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. Contrast to on-demand.
buffering: The receiving and storing of data before it is played back. A clip's initial buffering is called preroll. After this preroll, excessive buffering may stall the presentation.
byte: A common measurement of data. One byte consists of 8 bits.

C

cable modems: Devices that allow rapid transmission and reception of data over television cable. They are digital devices, unlike dial-up modems, which transmit analog data.
client: A software application that receives data from a server. A Web browser is a client of a Web server. RealOne Player is a client of RealSystem Server.
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.
DSL: Digital Subscriber Line. A technology for transmitting digital data over a regular telephone line at speeds much faster than dial-up modems.

E

encoding: Converting a file into a compressed, streaming format. For example, you can encode WAV files as RealAudio clips.
events file: A text file that specifies URLs to display at specific points as a RealAudio or RealVideo clip plays. A utility included with RealSystem Producer events file is merged into the clip using a utility.

F

Flash: A software application and an animation format created by Macromedia. RealOne Player can play Flash animations and stream them in parallel with other clips, such as RealAudio clips.

H

HTTP: Hypertext Transport Protocol. The protocol used by Web servers to communicate with Web browsers. In contrast, RealSystem Server streams clips to RealOne Player with RTSP.

K

kilobit (Kb): 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 (KB): A common unit of data measurement equal to 1024 bytes or 8 kilobits.

O

on-demand: A type of streaming in which a clip plays from start to finish when a user clicks a link. Most clips are streamed this way. Contrast to broadcast.

P

prefetch: To stream clip data to RealOne Player before the clip plays back. A clip's preroll can be prefetched minutes before the clip plays, for example, masking the preroll from the viewer.
preroll: Buffering that occurs just before a clip plays back. Preroll should be no more than 15 seconds.
presentation: A clip or group of clips streamed from RealSystem Server to RealOne Player. The presentation can also include HTML URLs that open in the RealOne Player HTML windows.

R

RealAudio: A RealSystem clip type for streaming audio over a network. RealAudio clips use the .rm extension.
RealOne Player: The successor to RealPlayer 8, the RealOne Player combines streaming and digital download technologies. It supports the SMIL 2.0 standard.
RealPix: A RealSystem clip type (file extension .rp) for streaming still images over a network. RealPix uses a markup language for creating special effects such as fades and zooms.
RealPlayer G2: The RealNetworks client software that introduced plug-ins and the ability to update itself. It, along with the later RealPlayer 7 and RealPlayer 8, supports the SMIL 1.0 standard.
RealSystem Producer: The primary RealNetworks tool for encoding RealAudio and RealVideo clips.
RealSystem Server: RealNetworks server software used to stream multimedia presentations to RealPlayer G2.
RealSystem: The RealNetworks system for streaming media such as RealAudio and RealVideo clips over a network. It consists of RealSystem Server, RealOne Player, and various production tools.
RealText: A RealSystem clip type (file extension .rt) for streaming text over a network. It uses a markup language for formatting text.
RealVideo: A RealSystem clip type for streaming video over a network. RealVideo clips use the extension .rm.
RTP: Real-Time Protocol. The open, standards-based data package protocol RealSystem Server uses (along with RTSP) to communicate with RTP-based clients. Contrast to RealAudio.
RTSP: Real-Time Streaming Protocol. An open, standards-based control protocol that RealSystem Server uses to stream clips to RealOne Player or any RTP-based client. Contrast to HTTP.

S

server: 1. A software application, such as a Web server or RealSystem Server, that sends requested data over a network.; 2. A computer that runs server software.
SMIL: Synchronized Multimedia Integration Language. A markup language for specifying how and when each clip plays within a presentation. SMIL files use the extension .smil.
stream: 1. To send a media clip over a network so that it begins playing back as quickly as possible.; 2. 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 RealNetworks technology that enables a RealAudio or RealVideo clip to stream at multiple bit rates. Available only in RealSystem.

U

URL: Uniform Resource Locator. A location description that enables a Web browser or RealOne Player to receive a clip stored on a Web server or RealSystem Server.

V

visualization: An animation built into RealOne Player that the viewer can display when playing audio-only clips.