Meeting Report: July 2011 – TV Loudness

On Thursday July 14th the AES Melb Section met at the JMC Academy auditorium, where Jean Paul Moerman of Salzbrenner Stagetec gave us an overview of the topic TV Loudness. This has always been a sensitive topic, but since the evolution of TV to digital systems the apparent problem has intensified.

Jean Paul described the new metering system developed by the European Broadcasting Union to better measure program “loudness” than the PPMs, QPPMs, and peak-reading meters now commonly used in Europe.

He described a project he ran when Head of Sound at Flemish TV, VRT – the Belgian National Broadcaster, to improve the loudness consistency and reduce viewer complaints.

This involved a 4-step process of  1)Standardizing metering and meter scaling using metering based on ITU-R-BS.1170 algorithm,  2)Appropriate and standard monitoring levels at all mixing points,  3)Modulation and processing rules, and 4) The Operators’ ears (somebody is monitoring and controlling levels). Implementation of the plan, which also involved significant operator training, reduced viewer complaints about the sound (which had previously been 75% of all viewer complaints) to 0.7% of the previous numbers.

Jean Paul also walked us through a typical Loudness Consultancy which he would now do – in this case RTM the Malaysian National Broadcaster in Kuala Lumpur.

He then described the loudness metering system based on the BS.1170 algorithm on which both the EBU and ATSC (US) loudness metering systems are based. He commented that the now largely abandoned VU meter was a “pretty good” loudness meter, but had some limitations –  which meters to the new EBU R128 standard address.

He also went into significant depth on the importance of consistent and appropriate monitoring levels for operators who are making mixing decisions. He explained that mixing at elevated levels compared to the average viewer’s listening level results in a mix with too high a dynamic range for the viewer, such that the dialog is unintelligible or the foreground effects are uncomfortably loud. The European broadcasters’ recommended monitoring level is 77dBSPL per channel, and his own measurements of viewer listening levels indicate this to be a valid monitoring level to generate mixes that translate well to viewers’ lounge rooms.

The talk was peppered with audio examples, and provided lots of information in an easily digestible form.
A lively question and answer session followed, and we all left the meeting with a better understanding of the challenges of maintaining consistency in TV audio loudness, and the tools that are coming into to play to meet those challenges.

A special thanks to Rob Care of JMC for providing the venue and facilities.

An audio recording of the meeting, courtesy of Graham Haynes and his nifty Tascam CF recorder is available for playback or download here.

Jean-Paul Moerman’s Presentations and Papers.
Presentation slides from a similar presentation J-P made on: Program Loudness Nuts and Bolts

AES paper – presented in 2005 on Loudness: Nuts-and-bolts

Charts of metering scales:
SMPTE EBU Meter scaling differences and SMPTE EBU2 metering scaling differences V2

EBU Publications
Summary of the loudness issue: EBU 10 things about loudness

ITU standard BS-1770 defines the loudness measurement: ITU R-REC-BS.1770 source document

Australian Proposed Operating Practice (FreeTV)
The Australian commercial television industry has a Loudness Engineering Working Group who have developed an Operational Practice similar to R128 (with a couple of differences) which is expected to be adopted by the industry by the end of next year.

This document is: FreeTV OP59 Measurement and Management of Loudness in Soundtracks

US ATSC Recommended Practice.
The Advanced Television Systems Committee’s document covering TV Loudness in the US is ATSC RP A/85-2011

 

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