Glossary of terms – Axis Communications 215 PTZ-E User Manual
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AXIS COMMUNICATIONS
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AXIS 215 PTZ/ AXIS 215 PTZ-E - Glossary of Terms
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 (Autofocus) - 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." GIFs
and JPEGs 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 the other. A