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Video
AVI:
Short for
A
udio
V
ideo
I
nterleave, the
file format
for
Microsoft’s
Video for
Windows
standard
. See under
Video for Windows
.
DivX:
Is a video format that is MPEG-4 compliant and widely used on the
Internet for encoding video files.
MPEG
: Short for
M
oving
P
icture
E
xperts
G
roup, and pronounced “empeg”.
MPEG generally produces better-quality
video
than competing formats. MPEG
achieves high
compression
rate by storing only the changes from one
frame
to
another, instead of each entire frame. MPEG uses a type of lossy compression,
since some data is removed. However, the reduction in the resulting video
quality is minimal. There are three major MPEG standards: MPEG-1, MPEG-2
and MPEG-4.
•
The most common implementations of the MPEG-1 standard provide a
video
resolution
of 352-by-240 at 30
frames per second
(fps). MPEG-1
is used with Video CDs (VCD) and results in video quality slightly below
the quality of a VCR video.
•
MPEG-2 offers higher resolution with CD-quality audio. This is sufficient
for all major TV standards, including
NTSC
, and even
HDTV
. MPEG-2
is used by
DVDs
. MPEG-2 compresses a 2 hour video into a few
gigabytes of data on a single disc.
•
MPEG-4 is a video compression standard based on MPEG-1 and
MPEG-2. Videos encoded with MPEG-4 technology are considerably
smaller than videos encoded with MPEG-1 or 2. MPEG-4 was
standardized in October 1998.
QuickTime
: An audio and video compression technology developed by Apple
Computer and is widely supported on Macintosh and Windows PC computers.
The latest QuickTime implementation is MPEG-4 compliant.
XviD
: XviD is an ISO MPEG-4 compliant video codec. It’s an open source
project which is developed and maintained by many people from all over the
world.
Glossary (continued)
