|HDMI: One Cable to Replace Them All?|
|Home Theater Feature Articles Other|
|Written by Bryan Dailey|
|Saturday, 01 October 2005|
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Before DVI and HDMI, component video was the cable of choice for transmitting megabit 720p and 1080i HD video. This connection is actually comprised of three separate cables that you commonly see on video displays and sources with red, green and blue RCA connections, labeled Y, B-Y and R-Y. On higher-end pieces, professional grade BNC twist lock connectors are often used. This connection is still commonly used, but it is an analog connection that requires digital to analog back to digital conversions that cut down on the integrity of the HD signal. Having seen an ISF-certified technician run tests on my display, using the same source via HDMI and Component into my JVC HD display, he showed me the dramatic benefits to using the HDMI all-digital connection.
One issue that has kept component video popular for delivering HD content to video displays and projectors is the fact that long HDMI runs have been plagued by signal loss over 15 feet and over 30 feet for DVI. Fiber optic cables from companies like Dtrovision and boosters from Ultralink can be used to run a longer than usual HDMI or DVI connection. Systems where the components and display are close together tend to not have this issue, as they are usually located near the source components, but projectors that hang on the ceiling and modern flat panel installations are more often than not well over the 15-foot distance from the source that causes problems with HDMI cables.
Some people prefer the screw-on DVI cable to the small, slender HDMI connector. However, I have recently learned to love the simplicity of the HDMI connection when I had to reach my hand into a virtually inaccessible space and plug in an HDMI cable with one hand. It would have been impossible to get a bulky DVI cable plugged in and would have required me to take out most of the components in the cabinet. The HDMI plug is robust enough to let you know when it is properly connected and yet very simple to plug in and out and does not get stuck and require an extreme amount of force as some RCA connectors can do when jammed together in close quarters.
HDMI comes on the heels of the previous direct digital HD video cable connection DVI. HDMI is backwards-compatible to DVI with the use of adapter of conversion cable. However, when HD-DVD and or Blu-ray hits the streets with a high definition audio format included, HDMI will really begin to shine as DVI does not have the capability to carry audio. What sets HDMI and DVI apart, besides the obvious different-looking connectors on the ends of the cables is the fact that HDMI has the ability to carry an audio signal along with the video signal and other control signals. Both formats carry the HDCP digital encoding that Hollywood movie studios endorse to prevent people from being able to make direct digital copies of high-definition content, but in the real world of installations of HDMI-based systems, this is one of the reliability issues that AV installers are beginning to face.