Harmonic Makes Audio History with First Live, On-Air ATSC Trial of Dolby AC-4

Harmonic recently played a key part in the world’s first live, on-air ATSC demo of Dolby AC-4, the 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, one of the nation’s most watched PBS television stations, based in San Francisco, utilized Harmonic’s Electra X2 advanced media processor for real-time video and AC-4 audio encoding. Harmonic and Dolby successfully demonstrated how the Dolby AC-4 format improves bandwidth efficiency for broadcasters to enable the delivery of enhanced audio content.
“Recently, 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,” says Bart Spriester, senior VP, video products, Harmonic. “This trial is another example of how Harmonic leads the industry in supporting new technologies. Having the Electra X2 media processor provide native Dolby AC-4 encoding for this trial, Harmonic allows broadcasters to deliver the future of audio entertainment.”

Harmonic’s Electra X2 advanced media processor today provides 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.

“Harmonic and Dolby are industry leaders and trusted partners in broadcast delivery solutions, and we are committed to collaborating with them as a part of our public service mission to enhance our audience’s experience” says Lee Young, director of engineering and facilities for KQED TV. “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. We are pleased to play a central role in this historic event.”

Dolby AC-4 solves a range 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 — the Oscars, the Grammys, and more. We revolutionized next-gen audio in the cinema, at home, and on mobile with Dolby Atmos, and now, with Dolby AC-4, we can solve for the broadcast challenges of today and tomorrow,” says Giles Baker, Senior VP, 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.”

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