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Chapter 7 |
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An Introduction to APTO™
7
An Introduction to APTO™
But First, a Word on Television Loudness
The introduction of compliance regulations and an overall increased awareness of television loudness control have generally
been successful in taming the wild loudness shifts that startled and annoyed viewers in the earlier days of digital television.
Real-time processing is ubiquitous and effective, content creators now have a better understanding of how viewers watch
(and listen to) their programs, and broadcasters have the necessary tools at their disposal to analyze and, if necessary, correct
pre-recorded programs upon ingest in the file domain.
That being said, there are still some misconceptions about loudness control and regulations being repeated as fact, and when
applied, are nearly always to the detriment of the audio.
Speaking in the most general terms, most loudness regulations specify an average audio level for each program segment . Some
are based on the loudness of the entire mix, while others are based on only an anchor element such as dialogue.
In either case, the regulations do not dictate that the audio be devoid of dynamic range nor do they mandate that levels
constantly stay at the target value so that your LKFS/LUFS meter looks more like an FM modulation monitor at a major market
radio station. Soft passages are allowed to stay soft and loud passages are permitted to pass through generally unaltered, so
long as the average over the duration of the program segment is maintained and, where applicable, True Peak values are not
exceeded.
Just like audio can be over-processed, it can also be under-processed. Trying to watch a sporting event in a noisy bar or
restaurant (or even the average living room) would be frustrating if presented with the amount of dynamic range appropriate
for a cinematic presentation in a high-end, multi-channel home theater.
The proper balance is found in what is commonly called the “comfort zone,” that is, the range in which the viewer never strains
to hear lower level programming yet is never annoyed by excessively loud levels. This is sometimes described as the situation in
which the viewer never feels the need to reach for the volume control on their television, mobile phone, or tablet.
What Is APTO?
The audio processing within ARC is performed by Linear Acoustic® APTO™, our latest and most advanced adaptive loudness
control algorithm to date.
APTO ensures that ARC can deliver audio that is compliant with various television broadcast regulatory loudness standards including
EBU R128, ATSC A/85, FreeTV OP59, ARIB TR-B32, and AGCOM 219/09/CSP as well as the AES-TD1006 streaming standard.
It also includes profiles for other non-broadcast delivery platforms and listening environments such as gaming, movies, earphones,
and in-flight entertainment.
APTO enhances the listening experience by providing consistent audio levels within a user-defined “comfort zone”, thus
eliminating listener annoyance due to sudden loudness shifts. It also improves dialogue intelligibility, addressing one of the
most common complaints with television audio. Best of all, it does so without audibly affecting the sound quality and artistic
intent of the original content.