Axis 2400+ Manual do Utilizador descarregar pdf (Página 50)

MPEG (Moving Picture Experts Group)

MPEG, the Moving Picture Experts Group, develops standards for digital

video and digital audio compression. It operates under the auspices of the

International Organization for Standardization (ISO). The MPEG standards are

an evolving series, each designed for a different purpose.

To use MPEG video ﬁ les, you need a personal computer with sufﬁ cient

processor speed, internal memory, and hard disk space to handle and play the

typically large MPEG ﬁ le (which has a ﬁ le name sufﬁ x of .mpg). You also need

an MPEG viewer, or client software that plays MPEG ﬁ les.

Note that .mp3 ﬁ le sufﬁ xes indicate MP3 (MPEG-1 audio layer-3) ﬁ les, not

MPEG-3 standard ﬁ les. You can download shareware or commercial MPEG

players from a number of sites on the Web.

Quads

A Quad displays images from up to four cameras on a single screen.

Router

A router is a device that determines the next network point to which a packet

should be forwarded towards its ﬁ nal destination. Connecting between at

least two networks, the router uses its understanding of the current state

of the network to determine which way to send each information packet. A

router can be located at any juncture of a network or gateway, including each

Internet point-of-presence. A router is often included as part of a network

switch.

RS-232

RS-232C is a long-established standard ("C" is the current version) that

describes the physical interface and protocol for relatively low-speed serial

data communication between computers and related devices.

RS-422

RS-422 is designed to replace the older RS-232 standard. By employing

differential pair signaling that transmits one signal in opposing states over

two wires, this transmission format supports higher data rates and greater

immunity to electrical interference than offered by the existing RS-232

standard.

RS-485

RS-485 is an upgraded version of RS-422 with the added capability to allow

up to 32 devices (transmitters and receivers) to share the same.

Server

In general, a server is a computer program that provides services to other

computer programs in a network.

SSL

SSL (Secure Sockets Layer) is a program layer created by Netscape for

managing the security of message transmissions in a network. Netscape's

idea is founded on the principle that the programming associated with

keeping your messages conﬁ dential ought to be contained in a program layer

between an application (such as your Web browser or HTTP) and the Internet's

TCP/IP layers.

Subnet Mask

A class B Internet address comprises of two components: the network address

and the host address. And, ‘subnetting’ enables a network administrator to

further divide the host part of the address into two or more subnets.

A subnet mask is used to identify the subnet to which an IP address belongs.

By performing a boolean AND operation on the bits comprising the mask and

the IP address, the subnetwork address can be derived.

Example:

Subnet Mask 255.255.240.000 11111111.11111111.1111 0000.00000000

AND

IP Address 150.215.033.009 10010110.11010111.00100001.00001001

Subnet Address 150.215.032.000 10010110.11010111.00100000.00000000.

Switch

A hub is transmitting all data to all devices that is connected to it and that is a huge

disadvantage. If you use a switch, data will only be transmitted to the device that

should receive it. We recommend you to use a switch in stead of a hub.

TCP/IP

TCP/IP (Transmission Control Protocol/Internet Protocol) is the basic

communication language (or protocol) of the Internet. It is also used as

a communications protocol in private networks called intranets, and in

extranets.

The IP address

The 32-bit IP address is often referred to as a dot address (sometimes called

dotted quad notation) - that is, four groups (or quads) of decimal digits

separated by periods. Here's an example: 130.5.5.25

URL

An abbreviation of Uniform Resource Locator, this speciﬁ es the global address

for resources made available over the Web. The ﬁ rst part of a URL address

speciﬁ es what protocol to use, whereas the second deﬁ nes the IP address or

the domain name at which the resource is located.

VCD

Stands for Video Compact Disc. An extension of CD based on MPEG-1 video

and audio format that allows playback of near-VHS-quality video on a video

CD player, or computer with MPEG decoding capability.

Web server

A Web server is a program, which allows Web browsers to retrieve ﬁ les from

computers connected to the Internet and network.

xDSL

The collective description for all types of digital subscriber lines; including

ADSL, SDSL, High-data-rate DSL (HDSL) and Very high DSL (VDSL). xDSL

technologies operate over existing copper telephone lines, but offer much

higher transmission speeds – with up to 32 Mbps for upstream trafﬁ c, and

from 32 Kbps to over 1 Mbps for downstream trafﬁ c.

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