime titles. It's pretty easy to tell if it was downloaded from a satellite with a low bitrate DCP, as the artifacting can get REALLY bad (anime films have a ton of banding, but the worst had to be when I saw King Kong- the amount of macroblocking was insane!).

That's really upsetting to hear that compression issues are being allowed to stink up the theatrical experience.

[Brian81]

Originally Posted by Phil92

DVDs and Blu-rays said the same thing once upon a time.

In short, it’s not comparable at all.

Theaters have poor contrast due to lighting that is out of your control. Despise that.


As long as a transfer isn't ruined with DNR/EE, poor compression, or some other crap, I'll take the end result that UHD brings most of the time, because I have more control over other variables. But I'll say that there are a LOT of screwed up transfers on home video.

[ditcin]

All I know when I went to see Fathom's release of CLOSE ENCOUNTERS it was horrible. Blurry, and bad color. It was nothing like any of the copies of the film on DVD, BD, or even UHD.
I was extremely disappointed - especially since I originally saw it 13 times starting with the original theatrical release, then the Special Edition release. Those were prints and look much better.
I complained to the theater and was given free passes to another show. They explained they simply downloaded the file and screened it.