Axis Communications AXIS FD-R M12 - Manual (Page 41)

41 AXIS 209FD/FD-R/FD-R M12
Glossary of Terms
ActiveX - A standard that enables software components to interact
with one another in a networked environment, regardless of the
language(s) used to create them. Web browsers may come into
contact with ActiveX controls, ActiveX documents, and ActiveX
scripts. ActiveX controls are often downloaded and installed
automatically as required.
AF (Auto focus) - A system by which the camera lens automatically
focuses on a selected part of the subject.
Angle - The field of view, relative to a standard lens in a 35mm still
camera, expressed in degrees, e.g. 30°. For practical purposes, this is
the area that a lens can cover, where the angle of view is determined
by the focal length of the lens. A wide-angle lens has a short focal
length and covers a wider angle of view than standard or telephoto
lenses, which have longer focal lengths.
ARP (Address Resolution Protocol) - This protocol is used to
associate an IP address to a hardware MAC address. A request is
broadcast on the local network to discover the MAC address for an IP
address.
ARTPEC (Axis Real Time Picture Encoder) - This chip is used for
image compression.
ASIC (Application Specific Integrated Circuit) - A circuit designed
for a specific application, as opposed to a general purpose circuit,
such as a microprocessor.
Aspect ratio - A ratio of width to height in images. A common aspect
ratio used for television screens and computer monitors is 4:3.
High-definition television (HDTV) uses an aspect ratio of 9:16.
Autoiris (or DC-Iris) - This special type of iris is electrically
controlled by the camera, to automatically regulate the amount of
light allowed to enter.
AVI (Audio Video Interleave) - A video format that supports
simultaneous playback of audio and video.
Bitmap - A bitmap is a data file representing a rectangular grid of
pixels. It defines a display space and color for each pixel (or “bit”) in
the display space. This type of image is known as a “raster graphic.”
GIF's and JPEG's are examples of image file types that contain
bitmaps.
Because a bitmap uses this fixed raster method, it cannot easily be
rescaled without losing definition. Conversely, a vector graphic image
uses geometrical shapes to represent the image, and can thus be
quickly rescaled.
Bit rate - The bit rate (in kbit/s or Mbit/s) is often referred to as
speed, but actually defines the number of bits/time unit and not
distance/time unit.
Bluetooth - Bluetooth is an open standard for wireless transmission
of voice and data between mobile devices (PCs, handheld computers,
telephones and printers).
Bonjour - Also known as zero-configuration networking, Bonjour
enables devices to automatically discover each other on a network,
without having to enter IP addresses or configure DNS servers.
Bonjour is a trademark of Apple Computer, Inc.
Broadband - In network engineering terms, this describes
transmission methods where two or more signals share the same
carrier. In more popular terminology, broadband is taken to mean
high-speed data transmission.
CCD (Charged Coupled Device) - This light-sensitive image device
used in many digital cameras is a large integrated circuit that
contains hundreds of thousands of photo-sites (pixels) that convert
light energy into electronic signals. Its size is measured diagonally
and can be 1/4”, 1/3”, 1/2” or 2/3”.
CGI (Common Gateway Interface) - A specification for
communication between a web server and other (CGI) programs. For
example, a HTML page that contains a form might use a CGI program
to process the form data once it is submitted.
CIF (Common Intermediate Format) - CIF refers to the analog video
resolutions 352x288 pixels (PAL) and 352x240 pixels (NTSC). See
also Resolution.
Client/Server - Client/server describes the relationship between two
computer programs in which one program, the client, makes a service
request from another program, the server, which fulfils the request.
Typically, multiple client programs share the services of a common
server program. A web browser is a client program that requests
services (the sending of web pages or files) from a web server.
CMOS (Complementary Metal Oxide Semiconductor) - A CMOS is a
widely used type of semiconductor that uses both negative and
positive circuits. Since only one of the circuit types is on at any given
time, CMOS chips require less power than chips using just one type of
transistor. CMOS image sensors also allow processing circuits to be
included on the same chip, an advantage not possible with CCD
sensors, which are also much more expensive to produce.
Codec - In communications engineering, a codec is usually a
coder/decoder. Codecs are used in integrated circuits or chips that
convert e.g. analog video and audio signals into a digital format for
transmission. The codec also converts received digital signals back
into analog format. A codec uses analog-to-digital conversion and
digital-to-analog conversion in the same chip.
Codec can also mean compression/decompression, in which case it is
generally taken to mean an algorithm or computer program for
reducing the size of large files and programs.
Compression - See Image Compression.
Contrast - Defines the degree of difference between the lightest and
darkest parts of an image or video stream.
DC-Iris - This special type of iris is electrically controlled by the
camera, to automatically regulate the amount of light allowed to
enter.
DHCP (Dynamic Host Configuration Protocol) - DHCP is a protocol
that lets network administrators automate and centrally manage the
assignment of Internet Protocol (IP) addresses to network devices in a
network.
DHCP uses the concept of a “lease” or amount of time that a given IP
address will be valid for a computer. The lease time can vary,
depending on how long a user is likely to require the network
connection at a particular location.
DHCP also supports static addresses for e.g. computers running web
servers, which need a permanent IP address.
DNS (Domain Name System) - DNS is used to locate and translate
Internet domain names into IP (Internet Protocol) addresses. A
domain name is a meaningful and easy-to-remember name for an
Internet address. For example the domain name www.example.com is
much easier to remember than 192.0.34.166. The translation tables
for domain names are contained in Domain name servers.
Domain Server - Domains can also be used by organizations who
wish to centralize the management of their (Windows) computers.
Each user within a domain has an account that usually allows them
to log in to and use any computer in the domain, although
restrictions may also apply. The domain server is the server that
authenticates the users on the network.
Duplex - See Full-duplex.
Ethernet - Ethernet is the most widely installed local area network
technology. An Ethernet LAN typically uses special grades of twisted
pair wires. The most commonly installed Ethernet systems are
10BASE-T and 100BASE-T10, which provide transmission speeds up
to 10 Mbps and 100 Mbps respectively.
ETRAX (Ethernet Token Ring AXIS) - Axis' own microprocessor.
Factory default settings - These are the settings that originally
applied for a device when it was first delivered from the factory. If it
should become necessary to reset a device to its factory default
settings, this will, for many devices, completely reset any settings that
were changed by the user.
Firewall - A firewall works as a barrier between networks, e.g.
between a Local Area Network and the Internet. The firewall ensures
that only authorized users are allowed to access the one network from