EBU R 128
EBU R 128 is a recommendation for loudness normalisation and maximum level of audio signals. It is primarily followed during audio mixing of television and radio programmes and adopted by broadcasters to measure and control programme loudness. It was first issued by the European Broadcasting Union in August 2010 and most recently revised in June 2014.
employs an international standard for measuring audio loudness, stated in the ITU-R BS.1770 recommendation and using the loudness measures LU and LUFS, specifically created with this purpose. The EBU Tech 3341 technical document further clarified loudness metering implementation and practices in 2016.
Premise
Before the adoption of, normalisation was based on the peak level of audio signals, which was leading to considerable loudness discrepancies between programmes and between broadcast channels. The same peak level does not necessarily produce the same loudness, because the use of dynamic range compression and limiting can increase the average level of the programme without increasing its peak level. Starting from the early 1990s through the early 2010s, both the music and the advertising industries urged this practice to ensure that music and advertising spots became louder without exceeding the maximum permitted peak level. This phenomenon is known as the loudness war.The resulting inconsistencies and changes in loudness became a frequent cause of complaints from viewers and listeners. To address these problems, ITU developed new algorithms to measure audio programme loudness adequately—in a similar way to how the human ear perceives sounds—and studied new methods to measure loudness over a long-term timeframe. This would allow normalising the loudness of different programs and programme contents appropriately.
Development
To find practical solutions on how to switch from peak normalization to loudness normalization, the EBU Production Management Committee formed an international working group comprising sound engineers from various radio stations and broadcasting institutes. Its name, PLoud, derived from a combination of the words "production" and "loudness".The group first developed evaluation and measurement methods to enable the industry to develop appropriate measurement instruments. It drafted a technical document to enable broadcasters and programme producers to change their sound processing to the new recommendation, while another technical document dealt with the procedures to follow in the signal distribution.
Specification
Definitions
To characterize the level and the dynamic range of an audio signal, introduced new units of measurement:Recommendation
recommends normalizing audio at the target level of. This measurement is calculated over the whole duration of the programme and in the entirety of its contents. A deviation of is permitted; when practical limitations prevent to achieve this result, a wider tolerance of is permitted. Furthermore, the whole programme must not exceed the peak level of.To make sure that loudness meters developed by different manufacturers provide the same reading, EBU Tech 3341 defines how to perform the measurement: this standardized method is called and adopts the algorithms introduced with the ITU-R BS.1770 recommendation.
EBU Mode metering
EBU Mode specifies three distinct methods which analyse loudness over three different timeframes:- Momentary, using a sliding time window of 400 ms, best describes the instantaneous loudness;
- Short-term, using a sliding time window of 3 s, describes a more averaged, less event-dependant loudness of the past three seconds;
- Integrated, averaging the programme from start to finish, describes the loudness of the whole programme.
Meter ballistics of real-time meters must provide an update rate of at least for short-term meters and of at least for integrated loudness meters.
Implementation
and have been implemented by several software developers, audio technology companies and content distributors, including Adobe, Apple, Dolby, iZotope, Magix, PreSonus, Sony, Steinberg, TC Electronic, Toyo and Waves.Real-time metering plug-ins aid engineers in their mixing decisions and in delivering -compliant programmes, while broadcasters and content distributors can check and normalize whole programmes by performing a faster-than-real-time analysis; programmes produced before the recommendation are likely to be lowered in volume to match the target level.
Adoption and aftermath
The recommendation encourages the use of a wider dynamic range in production, despite not deprecating employing heavy dynamic compression a priori. In essence, it ties the use of using dynamic compression to artistic and aesthetic decisions, rather than the necessity of obtaining a louder mix. Broadcasters and streaming platforms have been adopting loudness normalization since the introduction of, therefore reducing dynamic range doesn't repay anymore in terms of increased loudness. Widespread adoption of ITU-R BS.1770 and, combined with the prevailing of streaming over physical media distribution in the 2010s, put an end to the loudness war.Starting from 2012, European countries integrated to their audiovisual legislations, and television stations in Europe adopted it on all distribution channels. Sky UK adopted in 2013.
is applicable also to radio programmes and is gradually being introduced in European radio broadcasts: for example, German public broadcaster BR changed its radio programmes at the end of 2015.
Since implementation is not binding, some television stations imposed additional conditions on programme production. For example, Austrian public broadcaster ORF has a limit of for data-reduced formats; Franco-German TV network ARTE has published guidelines for LRA; various broadcasters impose maximum momentary and short-term loudness values for short reports, such as commercials.
Through the 2010s, Internet streaming services have implemented loudness-based normalization, even though each platform uses different methods and target levels: for example, YouTube and Tidal use downward normalization only. Spotify uses ReplayGain to measure loudness, although it is planning to use ITU-R BS.1770, and it has adjusted the algorithm calibration to approximately match the target level. Apple Music activates loudness normalization when the iTunes Sound Check option is enabled.
| Target level | Platform |
| −14 LUFS | Tidal, Amazon Music, YouTube, Spotify |
| −16 LUFS | Apple Music |
| −18 LUFS |