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
bit rate: In a digital network, the number of bits that
jump, at will, during playback, so long as chapteriza
pass a given point, in a given amount of time, usually a
tion is supported by the video architecture in use. True
second. Bit rate is usually measured in kilobits (Kbps),
streaming of video supports chapterization; pseudo
or thousands of bits per second. While the term bit
streaming, a.k.a. progressive download, does not.
rate is a synonym for data transfer rate (aka data rate),
client: In a client/server architecture, the client is a
bit rate seems to be used more often when referring to
software application that makes requests of the server
telecommunications transmission technology, and data
on behalf of the end user. A Web browser is a client
transfer rate (or data rate) is used more often when
application; a media player is also a client application.
referring to computing systems.
Sometimes the term client is also used to refer to
bluescreen: Video editing technique used to combine
a PC or workstation (hardware) on a network being
a subject with a background shot separately. The subject
used by an individual to access data and or applications
is shot against a solid blue (or sometimes green) color
hosted on a server.
screen. The blue color can be selected on a frame by
clip: A digitized portion of media, typically video or
frame basis, through the use of a video editing system.
A matte can then be generated to isolate the subject, in
order to composite it onto the desired still or motion
clipping: Clipping occurs when audio volume reaches
or exceeds 0 decibels (db) for 3 consecutive seconds. If
you don't lower the volume so it is within the clipping
broadband: High bandwidth network (Internet or
threshold, data will be lost.
intranet) connections higher than 56 Kbps (e.g., ISDN,
DSL, cable modem, T 1).
codec: Short for compressor/decompressor; comprised
of algorithms that handle the compression of video to
broadcast: A single stream transmitted to all clients
make it easier to work with and store, as well as the
on a network, whereby all the clients experience the
decompression of video for playback.
same portion of the media program, at the same time,
whether the program is live or pre recorded.
co location: An outsource, usually a dedicated facility
or facilities, that provides physical space for and/or
broadcast quality: Standard of quality associated
shared usage of essential computer equipment such
with current expectations of clearly received network
as Web servers and, often, mission critical managed
or cable television.
services. Co locations typically provide a high level of
browser: A client application, usually with a graphical
security and protection against fi re, theft, vandalism,
user interface (GUI), that provides a way to experience
power outages or irregularities, and other risks which
and interact with fi les hosted on a network, such as the
might, potentially, devastate a business that is reliant
Internet or an intranet. Web browsers provide access
on 24/7/365 computer operations.
via the Internet to fi les posted on the World Wide
compositing: The process of combining two or more
Web. Web browsers use the Hypertext Transfer Protocol
images to yield a resulting, or composite image.
(HTTP) to make requests of Web servers connected
to the Internet, on behalf of the browser user. The
compression: Algorithms used by a computer to
two most popular browsers in use today are Netscape
reduce the total amount of data in a digitized frame or
Navigator and Microsoft Internet Explorer.
series of frames of video and/or audio.
buffer: A temporary storage area, or holding place,
datagram: See packet.
usually in the RAM (random access memory) of a
data rate or data transfer rate: Amount of data
computer or peripheral device (e.g., a printer), where
moved over a period of time, such as 10MB per second.
data can be collected and/or held for ongoing or later
Often used to describe a hard drive's ability to retrieve
and deliver information. Also see bit rate.
byte: Eight (8) bits.
de interlacing: The process, usually performed by
camcorder: A video camera, i.e., a device that records
video editing software, of removing interlacing from
continuous pictures and generates a signal for display or
video originally intended for display on television
recording. To avoid confusion, it is recommended that
monitors, in order to make it suitable for display on
the term camcorder be used rather than camera in
contrast, a digital camera records still images, while a
delta frame: In interframe (a.k.a. temporal) com
digital camcorder records continuous video images.
pression, periodic keyframes store all the information
capture: If the source footage is analog, capture
that comprises a frame, while delta frames store only
refers to the act of digitization (conversion to a digital
the information that changes from frame to frame in
format) to make the video usable on a computer and,
usually, the simultaneous application of compression to
digital: In contrast to analog, digital representations
reduce the video to a manageable data rate for process
consist of values measured at discrete intervals. Digital
ing and storage. If the source video is DV, capture
clocks go from one value to the next without displaying
typically refers to the simple transfer of video from
all intermediate values. Computers are digital machines
an external device, such as a digital camcorder or tape
employing a binary system, i.e., at their most basic level
deck, to a computer hard drive.
they can distinguish between just two values, 0 and 1
(off and on); there is no simple way to represent all the
capture card: A printed circuit board that fi ts into an
values in between, such as 0.25. All data that a computer
expansion slot on a computer and provides functional
processes must be digital, encoded as a series of zeroes
ity for capturing video from an external source.
and ones. Digital representations are approximations
chapterization: The process of placing markers into
of analog events. They are useful because they are
the timeline of a video to demark the beginning points
relatively easy to store and manipulate electronically.
of sequences, or chapters, to which a viewer may