Friday, December 14, 2007

Expert View: HDMI Evolves

Photo of PC Magazine's Robert Heron

When shopping for a new HDTV, it's always a good idea to consider your current and future video connection needs. Also keep in mind that viewing a high-definition video source on an HDTV set requires the use of a cable (and corresponding port) that supports high-definition signals. Sorry, folks, the yellow composite video port and the S-video port are for standard-definition video only! The High-Definition Multimedia Interface (HDMI) is found on all modern HDTVs, and this all-digital interface has become the port of choice for connecting modern A/V gear. One of the primary benefits of HDMI is that it maintains the digital pathway between the source and display. This method avoids any image softening that usually results from digital-analog-digital conversions. If you must use analog video, though, the tried-and-true component-video input continues to be the analog HD (and SD) video connection of choice.

HDMI technology is also based upon a continuously updated spec, and the various versions of HDMI that have been developed so far have led to some confusion about which iteration is the best. For HDTVs the answer is simple: It doesn't matter. All versions of HDMI can support the maximum resolution of today's best HDTVs, which is 1080p.

Still, two features available in the more recent versions of HDMI may prove useful: Consumer Electronic Control (CEC) and lip-sync. A CEC-enabled television and connected source device can communicate via the HDMI connection. The beauty of this setup is that a source device (such as an HD disc player) could be placed out of sight, yet still receive remote-control commands as they are received by the television and passed along the HDMI connection. A lip-sync–enabled HDMI port on an HDTV takes into account any delays introduced by the TV's video processing and ensures the audio track is properly delayed, so what you see is aligned precisely with what you hear. Keep in mind that these extra features of the later HDMI versions are optional—not required. An HDTV equipped with HDMI v. 1.3a ports (the latest version available in televisions at press time) may support CEC but not lip-sync, or it may support neither. Check the specs carefully if certain HDMI features are critical for your needs.

HDMI's "one cable" solution for audio and video transport is certainly convenient, but it isn't always a flawless experience. One of most frequent complaints about HDMI in HDTVs relates to compatibility issues with other HDMI-enabled devices. I've experienced seemingly random losses of connection between HDMI-connected devices, or the initial "handshake" between two HDMI devices has failed, leaving the screen filled with DRM-induced snow (or nothing at all). A company called Simplay Labs offers an HDMI verification service that stamps any HDMI-enabled product that passes its tests with the "Simplay HD" logo. Television manufacturers such as Mitsubishi, Hitachi, Pioneer, HP, LG, and Samsung have all submitted various displays for "Simplay HD" verification, and the odds are pretty good that you won't experience any HDMI-related troubles when connecting devices that display this logo.


http://www.pcmag.com/article2/0,2704,2209815,00.asp

2 comments:

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