Best Practice: A/V Distribution Infrastructure

I miss the days when A/V distribution used to be oh-so-simple in the analogue domain with component video solutions that just worked. HDMI changed all that, and now we have to go through the learning curve all over again with HDMI 2.0.

Aylett home-AV-futureThose of you who have followed my HiddenWires column through the years may remember one that I wrote about my least favourite industry phrases, namely 'Future Proof'. It was not so long ago that companies were making this claim about the CAT5 infrastructure that was being installed in so many properties. Then came CAT5e, CAT6 and now we have CAT6A as a mainstream cable. Future Proof is only as good as the next big thing.

A Case for Fibre

Over the past few years HDBase-T has reached a plateau of productivity, giving us stable and reliable distribution. Questions still remain about HDBase-T and 4K over HDMI 1.4, and now HDMI 2.0 is upon us. The fact remains that going from the 10Gb/s potential bandwidth of HDMI 1.4 to the 18Gb/s potential bandwidth of HDMI 2.0 will bring many challenges to transporting it on twisted-pair cables over any reasonable distance. As many of us have experienced, implementation is far from predictable. Since fibre A/V distribution solutions have become available through some significant industry vendors, as a company, we have chosen to use these in preference to twisted-pair solutions whenever possible, even if length is not an issue. Fibre is simply more predictable, being immune to electromagnetic interference.

Source your cable with care, as all Multimode Fibre is not created equal.

Fibre isn't even that expensive any more. OM3 and OM4 fibre is available at relatively low cost and we now have reliable field-terminateable connector systems available, negating the need for specialist contractors - although we still build in the cost of a specialist company to terminate and test the fibre channels. Testing is even more critical with fibre - If you are not confident, leave it to a specialist.

What Now for A/V Distribution Infrastructure?
The future of A/V distribution will depend on two factors: desired level of quality, and availability of reliable fast Internet. As far as quality is concerned, we have probably all experienced the difference between Blu-ray and most streamed and downloaded content (with notable exceptions such as a Kaleidescape download, which is the same Aylett_amazon-primehigh quality as a Blu-ray disc). As screens get larger, this quality difference becomes more evident. The compression artefacts produced when compressing an approximate 50Mb/s, as read off a Blu-Ray disc, down to an Internet-delivered stream of approximately 4Mb/s, are evident. As professionals, our duty is to deliver the best quality possible. This means demonstrating the difference between disc and Internet content to customers. As yet, there are no streaming services that provide HD 7.1 audio and beyond, but watch this space as the likes of Dolby Atmos and Auro3D will be coming to broadcast and Internet-delivered content soon. The quality argument, however, is about to be turned on its head. I doubt that we will ever see 4K content being distributed on physical media. Yes, it is technically possible, but given the decline in Blu-ray sales with people deciding to stream and download, it would only ever be a niche product and not financially viable for the studios.  

As far as Internet speed is concerned, you need a stable 6Mb/s to be able to stream a 1080 movie. This jumps to 15Mb/s for 4K and neither of these figures take into account other Internet usage in the property or concurrent downloads. Internet speeds are highly variable - I have a friend who lives seven miles from Bristol City centre and is lucky to get 2Mb/s - and rarely totally reliable. With the average UK broadband speed still under 20Mb/s, it remains important to design for locally-stored content until streaming and progressive download services can provide us with both quality and reliability.

Flexible Cable Infrastructure 
As ever, the solution is to design a cable infrastructure that keeps things as flexible as possible. A combination of coax (of the required standard for the satellite or cable provider wherever you are), CAT6A and OM4 fibre from a central distribution point to every potential 'TV position' in a home provides options for both now and the future to either centrally locate source components or place them adjacent to the display device. The OM4 may seem excessive, but it is the current most pragmatic bet for a distributed HDMI 2.0 future. Also, do not forget to allow for: • If possible, an easy cable route from the head-end to the road for new provider services in the future. • Audio return from the TV to the A/V receiver to allow audio from TV apps to be heard through the room speakers.

CAT6A allows implementation of 10Gb Ethernet over the full 100m channel length.

It will be necessary to be geographically-sensitive and understand the available Internet speeds to a property as well as the available content providers before discussing the possibilities with a customer. While outlining all of the options, you need to ensure that your customer's expectations remain realistic and your suggestions remain practical. After all, were you designing a system for a yacht for example, it would be foolish to suggest relying on streamed Internet 4K content when at sea. Conclusion The next few years will inevitably see us dealing with far more Internet-delivered content. This will no longer be the poorer cousin of Blu-ray and may well be the only way of accessing 4K content. If the equipment is centrally-located in a rack and distributed, be mindful of the bandwidth requirements that HDMI 2.0 will place on infrastructure. Future Proof? Never. But don't let developments in the next few years catch you out!

Peter Aylett is a world-renowned speaker and lecturer in residential technology, and the Technical Director at Archimedia, a multinational high-end residential integrator in The Middle East. He is also currently Chair of CEDIA’s International Technology Council Applied Content Action Team, and a regular contributor to HiddenWires.