The final panel of the day before the social part of the event covered UltraHD.
Julien Libouban is from Orange where he works on audiovisual quality, but he was speaking as part of the 4ever consortium. Stefan Heimbecher is CTO from Sky Deutschland and he is looking hard at UltraHD. Andres Roman is from Sony where he works on strategic planning for home entertainment and he said almost every division of Sony (apart from financial services!) is working on 4K. Ralf Schaefer is from the Fraunhofer HHI where he looks after video technologies with 90 researchers. Jeff Yurek works on promotion for Nanosys, a maker of quantum dots. Kirk Barker is from Technicolor where he is VP of software strategy. He said that 80% of TVs have Technicolor technology and after the acquisition of Cisco’s STB business, it is now the second largest maker of STBs.
The first question was about whether “just pixels is enough”. Libouban said that 4ever did a lot of tests on resolution first at 1.5H (optimal for HD). The group asked viewers to rate the differences between resolutions on a scale of here is a small difference between HD and UHD, just 10 points, while the same test between SD and HD was rated by viewers 30 points. That means that UHD cannot make enough difference on it’s own to persuade consumers to upgrade. For HFR, testing showed there was a gap of around 20 points. However, when frame rates were tested, there was not much difference between true HFR and motion-compensated HFR with the set doing the conversion. The group also checked HDR content, with grades at 100, 300, 1500 cd/m² and above. There was a big gap in performance ratings for lower brightnesses, but at high peak luminance there was a lot of discomfort. The peak of comfort and quality seems to be at around 1,500 cd/m². Above that level, ratings dropped off.
Heimbecher said that Sky’s tests were more pragmatic, but came to many of the same conclusions. The firm also looked hard at live production techniques for HDR and UltraHD. Sky also found that there was not such a big step up for resolution alone. Early on, Heimbecher said he was dubious about the value of HDR in sports, but after the world cup in Brazil, there was a clear question about sunshine and shadow in soccer. After tests, he said, Sky found “it’s not just the nits”, it’s about contrast, but there is an optimum level of brightness. As he joked, the industry knows that getting people to wear sunglasses would be a failure! He said that the Dolby PQ approach is good for Blu-ray and movies, but not so good for live TV where a BBC or NHK approach may be more appropriate. (We believe this is because the real benefit of the dynamic metadata of the Dolby system that is created during ‘grading’ is not possible during live events. Static metadata is possible, but is less powerful. – Man Ed.)
Paul Gray asked when standards would be available. Barker said that the UltraHD Alliance has done something for content creation. MPEG is looking at standards, but there needs to be more time because of testing requirements. There are multiple proposals on the table, including Dolby, Technicolor and others. Barker said that an average brightness of 3000 cd/m² is no good, as 4ever found, but a very small peak of that brightness may be a good effect. Yurek said that if Hollywood was in charge, it would probably still be using film – it is very conservative about new technologies.
Schaefer said that he is bored with the topic, because he looked at WCG and HDR twenty years ago! He said, in reality, there are very few objects in the real world that are outside the Rec 709 triangle. He said that looking at HDR for codecs, most of the EOTFs are similar and much of the standards battle is about politics!
Roman said that to sell products, you have to have content. 4K sales started a couple of years ago and Sony started with WCG ten years ago, but there is little content. It is working with 4ever to help with technology. Sony wants to avoid legacy issues and can cope with all the EOTFs. For now Sony mainly wants to avoid problems of misleading consumers. He said that Sony is supporting the CEA standard, and if broadcasters use that standard, then it’s sets will be compatible.
In response to a question, Heimbecher said that it used a Sony camera with Slog3 (a Sony EOTF) and a converter box to try different EOTFs. He also said that Sky created a complete end-to-end chain from capture through transmission to display. It made a comparison between PQ and a hybrid log gamma and found that for SD sets, the modified gamma is better than PQ. The German TV platform will have a plugfest before the end of the year to check different HDR implementations.
Barker said that there is a lot of discussion about the need for backward compatibility (Technicolor is backward compatible).
Schaefer said that scalable solutions are often a problem for compatibility, so he is not optimistic.
Replying to a question about efficiency, Yurek pointed to the HK effect as helping apparent brightness even if the display is not so bright. He also said that even though the real world may not have extreme colours outside Rec 709, as Schäfer had said, the recent movie “Inside Out” used colours that are right at the edge of 2020 and are used for creative effect. Once colours are there, they will be used.
Barker said that you have to learn how to use the WCG and HDR with real meaning. It will take a few years for content creators to really understand how HFR, HDR and WCG can be used in combination for creative effects.
Gray asked “What about the consumer?”. Roman said that you have to start with content and then you have to be compatible. Heimbecher said there is no one consumer, there is a wide range of different consumers.
Heimbecher said that the live feed is 8.3 gigabits of data when you go from FullHD to UltraHD, from progressive to interlaced and from 8 bit to 10 bit. Although broadcasters can deal with that, it will take time.
