Glossary
67
Glossary
AE
Auto Exposure, a system for automatically setting the proper exposure
according to the existing light conditions. There are three types of AE
systems: programmed, aperture-priority, shutter-priority
AES
Automatic Electronic Shutter, the sensor will automatically adjust the
sensitivity according to the changes in illumination of detected area.
AF
Auto Focus, an ability by which the camera lens automatically adjusts
its focus on the captured subject.
AGC
Automatic Gain Control, an electronic circuit which amplifies the video
signal when the signal strength falls below a given value due to the
lack the light on the image device.
Auto-iris
A special type of iris, is used to adjust the amount of enter light,
electrically controlled by the camera. There are two main types of auto-
iris: Video-drive and DC-drive iris. See also Video-drive Iris and DC-
drive Iris.
AWB
Automatic White Balance, is used in digital camera to automatically
compensate the type of light (daylight, fluorescent, incandescent, etc.,)
or lighting conditions in the scene. To make it normal for the human
eye.
A
FCC
Federal Communications Commission, is responsible for a
administering the television and radio airwaves, satellite and cable
transmissions, and telegraph communications.
Fixed Iris
Fixed iris lens is one kind of iris and with fixed size iris.
F
Hue
It is an attribute of color and the other two elements are brightness
and saturation. Hue differences depend primarily on the variations of
wavelength and defined by its dominant wavelength.
H
IGMP
Internet Group Management Protocol, is a protocol that manages PCs’
multicast group membership. It provides the membership information
of a PC to a multicast router, which sends out queries periodically to
confirm the status of that PC. A PC can request to join in a specific
group, and when it becomes a member of that group, it will receive
data designated to that group.
I
MAC Address
Media Access Control address, is one unique code assigned to a
networking device. For example, the network card in a computer has
its own MAC address.
M
Optical Zoom
Optical zoom amplify the image size by adjusting the lens. It enlarges
the subject without sacrificing resolution.
O
Proxy Server
A server that provides the service for clients to make indirect network
connections to other network services.
Proxy server will save the previous data or resource in a cache when
the request is made for first. To provide it when the same request is
made again. It could be used to avoid occupying much bandwidth.
P
Saturation
A measurement of chrominance, or the intensity of color in the video
signal.
S
Video-drive Iris
One type of auto-iris, a Video-drive iris lens has an amplified circuit for
converting input video signal to a DC input for the camera.
V
RS-485
RS-485 is an electrical specification of a two-wire, half-duplex,
multipoint serial connection. It supports high data transmission speeds
and uses a different balanced line over twisted pair. It also spans large
distances.
RTCP
Real-Time Control Protocol, is used to monitor the session. It is mainly
used to feed the streaming server with reception statistics from the
client. The server may then decide to use these statistics (such as the
numbers of lost packets, the delay from reception) to adapt its strategy.
RTP
Real-Time Transport Protocol, is the protocol used to transport the
multimedia stream to the client. It sends a packet to the network but
cannot warrant that the packet will reach its destination.
R
Bit Rate
A unit of speed, defines the number of bits/time unit, usually expressed
in Kbit/s or Mbit/s.
B
CE
Consultants Europe, is a Technical and Legal organization specialized
in the CE marking, CE certification and Authorized Representation of
products.
Codec
Codec stands for Coder/ Decoder, which converts analog video and
audio signals into a digital format for transmission. The codec also
converts received digital signals back into analog format.
Contrast
Contrast is usually defined as a ration between the darkest and the
brightest posts of an image in image processing Images have a higher
contrast level generally display a greater degree of color grayscale
variation than those of lower contrast.
C
DC-drive Iris
One type of auto-iris, will automatically adjust the amount of light
allowed to enter. It requires simply a DC input from the camera without
signal converted.
Digital Zoom
Digital zoom takes part of the image and expends it. The resulting
image appears bigger but not as sharp as with an optical zoom.
D-SUB
D-SUB is used to indicate the type of connector for the VGA interface.
D
Frame Rate
The rate at which video frames are displayed on a monitor per second.
Frame rate for PAL is 25 fps, and frame rate for NTSC is 30 fps.
Summary of Contents for IP Surveillance
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