- April 2004 -
[Click Message To Learn More]
High-Definition (HDTV) and Digital (DTV) Television
Connection and Cabling
DVI is currently a format of choice for professional installers, favored for its ability to carry and deliver uncompressed digital video resolutions up to 1080i.
HDTV is undoubtedly beautiful and as prices continue to drop, more and more consumers are clamoring to install and enjoy it. Yet, we have found that there has been very little knowledge passed on to consumers regarding how HDTV or even high-resolution digital video displays should be connected, what cables are needed and why. All too often, HDTV-enabled displays are connected with component or analog video cable and connectors, which basically defeats the purpose of going digital or high-definition in the first place. This is because analog and component video transmission technologies (VGA, XGA, SVGA, UXGA) cannot accurately reproduce the higher resolutions required for DTV and HDTV; they were designed for lower-resolution analog video, typically 480p. They are also sensitive to phase changes of cable, which means the further that video signals are sent over cabling, as is so often the case in home theater systems, the greater the potential for imagery degradation.
Still, many of the current HDTV and digital video displays in the market are equipped with both analog and digital interfaces. Manufacturers are likely seeking to bridge the gap between old and new technologies. Itıs unfortunate that consumers generally donıt know the difference between the two and often default to the inferior analog connector and cables. The digital connector, known as digital visual interface (DVI), was never fully explained and therefore, largely ignored. Yet DVI was specifically created to transmit the higher-resolutions of digital video, and is able to maintain the integrity of high-resolution video even when sent over long lengths of cable. Some of you may have heard that DVI is limited to a distance of about 15-feet, according to the DVI 1.0 specifications, but with solid soldering techniques, using low capacitance, thicker DVI cables and fiber optic interface technologies, DVI can extend hundreds of feet from the source to the display.
There are two additional digital video transmission interfaces that are often used to connect and send high-resolution video for digital cameras and similar computer-related devices: IEEE 1394 FireWire and USB (universal serial bus) 2.0. Yet both of these interfaces use some form of compression to connect and send video data. When a signal is compressed, transmitted and then uncompressed, it has more potential for inaccurate video reproduction and signal degradation than one that is sent uncompressed, like DVI. Because of this, neither is the preferred format for connecting large panel, high-definition displays.
DVI is currently a format of choice for professional installers, favored for its ability to carry and deliver uncompressed digital video resolutions up to 1080i. The one challenge to DVI that sometimes hinders consumers is the fact that DVI transmits digital video only. Audio is generally routed through a receiver in home theater installations and though this results in greater video and audio quality and refinement capabilities, it can intimidate the general consumer. Using DVI also requires the purchase of new cables, namely DVI cables that use fiber optics to transmit video from source to display. Yet the resulting video is well worth it for those who value their video imagery and want the very best, most pristine results.
Most HDTV and digital video displays in the market today are equipped with DVI, yet there is a new transmission technology known as HDMI (high-definition multimedia interface) that supports uncompressed, high-definition video plus multi-channel audio in a single cable using a smaller connector that eliminates the need for multiple cables in home entertainment systems. It also supports bi-directional communication between devices, and is compatible with standard, enhanced and high-definition video formats, PAL and PC monitor formats, such as VGA, XGA and SXGA, plus compressed audio formats such as Dolby Digital, and uncompressed formats. HDMI can also extend high-definition video without visual degradation.
Because of these advantages, itıs only a matter of time before HDMI is expected to become the standard digital interface on future home theater devices, computers systems and displays. In the meantime, it is important for consumers to realize the necessity of using DVI for high-resolution, digital video and to understand that DVI can be manipulated just like analog video; the signal can be split, distributed, switched and extended to greater enhance the viewing environment.