Ensemble Designs BrightEye 90-F HD Up/Down Cross Converter and ARC with AES Audio and Optical Output - Manual (Page 37)

TM
BrightEye 90-F
BrightEye 90-F - Page 37
MPEG
The Moving Picture Experts Group is an industry group that develops standards
for the compression of moving pictures for television. Their work is an on-going
effort. The understanding of image processing and information theory is
constantly expanding. And the raw bandwidth of both the hardware and software
used for this work is ever increasing. Accordingly, the compression methods
available today are far superior to the algorithms that originally made the real-
time compression and decompression of television possible. Today, there are many
variations of these techniques, and the term MPEG has to some extent become a
broad generic label.
Metadata
This word comes from the Greek, meta means 'beyond' or 'after'. When used as a
prefix to 'data', it can be thought of as 'data about the data'. In other words, the
metadata in a data stream tells you about that data – but it is not the data itself.
In the television industry, this word is sometimes used correctly when, for
example, we label as metadata the timecode which accompanies a video signal.
That timecode tells you something about the video, i.e. when it was shot, but the
timecode in and of itself is of no interest. But in our industry's usual slovenly way
in matters linguistic, the term metadata has also come to be used to describe data
that is associated with the primary video in a datastream. So embedded audio
will (incorrectly) be called metadata when it tells us nothing at all about the
pictures. Oh well.
Multi-mode
Multi-mode fibers have a larger diameter core than single mode fibers (either 50
or 62.5 microns compared to 9 microns), and a correspondingly larger aperture.
It is much easier to couple light energy into a multi-mode fiber, but internal
reflections will cause multiple “modes” of the signal to propagate down the fiber.
This will degrade the ability of the fiber to be used over long distances. See also
Single Mode.
NTSC
The color television encoding system used in North America was originally
defined by the National Television Standards Committee. This American
standard has also been adopted by Canada, Mexico, Japan, Korea, and Taiwan.
(This standard is referred to disparagingly as Never Twice Same Color.)
Optical
An optical interface between two devices carries data by modulating a light
source. This light source is typically a laser or laser diode (similar to an LED)
which is turned on and off at the bitrate of the datastream. The light is carried
from one device to another through a glass fiber. The fiber’s core acts as a
waveguide or lightpipe to carry the light energy from one end to another. Optical
transmission has two very significant advantages over metallic copper cables.
Firstly, it does not require that the two endpoint devices have any electrical
connection to each other. This can be very advantageous in large facilities where
problems with ground loops appear. And secondly, and most importantly, an
optical interface can carry a signal for many kilometers or miles without any
degradation or loss in the recovered signal. Copper is barely useful at distances of
just 1000 feet.