Basic Cable: Choosing the Right Cables for Your System Page 6

HD Goes Digital The main types of digital video cables are HDMI, DVI, and FireWire (a.k.a. IEEE 1394; Sony and some others call it i.Link). FireWire is a high-speed (400 Mbps) interconnect that can carry digital audio, video, and control data on a single cable. But because it does not have enough bandwidth for uncompressed digital video, it's mainly used for transferring camcorder footage and digital photos.

A copyright-protected version of DVI (Digital Video Interface) called DVI with HDCP (High-bandwidth Digital Content Protection) quickly became the primary, if short-lived, digital TV connection. While capable of very high bandwidth, DVI is limited to just 15 feet for a standard run. Many monitors and some TVs still have DVI connectors.

DVI was quickly superseded by HDMI (High Definition Multimedia Interface), which, unlike its predecessor, can carry both digital audio and video signals on a single cable. It's also theoretically capable of supporting cable runs of up to 50 feet. An HDMI cable carries its signals on four twisted pairs - one each for red, green, and blue (which also carries the sync information), and one for carrying a digital "pixel clock," used to time the data stream.

HDMI is backward-compatible with DVI and DVI with HDCP, but requires an adapter to handle its smaller 19-pin connector. (A 29-pin Type B version has been approved for even higher-resolution displays.) HDMI has the bandwidth to support 1080p 60-Hz high-def video, plus eight channels of uncompressed 192-kHz/24-bit audio. The latest version, HDMI 1.3, doubles the bandwidth to 10.2 Gbps and adds support for 30-, 36- and 48-bit color depths and a new "xvYCC" color-space standard, as well as the new Dolby True HD and DTS-HD Master lossless audio formats available on some Blu-ray Discs and HD DVDs. (For more on HDMI 1.3, see HDMI 1.3: The Missing Link.)

Given the variety of choices available, you'll find no shortage of ways to get your rig up and running. Just remember to use the best available connection types to achieve the best possible performance.

For more on cable construction, see Inside a High-End Audio Cable.

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