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3G/HD/SD SDI to HDMI Converter User Guide
TM
BrightEye 72
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.
Tri-Level Sync
An analog sync reference signal that is used in High Definition systems. Tri-Level Sync is constructed
with three signal levels: the sync pulses extend above and below a mid-level average voltage (the
blanking level). Unlike conventional analog sync which is bi-level, the proper 50% pickoff point is
already identified in Tri-Level Sync. This contributes to lower jitter in digital systems.
VGA
Video Graphics Array. Traditional 15-pin, analog interface between a PC and monitor.
YUV
Strictly speaking, YUV does not apply to component video. The letters refer to the Luminance (Y), and
the U and V encoding axes used in the PAL composite system. Since the U axis is very close to the B-Y
axis, and the V axis is very close to the R-Y axis, YUV is often used as a sort of shorthand for the more
long-winded “Y/R-Y/B-Y.”
Y/Cr/Cb
In digital component video, the luminance component is Y, and the two color difference signals are Cr
(R-Y) and Cb (B-Y).
Y/Pr/Pb
In analog component video, the image is carried in three components. The luminance is Y, the R-Y
color difference signal is Pr, and the B-Y color difference signal is Pb.