A Word About Density, Clarity, And Intelligibility; Quality Versus Density - Omnia ONE Installation And Operation Manual

If you believe that you're in a density war and you feel a need to react, we can provide some suggestions that should
help. Conversely, if you have the luxury to strive for increased sound quality, we've got suggestions for you too!
There will always be a subjective compromise whenever there is a desire to shift the processing priority from the
highest quality setting to those generating the highest loudness.
Omnia.ONE Multicast has been designed to minimize the trade-offs between quality and loudness, and we
recommend that before starting the process of cranking it up, try to determine beforehand what sonic characteristics
might be lacking.
In many cases it's not just about increasing the drive to the limiters. Instead, it can be as non-intuitive as creating the
illusion of greater loudness by changing something simple – like a time constant. Sometimes the old adage of less is
more really applies!
Please give the following content some thought as it may assist you in developing an overall fine-tuning plan if you
feel changes beyond our factory presets are justified.

A Word About Density, Clarity, and Intelligibility

Processing for the coded audio world is quite a bit different than what is done for FM-Stereo and AM. There are two
significant differences, and both impact the overall sound of a coded transmission: First, there is no pre-emphasis
network in coded audio. Second, clipping should never be used for peak control.
In conventional broadcast applications the method of clipping that was used contributed substantially to the quality
vs. loudness tradeoff – it was a fairly simple two-way tug of war.
In the coded domain the tradeoff is much different - it becomes a three-way tug of war between quality, loudness,
and audible artifacts. Using the rules for conventional processing will cause trouble in a coded audio environment.
Why? Because Codecs complain. And they complain in the form of nasty and objectionable artifacts when harmonic
or intermodulation (IMD) distortion is presented to their input. In fact, dynamic peak limiters employing extremely
fast time constants (which generates a form of program-dependent IMD) can easily cause serious trouble for a
codec.

Quality Versus Density

The primary trade-off between quality and artifacts will be located within the processor's limiter sections. With
increased depth of limiting, intermodulation distortion increases and the 'fast' activity of the limiters causes the
audio to sound "tight" or "squashed". If limiting is taken to the extreme, the sound can be perceived as "pumping,"
"breathing," "dense," or "mushy." It can even induce exaggerated "swish/swirl" artifacts from the codec.
Please remember that the core objective of the Omnia.ONE Multicast product is maximum intelligibility at low
bitrates and processing that creates heavy density can completely mask that effort. A codec provisioning processor is
in quite a different role than a conventional on-air processor. It is far more of a tool than a weapon.
The following sections are provided to assist you in designing the personality of your sound. As we said earlier,
there is no precise recipe for setting up audio processing because each application is different. However there are a
few basics that we can share with you that can help get you to where you want to go. Setting up processing for the
absolute best end product usually requires a concerted effort, some extended periods of critical listening, and making
a few intelligently chosen and subtle changes over time. It will be time and effort well spent, and all you need to
know up front is that you must:
 Know your goals (have a plan).
 Take your time.
 Always adjust deliberately and methodically.
 Listen critically before making more adjustments.
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