Digital Cinema Technology
Frequently Asked Questions (FAQs)

What is DCI?

DCI is the abbreviation for Digital Cinema Initiatives, an organization whose owners are the six major motion picture studios (the same six studios that also comprise the MPAA). In July of 2005, DCI issued version 1.0 of its Digital Cinema System Specification, representing the consensus of DCI's members in regards to many technical details of digital cinema. The DCI specification can be thought of as the professional cinema equivalent of an agreement to exclusively use either the HD-DVD or Blu-ray consumer formats. The DCI specification is not a standard, however, it is significant input to the standards process. Standards for digital cinema are the domain of the Society of Motion Picture and Television Engineers (SMPTE). A copy of the most recent DCI specification (v1.2) can be downloaded from the DCI website. The latest version incorporates over 200 errata issued since the original release of the specification in 2005.

What does "DCI compliant" mean, and which products are DCI compliant?

"DCI compliant" is a term used to describe products that conform to the DCI specification. At the time of this writing, no products on the market are fully "DCI compliant."

Products installed today meet an informal specification called "Interop." A "Transitional 3" upgrade is scheduled for Spring 2010, in which content interchange will ideally be upgraded from "Interop" to SMPTE. Note that SMPTE-compliant distribution requires compliance to a larger set of standards than DCI. While products strive to meet the DCI specification today, eventually, all products will have to be SMPTE compliant.

DCI published v1.0 of its test plan, as developed by Cinecert. Formal arrangements for testing through 3rd party agencies were recently announced. Note, however, that these testing agencies will not be a central authority to determine whether or not a device is DCI compliant. That determination will be individually decided by each studio, which could produce less than uniform results. This issue becomes most complex during the phase when products do not pass the the test 100%, and this circumstance could continue beyond 2010.

Note that the term "DCI compliant" is not trademarked and there is no mechanism for managing its use. Anyone can claim their product is DCI compliant, so buyer beware.

Are the digital cinema standards finished?

Twenty-six (26) digital cinema standards were published by the The Society of Motion Picture and Television Engineers (SMPTE) at the time of this writing. Additional drafts for other aspects of digital cinema are either in progress or remain to be started. Further, some standards are being revised as experience in the field is gained with real products.

Closed caption and audio distribution standards are now published. A standardized link between digital cinema servers and 3rd party closed caption systems is still in progress in early 2009. Note that current standards will not insure the interoperability of digital cinema servers with different TMS products, or insure automated key delivery. Standards that will help in these areas will take longer.

What are NATO's Digital Cinema System Requirements?

NATO's Digital Cinema System Requirements (NSR) describe the needs of the exhibition industry. Combined with the DCI specification, it provides a complete set of digital cinema requirements to standards committees, service providers, system providers, and manufacturers. The most recent release of the Requirements is version 2.1. The Requirements call for equipment functionality and behavior within the projection booth, and establish a baseline for service providers, all from a user's perspective. It can be downloaded from the NATO web site.

How do I know if a product follows the latest SMPTE standards and/or NATO's Digital Cinema System Requirements?

There is no mechanism to learn if products meet SMPTE standards, or if they meet NATO's Digital Cinema System Requirements. It is recommended that those buying equipment refer to the relevant standards in their purchase specification. Note that simply asking for "DCI compliance" does not guarantee that ALL SMPTE standards are met, and will not guarantee that NATO's Digital Cinema System Requirements are met.

For guidance in determining if current products are acceptable for studio digital distributions, Disney posts its Approved Equipment List at digitalcinema.disney.com.

Where can I learn more about Inter-Society's ISDCF?

Inter-Society is an organization chartered to socialize issues across the industry. It is not a standards effort, nor is it a compliance or certification effort. However, it is an excellent organization for socializing issues and solutions. More can be learned about the Inter-Society's Digital Cinema Forum (ISDCF) at the ISDCF web site.

What is the difference between 4K and 2K projection?

"4K" is the term used to describe images that have approximately 4K vertical lines. In digital cinema, a 4K image with a 2.39:1 ("scope") aspect ratio is delivered having 4096 x 1716 pixels. A 4K image with a 1.85:1 ("flat") aspect ratio is delivered having 3996 x 2160 pixels.

"2K" is the term used to describe images that have approximately 2K vertical lines. In digital cinema, a 2K image with a 2.39:1 ("scope") aspect ratio is delivered having 2048 x 858 pixels. A 2K image with a 1.85:1 ("flat") aspect ratio is delivered having 1998 x 1080 pixels.

Do I need a 4K projection system to play a 4K movie?

No. 4K movies can be played on 2K projection systems with no modifications. Through the use of JPEG 2000 image compression technology, a 2K projection systems will extract a 2K image from a 4K digital movie. Likewise, a 4K system can increase the resolution of a 2K image for projection on a 4K projector. This capability results in the ability to share content between 2K and 4K systems, allowing a studio to deliver "single inventory" content (i.e., either 2K or 4K) with confidence that the movie can play on both 2K and 4K systems.

Can I use a single lens to project both scope and flat images?

According to NATO's System Requirements 2.0, yes. But some studios say no. The DCI specification prefers, but does not require, the use of separate lensing to project scope and flat images. This was requested due to the belief that the scaling engine used to resize images inside the projector was not of high quality. However, even though recent tests demonstrate that the scaling engine in the TI projector is of very high quality, some studios require that a separate lens is used for flat and scope images when side masking is employed.

Can I use an anamorphic lens on my projector?

While anamorphic lenses are the best way to make efficient use of the light available to the projector, not all studios may accept their use. (See the discussion on Single Lens above.)

Anamorphic lens do not rely on the distribution of anamorphically squeezed images, as with film. In digital cinema, the projector can electronically perform an anamorphic re-mapping of the image onto its electronic imaging device, requiring an anamorphic lens to correctly display the image. The benefit of this projection technique is that it utilizes the full imaging array, utilizing the maximum lamp power available. Images projected with an anamorphic lens can light up larger screens than in non-anamorphic installations. The anamorphic projection technique has proven useful for large screen 3-D presentations.

How are security keys (KDMs) delivered?

KDM is the acronym for Key Delivery Message. The security key for each movie is delivered in a unique KDM, one KDM per per digital cinema server. The security key is encrypted within the KDM, which means that the delivery of a KDM to the wrong server or wrong location will not work, and thus such errors cannot compromise the security of the movie.

The KDM is a small file, and is often emailed or delivered by means of USB thumb drive. DCI's specification requires the presence of a modem for security communications, which at least one studio still requires. More streamlined methods for delivery are actively being explored.

How are KDMs controlled?

KDMs have only a few conditions associated with their use:

• A KDM will only work for one movie title on one server.
  
• A KDM will only work within the prescribed engagement time period.
  
• The server will only work if connected to a projector that is listed in the Authorized Device list of the KDM. (Not implemented at the time of this writing.)
  

To play a movie on two servers requires two KDMs for the movie. This means that to move a movie to a 2nd server requires a 2nd KDM. The engagement time window of the KDM is set per the business requirements of the studio distributing the movie. If your KDM expires and you don't have a new KDM to continue on the engagement, then you cannot play the movie.

To create the KDM, the digital security certificate for the server must be known, as well as the certificates of equipment in the projection booth that the equipment may operate with. The certificates are validated by the KDM creator before generating the KDM. Validation takes place by looking up the equipment on a "trusted device list."

What other conditions will cause a movie to not play?

One of the "dark screen rules" stated in the DCI specification is that equipment will fail to function when a security sub-system is tampered with. To a theatre operator, this means that the security components of your equipment must be maintained by others who are certified to repair the security components. You will have to check with the equipment manufacturer to learn who is qualified for this role.

The DCI specification also requires the playout of a movie to fail if the forensic marking capability of the server is not functioning correctly. The server's forensic marking system will mark the image and audio of the movie such that camcordered copies can be traced to the location of theft. If the marking system fails, then the server will fail to playout the movie. However, the studio can enable a flag in the security key to disable the marking system, which will also allow the movie to play with a failed marking system.

What is a Facility List Message?

The Facility List Message (FLM) carries the list of digital certificates that exist in the secure playback equipment of a digital cinema. The FLM is sent to those who create KDMs, so that an accurate set of KDMs can be created. The FLM is assembled by the theatre owner's equipment, it is digitally signed by the equipment, and is transmitted by the theatre owner's system to those entities authorized to create KDMs. This information in the FLM is also used to populate the Trusted Device List of the KDM. The diagram below illustrates the relationship of the FLM to the KDM.

For those cases where only a single screen is to receive a KDM, such as special authorization for a sneak preview, a "partial" FLM can be created containing the security information for one or more auditoriums. In this case, the FLM is tagged as "partial," and the purpose of the partial FLM is described in prose inside the message.

Do I need a Theatre Management System (TMS)?

A TMS provides a multiplex theatre with centralized management of all screens. As to whether or not you'll need one, the answer is both yes and no. No, not everyone will need a full TMS. But, yes, you may want to consider a standalone Data and Key Management System (DKMS) component of the TMS, which can be sold independently of a full TMS. The DKMS will manage all system data, including FLMs and KDMs, but does not provide the full functionality of a TMS. (And shouldn't cost as much.)

What do I need to know about digital 3-D?

Digital 3-D bears some discussion. The term "3-D" is used in digital cinema to describe stereoscopic images, where left and right images are displayed on a 2-D screen, and a method for viewing these images is employed such that each eye only sees the intended images. The result is that the left eye sees a different image from the right eye, providing the stereoscopic effect.

The distribution of digital 3-D content is intended to be single inventory, where a single distribution works for all 3-D display methods. However, this is not quite true today. Real D installations require a "ghost-busted" version of the 3-D distribution.

While there are many techniques for creating 3-D images, there are only three "add-on" technologies available for viewing them when projected by a single digital projector. The add-on technologies can be classified as those using polarized glasses, those using active "shutter" glasses, and those using spectral division glasses. See the article Choice in 3-D for an explanation of how the various 3-D add-on technologies work. Notably, all methods for projecting 3-D can display any form of digital 3-D content, regardless of how it was created.

Three questions can be asked of each method in differentiating the methods:

• Are the glasses inexpensive enough to be given away (so that they don't require washing)?
  
• Does the method use a normal projection screen (and not a silver screen)?
  
• How much additional cost is involved to move a 3-D movie to a 2nd or 3rd auditorium?
  

None of the 3-D presentation methods can answer "yes" to the first two questions, and the answer to the 3rd question will have a wide variance. This makes it an individual choice when determing which system best suits your needs.

A noteworthy issue of digital 3-D, which is independent of the presentation method, is the "flash" rate. The flash rate is the at which a pair of left and right images are alternately and repeatedly rendered by the projector. "Triple flash" refers to an image projection flash rate of 72 stereo frames per second, or 144 individual frames per second. Note that most DLP projectors cannot utilize the full 2K imager array when triple flash is employed, requiring that a separate lens be used.

A fourth method for projecting 3-D images is dual-projection. Dual projection is gaining interest among exhibitors as it will light up larger screens, and the cost of the 2nd projector is not much more than the cost of a 3-D add-on technology.

Can a single projector display 3-D images with full (4:4:4) color representation?

No. Single projector 3-D images are displayed in 10-bit 4:2:2 color representation. While it's true that the DCI specification calls for 12-bit color with 4:4:4 color representation for 2-D images, the specification for 3-D distribution allows 4:2:2 color representation when displaying 3-D images.

However, some servers support 4:4:4 color with dual 3-D projection. Dual projectors provide more light as well. But not all studios are fond of dual projectors due to concern about edge alignment.

What questions should I ask of digital cinema system providers?

Not all system providers approach digital cinema in the same way. Differences exist in the implementation of the Theatre Management System (TMS), the central control center for a theatre. Notably, there are also differences that will affect exhibitor policies and system security. Suggested questions to ask your server provider:

• Moving the Movie
  How long does it take to move a movie from one auditorium to another?
• Central Office Reporting
  Will the system report to your central office the arrival of content and KDMs? Will it report when KDMs are only days away from expiration? (Note that more exceptions regarding content and KDM delivery are listed in NATO's System Requirements.)
• Maintenance
  Who maintains the system? What Service Level Agreements are offered?
• Security Log Data
  The security policy in the DCI specification is "control lightly, audit tightly." A security log will likely be requested by the movie distributor. The DCI specification and SMPTE standards allows the exhibitor to remove a certain level of sensitive information from the security log. Does your system give you this ability, as well as the ability to view and approve your security logs before they're sent?
• Security of Exhibitor Networks
  The digital cinema should respect the security of the theatre owner's network by insuring that the delivery of KDMs will not compromise exhibitor network security, and that the issuance of security log data is under the exhibitor's control. Is this how the system you are considering behaves?
• Review NATO's Digital Cinema System Requirements
  Download NATO's Requirements from NATO's web site. A lot more information resides in that document.

What work remains in digital cinema?

At its core, digital cinema relies upon state-of-the-art information technology. It is complex, and a lot of work remains, particularly in the supply chain, before digital cinema will be ready for tens of thousands of screens. Top items on the list:

• KDM Delivery
  KDMs today are delivered by email or USB stick. Some studios require KDMs to be delivered by modem. This will not scale when having to deliver several movies a week for 39,000 screens in the US. The problems multiply when delivering KDMs around the world. The lowest cost to the supply chain is for KDMs to be delivered by an automated process. A better method is needed for KDM delivery than what we have today.
• File Management
  Content distributors needs to track and confirm delivery of files, and exhibitors need to log and manage files once they are delivered. The lowest cost to the supply chain is for these processes to be handled automatically. The industry does not have a single method that allows multiple content distributors to deliver files to a theatre site and verify that their files have arrived. Similarly, theatre central office systems have no idea when digital content or KDMs have arrived, when KDMS are about to expire, or when security logs are created or sent out. Much better file management systems are needed.
• Digital Cinema Server as a Commodity
  Once installed, the theatre owner should be able to replace the digital cinema server with one made by a different manufacturer without having to install a new Theatre Management System (TMS). Unfortunately, that is not the situation we have today. Much work remains before the digital cinema server is truly a commodity.
• In-Theatre Standards
  Show playlists, show schedules, performance logs, and point-of-sale interfaces are all areas where standards are required. No standards yet exist in this area. More work is needed.
• Security Log Management
  No TMS today allows the exhibitor oversight of how security logs are handled, or the legitimate filtering of security logs as allowed by the DCI specification and the SMPTE security log standard. Exhibitors deserve these tools. Much more work in this area is needed.


What is the status of digital cinema today?

The installation rate slowed dramatically at the end of 2007 as the sales funnel was fulfilled. At that time, Cinedigm (formerly AccessIT) fulfilled its ability to sell more systems in its Phase 1 plan using Virtual Print Fee (VPF) financing. In October of 2008, Digital Cinema Installation Partners (DCIP) announced approval from four major studios to move forward with 20,000 screens using VPF financing. However, global economic problems have placed a temporary freeze on financing these systems. There is hope that DCIP will obtain financing and begin installations by end of 2009 or early 2010.



(click to enlarge)

Technology adoption cycles have been studied for over 20 years. Stagnant sales and lack of major market uptake following a successful early adopter period is indicative of what author-consultant Geoffrey Moore calls the chasm. The diagram below shows how the progress made with digital cinema maps onto the classic technology adoption curve. Digital cinema will soon be embraced by the mainstream cinema market, but is still too expensive for small exhibitors to install, both in the US and around the world. Digital cinema is a replacement technology, and with the exception of 3-D, it is not a technology that creates new revenue opportunities. Thus, the rate of adoption post-chasm may not be what the curve below suggests.



Digital Cinema Technology Adoption Curve
(click to enlarge)