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Installer's Insight - Padding the Pipeline

Padding the Pipeline

I had originally planned this "caution" on HDMI cables for a later date, but recent developments suggest "sooner better than later" timing.

As many of my past clients (and many among this readership) are in the process of moving to 4K/HDR systems, immediate consideration to the following could save you time, money and hassle down the road.

Whenever I install complete home theater systems I try to "future-proof" the hardware to the extent I can. That means installing a level of performance beyond the immediate requirements. This is always in the client's best interests as most of the upgrading to "the next new thing"—and you know it's comin'—is already in place when needed.

There is no better example of the merit of this practice than the current state of HDMI interconnect cables.

Recent advertisements have pretty much drilled into our heads that we need HDMI cables capable of 18Gbps transmission if we want unmolested 4K/HDR at even an 8-bit color depth. Turns out, a short look downstream sights much bigger demands.

See the "4K" chart below (courtesy of the Imaging Science Foundation) showing the pending potential bandwidth requirements (and HDMI cable designations) for the new HDMI 2.1 standard with 4K-resolution content at various frame rates. The first column shows the signal resolution and frame rate. The second column shows the potential options for chroma subsampling (i.e., color compression), where 4:4:4 represents uncompressed color and the highest quality. The third column represents the options for color bit-depth (Editor's note: you can read all about chroma subsampling and color bit-depth in the linked Tech Talk articles.-RS). The last two columns show the required bandwidth for each signal configuration and the official HDMI cable category that is certified to handle it.

HDMI2.1-4K-CableChart-640px
Courtesy of Imaging Science Foundation

You'll notice that as resolution, frame rate, color sub-sampling and bit depth become maximized, the required cable bandwidth quickly shoots to 48 Gbps.

Now get ready for 8K and screens with an aspect ratio of 21:9 (yes, 'Scope movies with no black bars—yea!...and yup, 45 million pixels). I predict the popularity of such screens will rise soon. By the way, these wider screens turn 8K into 10K!

So take a look at the "10K" chart below.

HDMI2.1-10K-CableChart-640px
Courtesy of Imaging Science Foundation

At maximum everything, we'll need cables capable of passing 120 Gbps comfortably—nearly seven times our current target. Clearly, these aren't on the shelf yet, but invention has always found a way to satisfy necessity in our industry when required to...especially when big bucks are involved.

Current advice: buy the very best carbon fiber-optic cables you can find (AVPro Store is a good place to look) as you transition to 4K/HDR. For long runs, pull two cables in conduit anywhere you go for a chance of not having to rip up the walls...again.

Comments (7) Post a Comment
Tod T. Posted May 13, 2019 8:37 PM PST
I suspect we'll just rid ourselves of copper wire to transmit anything other than DC. HDMI Gone. The future is totally fiber optic interconnects for everything except the 117 vac power.
Terry Paullin Posted May 14, 2019 7:47 AM PST
Actually, copper usage has recently spiked in the DIY jewelry business and roof construction going for that "patina" look .............

Go figure.
James Dahlberg Posted May 14, 2019 7:50 AM PST
Looking at HDMI over fiber cables, none of them appear to be rated at over 18 Gbps, so how do they future-proof your system? It looks like you can get much cheaper copper HDMI cables up to 30 feet long, with the same bandwidth rating - certified even. So unless you need a cable longer than 30 feet, you may as well stick with copper. You can also get 18 Gbps active HDMI cables up to 100 feet or so long, at prices way cheaper than fiber.
Terry Paullin Posted May 14, 2019 7:55 AM PST
James -

Actually, several companies now offer 48 Gbps fiber cable (AVPro is just one). Of course, you can only "future proof" up to what's currently available. I still do some systems where the requirements don't require 48, but I put it in anyway. Ditto for receivers that get HDMI 2.1 and HDCP 2.2
Paul Vail Posted May 14, 2019 1:13 PM PST
Truly, the word that mattered most was almost glossed over in the article.

Conduit!

HDMI specification calls for a head diameter of 7/8", so a 1" conduit should be enough, but a 1.25" or larger flexible orange conduit, most often from Carlon, should be the recommendation for all installations which have remote located equipment. Family room with a TV over the fireplace and equipment a few feet away? Run conduit! Projector at the back of the room, equipment off to the side, run conduit!

It's a great baseline strategy during construction to help ensure that there will be no need to retrofit cables by tearing up drywall. A hundred bucks or so worth of conduit installed from the beginning can save a thousand dollars in just a few years when the HDMI standard changes once again.

And by those charts, it is pretty obvious that the standard WILL change once again.
Terry Paullin Posted May 14, 2019 1:20 PM PST
Paul -

You are correct! I should have made a bigger deal out of conduit. I think I fell into the mode of talking to other custom installers like yourself who are well aware of the merit of conduit. DIY or new installers should always, always use conduit for anything through walls.

Thanks for the reminder.
Rob Sabin, Editor Posted May 14, 2019 2:11 PM PST
"A hundred bucks or so worth of conduit installed from the beginning can save a thousand dollars in just a few years..."

So very, very true, Paul.

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(05/24/19 - 10:11 AM PST)
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