HDMI (High-Definition Multimedia Interface) is today the best kind of digital audio and video connector available that promises to replace all connectors currently used by players, cable/satellite decoders, TV sets, videoprojectors and video monitors. The idea is to use a single cable instead of several cables when connecting your HD-DVD player to your TV set, for example. This new connection standard was developed by Hitachi, Matsushita (Panasonic/National/Technics), Phillips, Silicon Image, Sony, Thomson (RCA) and Toshiba.
The greatest advantage brought by this standard is the use of digital connection for both audio and video, bringing the best quality possible. DVI (DVI-D, actually) also provides digital connection between your devices and displays, but it doesn’t carry audio signal, meaning that you need an extra cable for the audio connection; and all other popular standards – component video and S-Video, for example – are analog connections. You can learn more about other video connection types available today by reading our Video Connectors tutorial.
There are three basic differences between HDMI and DVI-D. First, HDMI supports higher resolutions than DVI, including resolutions not commercially released yet (in theory it supports double the highest resolution available today in HDTV sets); second, DVI only connects video, audio connection must be done separately, while HDMI connects both audio and video; third, HDMI connector is far smaller than DVI’s.
It is interesting to notice that HDMI is fully compatible with DVI-D. It is possible to connect a device that uses DVI-D to another that uses HDMI, through a cable with a HDMI connector at one end and a DVI connector at the other.
Another important difference is that DVI standard was developed to be used by PCs, while HDMI was developed to be used by consumer electronics products, such as Blu-Ray, HD-DVD and DVD players, videoprojectors and HDTV sets.
HDMI also implements a copy-protection mechanism called HDCP (High-Bandwidth Digital Copy Protection), which was developed by Intel. You can learn more about it at http://www.digital-cp.com.