Harmonic ProView 7000 User Manual page 227

Glossary
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Numerics A B
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URL
Uniform Resource Locator.
USB
Universal Serial Bus.
UTP
Unshielded Twisted Pair.
V
VAM
Video Access Manager.
VANC
Vertical Ancillary data space. During the vertical interval of each field or frame, the ancillary data
space located between SAV and EAV markers. Digital information can be transmitted efficiently
in VANC (as opposed to VBI), since only the direct bits are sent. There are SMPTE standards
documenting the carriage of most services originally carried in VBI.
VBI
Vertical Blanking Interval. This is the space between the end of the vertical synchronization pulses
and start of the active video (lines 10 to 21 for
information can be transmitted during this time when encoded as waveforms. Examples of
signals transmitted in the VBI include teletext, AMOL, and CEA-608 closed captions.
VBR
Variable bit rate. Programs encoded at a variable bit are part of a statistically multiplexed pool
(see
Statistical Multiplexing Pool
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
Virtual Channel. A logical communications channel that provides sequential unidirectional
transport of
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
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
the cell header that identifies the virtual channel over which the cell is to travel.
ATM
© 2011 Harmonic Inc.
C D E F
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Q R S T
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) of programs. Each program in the pool has a set minimum and
cells.
ATM
G H I J
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U V W Y
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, and lines 6 to 22 for
NTSC
. It is defined by a 16-bit field in
VC
227
L M N O
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). Digital
PAL
ProView 7000 v.2.4, Rev. A
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