HDMI The Ins and Outs of An Evolving Standard

In this fast-changing era of new formats and technologies, HDMI is the accepted universal connector for digital home entertainment. The standard continues to evolve to meet the needs of high-performance home theatre equipment. All versions of HDMI are backward compatible with previous versions, as well as with DVI with the use of an adapter (however, a DVI connection passes video only, not audio). Part of the built-in intelligence of HDMI enables it to automatically send the highest quality video and audio formats that are mutually supported. In other words, if you connect two devices, one with HDMI version 1.3 and the other with 1.4, the system will be limited to the 1.3 feature set.

Although you'll often see the HDMI version listed as part of a component's specifications, it's probably best not to pay much attention to it. For specific details about a particular component's audio and video capabilities, you're better off focusing on the component's feature list. A product's HDMI version by itself doesn't mean that all the latest features have been implemented; it does not guarantee a particular feature set. The reason is that the capabilities listed for each version of HDMI are optional, not mandatory.

It's up to each manufacturer to decide which HDMI features to build into its gear. A perfect example is 1080p video input capability. Although the original HDMI 1.0 spec included 1080p video (before 1080p TVs even existed!), it wasn't until 2006 that a significant number of HDTVs included 1080p-capable HDMI inputs.

Do I need to worry about compatibility between HDMI versions?

Only if you're working with 1.4-rated gear, and want to take advantage of certain features that are new to the 1.4 spec (discussed below). However, each new HDMI version is backwards compatible with older versions, so your older and newer HDMI-equipped components can generally still work together. So even if you use a 1.2 cable on 1.4 gear, or a 1.4 cable on 1.1 gear, you'll still get a great high-def picture and sound.

HDMI versions

So what are the differences between different HDMI versions? Take a look at our summary of HDMI's evolution below:

HDMI 1.0:The original spec called for a single-cable digital audio/video connection with 165MHz bandwidth and a maximum bitrate of 4.9Gbps (enough for 1080p video). Two-channel audio only. Released December, 2002.

HDMI 1.1:Added multichannnel audio support for DVD-Audio (up to 5.1 channels). Released May, 2004.

HDMI 1.2:Added support for multichannel one-bit audio formats like SACD (Super Audio CD). Included support for HDMI connectors on personal computers. Required displays with HDMI 1.2 or later to support future low-voltage devices. Released August, 2005.

HDMI 1.2a:Fully specified the Consumer Electronic Control (CEC) features and command sets for remote control functions. Required cable manufacturers to submit longer cable lengths for additional testing for spec compliance. For a device to pass 1.2a testing, all of its HDMI connectors required inspection and approval by HDMI Licensing, LLC. Released December, 2005.

HDMI 1.3:Increased bandwidth to 340MHz and the maximum bitrate to 10.2 Gbps (plenty for 3D video). Adopted the "Deep Color" standard, which supports 10-bit, 12-bit, and 16-bit color for over one billion possible colors — previous versions were limited to 8-bit. (Note:Because color information is based on three primary colors — red, green and blue — you'll sometimes see 1.3's enhanced color depth described as 30-bit, 36-bit, and 48-bit.) Added support for the "xvYCC" extended-gamut color space standard (also known as x.v.Color), which supports 1.8 times as many colors as existing HDTV signals. (No commercially available video content currently uses Deep Color or x.v.Color.) Added ability to output new lossless compressed digital audio formats (Dolby® TrueHD and DTS-HD Master Audio™) for decoding by a compatible A/V receiver. Incorporated automatic "lip sync" control for perfect audio/video timing (sometimes an issue when audio is sent to a surround receiver or processor and video is delivered directly to the display). Also made available a new mini-connector for use with smaller devices such as digital cameras and camcorders. Released June, 2006.

The 1.3 spec has been recently updated to 1.3a, followed by 1.3b. However, for consumers, there is no difference between versions 1.3, 1.3a or 1.3b. These are minor revisions that relate to manufacturing and testing issues and do not affect features or functionality.

Setting up a 3D TV system? Look for an HDMI cable labeled "1.3," "1.4," or "high-speed."

HDMI 1.4:Added Ethernet capability. If one HDMI 1.4 device is connected to your home network, it can share that connection with other Internet-ready HDMI 1.4 devices via a 1.4 HDMI cable.Note: As of 1/7/11 we are unaware of any components that support Ethernet over HDMI.Also included the capability to send audio from your TV's tuner back to your home theatre receiver. Called an "audio return channel," it's ideal for folks who get their high-def programs over the air using an antenna and want to be able to enjoy surround sound with those TV shows. Released May, 2009.

What kind of HDMI cable do I need for 3D TV?

Most recent good-quality HDMI cables should be able to carry 3D video, especially if they're 2 meters or less in length. If you're buying new cables, look for ones labelled "high-speed," "1.3," or "1.4" to be sure. You'll need higher-bandwidth cables to carry the full 3D signal it's equivalent to nearly two 1080p signals, simultaneously.