Input M Enu - U Ndo; What I S U Ndo - Omnia .9 Installation And Operation Manual

Input M enu – U ndo
What E xactly I s U ndo?
In o rder t o u nderstand h ow t o b est u se U ndo, i t i s h elpful t o u nderstand e xactly w hat i t i s a nd h ow i t
works. Undo is actually two separate processes -­‐ a de-­‐clipper and a multiband expander – which
work together to "undo" the poorly mastered, hyper-­‐compressed and clipped audio found on so
many modern CD's. (Note: The de-­‐clipper works most effectively when using Omnia.9's digital
inputs. R egardless o f w hether y our u se a n a nalog o r d igital i nput, t he i ncoming a udio s hould n ot b e
equalized o r p re-­‐processed i n a ny w ay).
Take a look at the two waveforms below, captured using Omnia.9's built-­‐in oscilloscope. The top
window shows the unprocessed source audio. The bottom window shows the same audio after it
has passed through the de-­‐clipper. Notice how the peaks that were clipped during mastering have
been restored by the de-­‐clipper. (Note: The oscilloscope gain was kept at the same level for
comparison p urposes, b ut O mnia.9 h as s ufficient i nternal h eadroom, a nd t his i llustrations t hat f ollow
do n ot s uggest t hat t he a udio i s b eing c lipped a gain b y a ny p ortion o f " Undo").
The second stage of Undo is a multi-­‐band expander that is designed to restore dynamic range to
audio that has been excessively compressed. Each of the five bands of the expander has a
corresponding psychoacoustic dynamics detector and a peak detector that examine the peak levels
of the incoming audio, and based upon that information plus the settings of the various controls,
tells t he e xpander h ow m uch d ynamic r ange t o r estore t o t he a udio.
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