Glossary
© 2013 Harmonic Inc.
401
Ellipse 3000 r.3.0, Rev. B
VBR
Variable bit rate. Programs encoded at a variable bit are part of a statistically multiplexed pool
(see
) of programs. Each program in the pool has a set minimum
and maximum bit rate, and the encoder determines the best bit rate for the program based
on its complexity and the available bandwidth in the pool.
VC
V
irtual Channel. A logical communications channel that provides sequential unidirectional
transport of
cells.
VCC
Virtual Channel Connection. A concatenation of VCs that extends between the points where
the
service users access the ATM layer. The endpoints of a VCC are the points at which
the ATM cell payload is passed to, or received from, the users of the ATM Layer (such as the
adaptation point of datagrams or TS packets into ATM cells) for processing. VCCs are
unidirectional.
VCI
Virtual Channel Identifier. A unique numerical tag of a
. It is defined by a 16-bit field in
cell header that identifies the virtual channel over which the cell is to travel.
VI
Video Index. A signal defined by SMPTE 125 for Standard Definition digital video only. Use
standardized by SMPTE RP186:2008. SMPTE has deprecated this signal in favor of the use of
VANC which is applicable to HD as well as SD digital.
VIA
Video Input Adapter. Accepts either composite or digital video and generates digital video
components for Harmonic SD DiviCom encoders.
VOD
Video On Demand.
VP
Virtual Path. A group of
s that provides the sequential unidirectional transport of
VPC
Virtual Path Connection. A concatenation of VPs. Analogous to a VCC, but at the VP layer.
VPCs are unidirectional.
VPI
Virtual Path Identifier. A unique numerical tag of a
. An eight-bit field (on the
cell header that indicates the virtual path over which the cell should be routed. The
VPI logically divides the cable into one or more virtual paths. Each virtual path can have its
own bandwidth limitation.
