User`s manual

64
AXIS 216FD/FD-V/MFD/MFD-V - Glossary of Terms
on the 2.4 GHz band, while 802.11a allows up to 54 Mbit/s
on the 5 GHz band.
Image compression - Image compression minimizes the file
size
(in bytes) of an image. Two of the most common
compressed image formats are JPEG and GIF.
Interlacing - Interlaced video is video captured at 50
p
ictures (known as fields) per second, of which every 2
consecutive fields (at half height) are then combined into 1
frame. Interlacing was developed many years ago for the
analog TV world and is still used widely today. It provides
good results when viewing motion in standard TV pictures,
although there is always some degree of distortion in the
image.
To view interlaced video on e.g. a computer monitor, the
vid
eo must first be de-interlaced, to produce progressive
video, which consists of complete images, one after the
other, at 25 frames per second. See also Progressive scan.
IP (Internet Protocol) - The Internet Protocol is a method
transmi
tting data over a network. Data to be sent is divided
into individual and completely independent "packets." Each
computer (or host) on the Internet has at least one address
that uniquely identifies it from all others, and each data
packet contains both the sender's address and the receiver's
address.
The Internet Protocol ensures that the data packets all arrive
at the intende
d address. As IP is a connectionless protocol,
which means that there is no established connection
between the communication end-points, packets can be sent
via different routes and do not need to arrive at the
destination in the correct order.
Once the data packets have arrived at the correct
de
stination, another protocol - Transmission Control
Protocol (TCP) - puts them in the right order. See also TCP.
IP Address - An IP address is simply an address on an IP
ne
twork used by a computer/device connected to that
network. IP addresses allow all the connected
computers/devices to find each other and to pass data back
and forth.
To avoid conflicts, each IP address on any given network
must be uniq
ue. An IP address can be assigned as fixed, so
that it does not change, or it can be assigned dynamically
(and automatically) by DHCP.
An IP address consists of four groups (or quads) of decimal
dig
its separated by periods, e.g. 130.5.5.25. Different parts
of the address represent different things. Some part will
represent the network number or address, and some other
part will represent the local machine address.
See also IP (Interne
t Protocol).
I-VOP - See VOP.
JPEG (Joint Photographic Experts
Group) - Together with
the GIF file format, JPEG is an image file type commonly
used on the web. A JPEG image is a bitmap, and usually has
the file suffix '.jpg' or ".jpeg." When creating a JPEG image,
it is possible to configure the level of compression to use. As
the lowest compression (i.e. the highest quality) results in
the largest file, there is a trade-off between image quality
and file size.
kbit/s (kilobits per second) - A measure of the bit rate, i.e.
the
rate at which bits are passing a given point. See also Bit
rate.
LAN (Local Area Network) - A LAN is a group of
computers and associate
d devices that typically share
common resources within a limited geographical area.
Linux - Linux is an open source operating system within
the
UNIX family. Because of its robustness and availability,
Linux has won popularity in the open source community
and among commercial application developers.
MAC address (Media Access Control address) - A MAC
address is a unique
identifier associated with a piece of
networking equipment, or more specifically, its interface
with the network. For example, the network card in a
computer has its own MAC address.
Manual iris - This is the opposite to an autoiris, i.e. the
came
ra iris must be adjusted manually to regulate the
amount of light allowed to reach the image sensor.
Mbit/s (Megabits per second) - A measure of the bit rate,
i.e.
the rate at which bits are passing a given point.
Commonly used to give the "speed" of a network. A LAN
might run at 10 or 100 Mbit/s. See also Bit rate.
Monitor - A monitor is very similar to a standard television
s
et, but lacks the electronics to pick up regular television
signals.
Motion JPEG - Motion JPEG is a simple
compre
ssion/decompression technique for networked video.
Latency is low and image quality is guaranteed, regardless
of movement or complexity of the image. Image quality is
controlled by adjusting the compression level, which in turn
provides control over the file size, and thereby the bit rate.
High-quality individual images from the Motion JPEG
stre
am are easily extracted. See also JPEG.
Megapixel - See Pi
xel.
MPEG (Moving Picture Experts Group) - The Moving
Picture Expe
rts Group develops standards for digital video
and audio compression. It operates under the auspices of the
International Organization for Standardization (ISO). The
MPEG standards are an evolving series, each designed for a
different purpose.
MPEG-2 - MPEG-2 is the designation for a group of audio
and
video coding standards, and is typically used to encode
audio and video for broadcast signals, including digital
satellite and Cable TV. MPEG-2, with some modifications, is
also the coding format used by standard commercial DVD
movies.
MPEG-4 - MPEG-4 is a group of audio and video coding