EBU R 128 s4: What It Means, And How To Implement It Today

By Clark Novak on Nov 16, 2023 5:34:05 PM

Dialog Intelligibility Gets A Big Boost With New Recommendation

“Hey, Turn That Down!”
You’ve experienced the problem: you set your TV volume at a level that’s comfortable for listening to the characters talk, only to grab the remote and frantically hit the “down” button when the action starts. Or, vice-versa: a volume level that's comfortable during loud scenes is too low for scenes with conversational dialog. Well, the latest update to the European Broadcasting Union’s R 128 recommendation, issued on November 10, 2023, takes us one step closer to solving the problem.

"Hey! Turn that down!"

EBU R 128 comprises a detailed set of documents that address many technical situations, but if one were to boil it down to its essence, it would be that R 128 recommends a target overall loudness level of -23 LUFS for broadcast content to help ensure consistent audio levels regardless of program or channel. But this approach didn't consider the effect of applying a linear loudness normalization on the dialog level, particularly for cinematic content where audio is typically mixed with a higher dynamic range.

The New Recommendation
Supplement 4 (a/k/a R 128 s4), the newest revision published in November 2023, takes aim directly at this issue of dialog intelligibility. It is of particular interest to both OTA and streaming broadcasters since it elevates the guidelines detailed in EBU Technical Document 3343 to official status as part of the R128 recommendation.

To put this into context, consider that it is rather common for cinematic mixes to have dialog mixed to a level 10 to 15 LU below the overall program loudness. Contrast this to something like a documentary or a made-for-TV drama, where the dialog level will be mixed much closer to the overall loudness, and you can see how, even with R 128 compliant audio, there will still be potentially large jumps in dialog level when moving between channels or between the feature presentation and the commercials. 

R 128 s4 addresses this issue by requesting that the "loudness-to-dialog ratio" of cinematic content be reduced to no greater than 5 LU. The EBU PLOUD team have determined that this will help keep viewers from wearing out the keys on their remotes, provide greater consistency between different TV genres, and improve dialog intelligibility overall.

Compliance, Now
Luckily, broadcasters have a way to be R 128 s4 compliant immediately, using Minnetonka Audio® AudioTools Server, the state-of-the-art file-based audio processing software specifically developed to address loudness control issues for OTT, cable, satellite, terrestrial and IPTV, radio, and post-production facilities.

AudioTools Server

In fact, AudioTools Server’s optional Advanced Loudness Adaptation module provides the exact tools needed to comply with R 128 s4, including the ability to define the maximum difference between the overall program and dialog loudness levels - and has had these tools for over 10 years. If you’re already an AudioTools Server user, you already have access to the tools you need to be compliant with R 128 s4!

If you’re not an AudioTools Server user (or if you are but haven’t yet taken advantage of the capabilities of the Advanced Loudness Adaptation module), we invite you to download our free white paper, “The Challenge Of Dialog Across Modern Platforms” - then contact the Telos Alliance team to find out how you can be R 128 s4 compliant right now with Minnetonka AudioTools Server as part of your workflow.

For further reading about EBU R 128, you can download all the relevant publications at tech.ebu.ch/loudness.

Topics: TV Loudness Management, Audio Loudness, Automation, Television Audio, Minnetonka Audio, Audio Tools Server

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