Film-Tech Forum ARCHIVE: Digital Cinema Initiative

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Posted by Gary Davidson (Member # 2198) on 08-08-2005, 03:48 PM:

Just curious, what is the reaction amongst forumites on the new DCI proposal for implementing standards for digital cinema?
http://dcimovies.com/

Posted by Steve Guttag (Member # 268) on 08-08-2005, 06:54 PM:

I've made it through just about 1/2 the specification (it is something like 170-180 pages).

The bulk of it is all wrapped up with the Security of the movie. Very little of the DCI standards actually have to do with the standards.

At present, the DCI recognizes 2K (at 24 or 48 fps)and 4K (at 24fps)resolutions (with no mentino of 1.3K resolutions, that I've found yet) so I guess you are left out if you were an early adopter...perhaps a forshadowing of things to come.

At no time can the signal outside of the projector be in a decrypted form (i.e. there will be NO visual monitors). A DCI compliant projection system will perform the final decryption within the projector and also apply forensic marking that can be traced to the projector (btw...the same goes for the audio where the DCI audio decoder is to forensically mark the audio in some way). As I understand it...the current DCinema projectors do have "Link Decryption" within the projectors so concievably they can be used if the 2K/4K files can be downconverted suitably.

The Screen Managment System (SMS) will rat you out on everything...if you run the movie...it will be logged. Your "keys" for decrypting a movie will have a provision for a time limit (engagement) and will delete the files in a non-recoverable manner) when your engagement expires. Which should not be a problem, if everything works properly. At least now...if Technicolor shows up at your door when you still have the film booked they won't be able to take it off your platter...with DCinema...a simple mistake will erase your show.

You sound buffs should take note of the...anyone, anyone? 16-channel sound provision. Thats right...16 wonderful channels that are not entirely defined yet but I agree it is nice that more than the present 5.1 or even 8 can be accommodated. I'm sure 16 came up merely as 8 times 2. There is an example layout that has 7-screen channels (the five usual suspects, left and right upper...sorry IMAX, VOG is left out), the stupid 3-walls of surrounds (I say stupid since the back wall should be descrete left and right rear wall...for current EX films, they would be the same signal) and the long awaited Ceiling surround.

The above is merely a "suggested" layout. 5.1 remains the minimum configuration. However, I have not read yet how one, that has only a 5.1 system, would play a more sophisticated soundtrack or if a 5.1 is always to be made available.

But again, security remains the key to this document.

They should rename this document "There's a new Sherrif in town!"

Posted by Darryl Spicer (Member # 711) on 08-08-2005, 08:09 PM:

More on this can be found here....

More D-Cinema Morons

Posted by Steve Guttag (Member # 268) on 08-09-2005, 06:03 PM:

Darryl...the DCI is the actual group that has written the spec and is working with NATO on the implimentation of DCinema...the "Moron" thread has more to do with what "news" people have said about DCinema.

Posted by Lyle Romer (Member # 1266) on 08-09-2005, 06:48 PM:

Here are my comments from that other thread but I think they are more relevanat here:

Well, so much for quality. No anamorphic format for 'scope. I guess the way the spec is written, common width screens are the right way to design a theatre.

quote:
3.2.1.2. Image Structure
The DCDM shall provide an image structure container that consists of either a 2K (2048 x 1080) or 4K (4096 x 2160)image file as defined in Table 1. It is expected that the image structure shall use one of the two containers such that either the horizontal or vertical resolution is filled. For example, a 4K image file with a 2.39:1 aspect ratio would require an image structure of 4096 x 1714, therefore filling the horizontal resolution of the 4K container. The pixel orientation, as displayed on the screen, shall be understood to flow from left to right and top to bottom. Also, the horizontal and vertical pixel count shall begin with 0. For example, the top left pixel of the displayed image shall be anotated as (0, 0).

A few good things in the spec......

1) Audio will be uncompressed, 24 bit, 48 or 96 kHz and up to 16 discreet channels are supported

2) Image compression is JPEG 2000. Since JPEG 2000 compresses each frame without regard to preceeding or following frames, there shouldn't be the MPEG type motion artifacts.

3) Data rate will be 8 to 9 times the data rate of HD-DVD or blu-ray.

What I think they should have done is required that the image source and distribution be in 4k and then the playback equipment could be either 2k or 4k.

Posted by Joseph L. Kleiman (Member # 3097) on 08-09-2005, 06:57 PM:

A major misconception is that the DCI specs are the all-encompassing final word on digital cinema, when in fact they're not. DCI has been working with a number of SMPTE groups and committees, primarily the Digital Cinema Committee (DC28), which are responsible for determing the actual specifications for digital cinema. The DCI spces are intended to act as guidelines for the SMPTE standards, some of which have final draft papers already released and others which are currently going through the formulation process. There's even a group within DC28 working on speciciations for digital 3D cinema. Other committess, such as W25 (Metadata and Wrapper Technology) are involved in the formulatioin of digital cinema standards as well.

Posted by Steve Guttag (Member # 268) on 08-09-2005, 07:30 PM:

Ah...that may be true but the phrase "DCI-Compliant" has already worked its way into manufacturer's descriptions. Furthermore...if the DCI is the body that is trying to have uniform standards that all manufacturers are ensure they meet, then it can't be so wishy washy. How can a manufacturer make a product, spending great volumes of money, only to find out that they are not compliant with some aspect(s)?

The idea, as I understand it, is to have a single set of requirements such that if a manufacturer makes their product to the set specifications, then it will be compatible with the DCinema industry.

To put it in film terms...film projector manufacturers know that they must support 35mm film that is perforated in such and such a way, that it must advance at a rate of 24 frames per second....and so forth. The net result is that we have Century, Simplex, Kinoton, Christie....and the list goes on for quite a while...with everyone's equipment handling the same film without any surprises from the film itself. Some may do it better than others and one would expect that some DCinema systems will perform better than others too.

Note on the 2.39:1 shows...the DCI document does not preclude the use of anamorphic lenses...it does require that the change to a secondary lens be automatic and that the scaling done within the projector not introduce any visual artifacts. However...the spec does say that the master file be a 1:1 ratio file that fills the width of the 2048 (2K) or 4096(4K) imager. Thus, the scope image, that SHOULD fill a larger screen area, will actually start out with less data (fewer pixels).

A superior specification would have had all 1.85 and 2.39 images fill the imagers and that it was the responsibility of the projector to scale the height down for constant width theatres.

All that the current spec allows for is a 1:1 mapping of the pixels, regardless of format, upon projection if you have constant width....sounds like a screening room spec.

Posted by Darryl Spicer (Member # 711) on 08-09-2005, 10:31 PM:

Just go to page 17 of the above link and you will find more information on this very subject. However I do agree it does need it's own catagory.

Posted by Lyle Romer (Member # 1266) on 08-10-2005, 10:15 AM:

For some unknown reason, it's not even exactly constant width.

3.2.1.8. Aspect Ratio
Some examples for the accommodation of images of various aspect ratios in the
containers are shown in Table 3.
Where:
Ph = number of active horizontal pixels in image
Pv = number of active vertical pixels in image
AR = the aspect ratio of the image (ratio of width to height, expressed
as a decimal)

Level |Ph |Pv |AR |Pixel Aspect Ratio
1 |4096 |1714 |2.39 |1:1
1 |3996 |2160 |1.85 |1:1
2 |2048 |858 |2.39 |1:1
2 |1998 |1080 |1.85 |1:1

Table 3: Example Image Aspect Ratios

So the 1.85 ratio doesn't use the entire width of the chip.

Posted by Heath Dutton (Member # 3265) on 08-10-2005, 01:56 PM:

I have been a member of DCI for quite some time, so that I could read the beta specifications before the recent release of the first "public spec" sheet. I think all of this work should have been done years ago, but I'm glad someone has finally gotten around to doing it. And yes, I would agree that the specifications mostly concern security of the process, but the original betas up until recently did not even touch the surface of the security issue. Most of the early work was about deciding audio channels, pixel rates for 2K and 4K, not to mention decisions upon file types...

It has a long way to go, the file types and compression methods are very vague, and there are a couple requirements that are nearly impossible with current technology (i.e. a 10gbit connection inside the projector payout) which I do not believe are truly necessary. But of course there will be dozens of revisions over the next year or two I'm sure.

Now you may ask, why would I be interested in all this "digital mumbo jumbo", especially since my theater doesn't even have any DLP projectors? Well, I've seen the price tags on the DLPs and I find them hideously overpriced. I would like to one day build my own 2K projector, and after reading their specs I believe a slightly toned-down (using lcd instead of dlp) version of a 2K could be created for under $3000, including dci-compliant computer hardware with enough storage for 2 films.
The hardest part would be creating the software, and for that I would use a modified windows-media activeX for post-decryption.

Posted by Gordon McLeod (Member # 33) on 08-10-2005, 03:55 PM:

Also there is no assurance that a studio may not say this is our standard and if you want to show picture x then buy projector y similar to during the fifties and the birth of sound many obsolete expenses for theatres

Posted by Steve Guttag (Member # 268) on 08-10-2005, 05:27 PM:

Again, the idea behind the DCI is so that you DONT have a brand specific type of equipment...everyone is looking at the same specs.

As to LCD for $3000...I dunno...noone has a 2K LCD for that price...in fact, the ones I've seen are over 10 times that price (Sanyo's PLV-HD10 and Barco's iCon600).

Then you have the transmissive technology that creates a screen-door that has Morie issues with a perforated screen. Lastly, LCDs are notorious for their poor and changing color.

Posted by Darryl Spicer (Member # 711) on 08-10-2005, 06:50 PM:

quote: Heath Dutton
Now you may ask, why would I be interested in all this "digital mumbo jumbo", especially since my theater doesn't even have any DLP projectors? Well, I've seen the price tags on the DLPs and I find them hideously overpriced. I would like to one day build my own 2K projector, and after reading their specs I believe a slightly toned-down (using lcd instead of dlp) version of a 2K could be created for under $3000, including dci-compliant computer hardware with enough storage for 2 films.
The hardest part would be creating the software, and for that I would use a modified windows-media activeX for post-decryption.

DLP has got to be the foundation used for motion pictures. Anything else right now I would think is going in the wrong direction. Lets try to stear clear of any windows based anything. All you are asking for from windows is trouble.

Posted by Paul Konen (Member # 41) on 08-11-2005, 04:01 PM:

Windows has nothing to do with what is displayed on the screen. My servers are based on Windows XP Pro. If it would happen to blue screen, the screen will go dark and the sound would stop. The OS is mearly feeding data from the hard drives to the decoder and the decoder sends the audio / visual data to the appropriate devices.

I don't think even the digital slides would display a blue screen, unless you were running a "secondary" screen adapter. And even then, I don't think the secondary monitor will show the blue screen data.

Posted by Heath Dutton (Member # 3265) on 08-11-2005, 04:18 PM:

I realize windows is not the most reliable OS out there, but linux doesn't offer the broad functionality, at least not yet...

Windows XP can be extremely stable, if it is coupled with the right hardware. I have a 2ghz machine at home that has been running for the past 4 months, asside from occasional power-outages and upgrades. I attribute this mostly to the excellent motherboard, Intel CPU and ECC server grade ram. The machine was simply built for reliability. My other computer I built purely for speed, and although it is twice as fast, it doesn't have error checking ram and those rock solid hardware pieces, and it shows. It will occasionally lock up, or reset due to hardware related issues. But this is not the fault of XP.

If I were using windows for a hardware application such as a projector-to-screen presentation I would use a stripped down home-brewed version. Microsoft has all the tools available to do this yourself, and as long as you aren't marketing the device you don't have to pay licensing fees, etc.

Posted by Mike Blakesley (Member # 26) on 08-11-2005, 07:23 PM:

I think when we get our digital system here, whether it be in 2 years or 20, I am going to NOT TELL ANYONE. In fact, I might lie to people and tell them we're still showing film. If people start backlashing on digital cinema with the old "My home system looks just as good" argument (even if it is not really true), I'll be saying "we're still using the old fashioned, better system instead of that newfangled crap that everyone's dissing."

Of course if the inevitable media blitz trumpeting how wonderful digital is is eaten up by the gullible public -- or if digital really does blow film out of the water -- I reserve the right to change my mind about the above when the time comes. But if all the magazines and newspapers start printing "Digital Cinema? It's no big deal" articles, I'll be ready with my lie.