Digital Video Connections: FireWire, DVI, HDMI
FireWire, DVI (Digital Visual Interface), and HDMI (High-Definition Multimedia Interface) are some of the digital video connections used in home theaters. HDMI is considered state-of-the-art in digital video connections.
The consumer electronics industry (in association with content providers) has been working to develop digital video interconnection systems that preserve the digital signal, minimize cables, and provide copy protection.
FireWire, one of the first systems for digital video, crossed over from the computer industry. Here are some details on this type of digital video connection:
FireWire (also called IEEE 1394 or i.LINK) was originally developed by Apple Computer for connecting peripheral devices to Macintosh computers. Companies such as Sony picked up on the technology and began incorporating FireWire into its camcorders and PCs, and FireWire grew from there. (The FireWire in camcorders is often called DV.)
Some HDTV devices (such as JVC’s D-VHS) used FireWire connections for years, but FireWire appears to have all but gone away as a means of connecting HDTV devices.
FireWire is becoming more common in the audio side of the home theater. The DVD Forum (a coalition of companies that helps develop the DVD standard) has approved FireWire as a connection method for the audio output of DVD-Audio players.
Although HDMI, FireWire’s biggest competitors in the digital video connection world, appear to have won the war of digital video interconnects, FireWire may still have a little life left in it. A group called HANA (High-definition Audio-Video Networking Alliance) was formed to create yet another set of standards for connecting your A/V gear, and FireWire is a big part of that system.
DVI (Digital Visual Interface)
One reason that FireWire never took off in the world of home theater was the success of DVI (Digital Visual Interface). DVI is another technology adopted from the computer world:
DVI was developed as a means of connecting computers to digital LCD screens and projectors.
DVI picked up a strong copy protection system called HDCP (High-bandwidth Digital Content Protection) and became a favorite of the HDTV industry. HDCP can limit your ability to make a digital copy of what you’re watching — all it does is send video in one direction (for example, from the tuner to the display). Not all devices with a DVI connector incorporate HDCP. For example, LCD computer monitors may use DVI without HDCP.Use a DVI connector for great digital video quality.
DVI provides a great video connection but it doesn’t carry audio like its successor, HDMI does. In most newer TVs and home theater gear, DVI has been phased out in favor of HDMI.
If you have a piece of gear in your home theater that uses DVI but needs to be connected to a newer piece of HDMI-only gear, you can buy an inexpensive adapter to connect the two. There will be no audio over that DVI-to-HDMI connection, but the video will work just fine.
HDMI (High-Definition Multimedia Interface)
The latest and greatest in digital video (and audio) connections is the HDMI cable. HDMI is included in many devices, including HDTVs, DVD players, Blu-ray disc players, cable and satellite set-top boxes, Media Center Edition PCs, and gaming consoles. You can find out more about this technology at the HDMI Web site.
What’s so great about HDMI? Well, a few things:
It’s all-digital. Like DVI and FireWire, HDMI provides an all-digital path for your standard and high-definition video signals.
It’s high-bandwidth. HDMI can support data signals as fast as 4.9GB per second — with the newest High Speed variant supporting 10.2GB per second. That means it can handle HDTV with plenty of room to spare.
It can support all variants of HDTV. 720p, 1080i, even 1080p can run over an HDMI cable.
It can carry up to eight channels of digital audio. So a single HDMI cable can carry your HDTV and your 7.1-channel surround sound.
HDMI cables don’t have to be super-expensive. Certified HDMI cables can be relatively cheap, and there are many good online sources for them, such as the AVS Forum. As long as your HDMI cable runs are less than 10 meters (about 30 feet), you can buy an inexpensive cable and expect excellent results.