Cinepedia

The Technology Behind The Big Screen

Technology FAQs

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The information below is provided for those who seek to learn more about the technical issues of digital cinema.

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 the cinema equivalent to the consumer specification of the Blu-ray format. Note that the DCI specification is not a standard. 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 (v1.3) 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. Products that have been tested per the DCI Compliance Test Plan (CTP) are posted at the DCI compliance web site.

Note that DCI compliance does not require compliance to the full set of SMPTE DCP standards. Support for standards such as those for accessibility, for example, are not included in DCI testing.

Are the digital cinema standards finished?

A full suite of cinema distribution and security standards exist. But standards require ongoing maintenance, and new technologies emerge, leading to new standards and recommendations over time.

Are SMPTE standards used in distribution today? If not, then how is content distributed?

All digital cinema products are designed to meet an informal specification called “Interop.” The Interop DCP (digital cinema package) is based on early draft standards to promote interoperability in the early phase of the digital cinema rollout. Interop DCP is similar to, but not compliant with, SMPTE DCP. It does not support many of the features incorporated in SMPTE DCP, most notably SMPTE audio specifications. The specifications for both Interop DCP and SMPTE DCP, as recommended by the ISDCF, are listed in the ISDCF SMPTE-DCP Transition Review.

Learn more about the DCP in Cinepedia.

How do I know if a product follows the latest SMPTE standards?

The short answer is that you don’t. There is no formal test available that will tell you if a product meets all SMPTE standards. It is recommended that those buying equipment include detailed specifications in their equipment purchase agreements. Note that simply asking for “DCI compliance” does not guarantee that all SMPTE standards are met, and does not guarantee that the product is ready for use in the cinema.

How do I know if a product meets the High Frame Rate (HFR) requirements?

The DCI specification requires all projection systems to support 48fps at 2K resolution. Frame rate higher than 48fps are a feature of most if not all projection systems today. However, many older projectors cannot manage frame rates beyond the DCI spec. The high frame rates of interest today are associated with 3-D, at 48fps-per-eye and 60fps-per-eye. This equates to 96fps and 120fps in the total frame rate count.

The bottleneck is the media block and server. An in-projector media block (IMB) is required for HFR, and most media blocks support at least 500 Mb/s bit rates, which should be sufficient for anticipated 48fps-per-eye (96fps) releases. However, other bottlenecks exist as well, such as storage transfer rates, and CPU processing power, that can introduce further limits in system performance. If you’re planning to play an HFR movie, test your system first. 500 Mb/s may itself prove to be a bottleneck for higher performance systems in the future.

How do I know if a product meets accessibility requirements?

Closed captions and accessible audio are included in the SMPTE distribution standards. They are not specified by DCI, however. As such, DCI compliance testing does not guarantee the presence or behavior of accessiblity features. To insure that these capabilities are in products you purchase, you should specify compliance to the ISDCF SMPTE DCP transition review.

Where can I learn more about the Inter-Society Digital Cinema Forum (ISDCF)?

The Inter-Society’s Digital Cinema Forum (ISDCF) is on the web at http://ISDCF.com. Inter-Society is an organization chartered to socialize issues across the industry. The ISDCF is not a standards body, nor is it a compliance or certification effort. However, it is an excellent organization for socializing the unique issues and solutions that pertain to digital cinema.

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 system will extract a 2K image from a 4K digital movie. Likewise, a 4K system will automatically scale 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” distributions (i.e., either 2K or 4K).

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

According to NATO’s System Requirements 2.1, yes. But some studios interpret the DCI specification as opposing the use of a single lens for scope and flat images. A different interpretation of the DCI specification is that it prefers, but does not require, the use of separate lensing to project scope and flat images. If your systems are financed in part through VPF subsidies, then you should have this discussion with your deployment entity.

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.)

Note that an anamorphic lens in digital cinema does 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. A KDM is required to play an encrypted movie. Each KDM allows one version of a movie to be played on the targeted digital cinema server or media block during a specified time period. The KDM carries security credentials for the movie in encrypted form, which can only be decrypted by the target device. Thus, a KDM delivered to the wrong server or wrong location cannot be decrypted and will not work, nor will such an error compromise the security of the movie.

The KDM is a small file, that, in legacy systems, is typically emailed to the exhibitor. Automated key delivery using the Facility List Message is now available.

Learn more about the KDM in Cinepedia.

How are KDMs controlled?

KDMs have 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 all studios utilize the Authorized Device List.)

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 the engagement, then you cannot play the movie.

To create the KDM, the public key contained in the digital security certificate for the media block must be known. If the studio requires use of the Authorized Device List, then the public keys contained in the projector certificates must also be known. Certificates are digitally signed by the manufacturer, allowing those who make KDMs to know they’re encrypting keys for trusted equipment.

What other conditions will cause a movie to not play?

One of the “dark screen rules” of 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) is used in automated systems to carry the security information that exists in secure playback equipment to the KDM generating facility. This allows the correct KDM to always be created. The diagram below illustrates the relationship of the FLM to the KDM.

Facility List Message

The Facility List provides security information for the creation of KDMs

Do I need a Theatre Management System (TMS)?

A TMS provides a multi-screen complex with centralized management of all screens. The TMS is your tool for scheduling and monitoring your shows. As to whether or not you’ll need one, that’s for you to decide.

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.

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 (or color) filter glasses. See the MKPE article Choice in 3-D for an explanation of how the various 3-D add-on technologies work. All methods for projecting 3-D can display any form of digital 3-D content, regardless of how it was created.

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

  • What is the cost of the glasses?
  • Do the glasses require washing?
  • Does the method require use of a silver screen?
  • How much additional cost is involved to move a 3-D movie to a 2nd or 3rd auditorium?

A fourth method for projecting 3-D images is dual-projection. Dual projection is often used to light up big screens. If dual projectors are used, the exhibitor should be prepared to regularly align them for 3-D presentation.

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.

What questions should I ask of digital cinema system providers?

Digital cinema has matured, and you’ll find that most system providers offer equivalent capabilities. However, it is still useful to ask the following questions of your systems 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 may be requested by the movie distributor. Does your system give you the ability to view and approve your security logs before they’re sent?
  • Security of Exhibitor Networks: The digital cinema system should not compromise the security of the theatre owner’s network. The transmission of security log data to suppliers should be 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. It contains a wealth of information that guided the early development of digital cinema.

What is the anticipated lifespan of DLP projectors?

The common lifetime estimate for DLP projectors is 10 years. Longer life is possible, but maintenance costs will increase with age and are likely to drive the replacement decision. These figures are provided only as rough estimates, without any warranty of actual equipment performance.

What work remains in digital cinema?

Digital cinema will evolve as new formats emerge. More on this subject at mkpeReport.

What is the status of digital cinema today?

In mid-2017, there are over 160,000 digital cinemas installed worldwide. This is a 75% increase from 2012, when some 90,000 systems were installed, and the US had only reached the 85% conversion point. Graphs showing the progress of digital cinema in 2012 are in a NAB 2013 presentation at mkpe.com.

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, and this stage appeared in the early rollout of digital cinema. The illustration below maps US digital cinema conversion onto the technology adoption curve of Geoffrey Moore.


Digital Cinema Technology Adoption CurveDigital Cinema Technology Adoption Curve

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Business FAQs

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The information below is provided for those who seek to learn more about the business issues of the digital cinema transition.

Will my equipment become obsolete?

Probably one of the hottest topics for those attempting to finance equipment is that of equipment obsolescence. When addressing this issue, it’s best to think of digital cinema equipment in layers. There’s the “DCI” layer, which is the baseline for cinema. It’s the 35mm equivalent of digital equipment.  Movies will be distributed in the baseline DCI format for decades. Note that while DCI does not specify accessibility, all manufacturers now support it. So we can include accessibility in the baseline DCI layer. Then there’s the feature layers: 3-D image, 3-D sound, higher frame rate, laser illumination. Lasers first: laser illumination is several years away from achieving regulatory approval. Once available, it will produce brighter images, but for a big price, not for a little price. A lot of stars have to line up before it’ll be in wide use, and by that time, your equipment should be paid off. Add-on technologies such as 3-D image, 3-D sound, and higher frame rates can be added later, as the name “add-on” implies. There’s a cost to add-ons. In this framework, one can think of a media block and server as an add-on, replacing the old with the new as desireable features become available, including higher compression bit rates. The point to remember is that your core investment in new equipment, in particular, your projector, won’t go down the drain when add-on technology allows new features to be added later.

What is a VPF?

The Virtual Print Fee (VPF) is a financing mechanism for funding the first purchase of digital cinema equipment in the replacement of film projectors. The VPF is a method for redistributing the savings realized by studios when distributing digital prints in place of film prints. It is an effective mechanism, but it is not a perfect mechanism. First run cinemas benefit the most from the VPF, as that’s where print savings actually occur.

The VPF is based on the payment of a fee per booking by content-suppliers. Early VPF programs were designed to achieve a neutral P&L for studios, such that the expense for delivering a digital print (including financing fee) plus VPF was no greater than the cost of delivering a film print. Contemporary VPF programs are often designed to recoup a smaller portion of costs over a fixed term, often 5-6 years. Payment of the VPF will terminate once the equipment expense is fully recouped, or when the VPF term expires.


Virtual Print Fee (VPF) Neutral Cost Structure

How is the equipment financed?

Financing mechanisms vary. Most deployment entities offer off-balance-sheet financing, where the deployment entity or the bank hold title to the equipment throughout the VPF payment period. Some deployment entities require, and some exhibitors prefer, to finance the equipment themselves.

Do I need to sign up with a 3rd party integrator to gain access to VPF financing?

Generally, yes. If the exhibitor has sufficient scale, studios will consider a deployment deal directly with the exhibitor. However, in such cases, it is the obligation of the exhibitor to negotiate equivalent deals with each studio. More often than not, exhibitors start this process, but never complete it. Successful deployent entities are usually a collaboration of several exhibitors. In many cases, the collaboration is driven by a local equipment dealer who is motivated to complete the process. By developing scale, exhibitors reduce the cost per screen of managing the deal. If there is agreement to buy the same make of equipment, the exhibitors may also benefit through volume discounts.

Who do I talk to about financing and virtual print fee plan?

Exhibitors with sufficient resources can talk directly to studios, in which case they will be responsible for negotiating with each studio independently, as well as the bookkeeping and mangement of the VPF deal. A faster course is to arrange to receive VPFs through a digital cinema deployment integrator. Cinedigm, a major integrator in the US, can no longer accept new exhibitor applications for its US digital cinema rollout. However, Cinedigm is now undertaking a new rollout for independent exhibitors in Australia. European integrators include Arts Alliance Media in the UK, DCinex in Belgium, or Ymagis in France. Asia-based integrators include GDC Technology in Hong Kong, DCinema Alliance (Arrays Technology) in Philippines, and Scrabble in India. Sony Digital Cinema also offers VPF deals in several countries.

Is DCI the authority behind the VPF model?

There is no connection between DCI, the joint venture of the six major studios, and the studio willingness to pay VPFs. DCI’s sole contribution to digital cinema is its oversight of the DCI Specification.

Why is the financing of digital cinema so challenging?

VPF-financed equipment managed by a deployment entity is not the usual asset-backed financing deal that banks seek. If the exhibitor is not the guarantor of the loan, then another entity must do so. The relationship between parties can be complex, making these deals difficult for banks to understand and increasing the apparent risk. This is shown in the diagram below:


Typical Virtual Print Fee (VPF) Relationship of Parties

The strength of the VPF is that it rests on the delivery of movies by multiple studios. The strength of box office combined with the large number of movie distributors results in a relatively safe cash flow. However, it takes time to recoup costs. Digital projectors are a relatively new technology, and the replacement cycle and potential obsolescence factor is hard to gauge.

Why can’t a studio simply credit film rental?

Studios seek the minimum impact on the exhibitor-distributor relationship when paying VPFs. As such, they seek to maintain an arms-length relationship between themselves, the ownership of equipment, and the exhibitor’s operations.

Why is 3-D a driver for digital cinema? Does 3-D cost extra?

The early popularity of 3-D movies drove the adoption of digital projection. Up until the introduction of digital 3-D projection, there was little value added to exhibitor operations by converting to digital cinema. To show 3-D in digital, add-on technology is required in addition to the purchase of a digital projector. These costs are not covered by virtual print fee payments. Companies such as RealD, Dolby, Master Image, and XpanD are the the primary companies marketing add-on technology and glasses. Note that the cost of the 3-D add-on technology cannot be included in the total system cost to be recouped through VPFs. The technical differences in the various add-on technologies is discussed in Technology FAQs at Cinepedia.

Are all digital cinema projectors capable of High Frame Rates (HFR)?

No. All TI Series 1 projectors, and all Sony projectors installed to date, will not support HFR. TI Series 2 projectors will support HFR with a software upgrade and an HFR-capable In-projector Media Block (IMB) installed. Sony projectors will become HFR capable with a future hardware/software upgrade.

Does DCI require High Frame Rate (HFR) support?

No. DCI does not require or test for HFR capability in digital cinema equiupment. However, DCI issued a “Recommended Practice” in October 2012 to guide filmmakers in the practical production of HFR movies. SMPTE conducted a study of HFR requirements for future generations of digital cinema equipment. You can learn more about this by reading the Report from the SMPTE High Frame Rates Study Group at mkpe.com.

What is the value of 4K and HFR to my audience?

4K resolution can only be perceived by audience members that sit up close to the screen. This limitation is caused solely by the human visual system, and has nothing to do with the projection technology. In most auditoriums, the front seats are not the ones that the audience places a high value on. Thus, the most basic challenge faced by the 4K format is that it does not offer a clear-cut value proposition in most auditoriums.

Large format theatres, however, tend to place audiences up close to the screen to create an immersive experience. Such auditoriums can benefit from 4K projection. Having said that, getting 4K content is an entirely different matter.

High Frame Rate (HFR) is a projection system capability that can be perceived from any seat in the house. Where HFR presents a clear difference to audiences is with motion. Pans can be faster. In addtion, as motion becomes less blurred, our peripheral vision detects more information, leading to a more immersive experience. The skill to which these perceptions are exercised is in the hands of the director and cinematographer. Simply shooting in HFR does not necessarily make a movie more interesting to watch.

Should I wait and buy used digital cinema equipment?

It’s unlikely that there will be a significant used equipment market in digital cinema, for several reasons:

  • Unlike film projection equipment, digital projection equipment has an estimated 10-15 year lifetime. If you buy a projector that is 5 years old, then you could have 5 years of life left. Lifetime is limited by parts availability and the obsolescence factors associated with high technology. While a part for an old film projector can be custom machined in the worst case, no such fall-back is possible with sophisticated digital equipment. Semiconductor technology changes quickly, and the investment required to
    re-engineer the circuit boards of old products with new parts is better put to work in developing entirely new products. If you’ve ever tried to repair a 10-year-old personal computer, then you understand the problem.
  • Warranty can be an issue in financing used equipment. Deployment deals require a 10-year extended warranty on equipment. Unless the extended warranty is included in the used-equipment sale, it will not transfer.
  • Further, early replacement cycles are costly. If it’s hard to secure loans for 1st time digital equipment expenditures, then it’s unlikely that exhibitor’s will undergo the process again in 5 years. Consider that for DCIP screens, this would amount to $1B of capex every 5 years, versus every 10 years.

A pragmatic strategy for purchasing equipment must take into account the limited lifetime it has and the re-investment in capex required every 10-15 years. Waiting to convert has proven to be a beneficial strategy for many exhibitors, as pricing has come down over time, and financing has become more readily available. But if you are waiting for used equipment, you should consider the points above.

Is compliance with the DCI specification sufficient to receive a digital movie?

Generally, the answer is “yes.” Some studios require the exhibitor to sign a separate digital rental agreement to the existing film rental agreement, which may stipulate further requirements that must be met. It is important to note that owning a digital projector does not necessarily cause a change in booking pattern. If you’re expecting to convert from 2nd run to 1st run through the purchase of a digital projector, it’ best to first discuss this with your distributors.

Are there any restrictions I should know about?

In a VPF deal, the exhibitor is expected to maintain the equipment. If shows are lost due to maintenance issues, you may lose the VPF for that movie. Also, you will be expected to maintain a high quality Internet connection to each site. The Internet connection is necessary to pull security and performance logs for reconciliation by the deployment entity with studio-provided booking reports.

When will film distribution end?

The short answer is sooner than you may think. It may surprise you to learn that studios are not in control of the availability of film prints. The deciding factor will be the manufacturers of print stock. The US will be approximately 85% digital by end of 2012. Cinemas worldwide, including the US, will be approximately 70% digital by the end of 2012. The two major suppliers in the world of motion picture print stock are Kodak and Fuji. As you can see, by the end of 2012, these companies will have lost 70% of their motion picture print stock business. In September 2012, Fuji accepted its last orders for print stock, and announced that it will discontinue the manufacture of print stock in March 2013. That leaves Kodak, which declared bankruptcy in January 2012. Whether or not Kodak continues to manufacture print stock depends on the actions of the US court overseeing it. It is entirely possible that motion picture film print stock will cease to be available by the end of 2013.

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Accessibility FAQs

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Royalty-free and license-free standards define how accessible content is delivered to theatres in an open, interoperable manner. Cinepedia devotes a chapter to distribution practice and accessibility standards. Further information on accessibility standards is available at mkpe.com.  Motion picture distributors and equipment manufacturers are encouraged to adopt the accessibility practices and standards outlined.

For those seeking a cinema that offers accessibility for its movies, Captionfish provides such a service in the US.

More information is provided below to educate and clarify the application of accessibility in digital cinema.

Accessibility Terminology

  • Accessibility in Cinepedia refers to the use of specialized sound tracks and visual aids, enabling a wider audience to enjoy the cinema experience.
  • HI is the acronym for “Hearing Impaired” audio. It describes an accessibility audio channel whose dominant content is dialog.  This channel may be included in the DCP, or produced in the cinema audio processor as mix of left, center, and right channels, with a 3-6dB emphasis on center (for dialog). It is delivered to the audience member over a personal headset.
  • VI-N is the acronym for “Visually Impaired Narrative” audio, often referred to as “video description” or “descriptive narration.” This audio channel provides a narration of the action in the movie. It is delivered to the audience member over a personal headset.
  • Closed Captions refers to text that describes the dialog and action of the movie. It is transmitted discretely to an audience member over a personal display, for which several types of devices are now marketed.
  • Open Captions refers to text or graphics that describe the dialog and action of the movie. It is delivered on-screen, visible to all audience members.
  • CSP/RPL is an acronym for the standardized, Ethernet-based protocol used in digital cinema to synchronize and source content to a 3rd party closed caption display system.

Closed Caption and Accessible Audio Systems

The products below are known to utilize the closed caption standards and/or provide accessible audio for cinema (no warranty or endorsement implied):

What Exhibitors Need to Know

  • Legacy Rear Window display panels can be directly connected to legacy digital cinema products from Dolby, GDC, and USL. Note that the DTS CSS and DTS XD10 products are not needed for Rear Window operation in digital cinema.
  • Learn your distributor’s policies regarding the inclusion of accessibility content in their digital cinema distributions.

What Distributors Need to Know

  • License-free and royalty-free standards prescribe how accessibility content can be included in the DCP. The relevant standards are discussed in the Accessibility chapter.
  • Interop and SMPTE DCP closed captions will work with all closed caption display systems, including Rear Window systems.

last changed 2019-03-11 in FAQs by

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Interop DCP

The Interop DCP documentation below is provided for those who seek interoperability with older … more