1. Introduction
Terms and Definitions
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 image 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
