hobbyist wrote:Loudness units relative to full scale (LUFS) is a synonym for LKFS that was introduced in EBU R128.
LKFS came first, as it was introduced in the original Loudness-Normalisation spec, the ITU-R BS.1170 (now BS.1170-4). The term is an abbreviation of "Loudness (K-weighted) relative to Full Scale".
When the EBU's 'P-Loud' group set about writing their own practical implementation documents for European broadcasters -- now know as the R128 standard -- they decided to change the term to the simpler (and easier to pronounce as a word) LUFS , short for "Loudness Units relative to Full Scale".
Many manufacturers have adopted the LUFS term, but the American standards bodies have stuck with the LKFS nomenclature, as have some other standards documents in other regions.
So LUFS and LKFS are actually exactly the same thing, although some confusion sometimes arises as the American broadcast standards for implementing Loudness Normalisation requires slightly different targets and margins (specified in LKFS) compared to the R128 standards (specified in LUFS).
This was meant to help tame commercials and to normalise program levels on TV so people dont have to keep turning the volume knob. It failed. I have to adjust mine all the time and many commercials are still way too loud
I wouldn't say it's been a complete
failure -- it has definitely improved the situation considerably for the exchange of long-form HDTV programmes, as well as for level matching between (HD) channels (during long-form programmes). It's also made a big improvement on internet music streaming services, and -- most importantly of all -- it is encouraging the return to dynamic music instead of hyper-compressed, ear-destroying, garbage!
But adverts have always been a problem, and reigning in their producers was never going to be an easy fix. It was hoped that they would get on-board with the concept and self-regulate... but sadly they haven't, in general. The Integrated Loudness value doesn't work on short programmes, so the broadcast specs are tightening up on maximum peak values for the Momentary and Short/Sliding meter figures -- and the reason we are now on the fourth update of BS.1770 is because it is very much still a work in progress. Both the underlying technology and its practical implementation are still being tweaked and evaluated -- particularly for short-form programmes, adverts, and 'interstitial' items (station idents, trailers , etc). But with different broadcasters and standards bodies involved all around the world it takes a long time to test new ideas, assess the results, and get new agreements through!
It will get there, eventually, and the basic idea is certainly a massive improvement on what we had before!
The standard loudness target levels for broadcast HDTV are -23LUFS in Europe, or -24LKFS in America (with the rest of world aligning their own national standards to one of those two).
The AES has recommended -16LUFS as the optimum loudness target for online streaming services, and some are there already, but most are a little hotter at -14 or -15LUFS - -although it appears few if any streamers actually use the BS.1770 technology to assess loudness at the moment; they use their own bespoke (but similar) systems.
Broadcast radio doesn't yet employ this form of loudness-normalisation, but there are moves to introduce it in the not too distant future, probably with an initial target of -15 or -16LUFS...
But the end goal is to get everyone down to -23LUFS for consistency and to maximise dynamic range (once issues with consumer equipment headphone volume and peak-normalised protection are sorted out.... )
Here is my explanation of the tech and it's aims: https://www.soundonsound.com/techniques/end-loudness-war