October 2013

SMPTE Newswatch Masthead

Hot Button Discussion

The UHDTV Paradigm

By Michael Goldman 

 

Headed to IBC 2013, where Ultra High Definition Television (UHDTV) was to be a prominent topic, David Wood, Chairman of the International Telecommunications Union (ITU) working party 6C, the group responsible for making international recommendations associated with UHDTV, was eager to discuss the latest on UHDTV. UHDTV has clearly soared from being a buzzword and interesting technological experiment to a format that will have major implications for broadcasters, filmmakers, and consumers in the coming years.
 
The ITU agreed about a year ago on what Wood calls "the starting point"--a technical framework that "sets the stage for UHDTV to become a practical reality." That framework, ITU-R Recommendation BT.2020 proposes main parameter values for two stages or levels of UHDTV that will eventually be the successors to high-definition television.
 
While that development has "set the stage," there are numerous issues to address before the practical reality of UHDTV in the studio and home arrives, Wood says. The first is that UHDTV has two different, though related, quality tracks and, for now, is not just a single system.
 
The first track will be relevant in the near future, making it feasible for hardware manufacturers to make UHDTV televisions that consumers can use both to improve their current high-definition viewing experience, and for eventually viewing content with four times the resolution of 1080p material. That track, referred to as UHD-1, is also called Ultra HD in the U.S. by the Consumer Electronics Association (CEA). Wood describes UHD-1 as "the equivalent of four progressively scanned HD pictures stitched together. We use 1080p HD as the building block for UHDTV."
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The second track or quality level is called UHD-2, or Super High Vision in Japan. Wood describes UHD-2 as "not 4 HD pictures, but 16 1080p pictures stitched together--sometimes it's called an 8K system." "Four times and 16 times are not chance numbers," he adds. The actual value of increasing the definition that you see in the picture is proportional to the square root of the increase in the number of pixels. So you need a square law as you jump equal quality levels. The first step, HD to UHD-1, is roughly the same as the quality step when we went from SD to HD, though it is not quite as simple as that statement suggests. Then, we go from UHD-1 to UHD-2 with the same size step. But, again, it's a bit more complex, because the quality steps we see depend on other parameter values, as well."
 
Arguably, television manufacturers who want to sell higher resolution televisions to consumers as soon as possible, rather than wait until processing equipment and displays are sufficiently equipped to handle UHD-2 images are driving UHD-1 today. That could take until about 2020 to happen, Wood estimates. He points out that Japan Broadcasting Corp. (NHK) is currently planning to make the 2020 Tokyo Olympics a watershed moment for the broadcast of 8K UHD-2 images. So, one question facing broadcasters is "when is the best time to start something like this--now, or wait 'X' years time until you have the next-step technology?"  
 
The debate also remains regarding the technical characteristics involved with practically implementing UHDTV; first is the issue of frame or picture rates. Wood reports that BT.2020 includes the current cinematic frame rate of 24 fps up to 120 fps. This debate is important, because it impacts UHDTV's great potential over HD, for particular kinds of programming. Specifically, Wood says he believes that live sporting events could be the primary programming used to illustrate "the true punch that UHDTV can pack."   
 
"For programs with lots of movement across the image, to get moving people and objects sharp, higher frame rates really help," Wood explains. "Movie-makers avoid this issue by tracking cameras and avoiding pans, and with great knowledge of what will make an image judder or blur in a scene. Panning is a stable diet in American football and other games, so, for the sake of that kind of material, the ITU included higher frame rates. Now, we are having a discussion about whether they are, or will be, practical. The integrated circuits that would go into a UHDTV television, having the speed and storage capacity to cope with those higher frame rates, are something that may take a while to become practical."
 
Wood adds that UHDTV also brings with it the question of whether "to use or not use fractional frame rates [60/1.001 or 120/1.001, for instance], in addition to integer frame rates, because of the NTSC frame-rate legacy. Also, for the parts of the world where 50Hz is the electricity supply frequency, when discussing higher frame rates, the issue is whether 100 fps should be added to the BT.202 120 fps that are already part of the recommendation." 
 
Wood hopes that, eventually, scalable systems will handle all frame rates. For the time being, however, much of the broadcasting world believes that, because of available decoder chip capabilities, the starting point will end up being 50 or 60 fps. Wood elaborates one major concern: "will UHDTV at that quality level be sufficiently attractive to consumers to induce them to buy the new televisions in great numbers?"
 
The other major technical debate deals with the issue of colorimetry for UHDTV and whether UHDTV television broadcasts should be, as Wood suggests, "forward-looking enough for tomorrow's displays." In this area, he says the industry is debating whether today's HDTV BT.709 color primary system, the richer BT.2020 system that goes beyond BT.709, or cinema's XYZ color methodology would be best.
 
"There is a pull from Hollywood to use the XYZ system, where any primaries, however, wide, can be used, and there is a pull from television manufacturers to use technology easily available today in HDTV, BT.709," Wood says. "The ITU suggested what could be seen as a middle ground of using the BT.2020 primaries, which are just beyond OLED displays, but not as far out there as XYZ. There are different schools of thought playing out on that."
Wood adds that there are also inter-related issues of bit depth, and the Opto Electronic Transfer Function [OETF, or what used to be called the gamma curve] to resolve. "Having a high dynamic range will lend the picture 'sparkle,' and a new OETF could carry us more easily into an age of very high screen brightness, but that would come with a price of additional complexity in the TV set," he points out.
 
There is also the issue of upgrading broadcast facilities to record, process, and move UHDTV signals around their plants. Wood expects major broadcast entities will have the capability to produce and process UHD-1 up to 60 fps in the next two to three years. A few years after that, he anticipates 120 fps to be practical with the arrival of IP/fiber-optic wired studios.
 
"That's in keeping with the timetable being proposed by the Digital Video Broadcast (DVB) project for broadcasting UHDTV. The DVB system is in use in much of the world, but for the U.S., Korea, Mexico, Canada, and Japan, the ATSC would have to decide on its own timetable," Wood adds. Broadcasting UHDTV will likely involve the new MPEG-HEVC/H.265 compression technology--a scheme, as discussed in the April 2013 SMPTE Newswatch, which is about twice as efficient as the previous MPEG-AVC/H.264 scheme.
 
Other issues include the fact that more advanced HDMI connectors are needed to allow consumer UHDTV screens to take in the bit rates UHDTV requires. That progression is well in hand, with a new HDMI generation. HDMI 2.0 was announced recently by the HDMI Forum; it is capable of carrying UHD-1 video at 60 fps.
 
Meanwhile, the industry is waiting for news from the Blu-Ray Disc Association about UHD-1 Blu-Ray packaged media--many expect an announcement on this in 2014. A consortium of Hollywood studios called Movielabs is also currently discussing recommendations in terms of UHD-1 requirements for feature film delivery.
 
This points to the fundamental issue of supplying sufficient content to make people want to own UHDTV televisions to begin with. Live sports could eventually become a primary driver for UHDTV, Wood says. Beyond that, some UHDTV content is already available in the form of feature films from major Hollywood studios--content that could anchor Pay TV channels. For now, he insists the first UHD-1 televisions will potentially improve the existing HD viewing experience considerably.
 
Webcasting of UHDTV content will have to pass through the world's consumer broadband infrastructure and the way that content data is currently distributed over IP networks, which allows high bit rates to clog broadband pipes. Wood believes this issue will eventually be resolved with more content delivery networks (CDNs) and cloud delivery, as well as the ongoing drive to integrate web viewing and traditional broadcasting.
 
In terms of the home viewing experience, the challenge of UHDTV is compounded by the need for correspondingly better audio to get the full experience. So-called 3D audio will eventually be the choice because UHDTV televisions will continue to grow in size, and therefore, "you will get a better experience when you can tell the direction that the audio is coming from, both laterally and vertically. To do that, you need more than today's single layered 5.1 systems," Wood says. "There are competing schools of thought on this issue," he adds. "Korea, for example, is proposing a 10.2 discreet channel system that essentially involves two layers of speakers to provide the impression of the height of the sound, as well as where it is laterally. NHK has developed a 22.2 multichannel surround system, with three layers of speakers in your living room. Others in the ITU-R think those systems will not be practical for consumers. Most homes don't even have a correct 5.1 system set up, so what are the odds they will be able to set up a 10.2 or a 22.2 system? 
 
"This school of thought suggests that, instead, we need a system that adapts itself to the speaker layout of your particular room, whatever it might be. That would be more possible with what is termed 'an object-based' system. Here, the television would know where your speakers are located, and decide what sounds to send to each speaker. Such broadcast systems transmit both the sound and position in space of specific objects. The same principle is used in immersive cinema systems, such as Dolby's ATMOS System. The guys in the ISO/IEC/ITU-T MPEG standards group are analyzing options for advanced audio, and we hope they will agree on a single system. I suspect it will be one that does both channel-based and object-based audio. It's quite likely that SMPTE will also have an activity for advanced audio, so we are keeping our fingers crossed that we don't end up with conflicting systems," Wood says.
 
In any case, all of these issues naturally bring up the question if all this really necessary. Is the pursuit of UHDTV destined to take over the way content is viewed in the home in the future, or is it destined for niche territory as 3D home-viewing systems have thus far turned out to be? 
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Wood calls this "the 64-dollar question" and points to psychophysics studies that have suggested that one of the problems with viewing 3D content in the home is that it requires more mental energy on the part of the viewer than watching 2D, and is therefore less likely to succeed than distraction-free viewing in a cinema. Click here for one of the studies industry experts have made about image quality and viewing time. Wood suggests the industry is pursuing the UHDTV agenda partly because it believes that, if UHDTV can eventually be made feasible, consumers will end up watching shows longer, and paying more attention to their content. That means more and better opportunities to reach those consumers with advertising and marketing messages.
 
"With 3D, you have to perform complex brain functions that can sometimes be mentally exhausting," Wood states. "So UHDTV has the potential to be more successful in the home than 3D and to give the viewer a greater sense of involvement in what he or she is watching. Whether Joe Sixpack will be sufficiently impressed remains to be seen. But if Joe Sixpack typically gets a larger TV everytime he gets a new one, then that increases the incentive for him to want to get UHDTV."
 
For more on the latest issues and developments surrounding UHDTV, check out the recent SMPTE UHDTV Ecosystem Study Group Report.
 
News Briefs
HEVC at IBC 2013
Next to UHDTV, the ongoing maturation of the High Efficiency Video Codec (HEVC/H.265) was another big theme at IBC2013. A recent report in Broadcast Engineering states HEVC was widely showcased at IBC 2013, by various manufacturers in "a full range of potential use cases" and demos of all shapes and sizes. The report states there were at least 12 vendors featuring HEVC encoders or decoders. Some demonstrated technology designed to deliver high-end content to mobile devices. Others showed that in today's hybrid broadcasting world, even standard-definition content at low bit rates on mobile devices looked superior to the pre-HEVC era. The codec, as noted above, was demonstrably helpful in the delivery of beautiful UHDTV signals to gigantic displays, and everything in between those two extremes. Demonstrations also included online encoding using HEVC and MPEG-DASH, adaptive bit rate streaming (ABRS), various kinds of new HEVC-powered media players, and much more. The article noted that HEVC is clearly accelerating the drive toward software-based, rather than hardware-based, encoding. 
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Restored... to IMAX
September marked the grand re-opening of the famed Chinese Theater in Hollywood--a $5 million dollar remake that has transformed the historic venue into the world's largest IMAX theater, featuring a 90 x 46 ft tall screen that has been winning rave revues around the cinema world since reopening with screenings of a newly minted 3D version of The Wizard of Oz. The theater no longer has a film projection system, but reviewers say it has succeeded in blending old-time movie-house charm and architecture with the latest state-of-the-art digital picture and audio technology. Here's a report on the renovation and a YouTube time-lapse video of the work being done over several months. Also, view a blog posting from a Wizard of Oz scholar, insisting the 3D conversion is not only worthwhile, but also spectacular.
 
Ray Dolby Tributes
The audio and cinema world lost a major pioneering voice recently with the passing of Dr. Ray Dolby at the age of 80. The founder of Dolby laboratories, Dolby revolutionized both the technology and business of sound, including noise reduction and surround sound and the standardization and unification of many schemes and tools. He held 50 patents during his career. His company earned 10 Technical Academy Awards and 13 Technical Emmy Awards. During his lifetime, Dolby received honors from President Bill Clinton and Queen Elizabeth II, among many other notable achievements. Numerous tributes to Dolby are available on the Internet. Here are just a few: A moving tribute from the Dolby Laboratories home page, a lengthy tribute from Audio Pro International, and his obituaries from the Washington Post and the SMPTE Journal.