Axis 212 PTZ-V [54/57] Axis 212 ptz v glossary of terms
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Axis 212 PTZ-V [54/57] Axis 212 ptz v glossary of terms

Axis 212 PTZ-V [54/57] Axis 212 ptz v glossary of terms
AXIS 212 PTZ/-V - Glossary of Terms
example, 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
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
network 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 communication 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
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
after an alarm. These images are stored in a buffer for later retrieval.
Progressive scan - Progressive scan, as opposed to interlaced video,
scans 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
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
communicate. 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), for example, 320x240.
Alternatively, the total number of pixels (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 receivers 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, for example, 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
a starting point for negotiating transports such as RTP, multicast and
Unicast, and for negotiating codecs.
RTSP can be considered a “remote control” for controlling the media
stream delivered by a media server. RTSP servers typically use RTP as the
protocol for the actual transport of audio/video data.
Router - A device that determines the next network point to which a
packet should be forwarded on its way to its final destination. A router
creates and/or maintains a special routing table that stores information
on how best to reach certain destinations. A router is sometimes
included as part of a network switch. See also switch.
Server - In general, a server is a computer program that provides
services to other computer programs in the same or other computers. A
computer running a server program is also frequently referred to as a
server. In practice, the server may contain any number of server and
client programs. A web server is the computer program that supplies the
requested HTML pages or files to the client (browser).
Sharpness - This is the control of fine detail within a picture. This
feature was originally introduced into color TV sets that used notch filter
decoders. This filter took away all high frequency detail in the black and
white region of the picture. The sharpness control attempted to put
some of that detail back in the picture. Sharpness controls are mostly
superfluous in today's high-end TVs. The only logical requirement for it
nowadays is on a VHS machine.
Simplex - In simplex operation, a network cable or communications
channel can only send information in one direction.
SMTP (Simple Mail Transfer Protocol) - SMTP is used for sending and
receiving e-mail. However, as it is “simple,” it is limited in its ability to
queue messages at the receiving end, and is usually used with one of
two other protocols, POP3 or IMAP. These other protocols allow the user
to save messages in a server mailbox and download them periodically
from the server.
SMTP authentication is an extension of SMTP, whereby the client is
required to log into the mail server before or during the sending of
email. It can be used to allow legitimate users to send email while
denying the service to unauthorized users, such as spammers.
SNMP (Simple Network Management Protocol) - SNMP forms part of
the Internet Protocol suite, as defined by the Internet Engineering Task
Force. The protocol can support monitoring of network-attached devices
for any conditions that warrant administrative attention.

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