HDMI technology

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HDMI is a technology for transmitting audio and video signals with currently (V. 2.1) up to 8k resolution and permissible cable lengths of a maximum of 3 or 10 m, depending on the resolution.

But what to do if larger distances have to be bridged?

First, some theory.

HDMI standards

HDMI (High definition multimedia interface) was developed in 2002 and has now reached version 2.1. For licensing reasons, version numbers may no longer be used to differentiate between HDMI standards. The following terms now apply:

• HDMI standard (Full HD)
  (V 1.0) with up to 3.96 GBit/s at a maximum resolution of 1,080p (60 Hz)
  (V1.2) with up to 7.92 GBit/s at a maximum resolution of 1,080p (60 Hz)
• HDMI High Speed (4K, 3D, Deep Color)
  (V 1.3) with up to 8.16 GBit/s at a maximum resolution of 1,440p (60 Hz)
• HDMI Premium High Speed (4K)
  (V 1.4) with up to 8.16 GBit/s at a maximum resolution of 2,560 x 1,600p (60 Hz)
  (V 2.0) with up to 14.4 GBit/s at a maximum resolution of 3,840 x 2,160p (60 Hz)
• HDMI HDMI Ultra High Speed (8K)
  (V 2.1) with up to 42.67 GBit/s at a maximum resolution of 7,680 x 4,320p (60 Hz)

HDMI cable

The golden thumb rule: as short and as good as possible!

The higher the data rate to be transmitted, the more complex the manufacturing process. Cable made of hypercrystalline copper with an extremely high degree of purity, quadruple shielding, separated inner conductors and - of course - with 24 kt. Gold-plated connectors ensure extremely low-loss signal transmission and the highest possible speed.

For such cables - yes, you read that correctly - a good 800 euros are due, for a length of at least 12 m. Fiber optic cables can cost up to four-digit euros.

As mentioned at the beginning, the cable lengths should generally be kept under 3 - 5 meters if you want to buy cables at reasonably affordable prices and still have a usable transmission rate. It makes more economic sense to bridge longer distances with HDMI amplifiers, so-called expanders.

HDMI expander

These bridge up to 180 m expanderby transmitting the HDMI signal via network cable (CAT.7). They consist of a transmitter into which the HDMI signal is fed via a short HDMI cable and a receiver which converts the signal transmitted via CAT.7 cable back into HDMI and outputs it via an HDMI connection socket.

HDMI splitter

An HDMI signal source is divided into several HDMI playback devices using video distributors or so-called splitters.

Simple, passive splitters (around 20 euros) simply split the video signal between two HDMI output sockets, while active devices (with a power supply) (up to around 50 euros) slightly amplify the signal on the output side in order to halve the signal strength about to compensate.

For high transfer rates you need correspondingly good ones amplifier for each of the HDMI outputs, which is reflected in prices starting at around 100 euros (1 IN 2 OUT at 4K) or just under 250 euros (1 IN 4 OUT at 8K).