22
repr
esenting the input audio) causing the sonic artifacts generated by the process to continually change. Unless the audio
processor can predict these changing characteristics of the codec, it can’t possibly create output audio that is perfectly
tailored for the coding process.
Conventional processors utilize rather simplistic high frequency limiters and fixed low pass filtering that does not change
with the program material. When these less intelligent processors feed a codec the audio might sound acceptable one
moment and offensive the next. Because they cannot “know” what the codec will do next, the result is over
-compensated,
dull and lifeless audio… audio that
still
contains objectionable codec-generated artifacts!
Omnia ONE
Multicast and HD
Radio
The a
dvent of HD Radio
R
has introduced the capability to transmit multiple program streams, or “Multicast”, within a
single 96kbps digital broadcast data channel. To facilitate this, multicast relies on the use of codecs with comparatively low
bitrates. A broad
caster can choose to transmit a number of multicast channels and select the bitrate for each one. However,
the more multicast channels there are, the lower the bitrate each channel must have in order for them to all fit within the
total available bandwidth.
In the very near future, many low bitrate multicast audio channels might exist. To achieve maximum sound quality,
the
kind that attracts and holds listeners
, those channels will need specialized dynamics processing capable of creating great
sound
regardless
of program content and bitrate. They will need
Sensus
.
Omnia ONE Multicast was designed from the ground up for provisioning audio for codecs operating at these low bitrates.
With
Sensus
, the innovative algorithm inside Omnia ONE Multicast, it is now possible to have consistently high audio
quality with a minimum of codec-induced artifacts. Omnia ONE Multicast creates highly listenable audio lacking the dull,
muffled, ‘swirley’ sound usually associated with codecs operated at extremely low bitrates.
So… what’s so smart about Sensus
?
The fact is,
Sensus
is smart. In real time it predicts program content that will be troublesome for the codec, and by
modifying it’s own algorithms can make appropriate changes to the program material before it ever reaches the codec!
1
The result is consistently high audio quality through a codec-based system, even at very low (18kbps –
21kbps) bitrates.
The human voice is very difficult to code at low bitrates without quality and intelligibility suffering. But Omnia ONE
Multicast with
Sensus
can generate clean, smooth, crystal clear audio that’s consistently great sounding no matter what
the codec or bitrate is.
--- Important Note ---
1
It is
extremely
important to never directly audition the output of the Omnia ONE Multicast for audio quality without the
audio being first routed through a codec!
Why?
The processed output of the Omnia ONE Multicast has been ‘pre-corrected’ for the characteristics of the following codec
and because of this the audio may contain strange sounding artifacts that will imitate the ‘inverse’ of what that codec will
do. Because of this the audio exiting the Omnia ONE Multicast may be unpleasant to listen to and will certainly be inferior
to that which will exit the codec later on.
In other words, what you hear at the output of the Omnia ONE Multicast will bear no relationship to the audio quality that
will be achieved
after
the audio has passed through the coding process!
Need a corollary to this?
