|- Consumer Electronics
Control . .
|- Display Data Channel
|- Digital Display
|- Digital Flat Panel
|- Digital Theater Sound
|- Digital Television
|- Digital Visual
Interface . .
|- Extended Display
|- Electronics Industry
Digital Content Protection . .
|- High Definition
Multimedia Interface . .
|- On-Screen Display
|- Plug and Display (M1)
|- Phase Alternating
|- Plug and Play
|- Satellite Digital
|- Super Video Graphics
Array (VGA extensions) . .
|- Super Extended
Graphics Array (1280 x 1024) . .
Differential Signaling . .
|- Ultra Extended
Graphics Array (1600 x 1200) . .
|- VESA Bios Extension
|- Video Electronics
|- Video Graphics
Array . .
|- Extended Graphics
Array . .
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Why is digital better than the traditional analog
|DVI and HDMI are better than the
traditional analog transmission technology because analog is more
sensitive to the phase changes of cables. This is also the reason
DVI and HDMI are better than component video.
The only drawback of digital transmission technology is that the
data being transferred can only maintain full fidelity for about 5
meters with DVI and about 15 meters for HDMI. Cable runs can be
increased with the use of fiber optic technologies, amplifiers, and
repeaters, however, their incredible expense makes the idea commonly
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makes use of Transition-Minimized Differential Signaling (TMDS)
wherein eight bits of video data are converted to a 10-bit
transition-minimized, DC-balanced value. This value is then
serialized and sent to the receiver where the data is
de-serialized and converted back to eight bits.
The three TMDS signals needed for
RGB make up one TMDS link. A DVI connector can carry up to
two TMDS links providing for better resolutions and timing
requirements. Single TMDS link DVI cables can support
resolutions and timings that use a video clock rate of about
The following resolutions and
timings are supported by a single link DVI cable:
resolution (1280 x 1024) with 85-Hz refresh rate
Video clock rates of 165-330 MHz on the other
hand, are supported only by dual TMDS link DVI cables. With
dual link DVI cables, however, each TMDS link operates at only
one-half the frequency of single link DVI. So the clock and
bandwidth is shared by these two links.
UXGA resolution (1600 x 1200) with 60-Hz
SDTV resolutions of 480i, 480p, 576i and
HDTV resolutions of 720p and 1080i
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High-bandwidth Digital Content Protection
Along with the
introduction of DVI technology came the need to prevent the
digital video data from being pirated, or copied without
authorization. In order to address this issue
High-bandwidth Digital Content Protection (HDCP) was derived.
HDCP, developed by the
Intel Corporation, implements a key encryption encoded into
the DVI signal which, without the proper HDCP decoding
mechanism, produces either extremely low resolutions or static.
To avoid this, both source and display devices must have DVI
connections that support software key HDCP decoding.
used by the new HDMI technology, was
strongly endorsed by the entertainment industry, for obvious
reasons. What makes this technique of key encryption possible
is its renewability. The
Content Protection LLC, an organization responsible for
licensing of the HDCP technology, monitors the secret keys used
to encrypt the data. If at any time they believe a set of
secret keys has been compromised by an unauthorized source,
those keys are placed on a revocation list and new keys are
provided to devices authorized by license.
HDCP also uses a method of authentication to ensure that the
receiving device is licensed to receive HDCP encrypted data.
This authentication process repeats itself every few seconds in
order to be certain that an illegal device has not been
connected after the initial authentication. If and when this
authentication fails, the source device will immediately end all
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Consumer Electronics Control (CEC)
Consumer Electronics Control (CEC) is an optional protocol used in
HDMI systems that allows HDMI devices to pass
control functions along to all devices within the system. CEC
was designed to operate at low speeds with minimal processing and
The following is a set of all the features offered with CEC.
Devices may use all or only some of these features, depending upon
One Touch Play – A device may be played
and become the active source by the press of a single button.
System Standby – Enables devices to be set
on standby by the press of a single button.
Preset Transfer – A device’s presets can
be auto-configured to match those of the TV.
One Touch Record – Allows recordings to be
made by the press of a single button.
Timer Programming – Any device can program
a timer recording on a recording device.
System Information – Allows devices to
auto-configure their language and country settings.
Deck Control – Allows a device to control
and interrogate a playback device.
Tuner Control – Allows a device to control
the tuner of another device.
Vendor Specific Commands – Allows
vendor-defined commands to be used.
OSD Display – Allows a device to display
text using the on-screen display of the TV.
Device Menu Control – Allows a device to
control the menu of another device.
Routing Control – Enables control of CEC
Switches for streaming of a new source device.
Control Pass Through – Allows Remote Control commands to be
passed along to other devices within the system.
Device OSD Name Transfer
– Devices may request the preferred OSD name of other devices
within the system.
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