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Blu-Ray 1080p through cinema projectors


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#1 Keith Walters

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Posted 18 February 2012 - 03:46 AM

It's been stated ad infinitum that you can now get virtually the same resolution from a sub-$100 Blu-Ray Player as you get in the average 2K-Digital-Equipped Cinema.
Has anybody actually seen a Blu-Ray player connected to a cinema projector? Can you even do that? And if so, does it look comparable to the standard 2K from a hard disc they normally use?

You'd think if it was, they'd start distributing movies that way.
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#2 Brian Drysdale

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Posted 18 February 2012 - 04:19 AM

It's been stated ad infinitum that you can now get virtually the same resolution from a sub-$100 Blu-Ray Player as you get in the average 2K-Digital-Equipped Cinema.


Wouldn't the compression artifacts on motion be more of an issue when sitting near the front? Also isn't it 12 bit compared to 8 bit on the Blu Ray

Edited by Brian Drysdale, 18 February 2012 - 04:22 AM.

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#3 John Holland

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Posted 18 February 2012 - 05:45 AM

Yes i have seen Blu-Ray through a Sony 4K at the Apollo Piccadilly Circus in London. It was a BSC new Cinematographers evening i was stunned how good the shorts looked . They were shot on film , DSLR, Red.
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#4 Phil Rhodes

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Posted 18 February 2012 - 06:47 AM

Most projectors have bays where various input options can be plugged in; one of them invariably has a DVI input board in it. Remember that part of the promise of all this was that cinemas would be able to do things like sports events, which would require them to be able to hook the display equipment up to a satellite decoder. At that point, some enormous Christie D-cinema projector looks no different to a computer or DVD player than any other display. I've built hard disk recorders that have been hooked up to D-cinema screening rooms and it was no huge problem.

If you want particular kinds of colour processing, 3D, odd frame rates, or really accurate surround sound, things can get a bit more complicated. Most cinema audio installations do allow some sort of access to the individual amplifiers, so you can hook up the individual surround channels and achieve something listenable, even if it isn't strictly right. Using computer video cards as a playback device is dicey because of audio/video sync drift and the duplicate frames that computers end up inserting to solve the problem, although it'll probably be watchable. It may be necessary to add a screen mode with a resolution and refresh rate that's supported by the projector; this should be automatic, but often isn't with slightly exotic display devices.

The projection equipment will almost certainly not be set up for Rec 709 colour, although it may be possible to encourage it to be. If it's stuck in XYZ, the DCI standard, this will have the principal effect of putting a brightness offset into it which affects shadows. This can be mitigated by eyeballing a curve into the output of the computer.

Strictly speaking, the D-cinema "media block" which actually does the decoding of feature films is supposed to be in a secure cabinet, as they're often connected to the projectors via DVI or SDI, and if you can get at that connector you can trivially record the entire feature film...

...but I digress. Yes you usually can.

P
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#5 Bruce Greene

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Posted 18 February 2012 - 08:29 PM

I've done it and it looks great.

But it's not encrypted like a dcp, and theft is an issue.

Also, most cinemas are set up for dcp and the projectionist might not know how to show any other format, even though it's not hard to do:)
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#6 Marcus Joseph

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Posted 19 February 2012 - 12:36 AM

Yeah I saw a documentary at Dendy's Circular Quay just yesterday and the blu-ray looked great, motion, resolution, colours looked good and it was only shot on HDV. I wasn't sitting up close, but I'm sure it holds up against a lot of other methods.
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#7 Keith Walters

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Posted 19 February 2012 - 02:34 AM

Wouldn't the compression artifacts on motion be more of an issue when sitting near the front? Also isn't it 12 bit compared to 8 bit on the Blu Ray

You need 12-bit resolution for Post-Production, but for display, 8 bit is more than good enough.

Thanks for the other various replies.

So presumably, you could connect a cheapo Blu-Ray player via an equally cheapo HDMI to DVI cable.
The only question is the sound. Do most projectors support the SPDIF digital audio that comes out of DVD/Blu-Ray players? I know a lot of players also have 6 RCA sockets for analog sound, but since hardly anybody ever uses those, they will soon be going the way of S-Video outputs.

I've been astounded by the quality you can get from 1080p AVCHD recorded onto 20c DVD blanks. You only get 20 minutes or so, but that would be fine for shorts.
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#8 Brian Drysdale

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Posted 19 February 2012 - 03:16 AM

You need 12-bit resolution for Post-Production, but for display, 8 bit is more than good enough.


Maybe, but the Digital Cinema Initiative specifies 12 bits.

"3.2.1.7.
Bit Depth
The bit depth for each code value for a color component shall be 12 bits. This yields 36 bits per pixel."
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#9 Keith Walters

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Posted 19 February 2012 - 05:01 AM

Maybe, but the Digital Cinema Initiative specifies 12 bits.

"3.2.1.7.
Bit Depth
The bit depth for each code value for a color component shall be 12 bits. This yields 36 bits per pixel."

Are there any projectors that can actually reproduce that though? Accepting 12 bits is one thing, projecting it is quite another. I've yet to see a Digital projector that produce true blacks. Some cheat by modulating the illumination level, but that's not the same thing. In any case 0000 0000 0000 and 0000 0000 should both be pitch black, which they never are.

It all sounds a bit like NTSC YIQ coding vs simple NTSC YCrCb. Just about every NTSC Broadcast camera that was ever made does the full 1954-spec YIQ thing; over the next 50 years the percentage of TVs that could take advantage of it was infinitesimally close to bugger-all :rolleyes:

Anyway, it'll be interesting to see what Jannard and Co come up with this year. The world urgently needs cheaper and more reliable digital projection. In a world of locomotives, they're trying to sell Prius's....
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#10 Brian Drysdale

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Posted 19 February 2012 - 05:33 AM

Are there any projectors that can actually reproduce that though? Accepting 12 bits is one thing, projecting it is quite another. I've yet to see a Digital projector that produce true blacks. Some cheat by modulating the illumination level, but that's not the same thing. In any case 0000 0000 0000 and 0000 0000 should both be pitch black, which they never are.


Interestingly, a couple of years ago I pulled out my old Bell & Howell 16mm projector to screen a 12 year old short that was only available as a print. The blacks and colours totally beat the other shorts, which were on DVD and used a digital projector.

Edited by Brian Drysdale, 19 February 2012 - 05:33 AM.

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#11 Antti Näyhä

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Posted 19 February 2012 - 05:39 AM

As said before, any DVI/HDMI device can be directly connected to a D-Cinema projector. However, any cinema that’s properly equipped to handle ”alternative content” (= anything that’s not DCI content) has an external scaler/switcher connected to the projector for more flexibility. The scaler has all kinds of video inputs, both analog and digital.

Such cinemas are also able to directly feed their sound system with digital audio from non-DCI sources. For example, the popular Dolby CP750 D-Cinema sound processor has both coaxial and optical inputs for AES3 / S/PDIF audio. Venues with the older CP650 processor (for 35mm compatibility) commonly use a DMA8Plus adapter box to achieve the same thing, although it only accepts up to 5.1 channels. In either case, no need to fiddle with individual amplifiers.

I usually also install a box that splits a HDMI signal to separate DVI video and S/PDIF audio outputs. This way, you can conveniently connect any HDMI device to the D-Cinema system with just one cable.

Reasons why films aren’t distributed to cinemas on Blu-Ray instead of DCP:

1) Reliability. Blu-Ray is an optical media, and as such it’s just not reliable enough for professional use. It’s extremely prone to scratching, fingerprints, etc. For some reason, optical discs always work at home and test screenings, but will fail in a middle of a screening when there are paying customers in the screening room… Ideally you would always rip any optical disc losslessly to a hard drive before screening, and project it from a computer instead of a Blu-Ray drive.

2) Piracy protection. Phil: DCI content is not decrypted by the media block. The cables you are referring to carry encrypted content, which isn’t decrypted until at the very last stage deep inside the projector. Recording the content is by no means trivial – you are severely underestimating the paranoia of the studios who wrote the spec. ;) Ripping a Blu-Ray, though, is indeed trivial.

3) Quality. Yes, a good Blu-Ray can look (and sound) very good on a properly calibrated D-Cinema system. It’s certainly the best way to enjoy a Blu-Ray movie. But it’s still not quite up to D-Cinema quality due to intra-frame compression, much lower bitrates, narrower color space, etc. And Blu-Ray mastering quality varies a lot. There are a lot of Blu-Ray movies out there that I certainly wouldn’t pay to watch in a cinema.
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#12 Phil Rhodes

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Posted 19 February 2012 - 06:34 AM

Hi,

My mistake - I was misusing the term "media block".

I have certainly seen installations where unencrypted DVI was going straight into the projector (I know this because they were monitoring it). The intention was that all this would be inside a locked cabinet, but there are practicality issues with that in certain circumstances.

It's an insane design anyway - nobody is going to pirate stuff that way...

P
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#13 Bruce Greene

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Posted 19 February 2012 - 11:58 AM

FWIW...I've done premiere screenings by running DVI from my MBP to the cinema projector at the multiplex. It shows up on the laptop as a regular computer display with an sRGB color space when you set the projector to that preset in the projector menu. The projectionist didn't know how to do this but I figured it out in a few minutes. And I just used the quictime player set to " full screen " .

If you want surround sound, you'll need someting like the AJA I/O to output all the audio tracks, but then you'll need a theater equipped with HdSDI or Hdmi inputs or maybe an hdmi to dvi cable. I've only done that once, other times I've used the headphone jack for two channel stereo.

The ineresting thing is that even a 720p original looks as detailed as film print from a 2k scan DI.

The newish digital cinema projectors have quite good blacks and the overall experience, to me, is superior to film projection, especially of typical release prints.

So, to make this on topic, I'd prefer blue-ray on a good cinema projector to a film print almost always.

I'm completing post this week on a picture. We will be screening the dcp at the premiere, not the film print. The film prints are no longer the principal delivery, the digital version is.
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#14 Bruce Greene

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Posted 19 February 2012 - 12:03 PM

Hi,

My mistake - I was misusing the term "media block".

I have certainly seen installations where unencrypted DVI was going straight into the projector (I know this because they were monitoring it). The intention was that all this would be inside a locked cabinet, but there are practicality issues with that in certain circumstances.

It's an insane design anyway - nobody is going to pirate stuff that way...

P


Re. Piracy

I have found that as soon as non-encrypted masters are delivered for foreign distribution, that the movie is on the Internet within days. Even if nobody has ever heard of your movie...
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#15 Antti Näyhä

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Posted 19 February 2012 - 12:47 PM

I have certainly seen installations where unencrypted DVI was going straight into the projector (I know this because they were monitoring it).

OK, I believe you… but DCI servers / media blocks don’t have DVI outputs nor do they decrypt content.

So what you saw must’ve been something else. Perhaps a regular PC or a hard disk media player connected to a D-Cinema projector? This is sometimes done at festivals or special screenings, if a DCP isn’t available.
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#16 Jock Blakley

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Posted 23 February 2012 - 01:28 AM

I've projected Blu-Ray through a Barco DP4K-32B on more occasions than I'd like to have.

The BRD picture does come close to a 2K DCP for flat (1.77:1/1.85:1) images - although at the size we project to (19x9 metre common-height screen) I can pick the compression artefacts and minor but apparent lack of comparative sharpness.

For 'scope, of course, the 2K DCP's 2048x848 picture does noticeably outperform a BRD's HD letterbox image.

Of course this is just my impression from showing this content on a 4K projector on a very large screen with a long throw.

Said projector is easily switched between XYZ colour and REC 709 colour by loading the appropriate Projector Configuration File - which also controls pixel aspect ratio for non-DCI content.

It has two DVI inputs, both of which support HDCP so we can connect HDMI sources directly via a simple adaptor. For computer inputs via DVI, the projector appears as a display named "BARCO CINEMA" and offers 1920x1080 or 2048x1080 native resolutions.

Sound for both DCI and non-DCI sources is irrelevant to the projector. We use a combination video scaler / sound DAC that takes AES 6-channel audio from the D-Cinema server and converts it to discrete 6-channel analogue for input via our Dolby CP-500's 6-track input. The same DAC also takes Dolby Digital or LPCM over S/PDIF co-ax or TOSLINK and puts out the same 6-track output - so no fiddling directly with the amps. Other installations with more cash often use the Dolby DMA8+ for the same purpose, and often have new processors too :P

This news of media blocks having to be in secure cabinets is, well, news to me. I've never heard that requirement before. To the best of my understanding, even though they're often connected via HD-SDI for 2K systems, the server, media block, and projector are all part of the security system because the projector performs decryption inside it's own closed image path.

Because we show 4K we use an integrated media block - it's installed in one of the projector's expansion slots, but technically part of the server and is connected to it via PCI Express. Content from the IMB is then fed directly to the projector's ICP (which stands for something I've forgotten).

Antti's reasons for why BRDs are NOT a suitable professional playback medium are very accurate - plus of course there's all the home video bullshit like trailers, extra distributor logos, and my most fervently-loathed creations of all time, disc menus that have music or sounds playing over them. Especially when the feature ends three frames after the last credit has faded and dumps you directly back to the menu. Reaaaallly professional.

So, to make this on topic, I'd prefer blue-ray on a good cinema projector to a film print almost always.

I'm completing post this week on a picture. We will be screening the dcp at the premiere, not the film print. The film prints are no longer the principal delivery, the digital version is.


I'd take a well-cared-for print over a BRD any day, and even over some of the DCPs I've seen. The fact that that new films are being premiered from digital when there are prints in existence disappoints me greatly - but I will admit if the print is from the same 2K DI as the DCP than I suppose it's not so bad. If it was a photochemically-finished film, though, I wouldn't be sticking up for seeing the DCP.

Far cry from the days of a show print being struck directly from the OCN, or the master interneg at a pinch.

We had a small-ish film festival at our theatre a few months back that ended up presenting HD H.264 files. They looked... better than they could have, granted. The festival director was adamant that digital was better than anything else and had got shitty H.264s of two entries that were also available as prints. In the end I talked him into getting one on 35mm and we showed that.

Afterwards he came up to me and thanked me for opening his eyes.
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