HDMI? What is this?

HDMI stands for High Definition Media Interface.

It is a compact audio/video interface for transmitting uncompressed digital data. It supports, in a single cable, any TV/PC video format, including standard, enhanced, and high-definition video; up to 8 channels of compressed or uncompressed digital audio; and a Consumer Electronics Control (CEC) Connection. The CEC will allow the HDMI devices to control each other when necessary and allows the user to operate multiple devices with one remote control handset.

HDMI founders are Hitachi, Matsushita Electric Industrial, Philips, Silicon Image, Sony, Thomson and Toshiba. HDMI products was started shipping in late 2003.



HDMI has various versions.

1. Version 1.0 to 1.2

HDMI 1.0 was released December 9, 2002 and is a single-cable digital audio/video connector interface with a maximum TMDS bandwidth of 4.9 Gbits/s. It supports up to 3.96 Gbit/s of video bandwidth (1080p/60 Hz or UXGA) and 8 channel LCPM /192 khz /24-bit audio. HDMI 1.1 was released on May 20, 2004 and added support for DVD-Audio. HDMI 1.2 was released August 8, 2005 and added support for One Bit Audio, used on Super Audio CDs, at up to 8 channels. It also added the availability of HDMI Type A connectors for PC sources, the ability for PC sources to only support the sRGB color space while retaining the option to support the YCbCr color space, and required HDMI 1.2 and later displays to support low-voltage sources. HDMI 1.2a was released on December 14, 2005 and fully specifies Consumer Electronic Control (CEC) features, command sets, and CEC compliance tests.

2. Version 1.3

HDMI 1.3 was released June 22, 2006 and increased the single-link bandwidth to 340 MHz (10.2 Gbit/s). It optionally supports Deep Color, with 30-bit, 36-bit, and 48-bit xvYCC, sRGB, or YCbCr, compared to 24-bit sRGB or YCbCr in previous HDMI versions. It also optionally supports output of Dolby True HD and DTS-HD Master Audio streams for external decoding by AV receivers. It incorporates automatic audio syncing capability. It defined cable Categories 1 and 2, with Category 1 cable being tested up to 74.25 MHz and Category 2 being tested up to 340 MHz. It also added the new Type C Mini connector for portable devices.

HDMI 1.3a was released on November 10, 2006 and had Cable and Sink modifications for Type C, source termination recommendations, and removed undershoot and maximum rise/fall time limits. It also changed CEC capacitance limits, clarified sRGB video quantization range, and CEC commands for timer control were brought back in an altered form, with audio control commands added. It also added support for optionally streaming SACD in its bitstream DST format rather than uncompressed raw DSD like from HDMI 1.2 onwards.

HDMI 1.3b, 1.3b1 and 1.3c were released on March 26, 2007, November 9, 2007, and August 25, 2008 respectively. They do not introduce differences on HDMI features, functions, or performance, but only describe testing for products based on the HDMI 1.3a specification regarding HDMI compliance (1.3b), the HDMI Type C Mini connector (1.3b1), and active HDMI cables (1.3c).

3. Version 1.4

HDMI 1.4 was released on May 28, 2009, and the first HDMI 1.4 products were available in the second half of 2009. HDMI 1.4 increases the maximum resolution to 4K × 2K (3840×2160p at 24Hz/25Hz/30Hz and 4096×2160p at 24Hz, which is a resolution used with digital theaters); an HDMI Ethernet Channel, which allows for a 100 Mb/s Ethernet connection between the two HDMI connected devices; and introduces an Audio Return Channel, 3D Over HDMI (HDMI 1.3 devices will only support this for 1080i), a new Micro HDMI Connector, expanded support for color spaces, and an Automotive Connection System. HDMI 1.4 supports several stereoscopic 3D formats including field alternative (interlaced), frame packing (a full resolution top-bottom format), line alternative full, side-by-side half, side-by-side full, 2D+depth, and 2D + depth + graphics + graphics depth (WOWvx), with additional top/bottom formats added in version 1.4a . HDMI 1.4 requires that 3D displays support the frame packing 3D format at either 720p50 and 1080p24 or 720p60 and 1080p24. High Speed HDMI 1.3 cables can support all HDMI 1.4 features except for the HDMI Ethernet Channel.

HDMI 1.4a was released on March 4, 2010 and adds two additional mandatory 3D formats for broadcast content which was deferred with HDMI 1.4 in order to see the direction of the 3D broadcast market. HDMI 1.4a has defined mandatory 3D formats for broadcast, game, and movie content. HDMI 1.4a requires that 3D displays support the frame packing 3D format at either 720p50 and 1080p24 or 720p60 and 1080p24, side-by-side horizontal at either 1080i50 or 1080i60, and top-and-bottom at either 720p50 and 1080p24 or 720p60 and 1080p24.