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European broadcasters converge over loudness

Broadcasters in French-speaking Belgium have been the latest to make the switch to the EBU R 128 loudness specification this week, with others in Germany and elsewhere set to follow their Flemish counterparts later this year.

Programs of all French-speaking national broadcasters in Belgium, that is RTBF, RTL-TVI and BeTV, have normalized their audio transmission according to EBU R 128, the Loudness Recommendation created by the EBU’s PLOUD Group. Loudness is a still a big issue in broadcasting, often affecting Quality of Experience for the viewer more than problems with the video — even though the latter consumes much higher bandwidth. The issue is largely concerned with the sharp fluctuations in audio volume that can occur when switching between channels, or watching the same channel on different equipment. But, it is also about the desirable recording level for different types of content, since the needs of, say, a rock concert and news program are different.

Loudness has been described as one of the major regulatory issues still to be solved for broadcasting, with its origins dating back to the now disappearing era of analog radio, where stations competed for attention by listeners tuning their sets by transmitting their output as loud as possible. Now, the aim is to eliminate differential sound output, and EBU R128 addresses the issue by setting alignment levels that bring specific limits on variation.

Belgium’s RTBF has been a pioneer on loudness, and has closely followed the work of the EBU PLOUD group. Early tests with R 128 in mid 2011 already had convinced the broadcaster that viewer complaints could be reduced to zero. So, a plan was implemented to introduce the necessary tools at all stages of audio production, from recording to broadcasting, and to make sure staff understood exactly what loudness measurement and normalization entails. This is easier than it may seem, as the R 128 Loudness measurement algorithm fits well with the human perception of loudness.

From the end of August 2012, the main German and Austrian broadcasters will switch to R 128 as well, with Austria, Switzerland and France committed, while, in the UK, the BBC has been considering adopting R 128 unilaterally.