Review of NATO's v2.0 Digital Cinema System Requirements

by Michael Karagosian
©2008 MKPE Consulting LLC, all rights reserved worldwide
published in the November 2008 issue of Box Office magazine


please note: This article describes an older version of NATO's Digital Cinema System Requirements. The latest version of NATO's Digital Cinema System Requirements is posted here.

If you're an exhibitor and looking into digital cinema, you know it's anything but simple. Acquiring a server and a projector isn't enough to receive and play digital movies. In addition to contract addendums, one has to obtain components of a certain make and version of hardware and software. The purchase has to be approved by each studio individually. You'll hear about DCI* specifications, SMPTE* standards, ISDCF* recommendations…and NATO Digital Cinema System Requirements. How to make sense of all of these documents?

In terms of specifications, it may appear to be a puzzle. But the puzzle pieces fit with one another, and together the many specifications for digital cinema form a complete specification. While no one specification encompasses the full scope of requirements for digital cinema, NATO's Digital Cinema System Requirements is unique in laying down the foundation for exhibitor-friendly systems and services.

Digital cinema specification puzzle
Figure 1. NATO's Requirements is an important piece of the Digital Cinema Specification Puzzle

NATO's Digital Cinema System Requirements was first released in February of 2006, describing equipment functionality and behavior, as well as establishing a baseline for service providers, all from a user's perspective. It is the product of NATO's Technology Task Force, which is chaired by your author. In February of this year (2008), the group released version 2.0, which is a significant update to the Requirements. This article reviews the highlights of v2.0, and explains the progress made in implementing this important document.

Access Audio

Film theatres today have the option to provide audience members with Hearing Impaired (HI) and Visually-Impaired Narrative (VI-N) audio. The VI-N track is often referred to as "descriptive narration." In film systems, HI audio is synthesized by the cinema audio processor, while VI-N is typically distributed by means of CDROM. Although digital cinema has the capability of delivering up to 16 channels of audio, the DCI specification does not require that digital cinema systems support HI and VI-N audio. Only NATO's System Requirements requires support for these important tracks. This requirement is reflected in a draft document in development within SMPTE, 429-2, which identifies how 6-channel (5.1), 7-channel (6.1), and 8-channel (7.1) audio formats are to be efficiently distributed, and in particular, identifies how discrete HI and VI-N access audio tracks are to be included with these formats. In addition, the SMPTE 429-2 delivery method is defined such that the digital cinema server can route access audio tracks to specific audio outputs, regardless of the format. SMPTE 429-2 will mark a first for the motion picture industry in establishing a sound standard that includes access audio tracks.

Closed Captions

Closed captions are available today in film-based theatres through two commercially available products: the MOPIX® Rear Window system, and a relatively new system from Personal Captioning Systems (PCS). The closed caption capability in film systems only work with proprietary distributions developed independently by DTS and Dolby Laboratories. However, proprietary distribution files do not lead to the open market that is needed to create a competitive, low cost, closed caption market for digital cinema. A number of 3rd party manufacturers would like to bring closed caption systems to the digital cinema market, and these companies would be hampered from doing so without standards.

NATO's Requirements uniquely requires digital cinema to support closed captions. To execute its requirement, NATO actively supports standards development for both distribution of closed captions, and for interconnection between digital cinema servers and 3rd-party closed caption systems. Significant progress has been made. Closed caption distribution standards are expected to be available to the public by the end of 2008, and currently underway is the prototyping of a proposed standard interconnect between servers and closed caption systems. Notably, as many as four manufacturers of closed caption systems intend to sell products for use with digital cinema, based on the standards work in SMPTE.

Digital cinema closed caption standards
Figure 2. Digital Cinema Closed Caption Standards

Commodity Server

While a small complex can get away with only digital cinema servers and projectors, systems become more complex in the multiplex environment. It takes a certain level of digital infrastructure to manage show schedules, show playlists, and the movement of content and security keys among screens. To complicate this, there are no standards for how digital cinema servers interact with this digital infrastructure. Although SMPTE and DCI solved the significant problem of single inventory interchange of content, the DCI specification is silent in terms of interoperability within the digital theatre infrastructure. Thus, every make of server requires different or modified infrastructure, making it very difficult to replace one make of digital cinema server with another. Exhibitors deserve a better product replacement path. For this reason, NATO requires interoperability of servers - the so-called "commodity server." The standards activity required to meet this goal, however, is not expected to start until the 2009 timeframe.

Workflow

One of the most important distinctions of digital cinema from film is that of encrypted content. To decrypt digital content, the exhibitor needs a security key. The mechanism for encapsulating the security key (known as Key Delivery Message, or KDM) for delivery to the theatre is well-defined in SMPTE. Until NATO's v1.0 Requirements were published in 2006, no mechanism existed for properly instructing security key providers so that the correct keys would always be delivered. One security key will only work with one device. As equipment changes over time, reliance on old databases of equipment compiled at the time of installation generally leads to errors in security key delivery, and results in dark screens.

To overcome this problem, beginning with v1.0, NATO requires that digital theatre systems create a Facility List Message (FLM) containing only that information necessary for the correct delivery of security keys. NATO sponsored this work within SMPTE, and the FLM is now standardized in SMPTE 430-7.

Facility Identifiers

In order for theatres to generate data, such as Facility Lists, and to communicate this data to a wide set of business partners, such as security key providers, a mechanism is needed to uniquely identify the theatre. NATO's System Requirements requires use of a unique URI, or Uniform Resource Identifier, in such data communications that is supplied by the theatre owner. The URI is based on work established by the World Wide Web Consortium (W3C), and will allow a theatre owner to maintain their own identifier for a few dollars per year. Work towards this goal began in ISDCF.

Theatre Management System

The Theatre Management System (TMS) is the supervisory software that oversees operations in a digital multiplex theatre. A sophisticated TMS will manage the receipt of hard-drive-delivered and/or satellite-delivered content. It will manage the dissemination of FLMs (Facility List Messages, explained above) and the receipt of KDMs (encapsulated, encrypted security keys). A sophisticated TMS will synchronize the show schedules of digital cinema servers with that of the Point-of-Sale (POS) system. And of course, a TMS will manage operations, performance, and security logs, and provide the means for exhibitors to filter security logs per the DCI/SMPTE security log format.

NATO's Requirements divides the TMS into three component services, and describes the functionality and operations of each component. Perhaps the one component worth spotlighting in this area is the Data and Key Management System (DKMS). From a network perspective, the DKMS manages all digital cinema system-related traffic that takes place over the exhibitor's data backbone. Such traffic includes the handling of standard messages such as FLMs and KDMs. One advantage of describing the TMS in terms of its functional components is that some components, such as the DKMS, can be marketed independently. An exhibitor who has no desire to invest in the IT infrastructure and support required of a TMS may be interested in a standalone DKMS.

Why would a standalone DKMS be useful? If one does the math, a small 6-screen multiplex, each screen cycling through 17 movies per year, with delivery of all keys necessary to enable the movie to move to other screens, will receive over 5,000 keys per year. This assumes that one security key will enable a movie through its full engagement. As some studios require a key change per week, the total key count can substantially increase. In addition, the key count could double if more than one version of each movie is delivered, such as a version with and a version without subtitles. That's a fair amount of keys to manage manually, and a good reason for having at least a DKMS in the facility to automate the work. Despite the obvious utility of such a device, only one manufacturer to date has announced a DKMS-like product on the market. Hopefully there will be more such products in time.

Operations

Operational requirements are useful to convey to studios and service providers the degree of service called for by the exhibition industry. The need to move a movie to an in-house screen of the exhibitor's choosing and at the time of the exhibitor's choosing requires that all of the keys necessary to enable such movement be provided per movie, an important requirement of NATO's document. NATO's Requirements also spells out how far in advance of a show both content and keys should arrive to allow sufficient time for load and test. The Requirements also calls for movement of shows from auditorium to auditorium in 15 minutes or less. While such timing is commonly achieved with film systems, no digital system to date has complied.

The Future

If you are a manufacturer or service provider, you're aware that an important step towards achieving success with new products or services is close collaboration with your customers. With the introduction of digital cinema technology, there has never been a time where a close working relationship among exhibitors, manufacturers, and service providers was more in need. Accordingly, in June of this year, NATO members met for most of a day with representatives of the companies that provide digital cinema servers, projectors, theatre management systems, and fulfillment services, to review and discuss the v2.0 Requirements. It was a valuable opportunity to explain, listen, consider clarifications and improvements, and learn and appreciate the challenges of implementation. The Technology Task Force has been meeting regularly since by means of conference call and web collaboration tools, and plans to issue v2.1 by the end of 2008. The revision will largely be the result of input received in the June meeting. Another meeting with manufacturers and service providers is in the offing, either end of this year or early next.

When compiling these requirements, a question commonly asked is "will these be in products next year?" NATO has set a goal of achieving its access related requirements in the 2009 timeframe, and, as presented in this article, important steps have been taken towards implementation of other goals. But many of NATO's requirements may not be achieved quickly, simply because more standards work is needed to bring the desired capabilities into the marketplace. Digital cinema technology, as with any digital technology, will continue to evolve. NATO's Digital System Requirements is an important step in directing this evolution, and in doing so, it helps to insure the technology future for this industry.


* DCI stands for Digital Cinema Initiatives, a coalition of the 6 major film studios. SMPTE stands for Society of Motion Picture and Television Engineers, the organizational body for digital cinema standards, in cooperation with ISO (International Standards Organization). ISDCF stands for Inter-Society Digital Cinema Forum, a sub-group of Inter-Society.