Notwithstanding the disruptive intrusion of high dynamic range (HDR) technology into distributors’ preparations for Ultra HD services, the next-generation TV picture is starting to gain some much-needed coherency, thanks to progress in standards development on a number of fronts.
Two key developments in this vein are finalization of UHD standards by the Blu-ray Disc Association and release of an updated set of recommendations for protecting high-value UHD content from Motion Picture Laboratories (MovieLabs), the research and development joint venture founded by leading Hollywood studios. Adding to the momentum is the UHD Alliance, a consortium announced at the 2015 Consumer Electronics Show that brings together several key ecosystem players, including DirecTV, Dolby, LG Electronics, Netflix, Panasonic, Sharp, Sony Visual Products, Technicolor, Disney, Fox and Warner Bros.
HDR, which combines greater luminosity, deeper contrast and a broader color gamut to dramatically enhance the TV viewing experience, has added another set of elements to the Rubric’s Cube of issues that must be resolved by MVPDs (multichannel video programming distributors) as they evaluate how best to implement UHD services. In fact, HDR, which isn’t dependent on 4K-level resolution, offers such a powerful improvement in picture quality, many experts believe HDR should be used to enhance HD as well as UHD programming.
Thomas Wrede, vice president of reception systems at satellite distributor SES, echoed the point and went a step farther at his company’s UHD conference in London last month. “I think that this introduction is too big a topic to be just linked to Ultra HD,” Wrede said, according to press accounts. “So maybe we need to decouple the launch of Ultra HD, initially at least, from HDR, also because HDR is very relevant for HD as well.”
But it’s the impact on UHD that is the priority in industry-wide efforts to exploit the benefits of HDR. Some cable operators, for example, rather than decoupling HDR and UHD, are wondering whether they should shift focus from just getting UHD off the ground to making sure they can leverage HDR to bring a truly differentiated viewing experience to subscribers.
“We’re seeing a split developing among our customers between those who want to focus on UHD and those who believe the better approach is to figure out how to get HDR into their UHD services,” says an executive whose firm provides support for next-gen MVPD services. Speaking on background, he adds, “So we’re making sure we have both those bases covered.”
New Content Momentum
There’s a lot to cover when it comes to setting all the formatting, encoding and other workflow parameters for distributing HDR-enhanced UHD content. But MVPDs must be prepared, given the momentum among content owners and manufacturers toward resolving key issues that will contribute to making HDR UHD content available, possibly by year’s end and certainly at a rapidly escalating pace in 2016.
In a recent interview with consultant Benjamin Schwartz posted on the CTOi Consulting website, Thierry Fautier, vice president of video strategy for Harmonic Inc., stressed the challenges distributors face in arriving at an end-to-end template for delivering UHD services. But, he added, there’s no getting around the fact that consumers will have access to HDR UHD content.
“[T]he technologies are being set up and should be ready in 2016 to make live large-scale interoperability testing during the Rio Olympics and also have the first services to OTT or on Blu-ray Disc that supports the HDR and WCG (Wide Color Gamut),” Fautier said.
Netflix, for example, has publicly committed to begin streaming HDR-caliber content this year, starting with its Marco Polo original series. Netflix has been deeply involved with Dolby as that firm has developed backing for its high-end HDR technology known as Dolby Vision, but Netflix executives have indicated the OTT distributor will also be able to support HDR UHD in formats more suited to early rollout, now targeted for at least nine other series besides Marco Polo.
Speaking on an HDR panel at CES, Scott Mirer, who oversees the device partner ecosystem at Netflix, underscored the advantage OTT providers have over traditional distributors. “HDR is something that can move at Internet speed and not the speed of typical TV standards,” Mirer said. “I don’t think there is any holding this back.”
Things are moving rapidly on the studio front as well, said JoDee Freck, senior vice president for mastering and technical services at Lionsgate Entertainment. Freck predicted studios will bring HDR into the re-mastering process as they prepare their high-end catalogs for UHD.
And there’s great interest in being able to bring HDR into the initial creative process, Freck added. Noting responses from directors and cinematographers to viewings of HDR content, she said, “They are all excited. They want dailies on site to see what they’re shooting so, down the line, their vision will be easier to attain in different color spaces, as well as the blacks.”
Warner Bros. has already formatted three of its movies, Into the Storm, Edge of Tomorrow and The Lego Movie, for viewing onDolby Vision displays with more on the way. Twentieth Century Fox has announced an exclusive deal to make some of its movies available for viewing on displays using Samsung’s Open HDR. The studio showed clips of Life of Pi and Exodus: Gods and Kings in a joint demo with Samsung at CES.
Perhaps the biggest early driver to availability of content will be a new generation of
UHD Blu-ray players, which the Blu-ray Disc Association has announced will be in stores by the 2015 holiday season. With agreement on Blu-ray UHD standards, which include specifications for HDR, and the firming up of MovieLabs’ specs for protecting newly released movies, owners of UHD TV sets can look forward to having a better viewing experience then they’ve had so far with Blu-ray HD content, which most UHD sets automatically upscale to higher resolution, and with the trickle of UHD content now available from a handful of OTT and MVPD suppliers.
Buyers of UHD TV sets equipped to support one of the HDR formats will be able to experience the full impact of HDR with any Blu-ray UHD content that has been formatted for HDR. Owners of UHD sets without HDR capabilities who buy the new Blu-ray players will get the full 4K resolution benefits that come with having access to such content.
The Standardization Impact
The availability of UHD Blu-ray players and content formatted to the new standard should help set a benchmark for consumer expectations, which MVPDs can target as they work out the encoding bitrates and bandwidth allocations they’ll need to deliver a competitive next-gen TV service. Similarly, with MovieLabs’ latest release, operators now have a clearer idea of what the protection requirements will be for high-value motion picture content.
MovieLabs, whose founding members are Disney, Paramount, Twentieth Century Fox, Sony Pictures, Universal and Warner Bros., has updated the content protection recommendations it issued in 2013 without major changes. Based on “extensive interactions with industry partners and organizations that are working to adopt requirements in the Enhanced Content Protection Specification,” MovieLabs said it was publishing version 1.1 of the specs “primarily to clarify the intent of the original requirements.” Accordingly, content protection vendors are now in the market with forensic watermarking systems which distributors can deploy with assurance this hurdle to obtaining licensing rights to recently released movies has been cleared.
Many other UHD standardization issues are underway around the world, all of which factor HDR into the equation. These include the ITU’s pursuit of a global UHD standard; the U.S. broadcast industry’s development of ATSC (Advanced Television Systems Committee) 3.0; Europe’s enhancement of the DVB (Digital Video Broadcasting) standard for over-the-air distribution of UHD content; development of HDR production standards by SMPTE (the Society of Motion Picture and Television Engineers); work on a new HDR syntax for the encoding standards developed by the ISO’s Moving Picture Experts Group (MPEG); the end-to-end UHD agenda of the Harmonic-led Ultra HD Forum, and the efforts of the new UHD Alliance.
The Two-Track Approach to HDR
Amid all these efforts HDR has taken on a more practical dimension for consideration as a near-term enhancement to UHD, in contrast to how HDR was initially positioned by proponents like Dolby and Philips. For example, MovieLabs’ 2013 Specifications for Next-Generation Video established HDR contrast and color ranges in line with high-end approaches that set a bar too high for current LED (light-emitting diode) LCD (liquid crystal display) technology to meet. Since then, as evidenced at CES 2015, another tier of HDR proposals has emerged with broad support for parameters in line with what’s doable without waiting for a new generation of chipsets and displays.
At CES, most of the major brands had HDR-enabled UHD sets on display touting labels such as Wide Color LED from LG Electronics, Dynamic Range Remaster from Panasonic, X-tended Dynamic Range from Sony and SUHD from Samsung. These systems typically support a dynamic contrast range from close to absolute black to about 1,000 candela per square meter or “nits,” which is to say, the equivalence of the luminosity generated by 1,000 candles in a space roughly equal to a large TV screen.
This compares to the current standardized contrast range of just100 nits, which reflects the limitations of the cathode ray tubes that prevailed when that standard, known as ITU REC 709, was set 20 years ago. But 1,000 nits is far below the peak 4,000-nit luminance Dolby has set for the first phase of Dolby Vision, which was on display at CES via prototype systems from Toshiba, Hisense, Philips and Vizio. Ultimately, Dolby wants the Dolby Vision dynamic range to go all the way to 10,000 nits, which is the luminance peak set by the MovieLabs specifications and reflects what Dolby found in focus group studies to be about the limit of what viewers are comfortable with.
But even at the lower luminance peak, Dolby Vision requires a new type of display system that uses individually modulated LED semiconductors, which can be switched across multiple steps of luminance from 0 nits to the chosen peak level of brightness. In contrast, the current generation of LCD displays, particularly those with better local back-lit contrast controls, can be repurposed with firmware upgrades of current-generation SoCs at the factory to support HDR platforms operating in the 1,000-nit range.
One thing providing a big boost to the ability of LED LCD’s to support high contrast ratios is a technology known as “quantum dots,” which has been widely embraced by manufacturers as an alternative to much costlier OLED (Organic LED) displays. Rather than relying on the usual filtering process to generate multiple colors from LED backlit displays, which wastes a lot of light energy, manufacturers employ semiconductor nanocrystal technology – the quantum dots – to emit light at very specific wavelengths as they are stimulated from unfiltered blue-light LEDs. With its adoption of the high-contrast quantum dot technology, Samsung last year went so far as to say it was abandoning production of OLEDs.
Besides enhanced contrast range, the other big point of debate in HDR standardization is how far the color gamut should be extended beyond the 16.78 million colors supported by REC 709. The ITU’s REC 2020, used in the new Blu-ray UHD standard and the MovieLabs specifications, encompasses 1.07 billion colors with 10-bit encoding and 68.7 billion colors with 12-bit encoding.
But many proponents believe a more reasonable target to shoot for is the color gamut devised by SMPTE several years ago with the DCI P3 standard, which is the color range that cinema projectors are pegged to and which, therefore, is the color range used in the filmmaking postproduction process. With 10-bit encoding DCI P3 encompasses a range of about 750 billion colors.
Fortunately, by virtue of the overlay-approach Dolby and Philips have taken in conveying HDR parameters to display systems, it’s possible to incorporate the higher and lower dynamic ranges and their attendant color gamuts within an all-encompassing set of standards. These high-end systems deliver a basic REC 709 video stream with a metadata overlay that conveys the additional information for generating the enhanced HDR images on compatible display systems. The two-layer technique allows content formatted to these enhanced HDR specifications to be viewed on non-compatible UHD TV sets as well.
The Blu-ray Disc Association has taken the high-end/low-end HDR approach in setting its new UHD specifications. According to press reports, the new BDA specs, to be released later this year, will support an open HDR standard using 10-bit HEVC encoding and a new transfer function developed by SMPTE known as SMPTE 2084 while making provisions for Dolby Vision and the Philips plan as enhancement options that can be layered onto the basic platform using 12-bit encoding.
The Transfer Function Hurdle
The UHD Alliance appears on track to follow this course, where, at the lower tier, a single open HDR standard will be chosen setting parameters for a “premium” HDR option. In fact, the impetus behind the formation of the alliance was Samsung, which has made its version of HDR license free.
But there may be a significant difference between the approaches taken by the BDA and the UHD Alliance with regard to transfer functions, which have to do with mapping the grey scale signal strength of the display system to the color gamut and dynamic range of the postproduction master. Presently two approaches are under consideration: an enhancement to the traditional gamma function, also known as the Opto-Electric Transfer Function (OETF), used with REC 709 video or the aforementioned SMPTE 2084, also known as Electro-Optical Transfer Function (EOTF), which is designed to support operations in the REC 2020 domain at the highest dynamic ranges under consideration for HDR.
While enhanced OETF is meant to support HDR systems operating in the 1,000-nit range, SMPTE 2084 greatly adds to the flexibility of those systems as well as higher-range systems to support optimal HDR parameters. At the same time, SMPTE 2084, also embraced by MovieLabs, will require new cameras that can support the necessary changes in how light is encoded, which will add costs.
Unlike the Blu-ray UHD standard, there may be a dividing line in whatever emerges from the UHD Alliance between a baseline and a “premium” version of HDR based on the levels of HDR performance that can rely on the enhanced gamma function versus performance levels that require use of SMPTE 2084. This would greatly assist distributors who want to get rolling with HDR-enhanced UHD sooner than later by ensuring bitrates can be mapped to the baseline HDR requirements without having to accommodate the requirements of SMPTE 2084.
There’s no getting around the fact that the emergence of HDR as a near-term influence on consumer expectations complicates MVPDs’ preparations for UHD services. But by paying close attention to ongoing developments in the standards-setting processes they at least should be able to incorporate HDR into their UHD planning with some degree of assurance as to where the industry is headed.