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Old 28th November 2014, 04:45   #12  |  Link
manolito
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Join Date: Sep 2003
Location: Berlin, Germany
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Interesting discussion, but I'd like to bring this whole thing back to the real world...

No need to complain about this standard, for almost all TV and radio stations in my country (Germany) this standard is here, like it or not. The public TV stations started to adopt it in 2012, the private stations followed, and today the vast majority of all broadcasters observe it. And this is not about to please the advertisers as pandy suspects, just the opposite is true.

More and more viewers and listeners complained that commercials were much louder than the rest, these complaints even reached the European Commission. As a result a task force consisting mainly of broadcasting engineers was put together, and they hammered out this standard. (BTW it is a recommendation, not a mandatory standard).

My point is if and how this can be useful for DVD creation. There is a legitimate need for users to have a uniform loudness level for the multiple tracks of a compilation DVD. The older approach to achieve this was ReplayGain, but now everybody agrees that the loudness detection method of EBU R128 gives much better results.

The standard broadcasting level of -23 LUFS probably does not make much sense for DVDs, but of course the reference level can be brought up to -18 LUFS, maybe even to -14 LUFS. This brings the overall loudness to a level comparable with current commercial DVDs.

The problem with these higher reference levels is that the result might run into clipping. For my plugin implementation I use SoX to apply the gain correction determined by ffmpeg. As I see it SoX has two methods to deal with clipping:

1. Use the "gain" effect with the -l parameter.
2. Use the "vol" effect and add a "limitergain" parameter.

Both are not well documented. Right now I tend to use the second method with a limitergain value of 0.025. But I need to do more listening tests...
(any SoX specialists out there? )

Anyways, the concept works well, my favorite right now is to first apply DynamicAudioNormalizer (default settings) followed by EBU R128 loudness normalizing to -14 LUFS.


Cheers
manolito
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