Despite Lack Of Regs, TV Turns Down Volume

Since the Commercial Advertisement Loudness Mitigation (CALM) Act was signed into law by President Obama last December, broadcast vendors have been touting audio measurement, processing and monitoring solutions that stations can use to comply with the new law, which is aimed at stopping dramatic shifts in volume when a program goes to a commercial or promo.

But technically, there isn’t any “CALM Act-compliant” gear yet available because the FCC has yet to issue the formal regulations on what stations, as well as cable and satellite operators, will be required to do.

“Broadcasters don’t know what they have to do to comply with the act, since the FCC has until Dec. 15 of this year to issue the rules,” says Lynn Claudy, senior VP of science and technology for the National Association of Broadcasters.

Dec. 15, 2011, would mark one year from the day the CALM Act was signed into law. And once the FCC issues the regulations, stations would have another year — until Dec. 16, 2012 — to comply with the regulations.

The FCC is still in the “information-gathering mode,” says Claudy. “They’re trying to figure out what is the best way to have compliance for stations, so if they have a complaint, how do you know if the station was following the rules or not.”

The new regulations could require logging loudness data or archiving of programming, says Claudy. Another possibility, he adds, is that the FCC could put together a list of certified loudness-correction equipment. If stations purchased and installed that gear, then they would automatically be deemed in compliance with the law.

“Both of those ideas are kind of anticipated by the Act and being considered by the FCC,” says Claudy, although vendors say a certification process would be difficult to implement and could delay the rollout of new equipment, and some broadcasters worry about the costs of archiving.

While the manner in which broadcasters will record and report loudness data to the FCC has still not been determined, other obligations of stations are clearer. And despite the absence of the final regulations, some broadcasters are moving ahead with monitoring and control plans.

To avoid loudness problems in their digital television broadcasts, stations need a way to accurately measure the loudness of both their programming and commercials. And unless they want to rely on constantly adjusting their digital audio encoders, they will need some form of audio processing gear that can automatically adjust the audio to a predetermined loudness value so that viewers don’t experience a volume spike.

Loudness isn’t a new problem for broadcasters. In the analog NTSC world, it was standard practice to manipulate program audio to ensure efficient transmission and avoid big volume swings. But the Dolby Digital multichannel audio system for DTV (formally known as AC-3) requires more sophisticated loudness control. The Dolby system was designed to provide a wider dynamic range and to preserve the original audio from the program creator throughout the transmission chain, all the way to the consumer’s HDTV set. To do so, the DTV signal includes metadata that the audio decoder in the viewer’s receiver relies on to maintain a uniform loudness.

Under the U.S. digital TV standard, or ATSC (Advanced Television Systems Committee) A/53, stations are already required to make sure this metadata parameter of “dialnorm” — short for “dialog normalization” — accurately reflects the average loudness of the “anchor element” in the program audio, which is typically the dialog, so that DTV sets can effectively normalize the loudness.

But ATSC A/53 doesn’t provide any detail about how stations should do that. So, some measure loudness differently, while others never changed the default dialnorm settings on their AC-3 encoders to match the actual loudness of what they are broadcasting. The end result can be wildly fluctuating volume for viewers.

To address the problem, in November 2009 the ATSC came out with a “recommended practices” document (A/85, “ATSC Recommended Practice: Techniques for Establishing and Maintaining Audio Loudness for Digital Television”) that provides technical guidelines that program producers, broadcast networks and stations can follow to avoid wide variations in volume between different programs and excessive loudness in commercials.

The CALM Act actually codifies this document into law, as it directs broadcasters and multichannel operators to follow the ATSC guidelines, while allowing for temporary waivers to those facilities facing financial hardship in buying the necessary equipment. In fact, in light of the CALM Act, the ATSC has condensed the parts of A/85 that are germane to broadcasters into a new Annex J, which was being finalized at press time.

“A/85 covers a lot of material that is not really necessary to the regulation, as it starts with production and goes forward,” says ATSC President Mark Richer.

“The CALM Act is specifically for commercial advertisements,” Richer adds. “We’ve worked hard to get down to a short list of items that get down to the heart of matter. If broadcasters follow those items, the loudness issue should go away. A lot of broadcasters have already taken these steps. Network affiliates have implemented aspects of the recommended practice and are very near to what needs to be done.”

The most significant points in ATSC A/85 were the selection of a common way to measure loudness using the International Telecommunications Union (ITU)’s BS.1770 algorithm, which is based on human hearing and provides a numerical value indicating the perceived loudness of the content being measured, and agreement by the major networks on a target loudness for content that doesn’t contain loudness metadata.

BS.1770-compliant devices measure loudness in the unit LKFS (Loudness, K-weighted, relative to Full Scale), which is equivalent to a decibel (dB), in numbers ranging from -1 (loudest) to -31 (softest). For example, a -15 LKFS program can be made to match the loudness of a quieter -22 LKFS program by attenuating it by 7 dB. A particular loudness value in LKFS is also equivalent to the same dialnorm number that needs to be set in the ATSC audio encoder in order for a DTV receiver to properly decode the audio and normalize the loudness. For example, a -17 LKFS loudness value has to be matched with a dialnorm number of 17 to avoid volume spikes.

The loudness number can vary from program to program, as per the creative wishes of producers. As long as the dialnorm number is changed to match it, loudness problems should be avoided. But to make things simple for stations when they receive a spot or program without loudness metadata, ATSC has recommended a default target of -24 LKFS (plus or minus 2), which research has shown matches the average volume of the widest range of content.

Audio that doesn’t hit this loudness target can be changed to -24 LKFS through processing, which can be done in both real time and the file-based domain, or the dialnorm number on the encoder has to be changed to match the actual loudness.

Over the past year and a half, most networks and stations have been shifting their broadcast delivery chain to meet the -24 loudness number recommended in A/85. Stations are buying BS.1770-compliant monitoring devices to measure the loudness of commercials and syndicated programming, and both networks and stations are using a mix of hardware and software-based tools to adjust loudness.

Stations are required to prevent loudness problems on each program stream, including secondary multicast channels as well as primary high-definition program streams. Claudy says the investment required for loudness measurement and correction is generally $10,000 or less per stream. With the compliance rules still undetermined, he advises stations looking to buy new gear now to have an “in-depth conversation” with prospective vendors to make sure the equipment can support possible logging requirements.

Prices among vendors vary, but professional loudness measurement products generally range from $2,000 to $5,000 and loudness correction tools start in that range and can go up to $20,000 or more for a full-featured system capable of handling multiple program streams.

For the highest-quality loudness correction, stations will also want to have a separate file-based correction tool for analyzing non-real-time content that they get well in advance of air, in addition to a real-time processor for live and/or network programming.

Gray Television has already been tackling loudness across its 36 stations, investing in loudness analysis and correction tools from TC Electronic, Miranda and Linear Acoustic. The costs have run $15,000 to $25,000 per station, depending on the plant size and the number of multicast streams, says Jim Ocon, Gray VP technology.

“Ahead of any official enforcement standard by the FCC, Gray been proactive in the audio loudness matter, primarily because we don’t want to anger viewers,” says Ocon. He adds that loudness tools are often purchased as part of multifunction products such as Linear Acoustic’s AERO.air audio upmixer, which also converts stereo audio to Dolby 5.1.

In general, he is seeking to get the cost of loudness correction itself closer to $10,000. Once calibrated properly, the loudness correction tools available today work well, says Ocon, although one might be able to perceive a slight difference in loudness when going into a network break until the processor takes over. The loudness correction is performed downstream of the plant, just before the signal is transmitted.

Since he manages affiliates from multiple networks, Ocon would like to see the networks agree on a single loudness level, and is in favor of -24 LKFS being adopted as the industry benchmark.

He adds that the implementation of the Broadcast Exchange Format (BXF), which uses metadata to allow traffic systems to communicate directly with automation systems, could theoretically solve a lot of loudness problems as long as the loudness metadata for spots is correct.

“What I’m hoping is that the processing equipment doesn’t do the fixing, but that it’s fixed upstream using the metadata.”

In Part II next Thursday, TVNewsCheck checks in with some of the leading vendors and what they are pitching for loudness monitoring and control.