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APTO™ Processing
Adaptive Input Percentage
When the Adaptive Input Detection control (located in the Basic section) is enabled, the Dynamic Range
processing section of APTO dynamically adapts the amount of processing depending upon the actual measured
average level at the input. The degree to which the actual input levels influence the processing versus relying upon
the value of the Average Input Level control (10-2L) is determined by the Adaptive Input Percentage control
(10-2E).
The recommended setting to start is 50% in order to keep the effect of adaptation more consistent.
Foreground Sounds Coefficient
All programming has what is sometimes referred to as an "anchor element," that is, the audio content to which
the viewer will pay the most attention. This is typically (though not always) dialog. This is also referred to as
"foreground" audio to differentiate it from background audio, or in some cases, noise.
The Foreground Sounds Coefficient control (10-2F) sets the level in the Dynamic Range processing stage at
which program audio is no longer considered a foreground sound relative to both the lower border as set by the
Null Area Coefficient control (10-2G, described in detail below) and a minus infinite level (full silence) on a
proportional scale.
For example, if the Target level is set to -23dB LUFS, the Null Area Coefficient is set to 4, and the Foreground
Sounds Coefficient is set to 2, any audio between -27 and -25dB will be deemed foreground audio and therefore
be raised toward the target.
Audio at levels lower than -27dB will still be increased toward the target, but the degree to which gain is increased
slows down considerably. The lower the audio is from -27dB, the less the gain will increase.
Null Area Coefficient
The primary goal of APTO processing is to deliver a consistent average output level as set by the Target Level
control. This does not mean, however, that the actual output audio level must never deviate from this value. In
fact, a certain amount of dynamic range helps preserve the artistic integrity of the original programming and
makes for a more engaging audio experience for the viewer.
One of the things that makes APTO different from traditional processing is its ability to "do nothing" to audio
levels when no action is required to maintain the correct average output level. This avoids the "busy" sound of
traditional compressors and ACGs which by their very nature are always operating either over or under a thresh-
old, and therefore always increasing or decreasing gain - often for no good reason.
The Null Area Coefficient control (10-2G) sets the lower and upper thresholds that together determine the size
of the window in which APTO's Dynamic Range processing stage neither increases nor decreases gain, with the
user-determined Target level sitting in the middle of the range. Values are in dB, with larger values resulting in a
larger "do nothing" window.
Compliance Speed
How quickly gain changes are made in the Compliance processing stage are largely program dependent. However,
the maximum rate at which the gain can increase or decrease is set by the Compliance Speed control (10-2H).
The rate is calibrated in dB (or LU) per second.
Chapter 10 | 61
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