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M1 |
M1
is an interface designed for display devices. It is most often found on
projectors, and it can receive a variety of signals—analog video (VGA),
digital video (DVI), and even USB. The M1 connector is sometimes called
an “EVC” or “P & D” (Plug & Display) connector.
The M1 interface closely resembles a DVI connector. It
uses a 30-pin (3 rows of 10 pins) LFH connector, with an offset ground
bar. For cables that carry an analog video signal, there are 4
additional pins surrounding the ground bar. |
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| HD15 (VGA) |
A
very common connector used mostly as a video interface for computers
and monitors, and projectors. The HD15 is a High Density DB-style
connector, so it can also be called an HD DB15. Another popular name is
VGA connector, although it is used in video applications that support
much higher resolutions (SVGA, XGA, UXGA, etc.). An HD15 connector is
the same size as a DB9 connector, but it has three rows of 5 pins. On
most HD15 male connectors, there is one pin (pin 9) missing in the
middle row. |
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| S-Video |
Super
Video is an interface protocol first introduced by JVC with the very
first S-VHS video decks around 20 years ago. S-Video sends an analog
video signal on two 75-ohm coaxial cables. One conductor delivers a
luminance signal which is a black and white wide-bandwidth television
signal. The other delivers a chrominance (color) signal which normally
is a composite signal riding "under" the luminance information at a
frequency below the 3.58MHz "color burst" frequency.
Many sources transmit a video signal using this two-part
interface. Contrary to common belief, S-Video does not improve
resolution. That is a function of the bandwidth of the connection, a
commonly accepted "rule of thumb" being that you get approximately 90
lines of resolution for each MHz of bandwidth. S-Video does, however,
greatly improve color resolution allowing for a tighter and more
refined image. |
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| DVI™ |
DVI
(Digital Video Interface) is a trademark of the Digital Display Working
Group, an amalgam of corporations headed by Intel and including such
powerhouses as Compaq, Fujitsu, Hewlett Packard, IBM, NEC and Silicon
Image. The DVI connection was designed as a replacement for the P&D
(Plug and Display) standard, itself an upgrade from the digital-only
DFP format. Designed primarily to connect a computer to an LCD flat
panel monitor, DVI has found applications in advanced consumer
electronics image devices where it is used to deliver digital video
from a source to a display. One drawback for DVI is that it is limited
to about 20 meters. Beyond this length, signal degradation quickly
becomes evident. |
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| DVI-D |
DVI-D transfers uncompressed digital video in its native format between source and display or between components.
DVI-D precludes the typical digital-to-analog/analog-to-digital conversions between a computer’s video card and monitor
and provides a higher quality and faster (wider bandwidth) interface. DVI-D is the interface used on the equipment of
interest to the majority of readers of this site. Fortunately, DVI-D and the next iteration have much in common. |
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DVI Single Link
and Dual Link |
DVI uses a digital information format called Transition Minimized Differential Signaling (TMDS). Single link cables
use one TMDS transmitter, while dual link cables use two. A single link DVI connection can support a 1920 x 1080 image
at 60fps. A dual link connection supports up to a 2048 x 1536 image.
The digital interface uses 24 of the possible 29 pins found on a DVI-I interconnect. A single link DVI cable
enables 12 of those 24 digital pins. A dual link configuration enables all 24. For audio/video applications, a single
link interconnect is the correct choice. The dual link configuration, while not improving performance on a single
link system, will not hinder performance and is interchangeable in that application. |
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| Composite Video |
Granddaddy of all video connections, this simple single coax connection can be made via BNC or RCA connector. The
RCA plug is not, by its very nature, a 75-ohm design. This little detail hasn’t stopped it from becoming as ubiquitous
as a dust-bunny and only slightly more expensive. Older video formats such as analog C-Band satellite, laser disc,
and VHS or Beta should be connected using a composite interface for maximum performance. It is HIGHLY likely that
the comb filter function implemented in a modern performance-oriented projector or monitor is vastly better than any
comb filter added to one of these video devices in order to provide an S-Video output. |
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EIA 770.3 (YPbPr
Component Video) |
The component interface is the most common extended definition video interface in use on contemporary consumer products.
Component connections send one luminance and two phase-opposite chrominance signals on three 75-ohm coaxial cables.
Wholly analog, the 770.3 component interface boasts the same robust nature as RGBHV above. Regardless of other
connection schemes, this is one you have to include if you want your system to be truly universal in nature. |
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