SAN JOSE, CALIF.—At CES 2019, 8K television sets were all the rage. Every TV manufacturer showcased the pristine video quality that is associated with 8K viewing. But was it premature? Is the industry ready for 8K? This article will examine the primary differences between 4K and 8K, 8K video delivery challenges and the future outlook for the next-generation of video resolution.
THE DIFFERENCE BETWEEN 8K AND 4K
Many consumers—and even people entrenched in the media and entertainment industry—don’t truly understand the difference between 4K and 8K, beyond the latter providing better video quality. The number of pixels is a key area of differentiation, with the total pixel count for 4K resolution specified as 3820x2160 and 8K as 7640x4320 by ITUR (Table 1). The frame rate between 8K and 4K also varies. 8K requires up to 120 fps, and 4K only half the number of frames per second. The number of pixels and frames per second specified by 8K means that it requires a significant amount more bandwidth to deliver compared with 4K (100 Mbps vs. 25 Mbps).
From a deployment angle, 4K services are clearly winning the race. They’ve been successfully deployed for both VOD and live applications. On the 8K side, NHK is the only entity that has developed a complete ARIB (Association of Radio Industries and Businesses) specification for 8K distribution and has deployed it in Japan on a satellite distribution system, and we have seen some VOD announcements recently, such as Rakuten TV in Spain.
KEY CHALLENGES WITH DELIVERING 8K
One of the challenges of 8K is that it’s starting to reach the limit of what the eyes can optimally see. For a 2-3 m (6-10 feet) viewing distance, UHD-1 seems to be the ideal resolution on 85-inch screens, while UHD-2 can bring some visual differences at 1.5 m viewing distance on an 85-inch TV (Fig. 1). So the applicability of 8K is questionable.
At CES 2019, TV manufacturers were pitching either 8K displays being used to upscale HD or UHD signals, or to deliver video at a lower resolution, while the rest of the screen is populated by non-video items like decoration and social media. That’s because there’s a lack of 8K content right now.
On the distribution side, NHK faced some serious pain points when figuring out how to transmit a UHD-2 signal using HEVC Main 10 codec at a mere 100 Mbps. Delivering 8K requires a very high bitrate, making the ROI questionable. MPEG is defining its new codec called “VVC” (Versatile Video Codec) that will offer a 50 percent improvement in HEVC bandwidth by 2020. This will enable live UHD-2 encoded content to be delivered at less than 50 Mbps by the 2020-2022 timeframe.
Another limitation of 8K is price. The new Samsung 8K 85-inch TV is available for a mere $15,000. Even if the price is divided by four in the coming years, at $4,000, this is a niche market. Strategy Analytics predicts that by 2023 only 3 percent of TVs will be 8K capable.
THE INDUSTRY WEIGHS IN
The Ultra HD Forum and the UHD Alliance are two industry bodies that were created to help accelerate the delivery of current and future video resolutions. So far, neither group has commented publicly about 8K but they may take a position during the 2019 NAB Show in Las Vegas.
Additionally, DVB has launched a study mission on “Beyond 4K,” and Harmonic will actively participate. The recommendations are expected to be made available to DVB members around the time of the 2019 IBC Show in September. That will definitely be a development to keep an eye on, as this is the only cross industry group that will provide a report on 8K.
THE TOKYO OLYMPICS EFFECT
The Tokyo Olympics will be covered in 8K by NHK, giving the industry access to a broad library of 8K content that will be broadcast live in Japan. In the rest of the world, besides internet streaming, there will not be an infrastructure to support 8K live. We can expect to see, similar to BBC streaming UHD-1 over the internet during the FIFA 2018 World Cup, 8K internet streaming of the Tokyo Olympics. To watch, consumers need to be connected to a very high-speed network (i.e., fiber or DOCSIS 3.x) to enjoy the 8K experience.
Is 8K a viable business model today? Until a few issues are resolved, such as lack of available content, a more bandwidth- efficient codec and a lower price point for displays, mass deployment of 8K is some ways off.
Harmonic’s standpoint on 8K is that the video clarity of 8K is amazing and we will continue to test 8K but do not think the industry is ready to start transmitting it. Harmonic started shooting content in 8K in 2018 to compare the difference between 8K capture with 4K downconversion vs. 4K capture. We found that the resolution on a 4K screen is much higher and the colors are much more vivid. This can be easily explained by the Nyquist Theorem that says the resolution perceived depends on the sampling rate of the content.
At 8K, Harmonic has sampled 4K video at four times higher than a 4K capture. In this case, there is clearly going to be some difference. For sports applications, we have captured content in 8K with a pan and scan done not only at the production side, but also using tiling technologies at the 4K decode side. For this scenario, we used imaging point and zoom on the player or action, allowing viewers to follow outside of the main broadcast. Harmonic will demonstrate these innovative applications at Booth SU810 at the 2019 NAB Show.
Going forward, we hope the industry continues to invest in 8K production. Another important step is getting TV manufacturers to lower the price of 8K TV sets and also work on the right specification, as we still remember TV manufacturers introduced $60,000 4K 85-inch TV sets in 2013 that could only process 8 bits of color at 30 frames per second! To summarize, 8K isn’t ready for prime time just yet, but some exciting advancements are being made by Harmonic and other key ecosystem partners. Stay tuned in the years to come.
Thierry Fautier is vice president of video strategy at Harmonic.