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Glossary

B

bandwidth
The upper limit on the amount of data, typically expressed as Kilobits per second (Kbps), that can pass through a network connection.

bit
The smallest unit of measure of data in a computer. A bit has a binary value, either 0 or 1.

bit rate
A measure of bandwidth, expressed as the number of bits transmitted per second. A 28.8 Kbps modem, for example, can transmit or receive around 29,000 bits per second.

broadcast
To deliver a presentation, whether live or prerecorded, in which all viewers join the presentation in progress.

buffering
Receiving and storing data before playing it back. The initial buffering time is called preroll. After preroll, excessive buffering may stall the presentation.

byte
A common measurement of data. One byte comprises eight (8) bits.

C

client
A software application that receives data from a server. A Web browser is a client of a Web server. RealPlayer G2 is a client of RealServer G2.

clip
A media file within a presentation. Clips typically have an internal timeline, as with RealAudio and RealVideo.

codec
Coder/decoder. Codecs convert data between uncompressed and compressed formats, reducing the bandwidth a clip consumes.

D

download
To send a file over a network with a nonstreaming protocol such as HTTP. Contrast to stream.

E

encoding
Converting a file into a compressed, streaming format. For example, you can encode WAV files as RealAudio.

F

Flash
A Macromedia tool for creating animations that can be streamed as Flash with RealSystem G2. See also Shockwave Flash.

H

HTTP
The protocol used by Web servers to communicate with Web browsers. RealServer can use HTTP, but it streams clips to RealPlayer G2 with RTSP.

I

ISP
Internet Service Provider. A company that provides access to the Internet. Many ISPs have RealServer available to stream media clips.

K

Kilobit
A common unit of data measurement equal to 1024 bits. A Kilobit is usually referred to in the context of bit rate per unit of time, such as Kilobits per second (Kbps).

Kilobyte
A common unit of data measurement equal to 1024 bytes. Also equal to 8 Kilobits.

P

PNA
A proprietary protocol RealServer G2 supports for backwards compatibility with RealSystem 3.0 through 5.0. URLs using PNA start with pnm://.

port
A connection to a server designated by a number such as 8080. RealServer G2 uses different ports for the RTSP, HTTP, and PNA protocols.

preroll
Buffering that occurs at the start of a presentation. Preroll should be 15 seconds or less.

presentation
A group of clips coordinated through SMIL and streamed from RealServer to RealPlayer.

R

RDP
The proprietary data package protocol RealServer G2 uses (along with RTSP) when communicating with RealPlayer G2. Contrast to RTP.

RealAudio
A RealSystem clip type for streaming audio over a network. RealAudio clips use the .rm or .ra extension.

Flash with RealSystem G2
A RealSystem clip type for streaming Shockwave Flash animation along with a RealAudio soundtrack.

RealPix
A RealSystem clip type (file extension .rp) for streaming still images over a network. It uses a mark-up language for creating special effects such as fades and zooms.

RealPlayer
RealNetworks client designed to play multimedia presentations streamed by RealServer or a Web server.

RealServer
RealNetworks server software used to stream multimedia presentations to RealPlayer.

RealSystem
The system for streaming clips such as RealAudio and RealVideo over a network. It consists of RealServer, RealPlayer, and production tools.

RealText
A RealSystem clip type (file extension .rt) for streaming text over a network. It uses a mark-up language for formatting text.

real-time
Delivered as it occurs. For example, a live broadcast is streamed across a network in real-time.

RealVideo
A RealSystem clip type for streaming video over a network. RealVideo clips use the .rm extension.

RTP
The open, standards-based data package protocol RealServer G2 uses (along with RTSP) to communicate with RTP-based clients. Contrast to RDP.

RTSP
The open, standards-based control protocol RealServer G2 uses to stream clips to RealPlayer G2 or any RTP-based client. Contrast to HTTP.

S

server
1. A software application, such as a Web server or RealServer G2, that sends clips over a network.
2. A computer that runs server software.

Shockwave Flash
A compressed Flash file format (file extension .swf) used as the animation component in Flash with RealSystem G2.

SMIL
Synchronized Multimedia Integration Language. A mark-up language for specifying how and when each clip plays. SMIL files use the extension .smil.

stream
v. To send a media clip over a network so that it begins playing back as quickly as possible.
n. A flow of a single type of data, measured in Kilobits per second (Kbps). A RealVideo clip's soundtrack is one stream, for example.

SureStream
A technology that allows switching to a lower-bandwidth encoding in a RealAudio or RealVideo clip to compensate for network congestion. Available only in RealSystem G2.

U

URL
Universal Resource Locator. A location description that lets a Web browser or RealPlayer receive a clip stored on a Web server or RealServer.


Copyright © 1998 RealNetworks
For information on RealNetworks' technical support, click here.
Comments on this document? Click here.
This file last updated on 12/18/98 at 14:36:43.
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