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APTO™ Processing
Higher values (from 2 – 6 LU per second) allow compliance to be achieved more quickly but may introduce
audible gain changes to the average program level in the process. These faster settings are best suited for situations
when input levels are expected to be very inconsistent.
Lower values (from 0.2 to 2 LU per second) provide a subtler and more natural-sounding normalization but may
result in gain changes that are too slow and allow the audio to remain outside of the comfort zone for too long.
Slower settings work well for content that is more consistent and well-controlled. They are also recommended for
long-form content such as feature films or classical music.
Average Maximum Gain
The Average Maximum Gain control (10-2I) sets the maximum amount of positive gain (gain increase)
applied in the Compliance processing stage in order to reach the Target level.
Larger values will allow very soft program segments to be raised by a greater amount, but whether or not this is
desirable must be considered. For instance, some material may have been purposefully kept at a lower level for
dramatic effect, and of course there is always the risk of increasing unwanted background noise.
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 (10-2J) sets the maximum amount of negative gain (gain reduc-
tion) 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 (10-2K) 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.
Chapter 10 | 62
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