With 4K UHD only just turning the corner and with much of the world still in SD is 8K a distraction from the rollout progress of 4K or just natural technological progress? The Broadcast Bridge takes stock of the current fuss around 8K which, like it or not, will be a major talking point at IBC2019.
https://www.thebroadcastbridge.com/content/entry/13757/8k-tv-the-shape-of-things-to-come?cat_id=1
It was only seven years ago that NHK conducted its first 8K trials with the BBC during the 2012 Olympic Games, but that outlandish experiment has come home to roost. 8K broadcasts across Tokyo next year are unlikely to kick-start wider transmission outside Japan but will catalyse interest and propel the industry to look ahead to Paris 2024 by which time a commercially viable 8K media ecosystem will be fairly widespread.
Today, the two most commonly cited areas for 8K usage for the consumer are higher resolution displays (four times that of 4K, or 16 times that of HD) or 360-degree video immersion, including virtual reality (VR), augmented reality (AR) and related mixed reality. In this case, the higher resolution is spread across more than the direct window of view, filling the indirect viewing areas to give the effect of complete immersion.
On the content creation side, another area for 8K use is higher resolution capture for both archiving and enabling higher resolution zoom or similar video effects for 4K or HD delivery. And lastly, the consumer electronics industry is already pushing 8K televisions because technology has enabled it to do so, independent of whether or not the content creation or production of 8K is practical or economically viable.
For major special events, 8K does have a high value potential, concedes Matthew Goldman, SVP Technology, MediaKind though it is unlikely to reach beyond this niche in TV distribution within the next five years.
“It’s still quite expensive for Hollywood to produce feature length motion pictures in 4K, never mind 8K,” he says. “Bandwidth is still a premium for most distribution methods to consumers today, save the lucky few that have upwards of 100 Mbps or more broadband access or soon to be deployed 5G wireless technology.”
But it’s not just about the availability of 8K content that’s a serious issue. To truly appreciate the potential of 8K, some argue that you need an enormous screen to be able to process the quality and detail of the image in front of you.
That’s why major television manufacturers are shipping 8K TV screens from 88-inches to over 100-inches diagonal.
As Rian Bester, MD at 4K channel Insight TV jokes, “The biggest factor now is not the size of the TV, it is the size of the box that you can fit in the back of your car or through the front door.”
The Viewing Distance Conundrum
The proper viewing distance for the human visual system to resolve 4K resolution is approximately one and a half times the picture height of a 16:9 display. To process 8K content, the distance is halved again; the viewer needs to be within three quarters of a picture height to resolve all of the 8K resolution. Compare this to HD resolution, which can be seen in full from a distance of around three times the picture height.
“In most home viewing environments today, consumers sit between two and a half to three times picture-height back from the display – and there lies a major problem,” Goldman says. “If one is not at the proper viewing distance from a 4K or 8K screen, then even if it’s displaying 4K or 8K content, one may not actually be seeing the 4K or 8K resolution! If there is no real discernable difference in the picture, then this could cause widespread fallout.”
The belief that viewers won’t notice the difference, or need giant TV’s is being contested.
“There is a rather bizarre idea that you need to sit closer to the screen to perceive the benefit,” says William Cooper, founder and CEO at Informitv. “The whole point of increasing resolution is that the pixel structure of the image should be imperceptible. It is a psychovisual effect that results in an image that appears to be more realistic.”
He continues, “The human visual system is very sensitive to certain features. It is called hyperacuity. For instance, we can easily see the jagged edges formed by lines that are slightly off the vertical or horizontal axis. Using anti-aliasing techniques can help smooth them out but has the effect of reducing contrast and softening the image. The alternative is to increase the resolution of the image. That is why high pixel densities displays can appear almost like print. By comparison, the old days of VGA computer graphics, which were considered adequate at the time, look primitive today.”
There is a related trend in cinema currently, led by filmmakers like Ang Lee, who are pushing the boundaries of our visual storytelling by combining high resolution with ultra high frame rates. Lee’s new sci-fi feature Gemini Man is being released at 4K and 120 frames a second in some theatres, in stereo 3D also, to achieve an effect which is commonly described as like looking through a window. Video gaming experiences also favour high frame rates and is more HFR content is seen, it could be that our natural inclination to watching content at 24 frames is revealed as nothing more than a cultural construct.
“Of course, now we have further advanced technologies like tiled screens from Samsung and rollable screens from LG on the horizon,” says Bester. “In the not too distant future we will have screens that are significantly bigger than what we have in our homes now and they will be multi-application devices like our phones. For that reason, I don’t think people should get too hung up on the science of traditional viewing distance and screen size - this is completely changing.”
HDR Lessons To Learn
Another matter of heated debate concerns the introduction of HDR as it relates to the claims for an 8K format resting on resolution alone. While the rollout of 4K UHD content has been relatively slow, the combination of UHD content with High Dynamic Range is universally seen as a breakthrough to immersive viewing.
As broadcasters increase the amount of content in 1080p50/60 HDR, 4K TV displays are now able to upconvert these images to 2160p. If these sets can support HDR, this means we can deliver an experience that gets extremely close to the native 4K HDR viewing experience that consumers have been demanding.
“It would arguably represent the biggest upgrade in the viewing experience since color displaced black and white – without the much higher bandwidth required for native 4K distribution or 8K,” asserts Goldman.
Given the difficulties in getting HDR to market however (there are now seven different HDR formats: PQ10 (PQ; perceptual quantization), HLG10 (HLG; hybrid log-gamma), HDR10, Dolby Vision, Samsung HDR10+, and Technicolor/Philips SL-HDR1 and SL-HDR2) there are lessons for the industry in avoiding replicating such confusion in future formats.
“Given that perceiving the difference between 4K and 8K resolution requires such enormous advances in screen size and greatly reduced viewing difference and given the enormous costs involved for both content creators and aggregators in providing the necessary infrastructure to deliver 8K content, time would be better spent focusing on collaborating and converging around a single (or at least far fewer) long-term HDR format, maturing high-bandwidth delivery mechanisms, and better video compression techniques, regardless of the spatial resolution,” says Goldman. “By greatly reducing bandwidth requirements and offering a richer, more lifelike picture (regardless of the spatial resolution), the industry has far more to gain in the short and medium term.”
The role of organisations like UHD Forum and the 8K Association is important here.
Goldman contends, “What we cannot have is a situation – as with HDR today – where we have many options and both equipment providers and consumers are left risking making bad choices, as content and service providers elect to use different formats due to the complexities involved in various implementations. So, before we can create a viable ecosystem around 8K content creation and distribution, the industry must take a lead by coming to an earlier consensus around an end-to-end 8K proposition.”
There needs to be improvements in production, distribution and consumption. This involves better coding efficiency to reduce the bandwidth required, higher capacity distribution networks at economically viable cost points and the professional and consumer interfaces and infrastructure to support higher bandwidth needs.
For large venue viewing, 8K is a potentially great application and corporate AV applications such as at exhibitions, museums or digital signage are already being primed to receive these high end visuals.
But for broadcast, 8K represents an extremely challenging implementation – particularly for live production.
“The real question will be around cost efficiency – what will return the best user experience for the best economically viable implementation?” says Goldman. “The entire end-to-end ecosystem needs to improve technologically for 8K to become viable at scale.”
This would include, among other things:
Professional interfaces/connectivity and infrastructure at economically viable cost points in production that support the higher bandwidth needs required by uncompressed 8K video (40-50 Gigabytes per second).
Better video coding efficiency to reduce the required distribution bandwidth (likely two to three times that of compressed 4K, which in turn already is two to three times that of HD). Versatile Video Coding, currently winding its way through MPEG and due for release in 2020 is the key here.
Higher capacity distribution networks at economically viable cost points are also needed – such as higher-bandwidth wired and wireless (5G) networks.
“8K is a natural progression from 4K, but we are still in the very early stages of its development,” says Wrede. “Currently display and flat screen manufacturers have taken the lead on development, but some broadcasters would need to implement it for 8K to become dinner table conversation.”
The latest series of SES marketing videos ‘Mastering the Detail’ was filmed in 8K. “Across the industry it has been common for content to be shot in the best quality possible and then down converted in the process of distributing it,” Wrede adds. “For 8K to really work though, the viewer has to be incentivised to look at the detail, and that is easy to do more with certain types of programming, such as sports, live events and nature programmes.”
There will always be technology luddites but Ben Schwarz, speaking as an independent expert, Founder CTOiC and Communications chair of the Ultra HD Forum relays an excellent analogy.
“When cellular networks came of age, developed markets adopted them with difficulty as the incumbents would often perceive them as cannibalistic. Taking the train from London to Paris, even now, is a case in point, with no coverage in many parts. Travelling across South Africa over 10 years ago, I was astounded by the quality of cellular coverage, even in the bush. The lesson is that 8K can leapfrog 4K in the same way that cellular did over DSL.”
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