There’s a new digital cable standard for your AV kit, and like all the best inventions it uses old, cheap, readily available materials to make it work.

In the same way that ADSL over 50-year-old copper wiring has given us a decade of broadband internet without all that tedious laying of new pipes, so too HDBaseT will allow us to watch uncompressed HD on our TVs without having to shell out for HDMI cables.

HDBaseT – now supported by an alliance that includes Sony Pictures, Samsung and LG – uses distinctly old-fashioned Cat5 or Ethernet cabling to squirt five kinds of ‘stuff’ to your display and speakers.

Valens Semiconductor, the inventors of HDBaseT, call it 5Play. That’s because you can send HD video, HD audio, internet, power and system control over a single, cheap Cat5 cable. What’s more, the system works to a maximum distance of 100 metres – compare that to HDMI’s paltry
10 metre maximum (both systems can be boosted further by use of repeater boxes).

HDMI is not a bad standard, but it is an expensive standard. It’s maximum bandwidth is 10.2 gigabits per second – enough for HD video, audio and control. But it uses these highly customised cables that have no other application. Because of that, retailers can charge truly insane prices for them. Some stores still charge $50 for a three metre cable. Twenty metres of factory-built, top quality Cat5 will cost $15. Or you can make the stuff yourself with a $3 crimping tool.

Cat5 – Category 5 – is the cable standard used in every wired computer network. It’s ubiquitous and that makes it cheap.

This is the genius of HDBaseT. The specification – only finalised in June 2010 – takes existing cable and works that ol’ signal processing magic to mash an HDMI-matching 10.2Gbps of data up the pipe.

Watching HDBaseT in action is kind of unnerving. There’s this huge coil of ugly old network cable sitting on a desk, a Blu-ray player on one side of the room, and on the other is an AV rack showing 1080p video and speakers pumping 7.1 uncompressed HD audio. The cable itself is 100 metres long. That’s something HDMI can only dream about.

Just spent all your money on HDMI-equipped AV gear? Don’t worry. You’ll be able to buy converter boxes, rather inelegantly called dongles, that will convert the HDBaseT signal to HDMI. What’s more, because the standard transmits power too (up to 100 watts), the receiving dongle won’t need a power brick. It will just be powered by the dongle at the other end.

The people who will benefit from 5Play first and foremost will be projector users. It’s always been painful trying to position an HD projector behind your head, but still have all your gear in front of you so your remote can operate it.

With HDBaseT, you’ll just run a Cat5 cable up through your roof, around the chimney, down through the drywall, out to the back toilet, down to the mailbox, wherever you like, up to 100m, to your projector. Older projectors will need a dongle (powered by the cable, as mentioned) but devices sold late this year and from early 2011 will start to include HDBaseT support.

Of course HDBaseT and the 5Play system has its critics. The first complaint is that it only matches the bandwidth of HDMI (10.2Gbps) so what’s the point of making the change? Well the quick answer to that is cable length – 100m out of the box. The system also supports eight ‘hops’ for a total max distance of 800m. That’s the length of a freaking hotel.

Meanwhile, futurists point to Intel’s Light Peak standard. It’s primarily designed for PCs to replace the variety of transmission systems or ‘buses’ currently inside the average computer. It starts at an HDMI-like 10Gbps but goes all the way up to 100Gbps. What’s more, because it consists of two optical fibres, it can send data at full bandwidth in both directions at the same time.

But like our own optical-based porposed NBN, Light Peak is still in its early stages. It also needs to be integrated with a copper wire to transport power. And most significantly, optical cables are still relatively expensive.

We keep coming back to HDBaseT, not just because it can carry so much data and do so many things, but because its cables are so cheap. Of course, once it’s in the market, you’ll be able to spend $100 on a ‘specially shielded’ or ‘audiophile grade’ Cat5 cable, but this is one instance where we can say with absolute certainty that the $5 cable you buy from your local computer store will be every bit as good.

We know HDBaseT will work because real PC wonks already use it to transport HD content to specialist devices. What Valens Semiconducter is really doing is establishing a standard and securing investment in turning book-sized dongles into miniature chips that go inside your next TV and Blu-ray player.

Don’t believe the detractors, and don’t wait around for optical. HDBaseT is the future of HD content transport. You read it here first.