HDMI is an industry-supported, uncompressed, all-digital audio/video interface. HDMI provides an interface between any compatible digital audio/video source, such as a set-top box, a DVD player, a PC, a video game console, or an AV receiver and a compatible digital audio and/or video monitor, such as a digital television (DTV).
HDMI supports standard, enhanced, or high-definition video, plus multi-channel digital audio on a single cable. It is independent of the various DTV standards such as ATSC, and DVB (-T,-S,-C), as these are encapsulations of the MPEG movie data streams, which are passed off to a decoder, and output as uncompressed video data, which can be High Definition. This video data is then encoded into TMDS (Transition Minimised Differential Signalling) For transmission digitally over HDMI.
HDMI also includes support for 8-channel uncompressed digital audio. Beginning with version 1.2, HDMI now supports upto 8 channels of one-bit audio. One-bit audio is what is used on Super Audio CD's.
The standard Type A HDMI connector has 19 pins.
HDMI is backward-compatible with the single-link Digital Visual Interface (DVI) used on modern computer monitors and graphics cards. This means that a DVI-D source can drive an HDMI monitor, or vice versa, by means of a suitable adapter or cable, but the audio and remote control features of HDMI will not be available. Additionally, without support for High-bandwidth Digital Content Protection (HDCP) at both ends, the video quality and resolution may be artificially downgraded by the signal source to prevent the end user from viewing, or especially copying, restricted content (While nealry all HDMI connections support HDCP, many DVI connections do not).
