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AXIS Q1755/-E - Glossary of Terms
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 video
mus
t 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
transmitt
ing 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 th
e data packets all arrive at
the intended 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 destination,
another protocol - Transmission Control Protocol (TCP) - puts
them in the right order. See also
TCP
.
IP Address - An IP address is simply an addres
s on an IP
network 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 unique. 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
digit
s 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 (Internet 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
an
d associated devices that typically share common resources
within a limited geographical area.
Linux - Linux is an open source operat
ing 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 aut
oiris, i.e. the camera
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 set,
bu
t lacks the electronics to pick up regular television signals.
Motion JPEG - Motion JPEG is a simple
compressi
on/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 stream
are easily extracted. See also JPEG.
Megapixel - See
Pixel
.
MPEG (Moving Picture Experts 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 co
ding 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.
Multicast - Bandwidth-conserving technology that
reduces
bandwidth usage by simultaneously delivering a single stream
of information to multiple network recipients.
Network connectivity - The physical (wired or wireless) and
logical
(protocol) connection of a computer network or an
individual device to a network, such as the Internet or a LAN.
NTSC (National Television Syst
em Committee) - NTSC is the
television and video standard in the United States. NTSC
delivers 525 lines at 60 half-frames/second.
NWay - A network protocol that auto
matically negotiates the
highest possible common transmission speed between two
devices.
PAL (Phase Alternating Line) - PAL is the dominant television
st
andard in Europe. PAL delivers 625 lines at 50
half-frames/second.
Ping - Ping is a basic network program used diagnostically to
ch
eck 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