A   S t r e a m i n g   M e d i a   P r i m e r :  

G L O S S A R Y

HTTP command is sent to a Web server directing it to 

lossless:  A process that does not affect signal fi delity; 

fetch and transmit the requested Web page. 

e.g. the transfer of DV via an IEEE 1394 connection.

HTTP streaming: See 

progressive download.

MB:  Megabytes

hypertext:  A database system wherein objects (text, 

M Bone: The MBONE (Multicast Backbone) is a 

images, video, audio, and applications) can be linked to 

virtual network layered on top of the physical Internet 

each other. For example, while reading an article about 

to support the routing of multicast packets. For more 

jazz music, you might click on the name of a musician 

information, see www.mbone.com.

to see a photograph, biography, or discography; you 

Mbps:  Megabits per second

might click on the name of a song to hear it played or 

MBR:  Short for multiple (or multi) bit rate, and also 

to view score. A Web page is simply a graphical user 

known as adaptive streaming, MBR is a technique by 

interface (GUI) used to convey a hypertext document.

which several streams, compressed at different bitrates, 

IEEE 1394: The interface standard that enables the 

are encoded together into a single fi le. When the client 

direct transfer of DV between devices such as a DV 

calls for the media fi le,  a  negotiation  between  client 

camcorder and a computer; also used to describe the 

and server determines the available bandwidth, and the 

cables and connectors utilizing this standard.

appropriate stream is transmitted.

i.LINK:  The Sony trade name for IEEE 1394.

media: A term with many different meanings, in the 

inter frame compression: Also known as temporal 

context of streaming media, it refers to video, anima 

compression, inter frame compression reduces the 

tion, and audio. The term  media  may also refer to 

amount of video information by storing only the dif 

something used for storage or transmission, such as 

ferences between frames.

tapes, diskettes, CD ROMs, DVDs, or networks such 

as the Internet.

interlacing: System developed for early television 

and still in use in standard television displays. To 

media server:  Specialized server software that takes 

compensate for limited persistence, the electron gun 

advantage of appropriate Web transfer protocols such as 

used to illuminate the phosphors coating the inside of 

RTSP (real time streaming protocol), as well as special 

the screen alternately draws even, then odd horizontal 

communication techniques between clients and servers, 

lines. By the time the even lines are dimming, the odd 

to facilitate the continuous playback of synchronized 

lines are illuminated. We perceive these  interlaced  

audio and video in real time, adjusting the streams 

fi elds of lines as complete pictures.

transmitted to the actual bandwidth available. Media 

server software may be running on discrete hardware, 

intra frame compression: Also known as spatial com 

or can be deployed in combination with Web server 

pression, intra frame compression reduces the amount 

software running on the same device.

of video information within each frame individually.

metafi le:  A fi le containing information that describes 

IP: Internet Protocol, the basis of most Internet proto 

or specifi es another fi le. Some streaming media formats 

cols, breaks up large chunks of information into digest 

use metafi les to invoke the client media player and/or 

ible  packets. In addition to the data being conveyed, 

to specify the location of a streaming fi le on a media 

each packet (also known as a datagram) carries a header 

server.

containing the source and destination IP addresses, as 

well as a sequence number that allows the destination 

mic: Pronounced like  mike;  short for microphone.

computer to reconstruct the packets in the correct 

MPEG:  Motion Pictures Expert Group of the Inter 

sequence, when they arrive. 

national Organization for Standardization (ISO) has 

IP address: A numeric identifi er for a computer 

defi ned multiple standards for compressing audio and 

or device on the Internet. An IP address consists 

video sequences. Setting it apart from JPEG which 

of four numbers separated by periods, or dots (e.g., 

compresses individual frames, MPEG compression uses 

192.168.0.1), representing a unique 32 bit address. An 

a technique where the differences in what has changed 

IP address consists of a network portion and a host 

between one frame and its predecessor are calculated 

portion; how many bits designate the network and how 

and encoded.  MPEG is both a type of compression 

many designate the host varies. 

and a video format.   MPEG 1  was initially designed 

to deliver near broadcast quality video through a 

KB: Kilobytes

standard speed CD ROM. Playback of MPEG 1 

Kbps: Kilobits per second

video requires either a software decoder coupled 

keyframe: A frame selected at the beginning or end of 

with a high end machine, or a hardware decoder. 

a sequence of frames, that is used as a reference for any 

 MPEG 2  is the broadcast quality video found 

of a variety of functions. In inter frame video compres 

on  DVD's. It requires a hardware decoder (e.g.; a 

sion, keyframes typically store complete information 

DVD ROM player) for playback.  MPEG 4  is a rela 

namic Media

about the image, while the frames in between may store 

tively new standard, now being used in some architec 

y

only the differences between two keyframes.

tures for streaming media.

live feed: Data which is fed to a server in real time (i.e., 

multiple (or multi) bit rate: See MBR.

as it is recorded), rather than being pre recorded. 

multicast: Multicast is an effi cient way to transmit the 

live live:  Sometimes used to refer to the streaming 

same media stream to many recipients simultaneously, 

obe D

of a live feed.

by replicating the stream at router hops where the 

d

path to different multicast group members diverges. 

A

lossy: Generally refers to a compression scheme or 

Multicast end users experience the same portion of the 

other process, such as duplication, that causes degrada 

media, at the same time (in contrast to unicast, which 

tion of signal fi delity.

can allow each end user to control their own experience 

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