Ensemble Designs BrightEye 90-F HD Up/Down Cross Converter and ARC with AES Audio and Optical Output - Manual (Page 39)

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BrightEye 90-F
BrightEye 90-F - Page 39
video. This could refer to standard definition at 270 Mb/s, HD SDI or High
Definition Serial Digital video at 1.485 Gb/s, or to the newer 3G standard of High
Definition video at 2.97 Gb/s.
SMPTE
The Society of Motion Picture and Television Engineers is a professional
organization which has done tremendous work in setting standards for both the
film and television industries. The term “SMPTE’” is also shorthand for one
particular component video format - luminance and color difference.
Single Mode
A Single mode (or mono mode) optical fiber carries an optical signal on a very
small diameter (9 micron) core surrounded with cladding. The small diameter
means that no internally reflected lightwaves will be propagated. Thus only the
original “mode” of the signal passes down the fiber. A single mode fiber used in an
optical SDI system can carry a signal for up to 20 kilometers. Single mode fibers
require particular care in their installation due to the extremely small optical
aperture that they present at splice and connection points.
See also Multi-mode.
TBC
A Time Base Corrector is a system to reduce the Time Base Error in a signal to
acceptable levels. It accomplishes this by using a FIFO (First In, First Out)
memory. The incoming video is written into the memory using its own jittery
timing. This operation is closely associated with the actual digitization of the
analog signal because the varying position of the sync timing must be mimicked
by the sampling function of the analog to digital converter. A second timing
system, genlocked to a stable reference, is used to read the video back out of the
memory. The memory acts as a dynamically adjusting delay to smooth out the
imperfections in the original signal’s timing. Very often a TBC will also function
as a Frame Synchronizer. See also Frame Sync.
Time Base Error
Time base error is present when there is excessive jitter or uncertainty in the line
to line output timing of a video signal. This is commonly associated with playback
from video tape recorders, and is particularly severe with consumer type
heterodyne systems like VHS. Time base error will render a signal unusable for
broadcast or editing purposes.
Timecode
Timecode, a method to uniquely identify and label every frame in a video stream,
has become one of the most recognized standards ever developed by SMPTE. It
uses a 24 hour clock, consisting of hours, minutes, seconds, and television frames.
Originally recorded on a spare audio track, this 2400 baud signal was a
significant contributor to the development of video tape editing. We now refer to
this as LTC or Longitudinal Time Code because it was carried along the edge of
the tape. This allowed it to be recovered in rewind and fast forward when the
picture itself could not. Timecode continues to be useful today and is carried in
the vertical interval as VITC, and as a digital packet as DVITC. Timecode is the
true metadata.