TVN Tech | 1080p HDR Gains Momentum For Major Sports
4K TV sets may now be a mainstream product, but 4K ultra-high-definition (UHD) television content certainly is not. Movies and episodic TV shows have been produced and mastered in 4K UHD for several years, but their distribution in 4K has been mainly limited to streaming services like Netflix and Amazon Prime Video.
For live sports, networks like NBC, CBS, Fox, ESPN and MLB Network have done a smattering of big-time 4K events but distribution has also been limited, with most 4K sports to date carried by the pay TV operator DirecTV and some streaming apps.
While mobile truck companies have been supporting 4K productions for several years, 4K still represents 5% or less of their current business. Most sports coverage continues to be produced and delivered in the same 720-line progressive (720p) and 1080-line interlace (1080i) HD formats broadcasters have relied on for over a decade.
With every broadcast network now offering its own streaming platform or app and the rollout of the ATSC 3.0 NextGen standard on the horizon, broadcasters have new delivery options. But sports insiders don’t predict a flood of 4K production anytime soon.
The main reason is cost. Working in uncompressed 4K (technically, 2160p UHD) means dealing with 12 gigabit-per-second signals compared to the 1.5 Gbps required for 720p or 1080i HD. Starting at such a high data rate makes the rest of the production chain, particularly signal transport and instant-replay devices, much more expensive.
One of the biggest stumbling blocks is replays, because quadrupling the data rate means quadrupling the number of EVS servers, which run $200,000 to $250,000 each (Fox already had close to 40 EVS units at the Super Bowl, and even with an unlimited budget would have had troubling finding the space for 160 servers).
4K’s high cost is why most 4K sport productions to date have required collaborating with a pay TV operator that can charge for it, such as Fox Sports’ partnership with DirecTV, or receiving a subsidy from a TV set manufacturer, such as Samsung’s sponsorship of ESPN’s 4K college football coverage last fall.
“4K is basically a creature that has to be subsidized by somebody,” says Pat Sullivan, president of mobile vendor Game Creek Video, which has worked with MLB Network, Fox and CBS on 4K productions. “Unless there’s an interested party that’s going to subsidize it, it’s not going to happen.”
In fact, doing 4K sports on a full-time basis would require dozens of new IP-based trucks to hit the field and most networks to rebuild their broadcast centers to maintain current workflows. That kind of massive capital investment was already unlikely before the COVID-19 pandemic hit and shut down all major league sports production, as well as much of the greater U.S. economy. With the 2020 Olympics postponed and several major events like Wimbledon and the British Open cancelled, 4K international production is also stalled.
1080p HDR: A Practical Proposition
But that doesn’t mean sports television has to settle for basic HD. Insiders already see a big uptick in producing major league sports in 1080p, and specifically 1080p with high dynamic range (HDR). 1080p represents a jump in resolution from 720p, and HDR achieves better contrast in late-model TVs by sending additional information which the sets use to display brighter highlights and a wider range of colors (technically called Wide Color Gamut).
And many broadcasters say the improvement in picture quality with 1080p HDR is more readily apparent to consumers than the gain from 4K resolution, particularly in sets smaller than 70 inches.
For production there are many practical advantages. 1080p HDR at 60 frames per second equates to 3 Gbps in uncompressed form, which means it can be handled by older trucks and broadcast plants with legacy 3-gigabit HD-SDI routing infrastructures. 1080p HDR is supported by much of the existing production chain, including replay servers, with a few minor upgrades.
And on the transmission end for OTT or ATSC 3.0, it can be delivered at a much lower data rate, requiring around 8 Mbps with HEVC encoding compared to 15 Mbps or more for 4K.
1080p HDR is also easily upconverted to 4K HDR for distribution on pay TV or streaming platforms, or downconverted to standard dynamic range (SDR) to support legacy HD broadcasts. That is exactly what Fox did for its coverage of Thursday Night Football and the MLB post-season last fall, as well as Super Bowl LIV in February.
NBC has taken a similar approach for its coverage of Notre Dame football, producing in 1080p HDR and upconverting to 4K HDR for distribution on DirecTV, as did Turner and CBS for select NCAA men’s basketball tournament games last year.
“Everybody’s doing [1080p HDR], we all are capable of doing it with existing hardware, and we can do it wherever we want,” says Ken Aagaard, a former EVP with CBS Sports who still works with CBS and other major networks through his consulting firm CBT. Aagaard says that HDR is particularly impactful for sports with widely varying light levels like golf and football.
Among mobile vendors, there is a growing consensus that 1080p HDR will become the preferred format for sports production going forward while native 4K remains a niche product. For example, Mobile TV Group built its first 4K truck back in 2016 but still only counts 4K production as 3 or 4% of its business. Meanwhile, the focus has shifted to 1080p HDR.
“There was actually a little more 4K a few years ago, before 1080p HDR caught on,” says Mobile TV CEO Phil Garvin. “Now it’s all about 1080p HDR.”
4K is only about 5% of the business for mobile production giant NEP, while 1080p HDR currently represents 15%, says Glen Levine, president of U.S. broadcast services for NEP. 4K is about 5% of Game Creek’s business, while 1080pHDR is at 10% but growing sharply.
“Next year the majority of big events will be 1080pHDR, and three years from now, I think 90% of the productions we do will be 1080pHDR,” says Sullivan.
This year Game Creek trucks were already scheduled to support 1080p HDR production of college football and the NFL for Fox, Olympic gymnastics competition for NBC (since postponed) and perhaps one other major network deal.
1080p HDR is not without complexities. For starters, to do HDR well requires using cameras and recorders that support 10-bit color depth instead of the legacy 8-bit format. For example, Fox still upgraded to new EVS servers with 10-bit recording for the Super Bowl.
More important, camera “shaders” who adjust camera parameters to match light and color levels between multiple cameras on a live shoot have to make sure that what looks good in HDR will still look good when the video is downconverted to SDR. While doing 4K is simply a math problem — just add resolution — HDR still involves a fair amount of art, say experts.
“A lot of it is all about exposure,” says Larry Thorpe, senior fellow for Canon’s Imaging Solutions Group. “In HDR you have to be very disciplined in your exposure, learning how to expose so you can do justice to highlights like clouds while you also properly expose the players and the green of the grass.”
Thorpe says that Canon puts special antireflective coatings on the elements within its HDR lenses that minimize “optical noise” by making sure that the reproduction of deep blacks isn’t contaminated by the lenses themselves.
“Driving the blacks down and elevating the highlights, that’s dynamic range,” Thorpe notes.
Protecting The ‘Money Show’
The mantra among network sports executives is to protect the “money show” that is SDR, and engineers have spent considerable time figuring out what shading parameters will look good for both HDR and SDR.
“We spent plenty of time in the lab to make sure we had the right recipes to create good SDR while doing HDR,” says Michael Davies, SVP of field and technical operations for Fox Sports. “The huge preponderance of the audience, maybe 99.9%, is watching SDR, and that’s the challenge.”
For its part, Sony has developed its camera software to make sure that one workflow can simultaneously support both HDR and SDR, says Rob Willox, director of product marketing for Sony Media Solutions. He says customers can do camera shading with SDR in mind and then let the camera’s processing convert those parameters to HDR.
“The idea is that you tune that camera to handle the money show and you should still be able to get a very good HDR show out of it,” he says. “This way you’re using one set of cameras and one set of craftspeople, and you’re not painting for some slight difference that might look great in HDR but would be challenging in SDR.”
Grass Valley is taking a similar single-workflow approach to HDR production with its switchers, says Chief Technology Officer Chuck Meyer. He notes that a big part of working in either 4K or 1080p HDR is dealing with non-compliant sources, either from secondary cameras or outside feeds.
“What we recommend to our customers is to pick the high-end format you want,” Meyer says. “Then as other signals come in, you need to upconvert them. A lot of what gets upconverted is graphics. Upconverting an SDR to HDR graphic is very straightforward. And historical footage can also be upconverted.”
Managing The Format Mix
Game Creek customers use a mix of conversion equipment to switch between HDR and SDR formats, says SVP of Technology Jason Taubman. They range from high-end dedicated Sony HDRC-4000 converters, which often sit in the transmission path, to modular solutions from vendors like Evertz, AJA Video Systems and Cobalt Digital.
For high-volume conversions, such as mixing in SDR content from secondary cameras into the flow of an HDR production, broadcasters can use a “look up table,” or LUT, developed by the BBC. The LUT guides the converters to ensure that the red in an SDR image of a Coca-Cola billboard will still look red when it’s converted to HDR.
An additional complexity to HDR production is that there are multiple flavors of HDR across the broadcast equipment and consumer electronics universes, all with varying compatibility. Hybrid-Log Gamma (HLG) was developed by the BBC and NHK to deliver HDR information (technically, the Electro-Optical Transfer Function) along with an SDR broadcast signal without using metadata. That makes it compatible with older SDR TVs, which simply ignore the HDR info. HLG is the format used by most professional production equipment, and it is also supported by many newer TVs.
Meanwhile, HDR10 is the most common HDR protocol supported by most CE equipment including HDR TVs and phones, as well as 4K UHD Blu-ray discs. It is based on fixed metadata sent alongside the video, which means separate broadcasts or streams for SDR and HDR sets.
There are also two competing formats that use “dynamic metadata” to adjust the HDR in a TV on a scene-by-scene basis, one the proprietary “Dolby Vision” licensed by Dolby Labs and the other the open-source HDR10+ developed by Samsung. Both of these formats are supported by a smaller universe of newer TV sets and streaming devices.
What this means to broadcasters like Fox looking to serve HDR content to multiple outlets is that they need to be flexible. For Super Bowl LIV, Fox produced the game using HLG, streamed it on its Fox Sports and Fox NOW apps in HDR10 and also delivered a variety of HDR formats to cable and satellite providers.
When 1080p HDR will make its way to over-the-air ATSC 3.0 broadcasts remains to be seen, as 3.0 stations launching later this year initially plan to offer 720p and 1080i simulcasts and will look to upgrade based on the availability of network content.
For his part, Nexstar Media Group EVP and CTO Brett Jenkins doesn’t think there’s been enough experimentation with 4K and says it would “would be really fun” if one of the major networks tried 4K broadcasts. But he also sees a lot of support for 1080p HDR.
“A lot of broadcasters like the idea of doing 1080p HDR,” Jenkins says. “It would not surprise me if that’s where everybody ends up in the early phases. We’ve designed the air chain to be able to accommodate that pretty quickly.”