It’s an electronics enthusiast’s dream: one cable that replaces the rat’s nest of audio and video wires between the audio/video stack and the TV. That cable is HDMI (high-definition multimedia interface), and not only can an HDMI connector sub for the video cables running between your cable box and TV, but it can also streamline any multichannel audio feed. HDMI also contains HDCP (high-bandwidth digital content protection), which may be necessary to watch and record high-definition content in full resolution.

HDMI is an industry-supported, all-digital, uncompressed interface. All the high-definition sound and images you need for the highest-quality home theater playback travel in their original form—no compression required—from your sources to your TV. The term “industry supported” is key, because HDMI’s reach covers a broad swath of companies. More than 400 companies have adopted the standard and are building HDMI into their products. So your Hitachi TV will work with your Toshiba DVD player.

Maybe. Before you rush down to the electronics store to stock up on HDMI-enabled gear, know that HDMI is a work in progress. Interoperability and compatibility issues have nagged the movement from the start.

Steve Venuti, director of marketing for HDMI Licensing, the licensing agent for HDMI, confirms that some of today’s products pose compatibility problems due to improper implementation of the technology. Although this and other issues have been addressed through firmware upgrades by manufacturers, cable companies have been particularly slow to make set-top boxes compliant, Venuti says.

How are you to know? Simplay Labs in Sunnyvale, CA, recently put in place a testing program for HDMI compliance. Products that pass the SimplayHD Compatibility Test Specification are licensed to use the Simplay HD logo. That’s step one. The Simplay HD web site also has a list of verified products.

That still leaves confusion about the various versions of HDMI: 1.1, 1.2 and 1.3. What if you have a TV with HDMI 1.1 and an HD-DVD player with 1.3? Venuti suggests that consumers look at the features each version offers, versus a particular iteration of HDMI. For instance, a Blu-ray Disc player with HDMI 1.3 has support for the new, lossless compressed digital audio formats, Dolby TrueHD and DTS-HD Master Audio. If you wanted to match it with a compatible audio/video receiver, the latter would also have to offer those audio formats (and be 1.3 compliant) in order to decode them. If the receiver is 1.1 enabled, it could only reproduce earlier surround-sound formats such as Dolby Digital or DTS 5.1.

According to HDMI Licensing, most Blu-ray Disc and HD-DVD players—and a substantial number of conventional DVD players—will include HDMI 1.3 capabilities this year. “During the first half of 2007, we expect to see HDTVs with HDMI 1.3 functionality, allowing them to display ‘Deep Color’ content,” says Leslie Chard, president of HDMI Licensing.

Deep Color support will allow consumer home theater equipment to reproduce movies with greater color depth on higher bit-depth displays. In the past, movie studios have had to reduce the color depth of films for home distribution in order for them to be viewable on consumer equipment. The advent of 10-bit digital displays and HDMI 1.3 paves the way for players and media that can deliver nearly lossless video content. That translates to billions, versus millions, of colors—and with increased contrast ratio and more shades of gray.