Emerging Technologies, Standards and Specifications for Digital Cinema Architectures

(Direct View Displays, Laser Illumination and the Digital Cinema Picture Level project)

One of the mandates of the ICTA is to facilitate “…the exchange of ideas and constructive suggestions concerning improvement of manufacturing and technical standards for products used in the theatre industry.” LASS 2020 provided a fitting forum for this exchange, including presentations by Peter Ludé, CTO of the San Francisco-based engineering firm, Mission Rock Digital, and Jerry Pierce, Technical Advisor for National Association of Theater Owners (NATO) and past-chair of the Intersociety Digital Cinema Forum (ISDCF).

Ludé presented on both the successes and challenges of an emerging cinema technology: Direct View LED screens, and the latest standards for laser-illuminated projection systems, while Pierce followed with an update on NATO’s Digital Cinema Picture Level (DCPL) project.

Noting that going to the cinema has meant watching a large, reflective projection screen whose images are generated by a projector – with the xenon arc-lamp or solid state laser illumination currently the projectors of choice – Ludé asked what could be next. And then suggested that it could be Direct View Displays –often known as Emissive displays or LED displays –for theatrical cinema applications.

“Why might an emissive direct-view display be preferable over projection technology?” Ludé mused. Well, for one thing, higher contrast –or dynamic range – is possible because, unlike projector pixels, the LED can completely shut off.  LED’s are capable of far higher luminance levels then projectors – potentially in the 1000’s of nits.  And the surface could be designed to be non-reflective, eliminating the problems from back-scattered projector light and room ambient light ruining the deep-black portions of the picture. So blacks will be blacker.

Secondly, new and exciting screen configurations are made possible with wide-aspect-ratio immersive displays, configured with an emissive direct-view display.  Say goodbye to seams between projected images, since the screen can be curved in whatever radius is desired.   As well, there is no reflected light from one area of the screen to the other.

“The result is stunning contrast and bright images throughout your peripheral vision” enthused Ludé.

But what will spur the adoption of Direct View LED cinema technology? First, costs for the underlying surface-mount devices (SMD) need to drop. And that appears to be emerging. “Information from Futuresource, Yole Développement and reports from media such as MicroLED-info suggest that BOM (bill of material) costs for LED narrow-pitch displays has declined more than 20% in many areas, year over year,” Ludé noted. “And the indoor narrow pitch LED display market has grown by 24% in the past year, achieving 2019 estimated revenue of over $3 Billion US.”

Seeing is believing, to a point, and along with the consulting and research reports pointing to BOM reductions, at CES 2020 several firms exhibiting new, eye-popping LED displays. “TCL was showing a 132-inch 4K panel with a claimed contrast ratio of 2.5 million to one, and a ‘wide color gamut’.  I wasn’t able to get much more technical detail about this, but the display –called “the Cinema Wall” –looked beautiful,” said Ludé. As well, Konka–another Chinese company –had an even more impressive display: a 236-inch (nearly 20-foot) 8K display using a pixel pitch of 0.6mm.  The unit show was capable of 2,000 nit peak luminance and claimed a 10 million to one contrast ratio.  Ludé noted that “The color gamut was claimed to be well over DCI P3, and 16-bit drivers were used for higher bit depth.  So, in short, here is a high-end prototype that pretty much matches requirements for commercial cinema.”

Also at CES, Samsung returned with the latest –and largest –version of their MicroLED display branded “The Wall”.  This version was 292-inch (24-foot) diagonal with 8K resolution.  Ludé speculated that, although not specified, it has a pixel pitch of about 0.8mm, and their claimed peak luminance was 5,000 nits, “which would make for a very impressive HDR picture!”

Ludé then took attendees through a detailed examination of the complex yet mature supply chain for LED displays. The core LED die component has a strong base of manufacturers, with at least two now supporting off-the-shelf LED components capable of supporting the DCI –P3 Color gamut. Of equal importance is the Display Drive ASIC (Application Specific Integrated Circuit) – the commodity “engines” that drive the LED dies, and although most driver chips were aimed for the low-cost commodity market for digital signage and similar applications, Ludé has it on good authority that  “…there are at least three viable drive suppliers addressing the cinema market now.”

Waxing enthusiastic, Ludé went through info and numbers on TI, Macroblock, SiliconCore and CHIPONE as suppliers. Intriguingly, along with Sony and Samsung – who brought to market the first LED cinema technologies – Barco, LG Electronics, NanoLumens and NEC are also exploring the future of LED cinemas. Noting that Barco has begun to collaborate with, and made an investment in Unilumin – news that CelluloidJunkie connected the dots on – Ludé opined that this surely signaled some interest on the part of the world’s number one cinema-projector manufacturer in the Cinema LED market, but only when the time is right.

And NEC invested in a technologically-advanced German provider of LED displays called S[quadrat]. NEC has no publically-announced plans to bring LED Cinema to market, prompting Ludé to believe that NEC’s efforts are presently confined to the research labs, until it becomes sufficiently cost effective.

Some attendees were surprised to hear that Samsung Onyx will have some 78 commercial installs by year-end, and although Ludé conceded that the number is small compared to the xenon-and-laser illumination installations globally, he said that it’s a solid footprint of early adaptors in the first three years, “…not unlike the original adoption of digital cinema projectors replacing film, or the early days of experimentation in 3D technologies.”

Having built the case for true momentum for cinema LED displays, Ludé confirmed his own objectivity (and reined back the enthusiasm), with a detailed examination of the technical issues hindering immediate, wide-ranging adoption of this new display tech for the cinema industry.

Ludé noted that, if viewed from too close a distance, of course, the pixels in any display become visible, and therefore potentially distracting. Viewing distance and pixel visibility concerns are real and even if LED pixels are adjusted to perfect uniformity, Ludé cautioned his audience that “they are still mounted into a pile of different cabinets and if these cabinets are not precisely aligned, the result will be visible lines at the boundaries –brighter pixels if two adjacent cabinet are too close together, and dark lines if too far apart.” However, by a combination of careful physical alignment, and electronically adjusting the pixels along each boundary row and column, the problem is solved. “DCI has taken a stab at defining how good is ‘good enough’ in this regard, but further study will be helpful,” said Ludé.

Off-axis uniformity of LED light emissions — since these direct view displays are emitting light, not reflecting light coming from a projector across the room — is another way in which these displays behave differently than the projectors we’re used to.  In addition, they should be designed to absorb as much ambient light as possible. Otherwise, back-scatter from the movie image will degrade the contrast.

Providing realistic sound may be the biggest current challange to mass-introduction of LED cinemas. “The issue here is that in a typical cinema system, screen-channel sound comes from speakers mounted behind the projection screen, which is perforated so that it’s acoustically transparent, and it sounds like the dialog is coming from the mouths of the actors being projected onto the screen” noted Ludé. But the LED display is usually not acoustically transparent, requiring speaker placement somewhere that allows them to be audible.  “In doing so, I have lost my sound localization, so this needs to be addressed,” he conceded.

Several of the leading cinema sound companies have been actively involved in addressing this challenge, according to Ludé Harman has been deploying their “de-elevation” sound processing for the Samsung Onyx displays  – along with other innovations in speaker placement and sound processing –to produce good-quality sound for direct-view displays.

“And both Dolby and QSC have reported significant study and research, as well as extensive listening tests, in order to find a suitable audio solution for direct-view cinema,” so the solution is practically in sight.

Standard-setting is also not being ignored, Ludé said. Two DCI documents issued in November 2018 are being actively reviewed and revised by DCI, with feedback from the industry. Demonstrations and discussions specific to HDR cinema and direct view displays are being hosted by DCI with LED display manufacturers and other interested parties in January. “I’ll think we’ll see updated versions of both draft documents over the next few months, along with an invitation from DCI for further comments, as we all work to pin down the exact expectations for this advance in next-gen cinema.”

In conclusion, Ludé made some predictions, including that there will be at least 100 direct-view cinema screens in operation worldwide, from at least three different manufacturers, by January 2021. 2020 will also see DCI issuing their “final” addendum to the Digital Cinema System Specification on Direct View Displays, addressing image uniformity, off-axis performance, surface reflectivity and such, Ludé believes.

“These attributes are just as important for today’s standard dynamic range (e.g. 14 ft-L and 2,000:1 contrast) as they are for future HDR. And I believe that DCI will have published a draft of new HDR specifications – which will be applicable for both HDR projection as well as LED direct-view – but these may not be quite final by the end of this year.”

Turning to the realm of lasers, Ludé prefaced his presentation with an outline of the Laser Illuminated Projector Association (LIPA), which represents the cinema and pro AV industries’ leading projector manufacturers and supply chain companies. “LIPA was founded in 2011 and since then the association has sped the adoption of LIPs through cooperative-industry activities, including education, safety determinations and regulatory interventions,” said Ludé.

Then making an important distinction between laser projectors (for sound and light shows) and laser-illuminated projectors,’ (LIPs), Ludé proceeded with an interesting, short tutorial on laser-illuminated projector optical architectures and also revealed a joint NATO-LIPA industry survey. The survey showed that 58 percent of cinema owners polled had or were planning to add RGB or laser-phosphor illuminated projectors, but – perhaps due to the investments already made in the industry’s xenon-lamp projector workhorses – 41 percent had no current plans to install LIPs. Notwithstanding, PMA Research figures showed that laser-illuminated projector shipments will account for 75 percent of all 2020 shipments, leaving 25 percent to lamp-based projectors, and those laser projectors will account for 66 percent of revenues. So the advent of laser-illuminated projection is clearly here.

The regulatory outlook for 2020 also bodes well for a potential end to the variances currently required in some jurisdictions, including the United States, to install and operate LIPs. “Currently, for permanent installations, “Laser Light Show Variances” are required from the FDA, typically specifying that the ‘Hazard Zone’ be not lower than 3m for non-cinema LIP installs, 2.5m for cinema installs, with a horizontal clearance of 2.5m. LIPA is in discussions with FDA to have the vertical clearance distance reduced to 2m for permanent cinema installations. Barriers are also needed to restrict any human access and, of course, installation must be done by trained and authorized installers,” said Ludé. “And always check with your manufacturer or variance-holder for the projector, as FDA variances may differ,” he advised.

Following on from John Fithian’s strategic references to NATO’s Digital Cinema Picture Level (DCPL) project, announced in late 2019, Jerry Pierce, special advisor to NATO, went into more depth about its goals and its spoke to the DCPL. But first he shed some light on the origins, rationale for and current activities of the Inter-Society Digital Cinema Forum (ISDCF) – a body that will play a key role in the later stages of the DPCL.

“ISDCF has been serving the industry since 2006 and has more than 500 members, drawn from the studios, exhibitors, equipment manufacturers, service providers, and consulting community, who use the usual communication tools, as well as meeting in Burbank every 4-6 week,” noted Pierce.

“We’ve been responsible for solving a lot of problems (or potential problems), including specifying hard drive formats, how to set subtitles and closed captioning in multiple languages, defining test content (B2.1) as well as High Frame Rate (HFR) and audio routing.”  And from these beginnings, ISDCF continues to discuss and refine DCP (Digital Cinema Package), KDM (Key Distribution Message), FLM (Facility List Message), TDL (Trusted Device List), FIPS-140, DCI (Digital Cinema Initiatives), upgrade scheduling, 3D luminance, and SMPTE specifications for digital cinema/audio.

Key activities, besides meetings, include PLUGFESTS, “which are amazing events, where nominal competitors can gather in a safe environment to discuss problems and jointly suggest solutions, which we’ll document and send to SMPTE (the Society of Motion Picture and Television Engineers), who can then formalize them,” noted Pierce. As well, the ISDCF is the host and editor of the Digital Cinema Naming Convention (DCNC), which is used worldwide for more than 990 registered facilities.

Immersive audio is also a hot topic with ISDCF, which will educate the exhibitor community on the recently completed SMPTE immersive audio standard.

Segueing to the DCPL project, Pierce posed the ‘so what’ question: Why is the DCPL necessary? The answer lies in the need for advice and counsel, based on real, in-theatre experience, to guide projector replacements and upgrades over the next decade. Factors such as higher brightness and higher contrast come into play, with the exhibition industry needing to see and talk with creatives, manufacturers and the studios to understand the benefits of higher brightness and higher contrast.

For the exhibitor, the DCPL will help guide their procurement and exhibition decisions, as Pierce put it: “Exhibitors need answers to questions like ‘if you have a theater and replace the projector, what can you expect in terms of customer experience?; if you want to get a new system – how will it perform? Will it be supported in the future? What are the important criteria that you need to understand?  And can you in fact get content to play on the new system?”

“It’s a work in progress, in partnership with the ISDCF, to investigate theatrical display systems to identify the characteristics for higher brightness / dynamic range projectors and displays that will make a difference to movie patrons. The process is open anyone that might care, but especially for manufacturers, cinematographers, studios, service providers, etc., with the work being done in the ISDCF meetings,” said Pierce. “We’ll reserve meetings with NATO for high level planning only.”

The DCPL has gathered a lot of support and has defined the test procedures. Now the committee is at the point where its members are measuring existing, in-theater systems (DCPL-S, for 2D and 3D) and going forward, contrast ratio measurements will be made (sequential, DC contrast) to better understand and define topics like 1)  “Theater Black” and 2) What do the pictures look like? (aligned with the original creative intent). From there the test procedures will be adjusted, and content gathered for DCPL-H (for more advanced, state-of-the-art projectors in theaters).

How are DCPL experts making the measurements? “We use detectors on tripods, connected to laptops – like CR120, but others can work – to measure the room and record its specs. We load a set of DCPs with test content (in order), create playlists and fill in the measurements on spreadsheets,” said Pierce. And to date we’ve found that center brightness is not a great indicator of picture brightness, as gain screens add significant variability. People seem to “like” the image when the AVERAGE brightness is above 10 ft-L, but I admit we need to do more subjective testing of images,” said Pierce. On the plus side, ‘theater black’ is better than expected, with many achieving under 2 mNits, and projector black is very important, with anything above 40 mNits being objectionable.