Broadcasters will have quite a bit of latitude to decide what to do with their ATSC channels. Friedel said a single 6 MGz ATSC 3.0 channel has 36 "capacity units." (That's almost a threefold increase over the original ATSC spec, which offered 13 capacity units.) That means an ATSC 3.0 channel can hold a single UHD program, multiple HD programs (they take up six or 12 units each, depending on frame rate), or up to 36 SD programs.
It's not enough capacity, however, that bandwidth will not remain a primary concern. And that might mean that the future of broadcasting is not in UHD at all, but in high dynamic range (HDR) — or, rather, in what broadcasters are calling "HDR+".
HDR is mostly thought of as a 4K technology, since the first TV sets to enable it are UHD models, but there is no good reason HD content can't be encoded in HDR, then upres'd to 4K by the TV set. That's where HDR+ comes in. It's an HD-resolution stream that features HDR, wide color gamut, and 10-bit color depth (to eliminate the color banding that is arguably the most unsightly characteristic of HDTV images). Matthew Goldman, SVP of Technology, Media and Entertainment at Ericsson, said the increased payload when HDR+ content is delivered to consumers is at most 20% more than a standard HD stream, while HFR (60p to 120p) could require a 30% increase in bandwidth to the home and 4K can increase the required bandwidth by as much as 250%.
"If you want to get the best bang for the bit, what are you going to do?" Goldman asked the audience rhetorically. "I think you should look at doing 1080p HDR+. If you have the bandwidth, do the 4K. But if you don't have it, seriously, take a look at this. You can get, for a small increase in bandwidth, a much better user experience."
