UHD TV’s biggest challenge is interoperability

By Barry Flynn, Contributing Editor

Yesterday’s Videonet webinar on Ultra HD: What Is It And When Will We See It, sponsored by the UHD Forum, followed close on the heels of European standards body DVB’s confirmation that it had agreed the commercial requirements for the next phase of UHD TV, known as UHD-1 Phase 2 (see previous story). This will incorporate an HD 1080p profile, DVB revealed today.

DVB’s announcement implies that the first services to use the new standard, which will incorporate High Dynamic Range (HDR), could be available from 2017 onwards. (In this context, ‘HDR’ is generally understood to include Wide Colour Gamut (WCG) and 10-bit sample depth, a combination dubbed ‘HDR-Plus’).

DVB added that technical specifications would be included to allow users already using UHD-1 Phase 1 to make use of Phase 2 services, a theme that was expanded on by the panellists attending Tuesday’s webinar.

Skip Pizzi, Senior Director, New Media Technologies at the National Association of Broadcasters (NAB) in the US, singled out interoperability as “perhaps the most challenging [issue] of anything we face right now,” one which he hoped the UHD Forum would help resolve.

Pizzi distinguished three separate issues: the first being how to ensure that today’s HD TV sets, which mostly offer only Standard Dynamic Range (SDR), could accommodate HDR.  â€œHow do you create the content to address both [an HDR] display and an SDR display?” he asked. “Content creators would like to not have to create multiple versions of their content. So ideally, you would have a single channel broadcast that would address legacy SDR sets adequately – and still have the colour-mapping and tone-mapping and contrast to be appropriate and not look washed out or in other ways affected poorly and the producers’ intent changed – as well as have that same stream through one method or another be appropriately displayed on an HDR display.”

The second issue was the existing installed base of UHD-1 Phase 1 TV sets. “How do we make sure that future content that is addressing the next generation of sets that handle HDR, [will] also address those sets as well? So we have both [HD] SDR and early UHD – let’s call them 4k sets – [and we need to] make sure that those are both adequately considered when we put out HDR content that looks optimal on HDR sets.”

The third issue, said Pizzi, was “how do we make sure that we produce in a format that really does allow evolution?”

Pizzi concluded that these were “all elements that standards bodies are grappling with right now. They’re aware of them and are really trying to make sure that we get the most convenient single compatible system that allows producers to use this new toolbox of higher dynamic range and target those new sets that will be coming out – while not orphaning anything that’s already out there and certainly would represent the bulk of the market for some time to come.”

Fellow panellist Matthew Goldman, Senior Vice President Technology, TV Compression, at Ericsson, added that it was important to point out that “when we talk about HDR-Plus with HD or 1080p we’re really mostly focussing on a transmission format in order to save bandwidth in networks that have restricted bandwidth. We firmly believe there’s not going to be production of new televisions that are going to be HD/HDR sets, they’re going to be the 4k sets you see now. What will happen is they have pretty good up-converters in them and they’ll take the 1080p signal and convert it to 2160p.”

Goldman said “the exciting point about doing this with 1080p is you get a lot of the bang for the bit by getting the HDR-Plus information out there but in a transmission that is much more bit-rate efficient.”

Nandhu Nandhakumar, Senior Vice President at the LG Technology Center of America, commented that “the up-conversion today [from 1080p to 2160p or 4K resolution] is very good. You can see a small degree of softness between native 4K content and up-conversion in TVs: it’s discernible, but it’s minor.”

Nandhakumar pointed out that “a significant amount of the content that’s available today from the Hollywood studios is in fact mostly up-converted, very professionally done offline, so you still get a perfectly fine viewing experience with HD that’s up-converted to 4K. However, if you have good native 4K you can see the difference.”

Nandhakumar concluded that “it’s really up to the viewer to decide how much they want to pay for this extra discernible quality.”