Click on a letter to jump to that section of our glossary.
Layer Change - A DVD contains up to two data layers on each side.
Each data layer can hold about two hours of NTSC video. Movies
longer than two hours long or encoded at a high data rate,
are spread across the two layers on one side of the DVD.
The laser is refocused to play the second layer and when
the player changes to the second layer, the video and audio
may freeze momentarily.
LCD - Liquid Crystal Display.
A panel consisting of two transparent polarizing panels with a liquid
crystal material sandwiched between. When voltage is applied, individual
crystals turn dark. Behind the panels is a light source which flows through
clear crystals and is blocked by dark crystals. The pattern of off and
on crystals creates the image.
LCoS - Liquid
Crystal on Silicon. While similar to LCD projection technology,
instead of blocking or allowing light through (as in LCD
projectors), LCoS applies liquid crystals onto a silicon
chip which then either reflects or doesn't reflect the light.
Three chips are used, one for each color, which in better
picture quality and eliminates problems such as the"rainbow" effect.
Learning Remote - A form of universal remote that can control all the devices
in a home theater from a single controller. A universal remote
control can be programmed with control codes for broad range
of devices. A learning remote adds to this ability by being
able to "talk" with the original remote. By placing
an original remote head-to-head with a learning remote, the
signal from the original remote is learned and assigned to
a button on the new remote.
Letterbox -
Because some images, such as wide-screen movies, do not fill
a TV screen, black bars are placed above and below the image
to fill the unused space. This allows to movie to be shown
in its native aspect rather than being adjusted to fit the
screen. When bars are placed to the left and right sides
of an image it is called windowbox.
LFE - Low Frequency
Effects or the bass audio signal. Generally the signal between
20-150Hz that is played through a subwoofer.
Line Doubler - A device, or circuit in a device, which converts interlaced
video to progressive scan video. Interlaced pictures are
painted in two passes. Every other line is painted in the
first pass and the alternate lines are painted on the second
pass. A line doubler, aka deinterlacer, creates a complete
picture, filling in all of the lines, for each scan. More
lines results in a better picture.
Lossless Compression - A compression algorithm that doesn't lose any of the original
data. The original image or sound is completely preserved.
Lossy Compression-
A compression algorithm that removes some data, to reduce
the file size, while preserving the sound or image. Data
that is removed is lost, thus altering the original image
permanently.
Loudness Compensation - A feature on many receivers that attempts to compensate
for the loss in low-frequency sound at lower volume levels.
Luminance -
The brightness portion of a video signal, represented as "Y".
The luminance signal carries the picture detail information
and can produce a complete black and white image. When combined
with the chrominance signal or component color signals a
complete color image can be displayed.
