(High-Definition Multimedia Interface) A digital interface for both audio and video signals designed as a small-socket, single-cable solution for home theater and consumer electronics equipment. Introduced in 2002, HDMI is electrically identical to DVI, which is video only, and an HDMI source can detect a DVI device on the other end and switch to the DVI protocol. In the photo below, the 19-pin HDMI plug (left) is much smaller than the 19-pin DVI video-only plug, yet HDMI also supports up to eight channels of 24-bit uncompressed audio at 192kHz.
HDMI/DVI Compatibility
HDMI is backward compatible with DVI, and adapter cables let video transfer between HDMI and DVI devices. For example, a computer may have DVI output, and a DVI-to-HDMI cable lets it hook the video up to a monitor with HDMI input.
On a cable TV set-top box, the digital video output may be DVI. In this case, a DVI-to-HDMI cable connects the video to the TV, and the audio is cabled separately as in the example below.
This TV Has Only HDMI In
The HDMI socket on this TV is labeled HDMI/DVI because it accepts both. If the cable box has HDMI out, then only the HDMI socket is used. If the cable box has DVI, then a DVI-to-HDMI cable connects the video, and the audio must be wired separately from the analog audio outputs of the box to the audio inputs here.
HDMI 1.3
Introduced in 2006, HDMI Version 1.3 supports 2560x1440 HDTV resolution, "deep color" 48-bit pixels and high-definition audio for Blu-ray players. HDMI also has enhanced protocols that support audio and auxiliary data packets.
HDMI 1.3 uses HDMI Category 1 cables for 720p and 1080i TVs. For 1080p and above, HDMI Category 2 cables are required. For more information, visit HDMI Licensing, LLC (www.hdmi.org). See
HDTV,
HDMI switch,
HDMI CEC,
DVI,
HDCP,
Blu-ray and
UDI.
HDMI Year
Version Intro. Features
1.0 2002 4.95 Gbps bandwidth; 165MHz
165 megapixels/sec (24-bit)
1.1 DVD-Audio
1.2 SACD audio
1.3 2006 10.2 Gbps bandwidth; 340MHz
340 megapixels/sec (48-bit)
2560x1440 video
TrueHD and DTS-HD audio
1.3a Technical improvements
1.3b Stricter compliance with spec
An HDMI Switch
HDMI switches allow several HDMI sources to plug into TVs that have only one HDMI input. This 3X1 (3 in - 1 out) unit from Octava switches between three inputs. See
HDMI switch.
(Image courtesy of Octava Inc., www.octavainc.com)