ATSC A85 Loudness Compliance

ATSC_Color_LogoA85 Loudness Compliance

A lot of USA-based customers use eFF for Loudness Compliance, but there is often confusion as to the correct settings to fully comply with the ATSC A/85 regulations. This stems from the history of the CALM act, and the story we have heard is that there was political pressure to publish the Act, at a time when those working on the exact text hadn’t had sufficient time to complete their work. Whatever happened, it seemed that A/85 was published before ‘gating’ was introduced into BS1770, which is the basic specification commonly used for Loudness, and that A85 references. So the A85 document wished to use the gating algorithms mentioned in newer versions of BS1770, but the timing of the various publications meant this was not possible.

Our understanding of how to measure and correct to ATSC A85
Eff to includes algorithms based upon the latest versions of BS1770, so gating is available within Eff for A85.
We have also included the optional use of Dolby’s own Dialog Intelligence algorithm. We license the algorithm from Dolby for inclusion in our product.

Delivery specifications needing A85 need to state whether the dialog intelligence algorithm should be used to gate the audio, as the A85 treats dialog intelligence as an option that can be used if required. Note that if you compare measurements made using the dialog intelligence algorithm with measurements made not using this algorithm, the results can often vary by up to 2LU. Therefore it is important that you are consistent in your choice.
Here is a screenshot from Eff showing how we would configure for ATSC A85 measurement.
Here is a screenshot from Eff showing how we would configure for ATSC A85 correction.
For any queries with ATSC A85 loudness compliance, please contact us

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