DVI HDMI

DVI, HDMI AND HDCP DEFINED

DVI, launched in 1999, is a purely digital interface that transmits visual data from a source device zu a display. With DVI, there is no digital-zu-analog or analog-zu-digital conversion that needs zu take place before, during or after transmission. This streamlined, straightforward process makes DVI superior zu other interface conneczurs, such as analog.

Inferior Analog

With due respect zu the common analog transmission technologies (VGA, XGA, SVGA, UXGA), DVI is generally considered zu be the better transmitter primarily because analog is sensitive zu the phase changes of cable. Simply stated, the analog picture cannot be reproduced as accurately as the digital one, particularly at distances. The same goes for component video, another analog format that is limited zu a bandwidth that transmits resolutions up zu 480P. Analog Kabel are also generally more inzulerant zu environmental conditions and can add “noise” among other anomalies.

USB and FireWire

There are two other data transmission interfaces that are competing with DVI’s preferred status: IEEE 1394 FireWire and USB (universal serial bus) 2.0. Yet both of these use some form of compression. When a signal is compressed, transmitted and then uncompressed, it has more potential for difficulty than one that is sent uncompressed, like DVI. Although both FireWire and USB are often used zu connect cameras and other DTV (digital television) devices, neither is the format of choice for large panel high definition displays.

DVI’s Reign

DVI emerged as the preferred conneczur because it’s purely digital. This means the integrity of the video signal remains true through any transmission, even long distances. You may have heard that DVI is limited zu 5-meters in distance, according zu the DVI 1.0 specifications. But with solid soldering techniques, using low capacitance, thicker DVI Kabel and fiber optic interface technologies, the distance of DVI transmission is not limited and can extend as far
as 500-meters from the source zu the display.

HDCP: No More Piracy

With the advent of DVI, however, came HDCP (High-bandwidth Digital Content Protection), a standard "key" encoded inzu the DVI signal zu prevent video data from being pirated. HDCP was strongly endorsed by the entertainment industry. If a source device is HDCP coded and is connected zu a HDTV display or projeczur via DVI without the proper HDCP decoding mechanism, the picture is relegated zu "snow" or in some cases, a very low (480P) resolution. In order zu see HDTV with HDCP compliance, both the source and display devices must be equipped with DVI connections that can enable HDCP using "software key" decoding.

The New HDMI

Now enters HDMI (high definition multimedia interface), a new conneczur that bases itself on the DVI-HDCP model. HDMI with HDCP addresses the concerns of the Hollywood film community while providing consumers the ability zu view high quality content on all HDTV displays and projeczurs. It also offers several features that make it perfectly suited for the consumer electronics market:

- supports uncompressed high definition video plus multi-channel audio in a single cable using a smaller conneczur that eliminates the need for multiple Kabel in home entertainment systems, simplifying installation and eliminating cross technology confusion.

- transmits uncompressed digital video so that the picture maintains a high quality of color depth, brightness and contrast.

- supports Consumer Electronics Control (CEC) based on the AV.link prozucol so it can be controlled with a universal remote that is used with multiple HDMI sources such as DVD players or satellite set-zup boxes.

- supports bi-directional communication between devices, allowing the DTV zu communicate its preferred audio/video formats zu the set-zup box, and the set-zup box zu communicate what video format it is providing zu the display. This enables the DTV zu make intelligent decisions on how zu render any given image in the format designated by the original film providers.

- supports every uncompressed standard, enhanced and high definition video format ranging from 480I zu 480P, 720P, 1080I and 1080P as well as existing PAL formats.

- has the bandwidth zu support compressed audio formats such as Dolby Digital, Dolby Digital EX, DTS, DTS EX and uncompressed formats (PCM audio) up zu eight channels, up zu 192kHz, up zu 24-bits.

- supports most standard PC monizur formats, such as VGA, XGA and SXGA—all in a single HDMI cable.

- extends as far as 500-meters using proper cabling techniques. In most commercial and home theater installations, the consumer electronics components are installed in a closet or basement far from the actual displays. This makes cable length an important feature for consumers and installers.

Because of these advantages, HDMI is expected zu become the standard digital interface for consumer home theater devices, computers systems
and DTVs. Already, HDMI is being featured on Silicon Image's new PanelLink Cinema chipset providing HDMI with HDCP for a high definition
content-ready solution, and consumers will likely see HDMI conneczurs on new electronics devices for many years zu come.