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Dolby® Encoding and Monitoring
Loudness Practice
The AC-4 codec includes integrated loudness management via the Dolby Real Time Loudness Leveler. RTLL
normalizes the incoming audio signal prior to encoding. Presets provided in the Loudness Practice control (7-1F)
for the following regulations:
EBU R 128: Used primarily in Europe, audio is normalized to a target of -23dB LUFS as calculated over the
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entire duration of a program (integrated loudness) and without regard for isolating and measuring dialogue;
it specifies a deviation of +/- 0.5LU and a peak level below -1dBTP
ATSC A/85: Used in the United States and serving as the foundation and reference for the CALM Act; when-
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ever possible, the anchor element of the audio (typically dialogue) should be measured and normalized to a
target of -24dB LKFS, +/- 2dB which is accomplished here by enabling the dialogue intelligence feature
ARIB TR-B32: The Japanese broadcast standard which uses a relative gate (per ITU BS 1770-2, like EBU R
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128) but with a target loudness level of -24 LKFS and a maximum True Peak of -1dB.
Free TV OP-59: Used in Australia, this standard is based on the previous OP-48 regulations (which
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measured VU and digital peak levels and required a target level of -20dBFS) but instead measures average
perceived loudness using ITU-R BS 1770-3 with a target of -24dB LKFS and a maximum True Peak of -2dB.
Setting the control to "Manual" allows the target loudness value to be manually set with the Dialogue
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Normalization control.
Dialogue Normalization
When using one of the pre-defined Loudness Practice profiles, the Dialogue Normalization control (7-1D) is
set to "Auto" and grayed out, and dialogue normalization will be enabled or disabled per the selected profile. When
the Loudness Practice is set to "Manual", a specific loudness target can be set.
In addition, the Dialogue Intelligence control – described below in the "Advanced" menu section – can be turned
on or off.
Language
While the AC-4 codec supports the delivery of content in multiple languages, the primary language must be
identified using the language dropdown menu (7-1E).
Chapter 7 | 32
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