The Advanced Television System Committee (ATSC) recently published a guide for broadcasters and audio creators who produce SD and HD content under the American digital television standard, ATSC. This document recommends necessary practices in production, distribution, transmission to deliver the highest audio quality to the final viewer.
According to a document published by the NAB that analyzes the details of this guide, volume variations between programs and commercials, and between digital television channels have been a problem since the introduction of digital television. So far, the ATSC's DTV standards, A/52 and A/53, define and require the use of the meta data dialnorm parameter – which controls the decoding gain within the Dolby Laboratories Dolby Digital (AC-3) audio compression system – to monitor the audio volume level on the DTV receiver, but there has been widespread confusion about the correct implementation of this parameter across the transmission chain.
Therefore, in 2007, ATSC established an area within the Video and Audio Specialist Group (TSG/S6) to focus on this issue and produce a guide of recommendations to guide the industry. This working group delivered, in early November of this year, the outcome document entitled: "ATSC Recommended Practice: Techniques for Establishing and Maintaining Audio Loudness for Digital Television (A/85)".
The guide focuses on audio measurement, monitoring techniques in production and post-production, and methods to effectively control volume in delivered or exchanged content. It also recommends methods for monitoring volume in interstitial programming, analyzes meta data systems, and describes modern control ranges.
It also includes two annexes that function as quick guides for two specific communities of interest: MVPD station engineers (multichannel programming distributors) and audio production staff.
In general, the ATSC document provides technical recommendations and general information on:
- Volume measurements using the ITU-R recommendation BS.1770.
- Target volume for content exchange without metadata.
- Reference configuration for monitoring environments when produced for the widest range of digital television, with consideration of multiple listening environments in the home.
- Provides methods for effective volume control in intermediate programs.
- Effective use of audio metadata for the production, distribution and transmission of digital content.
For more information, see the ATSC document here.
