The EBU has published version 2.0 of its Loudness Guidelines for distribution and reproduction (EBU Tech 3344). The document has been completely rewritten and updated. The new guidelines are easier to read, as they have been halved in size (-3dB technically speaking), but without losing any of their power.
Guaranteeing quality
The main aim of EBU Tech 3344 is to make sure the quality of the audio provided by broadcasters is kept all along the chain. In today's multimedia world, programme audio can travel many paths and be subject to many changes along the way. EBU Tech 3344 arguably is the only document in the industry that provides a complete overview of how audio signals flow from studio via distributors to consumer devices such as IRDs, televisions, radios and media players. It covers audio levels in anything from legacy SCART outputs to the latest AC-4 and MPEG-H compression systems and includes checklists to help ensure compliance.
Important new information in this version includes:
- Inclusion of AC-4 and MPEG-H;
- How handle DRC for various codecs, including 'presentation mode' for MPEG-4 AAC & HE-AAC;
- Details on how to handle mono audio presented on stereo and multi-channel outputs;
- Updated FM alignment, better corresponding with FM networks based on 0 dBr MPX power;
- Automatic loudness matching in combined FM radio and DAB/DAB+ receivers;
- Down-mix advice to avoid arbitrary reproduction and to reduce loudness variances between consumer devices;
- Advice on loudness normalisation in mobile devices such as Personal Music Players;
Features that have become optional:
- Active normalisation in the distribution stage is now optional and meant to correct severe deviations only;
- Use of HDMI E-EDID is now optional, which increases acceptability for some manufacturers;
- Support for -27 LUFS referenced devices is now optional;
For more information on loudness, visit tech.ebu.ch/loudness