[tech] article
date: November 2004
[ - ]
Video Connections from a computer to a television (for
example, a Plasma high definition television), or from a DVD player to a high definition monitor/projector.
From "best"
to "worst":
HDMI
High Definition Multimedia Interface (HDMI)
HDMI is the first industry-supported, uncompressed, all-digital
audio/video interface. HDMI provides an interface between
any audio/video source, such as a set-top box, DVD player,
and A/V receiver and an audio and/or video monitor, such
as a digital television.
HDMI supports standard, enhanced, or high-definition video,
plus multi-channel digital audio on a single cable. It transmits
all ATSC HDTV standards and supports 8-channel digital audio,
with bandwidth to spare to accommodate future enhancements
and requirements.
It has 5 Gbps bandwidth of data bandwidth, plenty
enough for future expansion.
HDMI is compatible with DVI-D.
Note: HDMI and DVI both transport digital video signals, and are both capable of carrying the same level of "video quality". The main difference between HDMI and DVI is that HDMI provides a standardized form of copy-protection (which means its good for manufacturers, but often frustrating for users). Also, the HDMI plug is smaller. Since many DVI out ports are video only, the integrated audio of the HDMI ports is often touted as well.
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DVI (Digital Video Interface: DVI-D
or DVI-I)
aka HDCP
Specifically designed for digital
devices, DVI-D provides (arguably) the brightest, most accurate
colors and sharpest detail for your high-definition, all-digital
video receiving device.
DVI-D requires data to be transferred
in pure digital form in order to achieve the best-possible
performance from your digital devices. To obtain the highest-possible
resolution from DVI (digital video) technology, a dual-link,
24-pin connection is required. (Single-link (18-pin) connectors
can significantly limit the bandwidth potential of DVI;
Dual-link DVI cables provide the convenience of backward-compatibility
with AV (audio-video) hardware that is single-link-enabled
only.)
Some Plasma TVs now (November
2004) have DVI-D (HDCP) inputs, and some DVD players
(see example at the bottom of
this page) have DVI-D outputs.
DVI (Digital Video Interface) Inputs
This can be either a digital only connection (DVD-D) or
a combination digital and analog connection DVI-I. Many
new DVD's and STB's (Set top Boxes) for Satellite (DSS)
or Digital Cable TV will have these connectors this year.
Many new HDTV's and Projectors are using this connection
already.
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DVI-I jack (digital plus analog)
DVI-D output jack
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A DVI connection can be one of three types - DVI-I, DVI-D
or DVI-A (rare!) .
DVI-I:
DVI-I contains both the digital and analog connections,
(DVI-D + DVI-A).
It's essentially a combination of DVI-Digital and DVI-Analog
cables within one cable.
Has 24 pins plus 4 analog pins.
DVI-D:
DVI-D (like DFP or P&D-D (EVC)) is a digital-only
connection. If both devices being connected support a
Digital DVI connection (DVI-I or DVI-D compatible) and
are compatible in resolutions, refresh rates and sync,
using a DVI-D cable will ensure that you are using a digital
connection rather than an analog connection, without playing
around with settings.
DVI-A:
DVI-Analog is really rare. (Why use a DVI connector when
you can use a cheaper VGA (analog) connector? )
DVI-I P&D-A (EVC) was seen for a while on some projectors....
click here to view all
DVI connector types
DVI output sometimes has selectable scaling (selectable 480p,
720p or 1080i output); this enables users to best match
the characteristics of a video display device.
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Connections:
Output: computer (PC) ; progressive-scan
DVD player (rare)
Input: plasma TV, LCD TV , or monitor, HDTV/digital
satellite receiver,
[Example: A DVI cable from Belkin, ($80 as of 2005); DVI-D
to DVI-D dual-link, reportedly capable of 1600 x 1200 resolution] |
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 VGA
(Video Graphics Array) Inputs
[aka PC-Video (RGB); aka 15-pin
D-sub ]
VGA inputs are typically used to connect PCs to monitors or other screens.
The type of cable used is a 15 pin VGA cable, which is the same
type used to connect regular computer monitors to processors.
On certain models (such as the Sony PFM series
of plasma displays) the VGA input can also be used to connect
analog video components using an RCA-to-VGA cable or S-Video-to-RS232 cable. (The majority of plasma and flat-panel LCD
displays only use the VGA for computer use, so check with your
vendor before purchasing an RCA-to-VGA cable.)
 RGB
Video (VGA) Example:
This is a closer view of the PC-Video (RGB / VGA)
connector on the rear of an 18-inch LCD TV. This connection is used to connect the TV to an RGB video input source, such as a computer.
"Connect the 15-pin D-Sub RGB connector on the computer to the
RGB-IN."
a.k.a.  SVGA
a.k.a. RGB (red, green, blue), a.k.a. RGBHV a.k.a. RGB-HV
[ Red Green Blue Horizontal sync Vertical sync;
"RGB-HV" is sometimes used to refer to the video signal used by computers and high definition video. This is presumedly to distinguish the 15-pin D-Sub RGB cables from other RGB cables.]
SVGA is "a solution for connecting computers to projectors, plasma TVs,
LCD or CRT monitors, or flat-panel receivers". SVGA (Super VGA) transports video signals by separating the signal into each of three primary colors:
red, green, and blue. It carries full resolution of each color
on its own wire to allow for clear and bright images, and also transports sync data; this transport generally exceeds the performance of Component, and is better than Composite and S-Video connections.
(Note: the VGA connector should not be confused with the "RS-232" connector used for "control by wire".)
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Component Video
a.k.a. RGB (red, green, blue);
 Red,
Green, and Blue cables provide true color separation (one cable
for each primary color) and reduced interference for high picture
color, clarity, and resolution. These cables are capable of carrying full high definition (HD) signals, but this capability is usually restricted by the sending or receiving device (usually as part of the HDMI copy-protection scheme).
 [more info: see comparison of composite / s-video
/ component]
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Note for connecting PCs to standard NTSC CRT televisions:
CRTs (using Component Video or S-Video input) can generally only support a maximum of around 640x480
pixels (actually 480 lines at a max of 60 Hz), so computer to TV adapters are not able to clearly
display a computer desktop very well. Note that unless your TV
is high definition capable, it's only going to display at 640x480
(at best) so attaching your computer to it by any means will have
the same result.
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S-Video
S-Video separates brightness from color
using two separate conductors to create cleaner, more accurate
signals. It delivers better color accuracy and sharper picture
detail than Composite Video; however, it will not achieve the
optimal performance of Component Video, which uses three cables
to separate color into its primary components.
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Connection Scenario Example: An advertisement for a Widescreen LCD TV lists "Component,
S-Video, Composite, and 15-pin D-sub inputs".
This would mean your best connection from a DVD player would probably
be the Component input, and your connection from a PC would be the VGA
(15-pin D-Sub RGB) input.
The maximum physical display resolution of the external monitor is
640 × 480 dots when the aspect ratio is set to 4:3, and 852 ×
480 dots when the ratio is set to 16:9.
Note: "A/V cable" (audio/video) cable is too generic: it
could be an HDMI A/V cable, component A/V cable, Composite
(yellow-red-white) A/V Cable (*), etc.
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