At the HPA Technology Retreat in Indian Wells, California last month, a presentation was made focusing on ATSC 3.0. It was nothing special, simply an overview of the technology, like ones often done before.

However, a slide came up that answered what might be one of the hottest unanswered questions lingering about the state of ATSC 3.0 audio.

Jim Starzynski, director and principal audio engineer for NBCUniversal, said the ATSC’s ad hoc group working on audio is “drafting candidate standard now.”

But the remaining question is which of two standards will win? Will it be Dolby AC-4 or MPEG-H? No one has said and the secrecy surrounding the subject has been deafening.

Well, maybe a slip up has answered the question.

A slide used at the conference revealed the answer. Dolby AC-4 will be recommended by the S34-2 committee for use in the United States, the slide said. For the rest of the world, each country or region is free to choose an audio standard. 

Here is the slide. Sources have confirmed it was shown in public at the forum.