Matrox Electronic Systems Matrox RT.X2 - Manual (Page 201)

193
Glossary of terms
aspect ratio A width-to-height ratio. For
example, a 12-by-9-inch image has an aspect
ratio of 4:3 (four-to-three). Most TV screens
have a 4:3 aspect ratio. HDTV screens have a
16:9 aspect ratio.
assemble editing Recording new video
and audio material sequentially onto tape.
Because all the signals are recorded (video,
audio, and control track), the new material
completely replaces any previously recorded
material on the tape. See also insert editing.
AVI Audio Video Interleaved. A video file
format designed for the Microsoft Windows
environment. See also codec.
A/V drive A hard drive capable of storing
high-bandwidth audio/video data.
B
B-frame (Bi-directional frame) A frame
created during the MPEG or MPEG-2 IBP
compression process. A B-frame is generated
by forwards and backwards referencing of the
P-frames and I-frames respectively, which
allows it to have the highest compression ratio
of the three frame types. B-frames contain
only predictive data (that is, not enough data
to make up an entire picture), and therefore
cannot be edited independently.
BIOS Basic Input/Output System settings
for system components, peripherals, etc. This
information is stored in a special battery-
powered memory and is usually accessible for
changes at computer start-up.
bitmap A graphics image in which a set of
values defines each pixel’s relative brightness
and color.
black level The level of brightness at
which no light is emitted from the screen
(reference black). The standard black level is
7.5 IRE for NTSC video, or 0 IRE for NTSC-
EIAJ (Japan) and PAL video. Also called
setup (NTSC video only). See also white
level, super black, and super white.
Blue Book standard See DV.
blur/soft focus effect A Matrox effect
that uses various levels of intensity to blur an
image or simulate camera defocus.
bus A shared set of hardware lines that lets
different parts of your computer transfer
information between one another. A card
inserted into an expansion slot of your
computer makes an electrical connection to
the bus and effectively becomes part of your
computer system.
C
capture The process of digitizing video or
audio material, usually from a VTR or
camera, and storing it in a file on a hard disk.
chroma key An effect that makes portions
of a foreground image fully or partially
transparent based on the color of that image,
so that an underlying image can show
through. See also alpha key and luma key.
chrominance The color portion of a video
signal that carries the hue and saturation
information. See also luminance.
codec Compressor/decompressor. A
processor that compresses video to reduce its
file size by eliminating redundancies in
information. It also decompresses files to play
them back.
color bars A standard test signal that
appears as a series of vertical rows of color by
which the chrominance and video levels of a
camera’s output or a recorded signal can be
checked.
color correction effect A Matrox effect
that allows various color properties of an
image to be adjusted. There are controls for
adjusting the intensity level for hue,
saturation, contrast, and brightness. The color
correction effect can correct improper color
levels of an image that are due to varying