Be the Expert: What is an HDMI Cable?

What is an HDMI Cable

One cable rules them all and in the digital realm binds them

The acronym HDMI stands for High Definition Multimedia Interface. When HDMI cables first came on the market in 2002, they left early adopters elated, frustrated and sticker-shocked. Elated because this one cable eliminated wiring nests and kept both audio and video in the digital realm, uncompressed. Frustrated because the cables were stiff, tended to be difficult to plug in and would inexplicably pop back out. And sticker-shocked because a 6 ft. HDMI cable could easily cost $50.00 or more.

To add another wrinkle, installers couldn’t make their own to save money or customize the length like they could with many other kinds of audio, video and coax cables. The wiring and pins associated with HDMI were simply too complex.

Flash forward to today.

HDMI cables are a bit more flexible. Connections are more secure. And prices range tremendously, providing more affordable options. Plus, there are now many HDMI standards, suitable to the different kinds of HD standards. But installers still can’t make their own HDMI cables.

The HDMI evolution

HDMI standards have evolved to match the ongoing revolution in HD standards as well as its use in automotive applications and network connectivity. This has created confusion among consumers and retailers alike. Some may not even realize that there are different types of HDMI cables. Plus, there’s the misconception that cables should be constantly upgraded, even if the equipment has not.

When you, as a retailer, see a customer browsing HDMI cables, or if they are purchasing several A/V components to make up an entertainment system, you need to step in to ensure they buy the right standard of HDMI cabling. Plus, you should take advantage of the opportunity to explain why picking the right cable is so important.

HDMI 101

Let’s establish three basic HDMI principles right away:

  1. All HDMI cables are backward compatible—so upgrading to the latest-spec cable won’t affect playback performance of older devices.
  2. Length DOES affect performance, regardless of the HDMI standard. Depending on a number of variables, even 25 ft. cables can have performance degradation.
  3. System performance is only as good as its weakest link. For example, if a 4K TV is reading signals from a 1080p device via a 4K-compatible HDMI cable, the TV will display 1080p, not 4K, unless there’s an upconverter somewhere along the line. So key features need to be supported on both ends of the HDMI cable.

HDMI specification standards

The HDMI founding consortium in charge of creating and overseeing standards is made up of seven electronics giants—Hitachi Maxell, Koninklijke Philips, Lattice Semiconductor Corporation, Panasonic Corporation, Sony Corporation, Technicolor S.A. (formerly known as Thomson) and Toshiba Corporation.

Over the years, a few updates to the HDMI specifications standards have been made. The current standard is 2.1. The most significant previous standards are 2.0b and 1.4. These three standards encompass most of the electronic devices on the market today.

Equipment specification standards also form the underlaying basis on how the cables themselves are labeled for resale—more or less. In 2012, the HDMI standards organization moved away from specification numbers on packaging and product labels. They changed to more general terms relating to supported features. This applies to both cables and products.

This means that the cable label/name, found in the first bullet of each Specification listed below, is an approximate match to the entire specification parameters. They’ve been placed there to help you more easily decide which HDMI cables are most appropriate for your customers’ needs.

HDMI Specification 2.1

  • Generally labeled as Ultra High Speed HDMI cables
  • Supports resolutions up to 10K
  • Refresh rates including 8K @ 60Hz and 4K @ 120Hz for immersive viewing and smooth, fast-action detail. Rate types include:
    • VRR (Variable Refresh Rate) reduces or eliminates lag, stutter and frame tearing for more fluid and better detailed game play
    • QMS (Quick Media Switching) eliminates delay that can result in blank screens before content is displayed
    • QFT (Quick Frame Transport) reduces latency for smoother no-lag gaming and real-time interactive virtual reality
  • Dynamic HDR on a scene-by-scene or even a frame-by-frame basis
  • Supports up to 48 Gbps bandwidth, exceptionally low EMI emissions
  • This may be overkill for most home applications

HDMI Specification 2.0b

  • Generally labeled as Premium High Speed HDMI cables
  • Supports resolutions up to 4K/Ultra HD
  • Refresh rates up to 4K @ 50/60Hz
  • Supports up to 18 Gbps bandwidth
  • Supports wide-angle theatrical 21:9 video aspect ratio

HDMI Specification 1.4

  • Generally labeled as High Speed HDMI cables
  • Supports resolutions up to 1080p @ 60Hz as well as 3D and 4K
  • Supports Deep Color and additional color models used in digital graphics
  • Real time signaling of content types between display and source devices, enabling a TV to optimize picture settings based on content type

Older, Original HDMI specification

  • Generally labeled as Standard HDMI cable
  • These work with 720p and 1080i resolutions

Ethernet & Automotive varieties

HDMI cables are also available with Ethernet, in each of the specifications listed above. These support Internet connectivity. Automotive HDMI cables are available in Standard and High Speed. They also have a different type of connector end to better withstand jostling and sudden shocks, have a stronger signal and are tested to higher performance standards.

HDMI Connector types

As specifications evolved so did connector ends. A is the standard, full-size end most consumers are familiar with. B is also an early design but has not yet made its way into products. C is Mini and is used for portable devices like laptops and digital cameras. D is Micro, which brings HDMI to mobile devices such as smartphones and tablets. And as mentioned above, there’s an automotive connection system. It’s called E.

Courtesy Wikimedia Commons

There is debate whether gold-plated ends are important. Technical opinion has been mixed. However, the feeling is that if cabling will be in a sheltered environment where the chance of oxidation is reduced, gold plating is not necessary. This may help if a customer balks at paying a higher price for gold yet worries about the consequence.

Speaking about price…

As long as an HDMI cable is less than 25 ft. and is properly certified by the HDMI organization a less expensive cable should perform equally as well as a pricier one within the same performance parameters. There may be other factors that might influence a decision like cable flexibility, molded strain relief, color, etc. But performance should be identical.

HDMI alt, adapters, splitters and connectors

The HDMI revolution has also led to work-around devices that enable it to be used with other kinds of connectors.

  • HDMI to USB-Type C cable/HDMI Alt Mode specification
    • Combines two of the most popular connectivity solutions—small form factor, reversible and multipurpose
    • Is designed for 1.4b specs so supports resolutions up to 4K
    • Supports Surround Sound, Audio Return Channel, 3D (in either 4K or HD), Deep Color, x.v.Color and content types
    • Includes Ethernet channel (HEC) and Consumer Electronic Control (CEC)
    • High Bandwidth Digital Content Protection (HDCP 1.4 and HDCP 2.2)
    • It’s up to manufacturers to choose which HDMI features they support on their products with USB Type-C
  • HDMI adapters/docks
    • These run the gamut, connecting HDMI to DisplayPort, composite, VGA, USB 3.0, standard HDMI to micro HDMI, etc.
    • Not all may work with 4K so verify specification compatibility
  • HDMI splitters
    • These let you split the signal, so it can be routed to additional devices
    • Not all may work with 4K so verify specification compatibility
  • Braided HDMI cables
    • Provides added flexibility
    • Verify specification compatibility
  • HDMI extension cables
    • These have a male end and a female end
    • Verify specification compatibility

HDMI’s Achilles heel—length of cable run

As wonderful as HDMI is as a technology, serious problems occur if the cable length gets too long. The common consensus for HDMI is 50 ft. However, even 25 ft. cables can have issues. Only short cable lengths of 1 ft. to 12 ft. seem immune from signal degradation.

Plus, the reliability of longer lengths can vary by manufacturer. All quality cables are HDMI certified, but length is not a part of the certification process. A 25 ft. run by one company may perform just fine, while another company’s 25 ft. cable suffers performance issues. For installers, this means it’s best to test longer cable runs that don’t use boosters, to ensure that company’s cables provide good results. 

One cable rules them all

HDMI is king when it comes to transmission of uncompressed audio and video digital data. USB-C might eventually vie for that position. However, HDMI has been around a lot longer and is present in far more devices, especially home entertainment components.

So, let’s revisit the earlier scenario of a customer on your sales floor looking for HDMI cables for their current or brand-new entertainment system. You need to ask questions to determine the lowest resolution device in their hookup mix. Remember, system performance is only as good as its weakest link. Then you should explain that HDMI cables should match the lowest-common-denominator capability which will save them some money.

By purchasing what they need vs. what the future might hold, you can encourage your customers to spend those saved dollars on other add-ons in your store.

Better yet, once they understand the big picture, hopefully a customer will choose to replace that older-spec device with a higher-end one from your floor. And, they’ll purchase the correlating higher-specification HDMI cables. That way, their system operates in harmony. And you have satisfied, informed customers—plus more sales.

To ensure you have a wide variety of HDMI cables, connectors and adapters, be sure to check out!

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