IMAX DCP

[bengedlow]

Dear Carsten,

(referring to earlier posts about trying to make an IMAX DCP...)

1000 apologies. I got sidetracked shooting a film. And then spent more-time-than-planned-for trying to figure out the IMAX / DCP thing. After doing tests, and running both an IMAX and a standard DCP in an IMAX theatre with twin laser projectors it appears that IMAX does have a 'proprietary' code somewhere in their DCP's such that ... you can't see what is ON the DCP drive, and, it somehow fires up the twin projectors. Without the IMAX created DCP drive only one laser projector will work, with about half the lumens. Makes a big difference. IMAX charges $1,000 a minute to make the DCP. So a lot of people are wondering if there is in fact a patent proprietary system in play, or whether it's just a simple key. I think the issue for IMAX producers is you can't look at your rushes in an IMAX theatre without paying to have a DCP made (at $1,000 a minute).

I'm not a pirate or patent-offending kind of guy. But it might be intriguing to have a code expert poke around in one of those drives to see if it is in fact a simple key, or if there is some serious patent technology involved (in which case hands off). Tricky to do as getting one of those drives is a bit of a study. They are delivered straight to the theatre.

But, regarding DCP-o-matic, here is an intriguing thought for you: I just got a Panasonic GH5. It has a burst mode for stills ... but that burst mode goes on literally forever, there is no limit, at 30fps. That's 18 Megapixels per frame. And in 4:3, which is the IMAX format. There is no other camera out there that will do a live-action 4:3 at 18 Megapixels per frame. Granted it's not a huge sensor. But it's a very nice sensor. A huge improvement over the GH4, and it's a 4:2:2 colour space at 150Mbps IN-CAMERA ... which will be upped to 400Mbps shortly with a firmware upgrade. It looks like this will give you about a 5K in a 4:3 frame.

I've seen the older Canon 1Dc shooting 4K in a sequence with the Sony F65 and the full IMAX 15:70 (scanned). With the duel laser projectors it was not an easy thing to see which camera was which. Though they did restrict the Canon to close-ups and to mid-shot interiors (in a small space).

What was most interesting was that the 4K material looked just fine. IMAX film has been rated at 12K. But the digital 4K through duel 4K projectors? Very nice.

I'm going to do some 4:3 tests with the GH5. If they prove to be as exceptional as I'm thinking they might (given how nice the normal cinema 4K is), I'll post what I find out to you here. About 15 years ago I was thinking that one day we would be able to shoot IMAX with a small compact camera. Could be we are very close now. Or even there? Might open up the IMAX world a bit...

More soon,

All the best,

Ben

[Carsten]

To my knowledge, IMAX solves their equipment-use-exclusiveness by signing their DCPs with an IMAX certificate. This is part of the DCI system. But to my knowledge, you can't hack/emulate this. 'Their' DCPs come with a signature that the IMAX projector checks against an internal certificate. You can delete that certificate from the DCP, but then the projection system will run only throttled. At least that is how I understood.

But is the presentation really flawed with only one projector? They also run standard 2D shows with only one projector, so what gives?

Would still be interesting to get a hand on unencrypted original IMAX content, to see what they are doing. e.g. an IMAX 3D logo trailer. I still can't believe they use this weird resolution as a standard.

- Carsten

[bengedlow]

I'll see about getting an IMAX DCP drive.

There is a BIG difference between the one projector and the 2 projectors. Lots more luminosity, brightness, colour. It's very obvious. Once you've seen the one you don't want to go back to the other.

When we were watching a test for a particular film I was up with the projectionist, and at one point he ran a trailer and we went down into the audience just to make sure both projectors were running. I thought it was an ordinary DCP, given it was a cheap looking trailer for the theatre itself. So I was all charged up, and started that earlier conversation with you. But when we went back a few weeks later, with a standard DCP, it didn't work. And then I realised I had misunderstood the projectionist ... their cheap looking trailer reel had actually been DCP'd in LA, standard IMAX procedure.

Sigh.

When you say unencrypted original IMAX content? ... that would be set of TIFF or DPX files in an XYZ colour space (forget rec2020, they aren't ready for that yet apparently). I can make you a test - two or three shots - of that very easily. That's the bug. One can make the actual master file right out of a laptop using Resolve (or DCP-o-matic if you added in a custom frame size). It's what the IMAX post does ... as you suggest ... adding some kind of certificate that talks with the projectors.

It may eventually shift, this exclusiveness, when suddenly producers are able to produce IMAX quality imagery without the need of the million dollar 15:70 camera ... plus all attendant expenses. The theatres have been paying less and less and wanting more and more ... very hard on the producers.

B

[Carsten]

When you're there next time, can you ask the projectionist how they receive their trailers, logos, etc.? You could try to bring a laptop and connect one of their shipping discs to it (if content arrives on dics). I assume these discs being NTFS or ext2/3 formatted. If you bring a windows notebook, you would need to have ext2fsd installed on it to access ext2/3 drives.

How cooperative is your local IMAX staff? It's hard to judge how far they let you go there?

All I heard so far is that IMAX laser uses one projector only for 2D, and two projectors for 3D. Their color separation 3D still looses some light, so they need to have two projectors, one for each eye, and without the glasses, one projector should still meet brightness specs for 2D. I have only been to a laser IMAX once, and I remember the projectors being used that way. You can easily tell, because if you leave the 3D glasses on during 2D preshow, one eye is blind/dark.

- Carsten

[bengedlow]

As far as I could tell it looks like they are using BOTH projectors for 2D and 3D. That's the way the test came from LA ... this was scenes from a 2D film currently in production.

The impression I got was that 2D or 3D, for IMAX they used both projectors. But if I'm remembering right, the projectionist said the non-IMAX movies were run with a normal DCP, thus one projector. Unless it was high-end Hollywood, and they paid for a full IMAX DCP.

We tried to access the IMAX DCP drive with a normal Windows computer -- set up by the fellow from the local post house where my brother has often done the colour grading. He seemed to know his stuff. (Me, I'm just a filmmaker, trying to help out his brother, also a filmmaker -- neither of us a techie.)

The only way to see what's on the drive is to plug it into the projectors and the IMAX computer system attached to the projectors. The projectionist at the theatre here was most friendly and helpful. But he too had tried to SEE what's on the drive with his own laptop ... nada, no luck.

[Carsten]

You probably need ext2fsd installed in windows in order to see the content on an ext2/3 drive. ext2/3 is industry standard for DCP distribution.

- Carsten

[scorpio81]

Hi, guys. I have access to IMAX content. What exactly do you need? IMAX DCP structure? Unencrypted IMAX content? Or what?
If unencrypted content, then check these trailers:
IMAX 2D XENON - http://wdsspr.ru/W/GOTG2/trailer/Digita ... p?download
IMAX 2D LASER - http://wdsspr.ru/W/GOTG2/trailer/Digita ... p?download
IMAX 3D XENON - http://wdsspr.ru/W/GOTG2/trailer/Digita ... p?download
IMAX 3D LASER - http://wdsspr.ru/W/GOTG2/trailer/Digita ... p?download

[Carsten]

Wow - great, we'll have a look!

Hmm - as I expected, there is nothing special about the Laser Version. 4k Scope, plain 5.1 sound. It carries an IMAX signature. That's all. I guess it will play on any DCI system. It has been created by Doremi/Dolby Cineasset. I can open and play it in DCP-o-matic.

Scorpio - would you have access to an IMAX laser demo trailer showing off the new 12ch audio system?


- Carsten

[scorpio81]

Carsten, unfortunately, no. We only have Xenon IMAX with 5.1 sound setup. Sometimes we get both Laser and Xenon features but we never get features with 12 channel sound.

I confirm that all unencrypted IMAX content plays perfectly on any DCI system and any software player and it can be opened in DCP-o-matic. There's almost nothing special about it.

Why almost? IMAX DCPs may contain some commands embedded in the audio/video assets. I can tell that because some DCPs give command to Image Enhancer to change its operation mode and some don't. And we are not able to add these commands into show playlist manually. That's why I assume they are embedded in the assets.

P.S. Certificates for IMAX servers (mostly Doremi DCP2000) are not in the public domain and can be obtained only from IMAX by request.

[Aaron]

Hey everyone-

Figured I'd chime in on this thread to see if anyone has test IMAX content they could share with me. My company just released a Mac app called DCP Transfer which validates packages according to the stored hash, enables r/w support for ext filesystems and formats drives according to ISDCF specs, and displays metadata. You can check it out here: http://cinematiq.com/dcptransfer

If there truly is nothing special about the unencrypted IMAX package other than their signature, I'd like to ensure compatibility with our new product, just in case... But in order to do that, I need a test package. Anyone?