Feature: Covering the bases for loudness
Loudness monitoring and control is becoming established in TV but challenges remain in radio and cinema. Kevin Hilton rounds up the latest developments and opinions.
Loudness monitoring and control is becoming established in television but there are still challenges in radio and cinema. Kevin Hilton rounds up the latest developments and opinions...
Most people are deeply protective of their respective areas and tend not to see any crossover or similarity between them. Sometimes this is true but there can be more parallels than people care to acknowledge. Loudness is a case in point, as attention shifts from television on to radio and cinema.
Perceived variations in volume between different types of material is not a new issue in TV. It was recognised in the earliest days of the medium and has taxed the minds of engineers ever since. Radio has long had its own troubles with music of both wide and narrow dynamics against loud or softly spoken presenters, compounded by heavy compression on transmission. But today’s media landscape of TV and radio channels sharing both the same platforms and some of the same material means it is not confined to one area.
“Media today is not produced to be used only in radio or TV,” comments Michael Kahsnitz, head of product management at RTW. “It’s transmitted through very different channels, including broadband radio, broadband TV, data reduced TV, internet, for mobile platforms and more. So it seems to make a lot of sense to produce on the ‘general purpose’ layer around -23 LUFS [Loudness units relative to Full Scale; -23 is the average target set by the EBU R128 standard]. This allows compatibility for all platforms.”
Despite this commonality there are still enough specifics for TV, radio and cinema that need to be considered individually, with work progressing in all three.
There has been some form of loudness control available to broadcasters for at least 30 years. The 1990s saw more awareness of the problem but standardisation and widespread implementation of loudness monitoring, metering and control did not come in until the 2000s.
The ITU issued its BS 1770 in 2006, with the lead followed by regional and national bodies, including the EBU PLOUD group with R128 in 2010 and the ATSC in the US, whose A/85 is backed by law in the form of the 2010 CALM (Commercial Advertisement Loudness Mitigation) Act, which became fully enforceable in 2012.
All three have been updated or revised recently to accommodate particular areas of production. A supplement to R128 was released at the end of 2014 to cover short-form material, including commercials and promos. The original guideline was +3 LU (loudness units) but Florian Camerer, ORF sound engineer and chair of PLOUD, explained at the time that this was found to be “too restrictive”, so it was opened up to +5 LU.
The publication of R128 S1 and changes in production priorities has brought about revisions to three of the standard’s four supporting Technical Documents. TD 3341 Loudness Metering: EBU Mode now includes an expanded range of test signals, including for True Peak; 3342: Loudness Range (LRA) features a tighter means of calculating LRA to bring more consistency over different meters; while 3343: Guidelines for Production has been substantially rewritten to reflect practical experience of using R128 and includes a new Reference Listening Level. Tech Doc 3344: Guidelines for Distribution and Reproduction is set for an update in the foreseeable future.
Camerer comments that the consistency of loudness control is “generally very good” but that each broadcaster has the responsibility to keep “a weary eye on the situation and not let it get sloppy”. He adds that loudness levelling is becoming more the norm and almost taken for granted, as was peak levelling because it was something that just happened. “There are still countries, and of course areas like radio, where it is not as developed but things will get there eventually,” Camerer says.
Among the manufacturers involved with EBU PLOUD and its deliberations is TC Electronic. Esben Skovenborg, the company’s principal research engineer, says it has been working in the Metering Subgroup to produce revised versions of documents pertaining to Loudness Metering and LRA. “Rather than introducing any new measures, the update tightens the spec and test requirements for both true peak and loudness measurements,” he explains. “Thereby equipment from different manufacturers will behave more similarly. It is still up to the individual manufacturer, however, to make sure its products are compliant.”
Peter Pörs, chief executive of Jünger Audio, says TV is “in a good position”, with a lot of people paying attention to the issue. “On the other hand it doesn’t improve everything immediately,” he says. “Before this material could suffer from peak control limiting. Now it can be affected by loudness controlled audio. And there are still a number of situations that can’t be managed by -23 or -24 [the target set by A/85].”
Jünger Audio's Peter Pörs
Tim Carroll, president of Linear Acoustic, comments that not only is TV loudness now more consistent but the audio has greater dynamic range. “The trick is going to be making sure it does not become uncomfortably dynamic, or else it could backfire and result in random processing,” he says. “On the subject of short-term material and momentary loudness, Carroll comments that most meters accommodated this already and hopes that now it is documented producers will manage dynamic range, which he calls “the evil cousin of loudness”, manually and creatively.
While the general consensus is to do the majority of loudness measurement and normalisation on meters in the dubbing or on-air studio, file-based software programs are also used widely as part of the QC (quality control) process through the production chain to transmission. While the aim is to automate loudness checking further down the line, manual intervention will not disappear completely overnight.
The Digital Production Partnership (DPP), the organisation that sets programme delivery specifications in the UK, published Technical Standards for delivery of HD Commercials, Sponsorship material, Promos and Presentation Events during January. This incorporates the R128 guidelines for short-term material and introduces an Exceptions Process for content that is “intentionally quiet”. Something approaching silence is occasionally used by advertising agencies and producers for creative purposes; the potential problem in an automated environment is that it would be normalised to -23, thereby ruining the effect.
Under DPP recommendations the agencies and producers will have to fill in three metadata fields to highlight that the material is intentionally quiet. It is then marked as ex-R128, or out of spec, and the system manually compensated to accommodate it. MC Patel, chief executive of Emotion Systems, which produces the eFF (Emotion File Finish) software program, feels there is still a need for clarity on this issue: “In the file-based world we haven’t defined how to find out which material is intentionally quiet. It could go through post and be taken to -23. We’re keen to open a dialogue about how to resolve these issues because it is something that needs special treatment.”
A lot has happened with TV loudness in a relatively short time but it is clear there is still some way to go, both in fully implementing the standards and getting them to work in all broadcast applications.
While the audio-only medium is not completely unaware of the implications of loudness and its various standards, it is still in the early stages of coming to terms with it all. The first country to embrace R128 for radio was Norway. In February 2012 the three DAB digital radio operators, public broadcaster NRK and commercial counterparts P4 group and SBS agreed to monitor and report their own and each other’s output for loudness compliance.
Because those involved concluded that radio content is very different from that of TV they set an average target of -15 LUFS instead of -23. Camerer commented at the time that he hoped the Norwegian radio broadcasters would settle on -23 when the country switched off its FM transmitters and moved fully to DAB+ in 2017. While Swedish broadcasters have carried out loudness tests for radio Germany is now moving the issue on.
Camerer gives the example of Bavarian Radio (BR), which switched all its stations to loudness control in production during 2015. “Everything is produced to -23 LUFS before being aired,” he says. “To keep their current levels in FM, they boost the signal by 5dB at Master Control. But the -23 production paradigm makes interchange with TV really easy, an asset gaining importance in this tri-media world. We’ll see how fast the example of BR spreads around Europe.”
Compressors and other signal processors have been used routinely on the output of radio stations for many years, most commonly to make a channel stand out when listeners tuned across the FM or AM dial. Camerer comments that processing can “kind of level things out” but that some broadcasters have run tests that show normalising archive material allows the processor to be backed off and so less aggressive. “It achieves a better sound while not losing perceived loudness,” he explains. “This is promising news also for pop/rock stations. For cultural channels with more dynamics the situation is similar to TV, meaning the benefits are high.”
Pörs points out that radio services over DAB/DAB+, satellite and streaming can all have different loudness values. “There is an ongoing discussion over which loudness is suitable for streaming,” he says. “There is also the situation of DAB and DAB+ not fully covering areas, so there has to be simulcasting with FM. This means DAB gets the same processing as FM. But when analogue is switched off we will have almost transparent audio over DAB.”
Carroll picks up on this, saying “a common meter is the name of the game”. He explains: “From there, everything else becomes easier and will definitely result in better sounding audio. The processors will work less hard. It is worth noting that certain radio processors, such as the Omnia Audio 7 and 9 have had ITU meters in them for several years and that metering can be viewed remotely by operators.”
While radio is starting to come to terms with loudness an equally venerable medium that has had its own battles with high volumes is coming under closer scrutiny.
Back in the 1990s and into the 2000s there were concerns about the high playback levels of films. That situation appears to have changed but the wide dynamic range used by re-recording mixers in big dubbing theatres still poses a problem in achieving reasonable levels that satisfy all cinemagoers and the artistic aspirations of filmmakers.
The TC Electronic LM6n LoudnessRadar
Skovenborg observes sadly that cinema has invented its own version of the loudness war: “As feature films are mixed louder, the projectionist will turn the playback level down. This reduces the available dynamic range, so an even louder mix – and more compression – is applied to the next film and so on. Several working groups are currently studying how the tools, developed in connection with the ITU and EBU loudness recommendations, can be employed to solve the issue in cinema.”
Camerer confirms that there is “quite some activity in SMPTE and the AES” to agree suitable guidelines for cinema loudness. Under the auspices of the latter organisation he is working with Eelco Grimm, a member of the Sound for Digital Cinema and Television technical committee and co-owner of Grimm Audio, on a metric for cinema loudness, based on ITU 1770. “The issue is that most cinemas in Europe actually turn the level down because audience complaints are frequent.
That fuels the loudness war in the cinema, pushing levels up and squeezing dynamics down. The situation is not as severe in the US but in Europe it is quite dramatic. If you mix dynamically with a low level of dialogue, you risk being too low in the cinema.”
Kahsnitz is more optimistic about the state of cinema loudness, saying the sector was “ahead of TV and radio” in terms of audio because of standards such as TASA and SAWA for the production of film commercials. “Today’s loudness standards will improve the given situation ever more,” he says. “So it should be a goal to have these standards applied to all cinema film and additional material [commercials and trailers].”
As cinemas move towards even more loudspeakers with Dolby Atmos and Auro 11.1, the ITU has updated its original standard again as BS 1770-4 to include immersive sound systems. And with continuing evolution in cinema, radio and TV, dealing with loudness is clearly not going to be a fixed discipline either.
Main Image: The CLC (Continuous Loudness Control) software from RTW.