ATSC A/85 is the US broadcast loudness recommendation, given legal teeth by the CALM Act, which in 2012 made it illegal for television commercials to be louder than the programming around them. Like its European cousin EBU R128 it is built on ITU-R BS.1770 measurement, but it targets -24 LKFS (equivalent to LUFS) and frames its guidance around the 'anchor' loudness of dialogue. Its practical effect is the one viewers feel: ads no longer blast you when the show cuts to break. A/85 governs how stations and content providers measure, normalize, and pass loudness metadata through the broadcast chain.
The book · Volume 4 of 7
Audio for Video: A Complete Guide to Sound in Video Products: From PCM and Codecs to Loudness, Accessibility, and Real-Time Voice Processing
ATSC A/85 is the loudness target US broadcast must meet under the CALM Act, and streaming content repurposed for TV often fails it. Volume 4 covers ATSC A/85 in detail within loudness: LUFS and LKFS, ITU-R BS.1770 measurement, EBU R128, true peak and how to normalise programmes and ads. Written by Nikolay Sapunov, CEO at Fora Soft.
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