97 
 
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. 
• DVR: Acronym for Digital Video Recorder. A DVR is device that is able to accept video signals from 
analog 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 
•PPPoE: Point-to-Point Protocol over Ethernet, is a network protocol for encapsulating Point-to-Point 
Protocol (PPP) frames inside Ethernet frames. It is used mainly with ADSL services where individual 
users connect to the ADSL transceiver (modem) over Ethernet and in plain Metro Ethernet networks. 
• 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 synchronize the clocks of computers 
over a network. 
• NTSC: Acronym for National Television System Committee. NTSC is an analog 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 
centralized 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. 
 
 
删除的内容: