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Chapter 6 Glossary
Chapter 6 Glossary
Bit Rate
Displays the volume of data flowing across the network. Generally, the volume is expressed with
the unit “bps” (bits per second) which indicates the number of data bits transmitted per second.
DNS (Domain Name Server)
A server used to convert addresses such as “www.eizoglobal.com” into IP addresses.
Firewall
A system to prevent invasion from external networks.
H.264
A format for compressing images. This method is widely used for image remote transmission and
recording. The portion with movement is predicted based on the data of the frame immediately
before and after, and only the differential data between frames is used. This enables efficient
reduction of data, and is therefore widely used.
IP Address
An address that is allocated to a network device. Each network device is given an address. Unlike
MAC addresses, IP addresses change according to the installation environment.
MAC (Media Access Control) Address
A Mac address is a 48bit identification number assigned to a network device. It is assigned
statically, not duplicated, and uses a unique number for each network device.
Multicast
A network communication format in which multiple network devices receive a single stream. By
having multiple network devices receive the same image at the same quality, the network load of
transmitting devices can be reduced, however, it is necessary to have devices and configurations
that support multicast.
MJPEG (Motion JPEG)
This is a method for compressing images. It is used for remote transmission and recording of
images. Due to compression and decompression being performed for each frame, subsequent
frames are not impacted even when data are missing from some frames. Therefore, this method is
sometimes used in environments with poor signal quality. However, a downside is that the data
volume is larger than that for the H.264 format.
NTP (Network Time Protocol)
A protocol for synchronizing the time and the network server.
ONVIF (Open Network Video Interface Forum)
This is a standard that allows interconnection between network cameras and network recorder
equipment from different manufacturers.
