Specifications
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A Digital Video Primer
MPEG: Moving Pictures Expert Group of the International Organization for Standardization
(ISO), which has dened multiple standards for compressing audio and video sequences. Setting
it apart from JPEG which compresses individual frames, MPEG compression uses a technique
where the dierences in what has changed between one frame and its predecessor are calculated
and encoded. MPEG is both a type of compression and a video format. MPEG-1 was initially
designed to deliver near-broadcast-quality video through a standard speed CD-ROM. Playback
of MPEG-1 video requires either a soware decoder coupled with a high-end computer, or a
hardware decoder. MPEG-2 is the broadcast quality video found on DVDs.
MXF: Material eXchange Format, a wrapper technology designed to facilitate asset interchange
between dierent multimedia and post-production soware applications. Like AAF (of which
it can be an object subset), MXF is an open standard for the exchange of content (actual images,
video and audio clips, and so on) and its associated metadata across platforms and between
applications. MXF was designed for less complex metadata applications than AAF. While AAF
can contain the actual content or only a link to it, MXF always contains the actual content along
with the metadata. e primary objective of MXF is the streamlined exchange of the content with
its associated metadata. MXF les may be used as a source for AAF. With its greater emphasis
on actual content exchange, MXF is better optimized than AAF for real-time streaming of video
and audio assets, making it an excellent solution for such applications as broadcast news editing.
NLE: Nonlinear editing.
Noise: Distortions of the pure audio or video signal that would represent the original sounds and
images recorded, usually caused by interference.
Nonlinear editing (NLE): Random-access editing of video and audio on a computer, allowing for
edits to be processed and reprocessed at any point in the timeline, and at any point in the editing
process. Traditional videotape editing is linear, requiring that video be edited sequentially, from
beginning to end.
NTSC: National Television Standards Committee, the standard for color television transmission
used in the United States, Japan, and elsewhere. NTSC incorporates an interlaced display at 29.97
frames per second.
Offline editing: e practice of editing a nal version that is not intended for distribution using
low-quality clips. e oine version is then used in online editing to produce the nal distrib-
uted version using high-quality clips.
OMF or OMFI: Open Media Framework or Open Media Framework Interchange format, a media
and metadata exchange solution introduced prior to AAF. It was not broadly adopted. However,
as the industry transitions to the more widely accepted AAF standard, more applications and
utilities are including support for OMF interchange.
Online editing: e practice of editing that results in a nal product for distribution.
Out point: e point in a source clip at which the material used in a video program ends.
PAL: Phase-Alternating Line, the television standard used in most European and South Ameri-
can countries. PAL uses an interlaced display at 25 frames per second.
Panning: Moving a camera horizontally or vertically as a scene is being shot. Also, shiing stereo
sound between the le and right channels.
Phosphor: A luminescent substance, used to coat the inside of a television or computer display,
that is illuminated by an electron gun in a pattern of graphical images as the display is scanned.
Pixel: Picture element, the smallest computer display element, represented as a point with a
specied color and intensity level. One way to measure image resolution is by the number of
pixels used to create the image.
Poster frame: A single frame of a video clip used as an icon to represent and identify that clip in
parts of the Adobe Premiere Pro interface.
Post-production: e phase of a lm or video project that involves editing and assembling foot-
age, and adding eects, graphics, titles, and sound.