Using HDMI over long distances: Today, almost all of us use HDMI to connect our AV installations. A cable between the Blu-ray player and the TV, one between the decoder and the TV or all devices connected to the receiver or home cinema set via HDMI. These devices are often close to each other and can therefore be easily connected with a cable of 1, 2 or 3 meters. But, how do you solve it when you have to bridge longer distances with HDMI?
HDMI over long distances
Suppose you have a beamer in the back of the room and your sources such as the Blu-ray player and the TV decoder are located in the front of the room. Then you quickly need an HDMI cable of 10 meters or more. The HDMI specifications do not specify a maximum length, but the rule of thumb is that 10 meters is about the maximum that you can reliably bridge. Then you also have to use well-shielded and high-quality cable. Especially when you need a lot of bandwidth (for example because you want 4K @ 60fps or even 120 fps in perfect quality), the need for a good cable becomes increasingly important. Due to the enormous amount of data, and the higher chance of loss with a long cable, the chance of ‘sparkles’ (randomly flashing pixels) is much higher. Fortunately, there are other solutions.
Optical HDMI Cables
Where a classic HDMI cable sends an electrical signal via copper wire, optical HDMI cables use fiber optics to transmit a light signal. The conversion takes place, thanks to miniaturization, in the connector itself. As a result, in many cases you will not see any difference with a normal cable. With these cables you can quickly bridge 100m. All the latest HDMI features are supported by these cables. Such as uncompressed images in 8K at 60Hz and 4K at 120Hz. These cables have a bandwidth of 48 Gbps (48 G).
HDMI over Ethernet
If you want to send HDMI signals over great distances, and maybe even send HDMI signals throughout your house, a network with CAT cables (the well-known Ethernet cables) is interesting. The CAT5 to CAT7 cables are already widely used to distribute the internet connection indoors, but you can also use these cables to distribute your audio and video signal.
All you need for this is an HDMI-over-Ethernet extender. There are various extenders (sometimes called extenders or converters) for sale, and depending on the quality and the distance that can be bridged, you pay a few tens to a few hundred euros for this. At the transmitter, an HDMI cable goes in and an ethernet cable (UTP cable) comes out, at the receiver an ethernet cable goes in and an HDMI cable comes out.
HDMI over long distances: Wirelessly transmit audio and video signals
If wired is possible, we choose wired in most cases. This is to ensure that quality is maintained and to minimize the chance of interference. But, if you really want wireless, there are also options. There are various accessories for sale that can wirelessly transmit the audio and video signal over a large distance.
The products that can wirelessly transmit an HDMI signal from the source to the receiver are often a lot more expensive than the other solutions, and the range is also lower because it is wireless. For example, Marmitek has a wireless solution that costs you almost 300 euros and gives you a maximum range of 10 meters (in the field of view). The operation is quite simple; you connect the source, for example a Blu-ray player, to the transmitter using a short cable. This transmits the signal wirelessly to the receiver, which is connected directly to the display or via a short cable.
In addition, a number of standards for the wireless transmission of images and sound have been worked on for years. Two of the better known standards are WHDI and Wireless HD (WiHD)† Although progress is being made in terms of laptops and computers, we hardly see these standards in the AV world. It is still waiting for widely accepted and implemented standards to transmit audio and images in high quality and over great distances.
Incidentally, there are of course standards such as AirPlay 2 and Google Cast with which audio and video can be streamed from a (mobile) device to a television or other display. No HDMI is involved here, but the quality is therefore lower and various features and properties that HDMI does support are not supported with these wireless protocols.
