Axis M3203 用户手册

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AXIS M32 Series - 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. 
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 16:9.
Autoiris (DC-Iris) - This special type of iris is electrically 
controlled by the camera, to automatically regulate the 
amount of light allowed to enter.
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. 
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) - 
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.
DC-Iris (Autoiris) - 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