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13. Appendix
13.1 Glossary
Dual Stream:
Dual stream is a technology used to record high resolution
video locally while transmitting a lower resolution stream over the network.
The two streams are generated by the DVR, with the main stream having a
maximum resolution of 4CIF and the sub-stream having a maximum
resolution of CIF at 6fps.
DVR:
Acronym for Digital Video Recorder. A DVR is device that is able to
accept video signals from analogue cameras, compress the signal and store it
on its hard drives.
HDD:
Acronym for Hard Disk Drive. A storage medium which stores
digitally encoded data on platters with magnetic surfaces.
DHCP:
Dynamic Host Configuration Protocol (DHCP) is a network
application protocol used by devices (DHCP clients) to obtain configuration
information for operation in an Internet Protocol network.
HTTP:
Acronym for Hypertext Transfer Protocol. A protocol to transfer
hypertext request and information between servers and browsers over a
network
DDNS:
Dynamic DNS is a method, protocol, or network service that
provides
the capability for a networked device, such as a router or computer system
using the Internet Protocol Suite, to notify a domain name server to change,
in real time (ad-hoc) the active DNS configuration of its configured
hostnames, addresses or other information stored in DNS.
Hybrid DVR:
A hybrid DVR is a combination of a DVR and NVR.
NTP:
Acronym for Network Time Protocol. A protocol designed to
synchronise the clocks of computers over a network.
NTSC:
Acronym for National Television System Committee. NTSC is an
analogue television standard used in such countries as the United States and
Japan. Each frame of an NTSC signal contains 525 scan lines at 60Hz.
NVR:
Acronym for Network Video Recorder. An NVR can be a PC-based or
embedded system used for centralised management and storage for IP
cameras, IP Domes and other DVRs.
PAL:
Acronym for Phase Alternating Line. PAL is also another video
standard used in broadcast televisions systems in large parts of the world.
PAL signal contains 625 scan lines at 50Hz.
PTZ:
Acronym for Pan, Tilt, Zoom. PTZ cameras are motor driven systems
that allow the camera to pan left and right, tilt up and down and zoom in and
out.
USB:
Acronym for Universal Serial Bus. USB is a plug-and-play serial bus
standard to interface devices to a host computer.
