Polycom C12, C16, C8, SR12 - page 54

Design Guide for the Polycom SoundStructure C16, C12, C8, and SR12
3 - 10
Virtual Channels
A virtual channel can be thought of as a layer that is wrapped around one or
more physical channels. A virtual channel can represent either an individual
physical channel or it can represent a collection of strongly associated physical
channels, such as a stereo pair of signals as shown in the following figure.
Virtual channels are created by specifying a virtual channel name, one or more
physical channels, and a type of virtual channel. Once defined, the virtual
channel name becomes the primary way of referring to that particular input or
output instead of using the physical channel number. For example, an A/V
designer could define the virtual channel “Podium mic” that is connected to
input physical channel 9 as conceptualized in the next figure. From then on,
any settings that need to be adjusted on that input would be adjusted by
controlling the virtual channel “Podium mic”. The association between the
virtual channel and the underlying physical channel or channels means that
you can think of virtual channels as describing how the system is wired.
The main benefit of virtual channels is that once a SoundStructure design is
created and the virtual channels have been defined, it is possible to change the
particular physical input or output used by moving the physical connection on
the rear-panel of the SoundStructure device and redefining the virtual channel
to use the new physical input or output that is used. Because any control
system code must use the virtual channel name, the control source code does
not have to change even if the actual wiring of the physical inputs or outputs
change. By using virtual channel names the controller code controls (for
SoundStructure
Studio
Control
System
V
i
r
t
u
a
l
C
h
a
n
n
e
l
Physical
Channel
SoundStructure
Studio
Control
System
V
i
r
t
u
a
l
C
h
a
n
n
e
l
Physical
Channel
Left
Physical
Channel
Right
“
P
o
d
i
u
m
m
i
c
”
Input 9
popo
The virtual channel name is case-sensitive and needs to have the quotes around
the text. “Podium mic”, “Podium Mic”, and “PODIUM mic” would represent different
virtual channels.