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AXIS COMMUNICATIONS
<Product Name> Quick User’s Guide
49
AXIS 215 PTZ/ AXIS 215 PTZ-E - Glossary of Terms
Monitor - A monitor is very similar to a standard television set, but
lacks the electronics to pick up regular television signals.
Motion JPEG - Motion JPEG is a simple compression/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
extrac
ted. See also JPEG.
Megapixel - See Pi
xel.
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
cod
ing 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 and
relate
d 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 MPEG-4 are left to individual
dev
elopers 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 bandwidth
us
age by simultaneously delivering a single stream of information to
multiple network recipients.
Multiplexer - A multiplexer is a high-speed switch that provides
full-s
creen 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
(protoc
ol) 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 television
and video standard in the United States. NTSC delivers 525 lines at 60
half-frames/second.
NWay is a telecommunications protocol used to automatically negotiate
the
highest available transmission speed between network devices. The
NWay protocol is also known as auto-negotiation or auto-sensing.
OEM (Original Equipment Manufacturer) - This is a designation for
com
panies 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 standard
in
Europe. PAL delivers 625 lines at 50 half-frames/second.
PEM (Privacy Enhanced Mail) - An early standard for securing
ele
ctronic 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 - A pixel is one of the many tiny dots that make up a digital
imag
e. 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
netw
ork 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 interface
for com
munication between two network devices. For example, a PC
connected by a phone line to a server.
PPTP (Point-to-Point Tunnelling Protocol) - A protocol (set of
comm
unication 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).
Pre/post alarm images - The images from immediately before and after
an alarm. These imag
es are stored in a buffer for later retrieval.
Progressive scan - Progressive scan, as opposed to interlaced video,
scans the en
tire 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
screen,
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 server
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 the user that originally
requested it.
PTZ - Pan, tilt and zoom.
P-VOP - See VOP.
Resolution - Image resolution is a measure of how much detail a digital
image
can hold: the greater the resolution, the greater the level of detail.
Resolution can be specified as the number of pixel-columns (width) by
the number of pixel-rows (height), e.g. 320x240.
Alternatively, the total number of pixel
s (usually in megapixels) in the
image can be used. In analog systems it is also common to use other
format designations, such as CIF, QCIF, 4CIF, etc.
RTCP (Real-Time Control Protocol) - RTCP provides support for
real-
time conferencing of groups of any size within an intranet. This
support includes source identification and support for gateways like
audio and video bridges as well as multicast-to-unicast translators.
RTCP offers quality-of-service feedback from rece
ivers to the multicast
group as well as support for the synchronization of different media
streams.
RTP (Real-Time Transport Protocol) - RTP is an Internet protocol for
the
transport of real-time data, e.g. audio and video. It can be used for
media-on-demand as well as interactive services such as Internet
telephony.
RTSP (Real Time Streaming Protocol) - RTSP is a control protocol, and