4K is Only Part of UHD
The acronym UHD has a clear definition: Ultra High Definition. However, its meaning has evolved over the past decade, and it now stands for the next generation of video experience.
UHD is based on six pillars and has led to the development of other enabling technologies.
- 4K: 4K refers to the image resolution and provides clearer, crisper, and more detail-rich pictures than HD.
- WCG: Wide Color Gamut allows for more realistic and vibrant colors.
- HDR: High Dynamic Range provides a greater range contrast, including dynamic HDR.
- NGA: Next-Generation Audio delivers immersive, personalized sound perceived as coming from infinite points.
- HFR: High Frame Rate radically improves motion rendering, starting from 100 fps making for greater realism.
- CAE: Content-Aware Encoding offers the lowest bit rate and best quality for ABR delivery.
The State of UHD Deployment in 2021
The first 4K service was launched in 2013 on YouTube. Back then, delivering video in 4K resolution seemed like technical prowess. But now, deploying 4K video services is much more feasible and so much more common.
Almost 200 Commercial 4K UHD Video Services
One of the best places to track UHD deployments is the UHD Forum service tracker. The tracker shows what's happening in different markets and how they differ.
The UHD Forum defines a UHD service as having at least one 4K resolution or HDR. One thing is clear from the data collected by Forum members: When you filter out services with a maximum resolution below 4K, there are still 188 of 189 services.
Regulation and Government Incentive
Operators in countries like South Korea and Japan have favorable regulations that proactively push the market toward 4K. Governments, in some cases, enable services by investing in technology development, spectrum, and promotion.
On the other side of the spectrum, a French decree forbids SD resolution on broadcast networks, while such resolution is still active in countries like the UK or the US.
How Are Viewers Watching 4K UHD Video?
There is not yet much UHD consumption in the global broadcast market. Only a few real linear channels are available, despite the persistent buzz around UHD channels with 4K resolution content.
On-demand content, however, tells a different story. SVOD stakeholders — whose numbers are growing exponentially — are making relatively little noise about UHD, while 4K UHD and HDR content constitutes a growing chunk of their catalogs.
Netflix and Amazon, the leaders in SVOD, have encouraging statistics. For example, Netflix lists almost 1,000 titles available in 4K resolution. But there’s little clarity on actual usage. Despite the rise in adoption and the consumer interest in 4K UHD video, service delivery seems limited. But why?
Barriers to 4K UHD Video Delivery
Despite the general excitement around 4K UHD, several barriers exist preventing full adoption.
4K UHD Video Delivery Infrastructure and Interoperability
The most apparent hurdle that service providers face is infrastructure. That includes both network elements (processing and capacity) and devices. The other hurdle to overcome is bottlenecks in the network, especially as processing moves closer to the edge and the end-user.
As more networks transition to digital fiber, they can deliver UHD content more efficiently in 4K resolutions. For example, France is one country that is expecting 70% fiber coverage by the end of this year.
Infrastructure for video delivery also includes operator-managed STBs. Ensuring compatibility for UHD video content and connected devices has been a challenge. More traditional operators are, therefore, embracing the "BYOD model." BYOD stands for “bring your own device” and refers here to viewers using their own streaming devices rather than an operator-provided STB. Indeed, most operators now support tablets and a growing number of connected TVs with their TV services.
Getting UHD devices to work together seamlessly is the goal. Industry bodies like the UHD Alliance or CTA are working on this issue. Although the production and distribution issues are mostly solved, we still have progress to make before achieving out-of-the-box UHD solutions in the living room that preserve the creative intent. UHD technologies allow viewers to see a more faithful representation of real life, with more accurate colors and faster refresh rates. But they’re also suitable for filmmakers, who can use them artistically to take the video medium farther.
4K UHD Content Production
The second barrier to delivery is the amount of 4K UHD content available. In the early days of UHD, cost was the main issue in setting up a complete workflow. But today, the added cost has shrunk into something much more manageable.
Dynamic HDR, which I will discuss below, is still creating hurdles for 4K UHD content production.
Business Models for 4K UHD Video Delivery
It is essential to have business models that offer greater monetization and ROI for 4K UHD video delivery. Earlier, the HD version of a VOD title would typically cost 20% to 25% more than the SD version. Most industry pundits were expecting a similar price gap as we transition from HD to UHD. But some players, like Apple, have muddied the waters by offering UHD content at the same price as HD content.
End-to-end infrastructure needs an upgrade to handle UHD, and that cost needs to be covered somewhere in the business model. However, this issue is receding as UHD becomes the standard rather than the premium, at least for VOD.
In parallel, prices for UHD TVs are dropping. Today, $5,000 will get you a very decent 8K TV, whereas the first mid-range 4K TVs back in 2014 cost several times more than that.
Netflix doesn't break out numbers based on UHD and non-UHD titles, but the sheer volume of its UHD/HDR catalog is a business reality. When delivered in UHD/HDR, major events like the world soccer championship or other international sporting events favorably impact UHD TV sales.
Progress for 4K UHD Video Delivery
This section gives a 4K UHD video delivery roadmap for the next few years.
The Viewer Experience
UHD's real value comes from enhanced video quality that offers viewers images that rival real life. Filmmakers can then improve storytelling, and viewers feel deeper and wider emotions.
To get to that level of image quality, content creators are slowly embracing what the technology has to offer. Thanks to HDR, light sources are no longer limited within an image. With higher resolution, camera angles can be wider, especially in sports production. We must also consider a few short-term limitations, such as the need to slow most camera movements to avoid UHD compression artifacts.
The UHD Alliance has created a Filmmaker Mode feature that TV manufacturers can implement to ensure artistic intent doesn’t get lost when users have control over their TV settings. The Ultra HD Forum is similarly working on a broadcaster mode, so the same can be achieved during a live sporting event.
In the short term, there is still the issue of quality-of-experience, stemming from the fact that low-quality HD can look worse on a UHD screen. That’s because the UHD screen is more efficient at showing video artifacts.
HDR offers greater contrast and more vibrant colors, which is part of what makes for a premium UHD experience. It’s part of the UHD Alliance’s Ultra HD Premium spec., which also calls for 2160 resolution for any UHD content
HDR creative intent is still rare despite its wow effect. This new technology is far from mainstream for live content, with only the largest companies investing in it. For many reasons, the user experience was disappointingly inconsistent for major live events, especially sports. The whole creation chain needs retraining. Netflix has been a trailblazer here and provides grading expertise to production companies that need it.
Despite the advancement of standards and guidelines, TV set makers must still interpret HDR metadata. The availability of very low-end TV sets that claim to be HDR can be problematic. Some of these sub-$500 sets can indeed accept HDR streams, but they don't have the processing abilities or the required brightness to exploit it in any meaningful way.
HDR with Dynamic Metadata
Dynamic metadata promises to optimize color and brightness on a scene-by-scene level. This improvement is desirable but has only a marginal effect on high-end TVs with significant processing power and screen brightness. Indeed, these TVs already do a pretty good job here with static metadata.
Dynamic metadata will have a more substantial impact on mid-to-low-range TVs that support it. It also makes content more future-proof.
UHD Video Combined with Next-Gen Audio: Object-Based NGA
Ultra HD defines the next generation of audiovisual experience, of which audio is a central part. Indeed, studies have shown that improving audio can often have the most significant impact on the overall experience. NGA offers a more immersive experience and new personalization opportunities.
Since stereo replaced mono as the base level for audio, we have seen several other major upgrades. Multichannel audio, typically 5.1, has been around for several decades now, and many services include it. Immersive audio adds a vertical axis to the speaker layout, usually on the ceiling.
Next-Generation Audio promises a more personalized experience. It will initially allow viewers to select different audio commentaries or enhance dialog loudness, for example. As more sophisticated features get deployed, NGA will also fully exploit any device's audio capacity, depending on its environment.
Live UHD Streaming
A recent soccer world championship showed it is technically possible to deliver live UHD video streaming over the top (OTT). As the HDR workflow and sitting-room interop issues get resolved, we will see more examples of UHD video streaming emerge in 2021, perhaps for the 2021 European sports championship and the Tokyo Games.
Large-scale operators that manage their own fleet of STBs, or big internet platforms like Amazon Prime that are starting to offer more live content, have enough control over their end-to-end delivery to make live UHD video streaming possible.
Live UHD video streams can be delivered to multiple devices using over-the-top approaches to video delivery. For example, software-based cloud streaming platforms. But, for more traditional broadcast, it’s more complex to deliver different formats for all devices. Live streaming distribution will likely replicate SVOD platform success regarding UHD, although it may take more time to attain a similar reach.
1080p vs. 2160p UHD
In the US, one ATSC 3.0 deployment already uses HDR with only 1080p resolution. The jump from SDR to HDR has a consistent "wow" effect, whatever the content or screen size. However, the leap from 1080p to 2160p only has a wow effect with the right content and screen size.
Here again, markets differ, and Southeast Asian markets have a greater appetite for high resolution than US markets. Europe's demand is less present. The proposed French DTT hybrid approach — to broadcast 1080p HDR in alternation with 2160p HDR content — is an example of this. Thanks to streaming, we can also create 2160p offerings for replay services, while 1080p is delivered OTA to cope with bandwidth limitations.
High Frame Rate (HFR) Explained
Refresh rates of 100fps or above are further down the road. The sheer volume of uncompressed data going through the TV set is too challenging for all but the high-end TVs to handle at the device level. Unlike other UHD features held back by backward compatibility issues, some neat multi-PID HFR solutions avoid this pitfall.
Without going in depth, the idea is to transmit one image in two within one Program Identifier (PID). TV sets that understand HFR can use a second PID with the missing images, while non-HFR-compatible devices simply ignore the second PID. EBU has conducted research that shows 1080p100 has better motion rendering than 2160p50 for sports content.
Consumer Experience Is All That Matters
Today, UHD is making progress, and potential accelerators exist.
Our industry is consumer-driven, and if we meet the challenges of 4K UHD video delivery head-on, we'll gradually see more UHD features fully deployed.
In the short term, TV operators might prefer to improve HD, especially for live content, and turn on only static HDR for entry-level UHD services.
One risk I see is that we might take too long to fix the remaining UHD interop issues to keep market momentum. However, the long-term commitment of operators like NHK to very high resolutions helps keep me optimistic.