HDMI is an industry standard digital interface that supports both audio and video data components.
HDMI has quickly become the standard for connecting consumer electronic devices together and was pioneered by a group of companies including Sony, Philips, Hitachi and Matsushita.
HDMI supports standard, enhanced, or high-definition video as well as multi-channel digital audio on a single industry standard cable. HDMI is capable of carrying any type of compressed audio data such as Dolby or DTS.
HDMI can transmit all HDTV standards and supports 8 channel digital audio and up to 5Gbps (Giga bits per second ) bandwidth.
The HDMI standard can support exisiting high definition video formats of 720p, 1080i and 1080p. It also has the potential to support enhanced definition formats such as 480p as well as the more common formats such as PAL and NTSC.
720p is the resolution of 1280x720 pixels. The p stands for progressive format.
1080i is the resolution of 1920x1080 pixels. The i stands for interlaced format.
1080p is the resolution of 1920x1080 pixels.
480p is the resolution of 640x480 pixels with an aspect ratio of 4:3.
A standard Type-A HDMI connector has 19 pins. A Type-B definition also exists which has 29 pins and is targeted at carrying expanded digital signals for video resolutions greater than 1080p.
Importantly the Type A HDMI connector is backwardly compatible with the existing DVI video input that is used on most modern PC video cards.
Typically the maximum length for a 'standard' HDMI cable is about 15 metres, however high performance cables are available and 15 metres (49.2 feet) or more is possible.