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
digital rights management (DRM): Server software
streaming, Flash does not fi t the defi nition of true
that protects against the illegal distribution (a.k.a.
streaming used in this Primer. While Flash shares
pirating) of copyrighted content over the Internet.
some characteristics with streaming media, and can
digitizing: Act of converting an analog audio or video
simulate video by animating sequential frames, it does
signal to digital information.
not deliver standard, full motion video fi le formats
over the Web and is constrained to fi les containing no
download: The act of one computer requesting and
more than 16,000 frames (approximately 17 minutes of
receiving data, via a network, from another computer.
material at 15 fps). The Flash fi le format, SWF, can be
downloadable media: Media (i.e., video and/or
created using Adobe After Effects and Adobe GoLive
audio) that can be downloaded and written to disk
software, as well as other applications.
(i.e., saved onto a computer hard drive); typically refers
FPS: Number of frames per second; a method for
to media fi les hosted on a Web server (as opposed to
describing frame rate.
a media server) which can, and often must, be entirely
downloaded and written to disk in order to be played
frame: A single still image in a sequence of images
(as contrasted to streaming media).
which, when displayed in rapid succession, creates the
illusion of motion the more frames per second (FPS),
DV: Generally refers to a digital video format that
the smoother the motion appears.
incorporates DV compression, the type of compression
used by DV systems or by a DV camcorder that employs
frame rate: The number of images (video frames)
the DV format. A standard consumer DV camcorder
shown within a specifi ed time period; often represented
uses mini DV tape, compresses the video using the
as FPS (frames per second). A complete NTSC TV
DV25 standard, and has an IEEE 1394 port for connect
picture consisting of two fi elds, a total scanning of all
ing to a desktop computer. The DV designation is also
525 lines of the raster area, occurs every 1/30 of a
used to for a special type of tape cartridge used in DV
second. In countries where PAL and SECAM are the
camcorders and DV tape decks.
video standard, a frame consists of 625 lines at 25
DV25: The most common form of DV compression,
using a fi xed data rate of 25 megabits/sec.
File Transfer Protocol is the simplest way to
exchange fi les between computers on the Internet.
dynamic media: Refers to design elements that incor
Like the Hypertext Transfer Protocol (HTTP), which
porate motion and/or sound such as video, animation,
transfers displayable Web pages and related fi les, and the
Simple Mail Transfer Protocol (SMTP), which transfers
effect: Distortion of a frame or frames of video to
e mail, FTP uses the Internet's TCP/IP protocols.FTP is
change its appearance; distortion of audio to alter the
commonly used to transfer Web page fi les from the on
quality of sound.
which they were created to a Web server.
encoder: A software application or a device (hard
erm used in Apple's QuickTime
ware) used to encode i.e., compress and format (see
architecture for video fi les that are formatted for true
encoding) digital video or audio.
encoding: Encoding accomplishes two main objec
hint track: Term used in Apple's QuickTime archi
tives: 1) it reduces the size of your video and audio fi les,
tecture for the set of streaming instructions which, in
by means of compression, making Internet delivery
the QuickTime streaming format, are embedded right
feasible, and 2) it saves your fi les in a format that
into the movie. Other architectures provide streaming
can be read and played back on the desktops of your
instructions as metafi les which are often downloaded
targeted audience. Some encoding solutions may also be
separately from the actual movie fi le.
confi gured to provide additional processing functions,
such as digital watermarking, for example. Encoding
host: A computer system providing data to be accessed
may be handled by a software application, or by special
by a user working on a remote system, via a network
ized hardware with encoding software built in. Note
such as the Internet; can be a synonym for server. The
that the term compression is often used interchangeably
term host is also used to refer to businesses that pro
with the term encoding when referring to the fi nal
vide such systems. A hosting services provider (HSP)
step in preparing media fi les for Web distribution; but
is an application service provider (ASP) dedicated to
compression is only a part of the encoding process.
providing hosting services. A hosting services provider
typically operates a Web server farm, at a data center or
fast start streaming: Term used in Apple's QuickTime
co location facility. The term host may also be used
architecture for progressive download.
as a verb, as in to host fi les on a server.
fi elds: The sets of upper (odd) and lower (even)
HTML: Hypertext Markup Language is a lexicon of
lines drawn by the electron gun when illuminating the
formatting commands typically used to create Web
phosphors on the inside of a standard television screen,
pages. HTML is the language that describes all the basic
thereby resulting in displaying an interlaced image.
elements of a page (such as text and graphics), but
In the NTSC standard, one complete vertical scan
its current incarnation can't do much to make a page
of the picture or fi eld contains 262.5 lines. Two
interactive; Java and ActiveX are often used to build
fi elds make up a complete television frame the lines
interactivity into Web pages.
of fi eld 1 are vertically interlaced with fi eld 2 for 525
lines of resolution.
HTTP: HyperText Transfer Protocol is comprises the
underlying set of rules used by the World Wide Web
FireWire: The Apple Computer trade name for
to defi ne how messages are formatted and transmitted,
and to communicate what actions Web servers and
Flash: Macromedia Flash is a popular architecture
browsers should take in response to various commands.
for vector based Web animation. Often referred to as
For example, when a URL is specifi ed in a browser, an