AES Tackles Online Content Loudness
Loudness units relative to full scale (LUF) is the most accurate way to measure the audio level of a program or commercial.
It was on December 13, 2011 that the Federal Communications Committee (FCC, the governmental body that oversees TV broadcasting in the U.S.), along with many irritated consumers, had had enough and decided to do something about the often times huge disparity in the audio level of commercials versus program content. This was after the U.S. congress passed the Calm Act bill on September 29, 2010.
The legislation has had the expected result, as most TV stations have complied with the law and implemented a variety of in-house rules and loudness measurement equipment for limiting audio levels on the output channel. Fines of $10,000 were threatened for those that didn’t comply, however enforcement basically comes down to when the audience starts complaining to the government.
But even current FCC commissioner Ajit Pai acknowledges that “the CALM Act does not apply to radio or streaming services.”
The Audio Engineering Society (AES) wants to create similar rules for audio loudness online and has a sponsor in Rep. Anna Eshoo (D-Calif.), the same member who championed the cause for TV broadcasters in 2010. Many experts agree that audio loudness is a problem that is widespread across the world wide web but, because it’s audio, it might not carry the same weight in Congress and therefore could have a tougher time getting enacted into law.
One Loudness monitoring option is TSL Products’ PAM PiCo, a compact and fully featured Audio and Loudness meter.
The AES has formed a Technical Committee (TC) for Broadcast and Online Delivery and has been working on a specification that it hopes to release sometime next year. The AES has introduced Recommended Loudness Practices for Audio Streaming (TD-1004) and Over the Top Television (OTT) (TD-1005 and TD-1006). TD-1005 and TD-1006 led to a standard called AES71 (which is for content delivery and distribution). The Consumer Electronics Association has also supported the online loudness cause and created ANSI/CTA-2075, which covers playback on portable devices. TD-1004 is now being revised and the committee plans to introduce a Loudness Education Website soon.
The committee said that these recommendations are intended for “radio-like mono and stereo streams as opposed to very dynamic stereo and surround sound streams with content such as movies or video specials.”
“You are watching a video online or just listening to music online, and suddenly an ad starts playing and it’s a lot louder than the content I was just listening to,” said David Bialik, consulting audio engineer and Co-Chairman of the AES Technical Committee (TC) for Broadcast and Online Delivery. He’s also co-chairman of the Broadcast and Online Delivery Track within the AES Convention, which has been held virtually this year.
“You don’t want them to be 6 db louder,” he said. “You never want to encourage the listener to touch that volume knob, because if they are reaching for that volume they might move on to another online site or video. You might lose your audience.”
Among the preliminary recommendations now being discussed:
- The Target Loudness of the stream should not exceed -16 LUFS: to avoid excessive peak limiting and allow a higher dynamic range in a program stream.
- The Target Loudness of a stream not be lower than -20 LUFS: to improve the audibility of streams on mobile devices.
- That short-form programming (60 seconds or less) be adjusted by constraining the Maximum Short-term Loudness to be no more than 5 LU higher than the Target Loudness: This ensures that commercials and similar short-form content are consistent with the stream loudness.
- The maximum peak level should not exceed −1.0 dB TP: to prevent clipping when using lossy encoders.
It reads, in part: “Loudness is measured relative to digital full scale, not SPL. Absolute loudness is measured in LUFS, “loudness units relative to full scale”. Relative loudness is measured in LU, “loudness units”. ITU-R BS.1770-3 defines Integrated Loudness, a measurement of the total amount of audio energy between two points in time divided by the duration of the measurement. The measurement is frequency-weighted to approximate the sensitivity of the ear to different frequencies and is level-weighted to emphasize the parts of the program contributing most to the sensation of loudness. Program Loudness is a measurement of one program from top to tail. EBU - TECH 3341 and ITU-R BS.1771 distinguish the measurement windows of Integrated Loudness and Short-term Loudness. EBU R 128 defines Maximum Short-term Loudness.”
The hope is that, like TV broadcasters did the past few years, Internet content providers will adopt the technology required to ensure a smooth transition between ads and program content online. This loudness metering technology is offered by companies like Actus Digital, Linear Acoustic, Telestream, TSL Products and others.
“At the end of the day we’re trying to improve the listening experience for online consumers,” said Bialik. “I think the CALM Act has worked for linear broadcast channels. We’re hoping that the Congress does not have to regulate this.”
During the AES virtual convention (through mid-November), Bialik will moderate a panel discussion entitled “The Importance of Loudness” that will include Jim Starzynski, Director and Principal Audio Engineer for NBCUniversal. Other panels related to the topic include “Using ITU-R BS.1770 to Measure the Loudness of Music versus Dialog-based Content”
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