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AXIS 214 PTZ
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
w
hich bits are passing a given point. See also Bit rate.
LAN (Local Area Network) - A LAN is a group of computers and
a
ssociated 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 id
entifier 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 camera iris
m
ust 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
a
t 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 set, but
la
cks the electronics to pick up regular television signals.
Motion JPEG - Motion JPEG is a simple compression/decompression
te
chnique 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 stream are
e
asily extracted. See also JPEG.
Megapixel - See Pi
xel.
MPEG (Moving Picture Ex
perts Group) - The Moving Picture
Experts 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
c
oding 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 standards
a
nd related technology. The primary uses for the MPEG-4 standard
are web (streaming media) and CD distribution, conversational
(videophone), and broadcast television.
Most of the features included in M
PEG-4 are left to individual
developers to decide whether to implement them or not. This means
that there are probably no complete implementations of the entire
MPEG-4 set of standards. To deal with this, the standard includes the
concept of "profiles" and "levels", allowing a specific set of
capabilities to be defined in a manner appropriate for a subset of
applications.
Multicast - Bandwidth-conserving technology that reduces
b
andwidth usage by simultaneously delivering a single stream of
information to multiple network recipients.
Multiplexer - A multiplexer is a high-speed switch that provides
full-scree
n images from up to 16 analog cameras. Multiplexers can
playback everything that happened on any one camera with no
interference from the other cameras on the system.
Network connectivity - The physical (wired or wireless) and logical
(p
rotocol) connection of a computer network or an individual device
to a network, such as the Internet or a LAN.
NTSC (National Television System Committee) - NTSC is the
televisio
n and video standard in the United States. NTSC delivers 525
lines at 60 half-frames/second.
OEM (Original Equipment Manufacturer) - This is a designation for
compa
nies that manufacture equipment which is then marketed and
sold to other companies under their own names.
PAL (Phase Alternating Line) - PAL is the dominant television
s
tandard in Europe. PAL delivers 625 lines at 50 half-frames/second.
PEM (Privacy Enhanced Mail) - An early standard for securing
elec
tronic mail. The PEM-format is often used for representing an
HTTPS certificate or certificate request.
Ping - Ping is a basic network program used diagnostically to check
the
status of a network host or device. Ping can be used to see if a
particular network address (IP address or host name) is occupied or
not, or if the host at that address is responding normally. Ping can be
run from e.g. the Windows Command prompt or the command line in
UNIX.
Pixel (Picture element) - A pixel is one of the many tiny dots that
make up
a digital image. The color and intensity of each pixel
represents a tiny area of the complete image.
PoE (Power over Ethernet) - Power over Ethernet provides power to
a n
etwork device via the same cable as used for the network
connection. This is very useful for IP-Surveillance and remote
monitoring applications in places where it may be too impractical or
expensive to power the device from a power outlet.
PPP (Point-to-Point Protocol) - A protocol that uses a serial
interfa
ce for communication between two network devices. For
example, a PC connected by a phone line to a server.
PPTP (Point-to-Point Tunnelling Proto
col) - A protocol (set of
communication rules) that allows corporations to extend their own
corporate network through private "tunnels" over the public Internet.
In this way a corporation can effectively use a WAN (Wide Area
Network) as a large single LAN (Local Area Network). This kind of
interconnection is known as a virtual private network (VPN). See also
VPN.
Pre/post alarm images - The images from immediately before and
afte
r an alarm. These images are stored in a buffer for later retrieval.
Progressive scan - Progressive scan, as opposed to interlaced video,
sc
ans the entire picture, line by line every sixteenth of a second. In
other words, captured images are not split into separate fields as in
interlaced scanning.
Computer monitors do not need interlace to show the picture on the
s
creen, but instead show them progressively, on one line at a time in
perfect order, i.e. 1, 2, 3, 4, 5, 6, 7 etc., so there is virtually no
"flickering" effect. In a surveillance application, this can be critical
when viewing detail within a moving image, such as a person
running. A high-quality monitor is required to get the best from
progressive scan. See also Interlacing.
Protocol - A special set of rules governing how two entities will
comm
unicate. Protocols are found at many levels of communication,
and there are hardware protocols and software protocols.
Proxy server - In an organization that uses the Internet, a proxy
se
rver acts as an intermediary between a workstation user and the
Internet. This provides security, administrative control, and a caching
service. Any proxy server associated with a gateway server, or part of
a gateway server, effectively separates the organization’s network
from the outside network and the local firewall. It is the firewall
server that protects the network against outside intrusion.
A proxy server receives requests for Internet services (such
as web
page requests) from many users. If the proxy server is also a cache
server, it looks in its local cache of previously downloaded web pages.
If it finds the page, it is returned to the user without forwarding the
request to the Internet. If the page is not in the cache, the proxy
server, acting as a client on behalf of the user, uses one of its own IP
addresses to request the page from another server over the Internet.
When the requested page is returned, the proxy server forwards it to