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

when accessing pre recorded, or on demand, fi les). The 

progressive download: Also known as pseudo 

infrastructure to handle multicasting, known as the 

streaming,  progressive download  allows end users to 

M Bone (multicast backbone) is still emerging; the 

experience media accessed via a network such as the 

Internet is not yet ready for the popular proliferation of 

Internet, while the media fi le is still in the process 

multicasting. The terms  multicast  and narrowcast are 

of downloading; as opposed to downloadable media, 

sometimes used interchangeably, although  multicast  

which cannot be played back until the entire fi le  is 

more specifi cally refers to the actual technology inher 

received. Unlike true streaming, progressive download 

ent in the process.

leaves a copy of the media fi le on the client. Progressive 

narrowband:  Low bandwidth (typically dial up) net 

download is also called HTTP streaming because Web 

work connections usually 56 Kbps or lower.

server software using standard protocols (HTTP serv 

ers) can deliver progressive download fi les,  unlike 

narrowcast:  Transmission of media to multiple end 

true streaming, which takes advantage of the special 

users but, as differentiated from broadcast, not to 

protocols used by media server software to adjust 

everyone on a network

transmission to match the actual available bandwidth.

NTSC:  National Television Standards Committee stan 

protocol: A formal description of, i.e., rules for, how 

dard for color television transmission used in the 

specifi c types of computer systems interact.  

United States, Japan and elsewhere. NTSC incorporates 

an  interlaced display with 60 fi elds per second, 29.97 

pseudo streaming: See progressive download.

frames per second.

QuickTime: Apple's multi platform, multimedia soft  

on demand: Media which is not transmitted live, as 

ware  architecture; used by software developers, hard 

it is recorded, but is made available as an archive 

ware manufacturers, and content creators to author 

on a server, for end users to access when they wish. 

and publish synchronized graphics, sound, video, text, 

A television broadcast is  live;  renting a video and 

music, VR, and 3D media.  QuickTime 4  includes 

watching it at home is  on demand. 

strong support for  real  (RTSP) streaming.   

optimize: Another term for pre process.

RealMedia:  Architecture developed by RealNetworks 

to deliver audio and video content on the Web. Along 

packet:  Although computers and modems can send 

with QuickTime and Windows Media, one of three 

data one character at a time, it's more effi cient to send 

dominant streaming architectures.

information in larger blocks called data  packets,  or 

datagrams. When using the standard Internet protocol, 

real time:  In computing, refers to an operating mode 

TCP/IP, packets are typically around 1,500 characters.   

under which data is received, processed and the results 

Packets consist of the data being transmitted plus the IP 

returned so quickly as to seem instantaneous. In terms 

address information of the sender and the recipient 

of streaming media, refers to content streamed live, or 

as it happens.

PAL:  Phase alternating line television standard popu 

lar in most European and South American countries. 

reference movie: A metafi le in the QuickTime archi 

PAL uses an interlaced display with 50 fi elds per second, 

tecture, used to invoke the QuickTime player and/or  to 

25 frames per second.

refer the browser to an adaptive bit rate (MBR) fi le.

pixel:  An abbreviation for picture element. The mini 

resolution: The amount of information in each frame 

mum computer display element, represented as a point 

of video, normally represented by the number of hori 

with a specifi ed color and intensity level. One way to 

zontal  pixels times the number of vertical pixels (e.g. 

measure image resolution is by the number of pixels 

640x480). All other things being equal, a higher resolu 

used to create the image.

tion will result in a better quality image.

player:  In a multimedia architecture, the client soft 

rich media: Another term for multimedia. 

ware application, typically a plug in, that enables play 

RTP: Realtime Transfer Protocol is used as the transfer 

back of the media.

protocol for RTSP streaming (true streaming), and can 

plug in: A plug in extends the capabilities of a Web 

deliver a streaming media fi le to one or more end users  

browser, enabling the client to display or playback a fi le 

simultaneously (i.e., can unicast or multicast).

type which the browser itself cannot handle. 

RTSP: Realtime Streaming Protocol provides the func 

Pre processing:  Sometimes called optimizing, pre 

tionality allowing end users to randomly access and 

processing removes non essential information from 

control the delivery of streaming media content.

your video and audio information that is diffi cult 

server cluster or server farm: A group of networked 

to encode and/or does not substantively add to the 

servers that streamline internal processes by distribut 

quality of the streamed media. So pre processing prior 

ing the workload and expedite computing processes 

to encoding reduces the burden on the compressor, 

by harnessing the power of multiple servers. Load 

potentially saving time and CPU capacity.

balancing software tracks demand for processing power 

namic Mediay

post production: The phase of a fi lm or video project 

from different machines, prioritizing the tasks, and 

that involves editing and assembling footage and adding 

scheduling and rescheduling them depending on prior 

effects, graphics, titles, and sound.

ity and demand users put on the network. Redundancy 

ensures that if one server in the farm fails, another can 

pre production:  The planning phase of a fi lm  or 

step in as backup.

obe D

video project usually completed prior to commencing 

SECAM:  Similar to PAL at 25 FPS, the SECAM format 

d

production. 

is employed primarily in France, the Middle East, and 

A

production:  The phase of a fi lm or video project 

Africa.  It is only used for broadcasting. In countries 

comprised of shooting or recording raw footage.

employing the SECAM standard, PAL format cameras 

46

and decks are used.