AC-4 ‘Likely’ To Recommend ATSC 3.0 Audio Codec for North America, Richer Says

LAS VEGAS -- ATSC “likely” will recommend adoption of Dolby AC-4 as the ATSC 3.0 audio codec for the U.S. “and perhaps North America,” by year-end, ATSC President Mark Richer told us exclusively Monday at the opening of the ATSC 3.0 Consumer Experience exhibit at the NAB Show. Dolby Labs executives were at the exhibit to showcase AC-4's immersive audio qualities through an off-the-shelf soundbar mounted next to an LG Ultra HD TV. It was there that Mathias Bendull, Dolby vice president-broadcast consumer audio, told us ATSC would announce AC-4 as its recommended ATSC 3.0 audio codec for North America by the end of 2016.

“What we’ve said so far is that there’ll be two codecs in the standard,” AC-4 and the MPEG-H system promoted by Fraunhofer, Qualcomm and Technicolor, Richer said. It’s recommended “that only one be used in a given region, and it’s likely that it will say that for the United States, the recommendation is to use the Dolby system,” Richer said. That recommendation isn't contained in ATSC’s A/342 candidate standard document now out for balloting among ATSC members, Richer said. His disclosure potentially puts to rest questions about how ATSC's decision to kick the can down the road and letting the market decide might bring clarity to choosing an ATSC 3.0 audio codec, at least for North America.

MPEG-H consortium representatives didn’t comment on Richer’s disclosure Monday. But a consortium spokesman emailed us last week to say MPEG audio codecs “provide half the world's television audio delivery today,” even though “a number of worldwide standards allow for inclusion of more than one audio codec,” and the consortium expects “a similar level of deployment” of MPEG-H for ATSC 3.0.

The recommendation that AC-4 be adopted for ATSC 3.0 in North America will be contained in the A/300 “master document” that won’t go out for a ballot until later in 2016, Richer told us. “But it’s also true that Korean broadcasters have indicated they prefer MPEG-H,” he said. “So we’re going to see both codecs out there, I would expect. Part of the standard is flexibility, and that’s just one of the many areas where there’s flexibility.”

At ATSC, “we always identified the possibility of one or more audio codecs” being documented in the ATSC 3.0 suite of standards, Richer said. “Anything we do is because there’s a consensus of our members, and ultimate approval by two-thirds of the membership. So it’s what industry wants to do, it’s not what ATSC as an organization wants to do. So if the Dolby system, if that’s what’s desirable to the industry, and they want it in the United States and perhaps North America, then that will get specified that way. Same thing in Korea, they’ll specify what they want. We can’t say this is cast in concrete, because we’re not that far into the work yet.”

A/300, which will contain the AC-4 recommendation, will be “the mother of all standards” because it “points to all the other documents” in the ATSC 3.0 suite of standards, Richer said. “It’s always subject to change until we’re done. I’m giving you kind of a snapshot of where we are, and I can’t absolutely say that’s how it will turn out.” A/300, like all the other ATSC 3.0 standards documents, also will be put to a four-week ballot among the ATSC membership, Richer said. He hopes that ballot will be ready to go out by the end of 2016, he said. “It’s definitely toward the end of the work.”

Adopting AC-4 as the recommended North American audio codec for ATSC 3.0 ultimately will go “to a vote of our membership, and it takes two-thirds of the members voting to approve anything,” Richer said. “To go to candidate standard, it’s only at the technology group level, but once it goes to ballot for final standardization, that’s a vote of the entire membership. It’s basically the same process we’ve had for 33 years.” The likelihood that AC-4 will be adopted for North America is based on a “snapshot that this is what the current thinking of the groups that are working on it feel,” he said. “But that’s not been approved at any level, so I can’t say it’s an absolute decision.”

Richer also emphasized that the AC-4 and MPEG-H codecs “both work.” They "both do many of the same things.” They might differ in their “ecosystem ramifications,” he said. “There’s other issues about backward compatibility with the current audio system, and how signals are routed around networks and plants, so it’s pretty complicated. It isn’t just about the audio codec itself. So rather than choose one and make a lot of people unhappy, we can do both, we can define both, and different regions can use different audio systems.”

For those not familiar with ATSC 3.0, “it’s quite simply the platform for the future of terrestrial broadcasting," Richer said Monday at the ribbon-cutting for the opening of the ATSC 3.0 Consumer Experience exhibit on the upper-floor entrance to the Las Vegas Convention Center’s South Hall. ATSC 3.0 “will enable all kinds of services and new products,” and the exhibit, sponsored by ATSC, CTA and NAB, is designed to give visitors “a glimpse of some of those,” Richer said. “As you walk through here, I think you will see that ATSC 3.0 is an Internet-centric, powerful and flexible and extensible standard that will really be the basis of broadcasting moving forward.”