One of the more obvious differences that strikes a lot of HD viewers these days is often the obvious disparities in audio level between channels and within various program segments on the same channels. The problem goes well beyond the old analog gripes about commercial spots being louder than the shows in which they're embedded.
Now the Advanced Television Systems Committee is doing something about it, thanks to its Specialist Group on Video and Audio Coding (TSG/S6), established back in 2007.
The ATSC DTV standards A/52 and A/53 define and require the use of so-called "dialnorm metadata" to control loudness levels of audio at the DTV receiver end, but there's been a lot of industry confusion about the right method of implementation through the broadcast chain. On Nov. 4, a Recommended Practice for the industry from the Audio Loudness Group (S6-3) — led by Jim Starzynski of NBC Universal — was approved by the ATSC membership.
Key portions of the ensuing publication, "ATSC Recommended Practice: Techniques for Establishing and Maintaining Audio Loudness for Digital Television (A/85)," is available for download from the ATSC Web site.
The new ATSC Recommended Practice provides guidance both for HD and SD content production and transmissions.
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