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Advanced Processing Controls
Another unwanted byproduct of setting this control too high - especially with profiles that use a lower Adaptation value – is
that it can result in APTO taking too long to lower levels when loud content immediately follows soft content, such as when a
loud commercial follows a quiet passage from a TV drama, as it will take longer to reduce a greater amount of gain.
For these reasons, it is advisable to set the Average Maximum Gain for no more than 2 LU.
One way to enhance the efficiency of the processing across programs is reset APTO at the transition point, which will in turn
reset the amount of average gain or attenuation being applied and allow each individual program element to be optimally
processed from the beginning.
Average Maximum Attenuation
The Average Maximum Attenuation control (L) sets the maximum amount of negative gain (gain reduction) applied in the
Compliance processing stage in order to reach the Target level.
Larger values will allow loud program segments to be reduced by a greater amount. However, setting this control too high
– again, especially with profiles that use a lower Adaptation value - can cause APTO to take too long to raise levels when soft
content immediately follows something loud, such as when transitioning from a loud commercial back to a quiet TV drama, as
it will take longer to boost a greater amount of gain.
Just as with the Average Maximum Gain control, resetting APTO at the start of each program segment can help minimize such
issues and optimize overall processing for each individual program segment.
Compliance Window
The Compliance Window control (J) adjusts the size of the sliding time window used in the Compliance processing stage to
align the output program to the target level. It is similar to the rolling integration time on an LKFS/LUFS loudness meter.
Note:
The Compliance Window setting only applies to profiles that do not use Dialog Normalization. Profiles that
do use Dialog Normalization rely upon the settings of the Dialog Compliance control to determine their
time window.
Many factors can influence whether or not content at the output of ARC is compliant. These include the level consistency of
the incoming audio, program duration, the difference between the average input level and the Target level, the amount of
Adaptation employed, and the settings of many of the controls listed in this chapter.
That said, a smaller compliance window value more easily delivers a compliant output for shorter program durations, but can
produce more variations in long-term programming.
On the other hand, a larger compliance window value will allow for a smoother and more consistent average overall for longer
program durations, but can reduce the effectiveness of short-term normalization, especially program elements shorter in
duration than the compliance window.
For short-term programs, a value in the range of 20-30 seconds is recommended. Larger values, from 60-120 seconds, are
recommended for mid- to long-form content. For profiles which rely upon Dialog Normalization, a setting between 120-180
seconds is highly recommended.
Chapter 9 |
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