Michael Grotticelli /
10.12.2009
Originally featured on BroadcastEngineering.com
Broadcasters listening to loudness level set in Congress

Although both broadcast network representatives like Jim Starzynski, of NBC Universal, and members of the audio processing equipment vendor community, like Tim Carroll, president of Linear Acoustic, have promoted good audio practices for years, the majority of broadcasters have been slow to correctly adapt from analog to DTV audio. They’ve had plenty to worry about with the DTV transition but now it’s time for the industry to turn up their attention to DTV loudness.

The issue revolves around program and commercial loudness and a DTV audio function called dialog normalization or “dialnorm.” This is a parameter of digital audio metadata that accompanies the transmitted sound and sets the volume in all DTV home receivers. For programs and commercials to transition smoothly, all content must be encoded with the proper dialnorm value.

Viewers continue to complain that some TV commercials are louder than others and in most cases are presented at a much higher volume than the program dialogue they precede or follow. As per the Advanced Television System Committee’s (ATSC) DTV standard adopted by the FCC and made law by reference in 1996, all digital TV transmissions in the United States must broadcast properly matched loudness and dialnorm.

Unfortunately, that requirement was never clearly explained, and viewers continue to sound off. Some have threatened to get their programming elsewhere (such as the Internet or DVD), which is a threat for stations in today’s highly competitive environment.

NBC’s Starzynski said the broadcast and content creation communities, now aware of pending governmental mandates, are taking notice to what Congress has to say. The ATSC, however, was already engaged in a solution. Since May of 2007, Starzynski has chaired a special expert’s group on DTV Audio Loudness (S6-3) of the ATSC to develop a Recommended Practice (RP) on how to establish and maintain audio loudness for program and commercial content. The task force includes representatives from all networks, PBS, cable TV, the production and post-production community, commercial stations, manufacturers and education.

The resulting 60-plus page document — which details how to measure, monitor and prepare material for broadcast, including managing program to interstitial content transition loudness — is now in its final stages of approval by ATSC members with release on track for the fourth quarter of this year.

A reference to that RP document was prevalent in the testimony that Starzynski and others gave to the House Subcommittee on Communications, Technology and the Internet on June 11, as Congress continues to look into the issue of DTV loudness. Congress had called members of the industry to the Hill to discuss the Commercial Advertisement Loudness Mitigation Act (CALM Act), a bill originally sponsored by democratic representative Anna Eschoo, from Silicon Valley, CA, in 2008 and reintroduced in January of this year.

“Most Americans are not overjoyed to watch television commercials, but they are willing to tolerate them to sustain free over-the-air television,” Eschoo said. “What annoys all of us is the sudden increase of volume when commercials are aired.”

Last month Sen. Roger Wicker, R-MS, introduced similar legislation that would require the FCC to bar commercials from being broadcast at louder volumes than the program material they accompany. If approved, the bill would mandate the FCC to control loudness.

Starzynski personally testified before the subcommittee, urging the members to drop the bill in place, recommending industry self-regulation. The ATSC-recommended practice initiative was identified as the primary solution to the problem.

The ATSC, with its experts and engaged leadership, took the initiative early on, wanting to make sure broadcasters knew exactly what is expected of them and began work on the RP. The subsequent interest from Congress has created an added level of awareness. Now, with the RP in sight, networks and local broadcasters are jumping onboard, wanting to manage their audio correctly.

Linear Acoustic’s Carroll echoed many in the industry when he said, “We don't need any more legislation telling engineers how to do their job. If [the CALM Act] goes through Congress, there’s going to be a panic because it will be the government, not the creatives, who are controlling content, and that will drive viewers away.”

Although the ATSC rules for DTV broadcasting (A53 part 5) clearly state that a broadcaster’s dialnorm parameter must match its content loudness, this practice has not been accurately adhered to by many in the industry, due to “unawareness and/or a misunderstanding of the requirements of DTV audio,” Starzynski said.

“The ATSC Recommended Practice provides clear guidance and eliminates possible ambiguity about the process‚” Starzynski said, adding that, “the RP includes two quick reference guides condensing critical information from the RP; one on station and multichannel video program distribution and the other on content creation. These task-specific documents give immediate access to the most important key ideas of the main document.”

NBC Universal has been a long time proponent of the ATSC DTV Standard and took a leadership role in the S6-3 experts group. In January of this year, NBCU completed a dialnorm initiative for all of its cable properties. NBCU Local Media (owned and operated stations) completed its loudness and dialnorm initiative in December of 2007. The company is now in the process of testing file-based scaling technology that will automatically adjust commercial loudness to -24LKFS, NBC’s specific target value and the figure recommended in the ATSC RP document.

Across its cable properties NBCU uses specific program delivery requirements and the Linear Acoustic AeroMax system to manage loudness. The NBCU DTV network and stations do not use any external audio processing, mandating instead that program and commercial providers deliver their material at the NBCU specified loudness. NBCU’s goal is for all audio to be delivered to the home exactly as the content creator intended.

The National Cable & Telecommunications Association (NCTA) is also working with its member cable system operators on a loudness and dialnorm initiative.

On Thursday, Aug. 27 in conjunction with the NCTA, NBCU performed a series of network-to-cable operator tests to confirm loudness of its USA-HD channel across many points of cable distribution.

“The most important outcome of the ATSC S6-3 process (and perhaps even of the congressional intervention) is that much of the industry, including all the networks and PBS have joined together and formed a consensus on how to do DTV audio loudness‚” Starzynski said. “This is a huge accomplishment made possible by working in a expert’s environment within the ATSC and is a leap forward for DTV audio.”

“The disturbing thing about audio loudness is that there has been a mandated specification on the books since 1995, but not many have chosen to adhere to it,” Carroll said. “The problem is that it is a lot of work for broadcasters to get right, and not many have been willing to expend the necessary resources.”

Those resources include investing in loudness meters for audio mixers and/or automated audio processing technology that monitors signal levels and corrects those out of the recommended specification.

The International Telecommunication Union (ITU) has established a recommendation for audio loudness measurement that is recognized around the world. The proposed ATSC RP recommends those algorithms from the ITU specification. With the ATSC RP and ITU standard in place, the industry in the United States will finally have a universal DTV audio measurement recommendation.

“The ITU is also working on a loudness recommendation for content exchange when audio is delivered without metadata. Domestically, the ATSC’s proposed recommendation of -24LKFS will aid all broadcasters, operators and creators in the distribution and production of content when metadata isn’t present with the material.

“I really thought there would be a mad rush to get audio level consistent by the end of analog TV, but that didn’t happen,” Carroll said. “I am aware of cable operators that are stomping on the local stations’ signals in a profound way because they need to stop viewer complaints and have been left with no choice. That’s why we are stressing to broadcasters to get it right on their end and preserve the integrity of their programs. And now we’ll have a published [ATSC] recommendation that the broadcaster can take to the cable operator and collectively solve their problem.”

With the work in the ATSC and its RP at completion, there is a movement toward coordinated voluntary compliance in the industry.

“I’ve seen some real progress happening on this front, so I am optimistic that the industry is aware and working to give the audience the best possible DTV audio experience,” Starzynski said.



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