VRT adopts EBU loudness measure

Belgium’s Flemish language public broadcaster VRT has joined the country’s French-speaking services in adopting the EBU’s R 128 Loudness Recommendation.
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Belgium’s Flemish language public broadcaster VRT has joined the country’s French-speaking services in adopting the EBU’s R 128 Loudness Recommendation. As a result, viewers of VRT’s Flemish commercial TV channels will be spared the irritating jumps in volume when zapping between channels or across different types of content on the same channel.

The Loudness Recommendation has been spreading throughout Europe, with R 128 now applied in France, Germany, Austria, Switzerland, the Netherlands, the Spanish Autonomous Community of Catalonia and now the whole of Belgium. The move, which involves adjusting audio levels against averages rather than peaks by using loudness meters instead of traditional peak meters, applies to all programming as well as announcements, advertising and live events.

It might seem strange that in the age of HD, surround sound and 3-D, the broadcasting industry is only just getting to grips with the loudness issue. But, it is more complex than it sounds because different levels and types of audio are perceived differently and reaching agreed definitions and standards has proved elusive. As with many aspects of broadcasting, different standards were adopted in the Europe and the U.S. But, on both sides of the pond, the emphasis has switched from simple level control to relative loudness between channels and content, since that is what viewers found most annoying. With modern loudness control, they can set the level for one channel in the knowledge that it will stay the same for all the others.

In the U.S., loudness has been addressed by the Commercial Advertisement Loudness Mitigation (CALM) Act, introduced in 2008. This requires the FCC to regulate the audio of TV commercials, program interstitials and promos from being broadcast at louder sound volumes than the TV program material they accompany. That, in turn, has prompted a re-evaluation of how broadcasters and program makers approach the issue of level and loudness across their entire output.

This all led to the ITU setting a standard called ITU BS 1770, introducing the concept of ”Loudness K-Weighed, relative to Full Scale”, or LKFS, as a way of quantifying loudness. LKFS meters loudness over a set time period, sometimes the length of an entire program. Then the EBU, in 2010, introduced its Recommendation 128 (R 128) with yet another new term, called Loudness Unit, referenced to Full Scale (LUFS). According to the EBU, this introduced the concepts of “Loudness Range and Maximum True Peak Level to be used for the normalization of audio signals, and to comply with the technical limits of the complete signal chain as well as the aesthetic needs of each programme station depending on the genre(s) and the target audience."

In practice, the LUFS is now almost interchangeable with the LKFS measure of loudness used elsewhere, with the original difference being that the LUFS, as embodied in R 128, ignores quiet periods of a program when the level drops below a set threshold. The EBU had noticed that people judge the audio level of a program by the high volume rather than the low volume sections, which was one motivation for the U.S. CALM legislation aimed at curbing unduly loud commercials. The EBU also observed that long periods of low volume audio within a program brought the average down such that there was the potential for unduly loud portions within it to slip through and still possibly cause annoyance for viewers when changing channels.

Overall, it makes very little difference since over the course of an average half hour program, when the two measures usually give similar results. In any case, the ITU has since accepted the EBU view and updated its ITU-R BS standard to come in line by also ignoring quieter parts of an audio track, although there are still minor differences.

Meanwhile, the EBU insists that there is still more work to be done on loudness control, so that the work of its Loudness project group, PLOUD, goes on. During 2013, there will be a particular focus on the role that loudness normalization can play in radio, building on early experiences of broadcasters in Norway and France in particular.