What is HDMI? – More about the High Definition Multimedia Interface

HDMI stands for High Definition Multimedia Interface. Introduced in 2003 to work with the then upcoming high definition content, HDMI is more than just a cable, it’s actually a set of rules, an interface that connects multiple devices and lets them communicate with increased fidelity.

Now used in pretty much all televisions, PC monitors, laptops and computers, HDMI was a huge step forward from previous audio/video connectors used in home entertainment systems, called component cables. Anyone with an old CRT TV remembers the smorgasbord of colored cables, and probably also the confusion in connecting various devices together.

While the component cables had one cable each for left channel audio, right channel audio and video, HDMI is just a single cable that does it all. Furthermore, component cables relied on analog signals, while the newer HDMI standard was all digital.

HDMI is capable of displaying the Standard Definition resolution of 480i (640 x 480) up to 8K Super Hi Vision resolutions, the latter of which will work only with HDMI 2.0, a new update which you will read about in a while.

HDMI 1.0, 1.1, 1.2 and 1.2a – The Beginnings

Founded by electronics giants like Sony, Thomson, Toshiba, Hitachi, Philips, RCA and Matsushita Electric Industrial (National/Panasonic/Quasar), HDMI allowed uncompressed video and audio signals to be sent through the same cable, eliminating the need for extraneous cables, while simultaneously improving audio-visual quality. HDMI had certain specifications that changed with each version, to accommodate higher bandwidth data transfer for the ever increasing rate of technology.

The first version, 1.0, had a maximum bandwidth of 4.95 Gb/s, of which 3.96 Gb/s was dedicated to 1080P video at a refresh rate of 60 Hz. It supported 8 channel audio, at 192 Khz and 8 bits. Consecutive versions, HDMI 1.1 and 1.2 added support for DVD Audio and One Bit Audio (used in Super Audio CDs). The next version, HDMI 1.2a, was a minor revision that complied with Consumer Electronic Control (CEC) rules.

HDMI 1.3 – The Evolution

HDMI 1.3 was released in June 2006, and was an actual large update to the technology. It raised the bar by increasing single link bandwidth to a whopping 10.2 Gb/s at 340 MHz, and also increasing color depth by up to 48 bit Deep Color. This was also when support for Dolby True HD and DTS-HD Master Audio was added. Subsequent minor revisions, 1.3a, 1.3b, 1.3b1 and 1.3c added minor technological changes and complied with new CEC rules.

HDMI 1.4 Version

HDMI 1.4 – The Current Version

Released in May 2009, HDMI 1.4 is the version that we use today. Again, it was a significant improvement over its predecessors, essentially future proofing the technology for forthcoming generations. HDMI 1.4 finally brought with it support for 4K Ultra HD resolution, which is only now becoming mainstream. It was capable of 3840 x 2160 at a refresh rate of 24/25/30 Hz or 4096 x 2160 at 24 Hz, which is also the resolution used in most movie theatres today.

Other new features introduced included a new micro HDMI connector, the capability to display additional types of 3D content (3D over HDMI), and most importantly, the ARC (Audio Return Channel). The Audio Return Channel gave consumers the ability to keep a separate audio receiver with surround sound speakers and a Blu Ray player connected to a television and still get native channelized surround sound.

Finally, the HEC (HDMI Ethernet Channel) was also introduced, which allowed connected multimedia devices and appliances to share an internet connection, an absolute necessity in the fast changing world of digital entertainment. Online streaming services were able to gain a foothold in many homes because of this new feature. It allowed for a connection up to 100 Mb/s between the two devices.

Subsequent versions, HDMI 1.4a and HDMI 1.4b added support for additional 3D resolutions and refresh rates, with the latter supporting full HD (1080P) 3D video at a refresh rate of 120 Hz, using the frame packing method, a much more efficient and full resolution 3D format that was superior to interlaced video.

HDMI 2.0 – The Future

Introduced at the end of 2013 at the IFA Trade Show, HDMI 2.0, also known as HDMI UHD, is the interface that will truly bring next generation content to the world. First and foremost, to accommodate the ever increasing content resolutions, HDMI 2.0 bumps up the maximum thorough put to an even more amazing 18.8 Gb/s. This bump in bandwidth means that 4K Ultra HD content is now supported at a buttery smooth 60 frames-per-second.

Naturally, this also includes support for more 3D formats, a higher aspect ratio of 21:9, new standards and additional CEC compliances. What really makes it an interface of the future though, is the support for a whopping 32 channels of audio at 1536 kHz and support for 8K resolutions at 24 frames-per-second. That’s a mind boggling 7680 x 4320 px!

But now comes the best part, there won’t be anything such as HDMI 2.0 cables. While HDMI 1.3 and 1.4 suffered from compatibility issues, there won’t be any such trouble here. Since HDMI 2.0 and HDMI 1.4 signals are pretty much the same, any short length High Speed HDMI cable from today will work with HDMI 2.0.

So how do you get it, you ask? Currently there are two ways newer UHD televisions can get this upgrade. Since HDMI 2.0 requires faster processing chips, some manufacturers have included higher performing processors in their UHD TV lineup, and will need a firmware update to use these new cables. Some manufacturers will apparently provide a minor hardware upgrade for external media input boxes, like Samsung, so you won’t be left behind even if you own a UHD TV from 2013. However, some manufacturers haven’t announced an upgrade path yet, but there should be a measure for those who adopted 4K TVs in their early stages, especially from large manufacturers.

Comparing the HDMI versions

Here’s a couple of tables (courtesy Comprehensive Cable) that highlight the differences between the different HDMI versions:

Types of Cables and Why Length is Important

When you’re out shopping for cables, length isn’t usually something you’re bothered about right? But in case of HDMI, it’s a little different. Since there’s a lot of high bandwidth data coming through, you can’t have a cable that’s too long, because of signal attenuation. Depending on cable quality and testing, cables are classified into two categories:

• Category 1 (Standard): Tested at 74.5 Mhz, capable of displaying resolutions of 720P/1080i at 60 FPS
• Category 2 (High Speed): Tested at 340 Mhz, capable of displaying resolutions of 1080P/2160P at 60 and 30 FPS respectively

Most cables with standard quality materials under 5m can work for Category 2 purposes, but it’s recommended to get specific cables if you’re looking for high resolution content.

HDMI 1.4 defines cable types in the following way:

• Standard HDMI: Upto 720P/1080i
• Standard HDMI with Ethernet
• High Speed HDMI: Upto 4K UHD, including 1080P, 3D and Deep Color
• High Speed HDMI with Ethernet
• Automotive HDMI: Used by vehicle manufacturers

Types of HDMI Connectors

HDMI is not limited only to home entertainment systems and video game consoles, even high powered smartphones and automotives make use of this high bandwidth connection, because of the growing demand for entertainment on the go. Basically, pretty much all high end cars with entertainment systems also use a special type of HDMI connector. Here’s the types of connectors:

Types of HDMI Connectors

• Type A: Standard 19 pin connector, used in home entertainment systems, televisions, video game consoles, PC monitors and more. Can be converted to single link DVI-D.
• Type B: 29 pin connector, reserved for use with future WQUXGA displays (3840 x 2400). Can be converted to dual link DVI-D.
• Type C: Smaller version of the Type A connector (Mini), with 19 pins. Used in portable devices and can be connected to Type A via cables.
• Type D: Even smaller version of the Type A connector (Micro), with 19 pins. Again used in portable devices.
• Type E: Specialised connector used by automotive manufacturers. Known as the Automotive Connection System.

Applications

As mentioned above, HDMI is a highly versatile interface that has now become the de facto standard for display and multimedia. Here’s some of the applications:

• Personal computers
• Televisions
• Home entertainment systems
• Video game consoles
• Smartphones
• Digital cameras and camcorders
• Tablet computers
• Automotive entertainment systems
• Satellite television

From current trends, it looks like we’ll be sticking with HDMI for a long time to come, there’s pretty much no other competition, and even though there’s similar interfaces like Display Port and DVI, they’re still in the minority. Then again, few interfaces have evolved and adapted like HDMI, so it’s no surprise that we’re going to stick with it for the near future!