High Definition Multimedia Interface, or HDMI, is the high definition interconnect preferred by television and home theater equipment manufacturers. Able to deliver uncompressed audio and high-definition video at the highest rates, HDMI only requires a single cable from the satellite, Blu-ray or HD cable box to the television. Choosing the right HDMI cable addresses current needs, while helping to prevent your system from becoming obsolete.
Arguably one of the most confusing aspects of the HDMI standard revolves around speed. As high-definition sources increase in audio and video capability, speed becomes more important. Although some manufacturers have taken the approach of using multiple titles for their cables such as "Ultra High Speed" and the like, HDMI Licensing only allows discussions of "Regular" (v1.2) and "High" (v1.3/1.4) speeds. The former is rated for 720p/1080i resolutions, at 742.5 megabits per second, per channel. High-speed versions are rated to address 1080p and above, at up to 3.4 gigabits per second, per channel. High-speed cables are backward compatible with older sources and televisions limited to the lower resolutions and data rates.
The longer the HDMI cable run, the more likely the risk of intermittent picture quality or a signal loss. Most HDMI cables operate perfectly up to 50 feet. Beyond this distance, especially used in conjunction with an HDMI switcher for multiple sources, a signal booster is recommended. These devices essentially regenerate the signal, so long HDMI runs to a television or projector remain clear and sharp. Some manufacturers take special pride in sending HDMI signals over cables longer than 50 feet without a booster, so examine this carefully when making a selection. Boosters, or repeaters, come integrated in some HDMI cables, while others use an outboard powered box. Often, the cables with built-in repeaters are called "active." From an installed cost perspective, removing and reinstalling an HDMI cable routed through a wall or ceiling is often more expensive than installing the right one to begin with.
Most HDMI cables are sourced from only a few manufacturers, but there are things you can examine that help define overall HDMI cable quality. Like most wires, a larger gauge helps reduce signal loss, at any distance. Most HDMI cables are 28 gauge per inner conductor. Better cables, and certainly ones expected to send signals up to an potentially over 50 feet, should be 24 gauge. These cables are sturdier and, while slightly stiffer, help to ensure a reliable signal from source to display.
HDMI is backward compatible with Digital Video Interface, or DVI. This is important if you have a DVI-equipped television or audio/video receiver from the inception of the format, around 2003. Remember that DVI's video capabilities are compatible with HDMI, but DVI cannot carry audio. In these circumstances, you must run an optical or digital coaxial audio cable alongside the DVI video cable.
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