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AXIS 214 PTZ
the user that originally requested it.
P-VOP - See VOP.
Resolution - Image resolution is a measure of how much detail a
d
igital 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 pixels (usually in mega
pixels) 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
re
al-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 feedba
ck 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 rea
l-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,
a
nd 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
strea
m 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
p
acket 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
se
rvices 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 origina
lly 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
c
hannel can only send information in one direction.
SMTP (Simple Mail Transfer Protocol) - SMTP is used for sending
a
nd 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
re
quired 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 IETF (Internet
Engineering Task Force). The protocol can support monitoring of
network-attached devices for any conditions that warrant
administrative attention.
Sockets - Sockets are a method for communication between a client
p
rogram and a server program over a network. A socket is defined as
"the endpoint in a connection." Sockets are created and used with a
set of programming requests or "function calls" sometimes called the
sockets application programming interface (API).
SSL/TSL (Secure Socket Layer/Transport Layer Security) - These
two protoco
ls (SSL is succeeded by TSL) are cryptographic protocols
that provide secure communication on a network. SSL is commonly
used over HTTP to form HTTPS, as used e.g. on the Internet for
electronic financial transactions. SSL uses public key certificates to
verify the identity of the server.
Subnet & subnet mask - A subnet is an identifiably separate part of
an organiza
tion's network. Typically, a subnet may represent all the
machines at one geographic location, in one building, or on the same
local area network (LAN). Having an organization's network divided
into subnets allows it to be connected to the Internet with a single
shared network address.
The subnet mask is the part of the IP address that tells a network
ro
uter how to find the subnet that the data packet should be delivered
to. Using a subnet mask saves the router having to handle the entire
32-bit IP address; it simply looks at the bits selected by the mask.
Switch - A switch is a network device that connects network
s
egments together, and which selects a path for sending a unit of data
to its next destination. In general, a switch is a simpler and faster
mechanism than a router, which requires knowledge about the
network and how to determine the route. Some switches include the
router function. See also Router.
TCP (Transmission Control Protocol) - TCP is used along with the
Inte
rnet Protocol (IP) to transmit data as packets between computers
over the network. While IP takes care of the actual packet delivery,
TCP keeps track of the individual packets that the communication
(e.g. requested a web page file) is divided into and, when all packets
have arrived at their destination, it reassembles them to re-form the
complete file.
TCP is a connection-oriented protocol, which means that a
conne
ction is established between the two end-points and is
maintained until the data has been successfully exchanged between
the communicating applications.
Telnet - Telnet is a simple method with which to access another
netwo
rk device, e.g. a computer. The HTTP protocol and the FTP
protocols allow you to request specific files from remote computers,
but do not allow you logon as a user of that computer. With Telnet,
you log on as a regular user with whatever privileges you may have
been granted for specific applications and data residing on that
computer.
TVL (TV Lines) - A method of defining resolutions in analog video.
UDP (User Datagram Protocol) - UDP is a communications protocol
tha
t offers limited service for exchanging data in a network that uses
the Internet Protocol (IP). UDP is an alternative to the Transmission
Control Protocol (TCP). The advantage of UDP is that it is not required
to deliver all data and may drop network packets when there is e.g.
network congestion. This is suitable for live video, as there is no point
in re-transmitting old information that will not be displayed anyway.
Unicast - Communication between a single sender and a single
recei
ver over a network. A new connection is established for each
new user.
UPnP
TM
- A set of computer network protocols that allows the
automatic peer-to-peer detection of devices on the network. UPnP is
promoted by the UPnP Forum.
URL (Uniform Resource Locator) - An "address" on the network.
USB - (Universal Serial Bus) A plug-and-play interface between a
computer and perip
heral devices, e.g. scanners, printers, etc.
Varifocal lens - A varifocal lens provides a wide range of focal
lengths, a
s opposed to a lens with a fixed focal length, which only
provides one.
VPN (Virtual Private Network) - This creates a secure "tunnel"
betwe
en the points within the VPN. Only devices with the correct
"key" will be able to work within the VPN. The VPN network can be
within a company LAN (Local Area Network), but different sites can
also be connected over the Internet in a secure way. One common use
for VPN is for connecting a remote computer to the corporate
network, via e.g. a direct phone line or via the Internet.