What is HDMI?

Explaining what HDMI (High Definition Multimedia Interface) is and how to increase the distance of your HDMI signal

HDMI explained

HDMI stands for High Definition Multimedia Interface and is the most frequently used HD signal for transferring both high definition video and audio over a single cable. 

HDMI is used both in the commercial AV sector and is the most used cable in homes connecting devices such as digital TV, DVD player, BluRay player, Xbox, Playstation and AppleTV with the television.

More and more home AV devices are being connected using this simple, effective cable, but now HDMI is also featuring on laptops and PCs and therefore becoming the standard for the corporate and commercial markets – for education, presentation, digital signage and retail display.

Fitting a HDMI cable into the AV system

HDMI is a digital interface, single cable solution for combined HD video and audio, replacing analogue solutions which require separate video and audio cables (such as VGA and audio jack).

Use a HDMI cable to connect the output from our HD source (the Blu-ray player or the Skybox, etc.) to the input of our HD displays – whether that be your TV, commercial screen or projector, all the way up to a multi-screen video wall!

Differences in HDMI cables

The standard 14mm version of HDMI comes as a ‘Type A’, ‘plug’ or ‘male’ connector on the cable - and ‘Type B’, ‘socket’ or ‘female’ socket on our connecting device.

But there are also mini and micro versions of HDMI out there on the market too, as smaller and smaller devices, such as our smart phones and tablets increasingly become our personal HD AV sources. 

However, there are limitations to the distance HDMI transmissions can travel. At CIE we recommend when using Category 1 'standard' HDMI cable that the lengths are limited to probably no more than 10 meters. 

There is high grade Category 2 HDMI cable available, using which we can successfully achieve cable lengths of up to 15 metres.

Ways of increasing the distance of the HDMI signal

There are a number of options to increase the distance of your HDMI signal:

- Using HDMI switchers and repeaters
- Using the latest HDMI over Cat cable or HDBaseT technology
- Using HDBaseT technology you can extend your signal to up to an incredible 100 metres over standard cat 5e, 6 or 7 ethernet cable.

These systems require specific transmitter/receiver devices, all of which we look into in great detail in other videos on the HowToAV video channel.


Find out more about HDMI

CIE's HowToAV.tv has a whole host of videos and blogs on HDMI, which format to choose, how to get the most out of your signal and more.  Click on the links below for the best HDMI cable and signal information..

We take a look at the distance limitations siganl transmission over standard Category 1 and Category 2 HDMI cable.

There are a whole host of reasons why a seemingly good HDMI signal can drop out without warning. We take a look at a number of reasons for HDMI signal drop-out and provide a checklist for fault-finding on your system.

The latest HDMI cable certification for High Speed HDMI Cables have been designed for ultra-reliable performance for 4K/UltraHD including advanced features such as 4K60, HDR, expanded colour spaces, meeting the demands of 18Gbps bandwidth signals. We find out if Premiuim HDMI cables really7 make a difference...

With more and more HDMI sources being connected to your TV or screen, chances are you're limited to just 2 or 3 HDMI inputs? So how can you add more HDMI inputs without having to invest in a new TV? HowToAV explains how HDMI Switchers and Matrix devices provide the solution.

With recommended transmission distances of just 5 to 10 metres (20 metres at very best) over standard HDMI cable, getting your HDMI Source signal to the Screen can often seem a challenge. But their are a number of devices and technologies out there - from simple HDMI equalisers and repeaters, to the latest in HDMI over Ethernet or Fiber - that can increase your signal transmission distances to hundreds of metres!

Good question! ..and one that seemingly everyone has a very strong opinion about - and that they want to share!
So we talk to cable expert James Chen of Kordz to get his industry opinion on choosing the right HDMI cable for the job.

Though HDMI carries both video and audio signals simultaneously of course, there are certain (commercial) applications where you might need to embed an alternative audio signal (think sports bars showing sports TV channel but playing music from a different source, for example).
We look at how HDMI audio embedders offer a simple solution.

Whether it's for commercial or residential systems, the number of AV Source and Display devices we own continues to increase. And, therefore, many integrated system require the ability to switch and change between which Source is transmitting to which Display or TV.
HDMI Switchers, Matrix devices and the latest software solutions provide management, control and distribution of the growing multi-device AV system.

HDCP - or High-definition Digital content Protection - is encrypted within the HDMI signal as a 'digital handshake' between devices to help protect content from being copied. However, ti can cause huge headaches between devices, with the much maligned 'HDCP error' message appearing on screen!


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Subscribe to our YouTube channel now at howtoav.tv for all the latest video casts or send us your questions to findout@howtoav.tv

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