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Chapter 6: Appendix
77
“SDI”: Serial Digital Interface. The standard based on a 270 Mbps transfer rate. This is a
10-bit, scrambled, polarity independent interface with common scrambling for both
component ITU-R 601 and composite digital video and four channels of (embedded) digital
audio.
“Seamless Switching”: A feature found on many video switchers. This feature causes the
switcher to wait until the vertical interval to switch. This avoid a glitch (temporary
scrambling) which normally is seen when switching between sources.
“SMPTE”: Society of Motion Picture and Television Engineers. A global organization, based in
the United States, that sets standards for baseband visual communications. This includes
film as well as video and television standards.
“S-Video”: A composite video signal separated into the luma (“Y” is for luma, or black and
white information; brightness) and the chroma (“C” is an abbreviation for chroma, or color
information).
“Sync”: Synchronization. In video, sync is a means of controlling the timing of an event with
respect to other events. This is accomplished with timing pulses to insure that each step in
a process occurs at the correct time. For example, horizontal sync determines exactly when
to begin each horizontal scan line. Vertical sync determines when the image is to be
refreshed to start a new field or frame. There are many other types of sync in video
system.(Also known as “sync signal” or “sync pulse.”)
“TCP/IP”: Transmission Control Protocol/Internet Protocol. The communication protocol of
the Internet. Computers and devices with direct access to the Internet are provided with a
copy of the TCP/IP program to allow them to send and receive information in an
understandable form.
“USB”: Universal Serial Bus. USB was developed by seven PC and telecom industry leaders
(Compaq, DEC, IBM, Intel, Microsoft, NEC, and Northern Telecom). The goal was easy
plug-and-play expansion outside the box, requiring no additional circuit cards. Up to 127
external computer devices may be added through a USB hub, which may be conveniently
located in a keyboard or monitor. USB devices can be attached or detached without
removing computer power. The number of devices being designed for USB continues to
grow, from keyboards, mice, and printers to scanners, digital cameras, and ZIP drives.
“VESA”: Video Electronics Standards Association. A nonprofit number organization
dedicated to facilitating and promoting personal computer graphics through improved
standards for the benefit of the end-user. www.vesa.org
“VGA”: Video Graphics Array. Introduced by IBM in 1987, VGA is an analog signal with TTL
level separate horizontal and vertical sync. The video outputs to a 15-pin HD connector and
has a horizontal scan frequency of 31.5 kHz and vertical frequency of 70 Hz (Mode 1, 2)
and 60 Hz (Mode 3). The signal is non-interlaced in modes 1, 2, and 3 and interlaced when
using the 8514/A card (35.5 kHz, 86 Hz) in mode 4. It has a pixel by line resolution of
640×480 with a color palette of 16 bits and 256,000 colors.
“YCrCb”: Used to describe the color space for interlaced component video.
“YPbPr”: Used to describe the color space for progressive-scan (non-interlaced) component
video.
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