PBS Station KQED-TV Tests Dolby AC-4 as Part of On-Air Trial of ATSC 3.0

Harmonic supplied its Electra X2 advanced media processor to PBS station KQED-TV, based in San Francisco, for real-time video and AC-4 audio encoding during an on-air trial of the emerging ATSC 3.0 television specification.

Dolby’s AC-4 is a new audio format that addresses the current and future needs of next-generation video and audio entertainment services including broadcast and Internet streaming.

During the trial, KQED-TV, used Harmonic’s Electra X2 processor to show how the Dolby AC-4 format improves bandwidth efficiency for broadcasters to enable the delivery of enhanced audio content.

Bart Spriester, senior vice president, video products at Harmonic, said members of the ATSC audio subcommittee convened with Dolby in San Francisco to evaluate Dolby AC-4 for use within the new ATSC 3.0 broadcast standard.

“During the meeting, Harmonic and Dolby helped KQED become the first television station in the U.S. to broadcast live audio encoded with Dolby AC-4, a major, and historic, milestone for the next-generation format,” Spriester said.

Harmonic's Electra X2 advanced media processor offers real-time AVC encoding of SD and HD video, as well as audio encoding of E-AC-3 (commonly known as Dolby Digital Plus) content, the predecessor to Dolby AC-4. This enables broadcasters to deliver market-leading video and audio quality at a low total cost of ownership. For the trial at KQED, Electra X2 added native Dolby AC-4 encoding, enabling the station to deliver 5.1 surround sound and HD video at a low bit rate of 2 Mbps.

“I was impressed by the quality of the Dolby AC-4 broadcast at such a low bandwidth and see technology like this as an essential element to the future of KQED TV,” said Lee Young, director of engineering and facilities for KQED TV. “We are pleased to play a central role in this historic event.”

Dolby said its AC-4 solves a variety of broadcast challenges, offering significant benefits to stations and television viewers. Bandwidth efficiency is one of the key advantages: the format offers up to 50 percent improvement in compression efficiency for the same audio quality level compared with E-AC-3 and comparable codecs. This means broadcasters can deliver industry-leading audio quality at low bit rates, reducing operating expenses. Dolby AC-4 also provides enhancements for dialog management, making it easy for broadcasters to substitute dialog tracks for multilingual audiences, and gives viewers greater control over dialog levels, making the spoken part of the program more intelligible.

“Dolby already provides seamless broadcast audio solutions for the world's biggest events,” said Giles Baker, senior vice president, broadcast business group, Dolby Laboratories. “We are thrilled with this successful Dolby AC-4 trial with KQED and could not have done it without the encoding expertise of our friends at Harmonic. Harmonic was one of the first partners to implement Dolby Digital Plus, and we are glad to work with them again on this next audio innovation.”

Harmonic will demonstrate its Electra X2 processor at the IBC 2015 Show (stand 1.B20) in Amsterdam.

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