Debunking ‘High Speed’ 4K HDMI 2.0 Data Rate Claims

Industry veteran Joe Perfito of Tributaries Cable goes on a fact-checking journey on how a “High Speed” 10.2Gbps HDMI cable can somehow now claim to send at a 18Gbps data rate for 4K video. New Ultra HD Blu-ray Discs will require at least 11Gbps data rate. Integrators are the last layer of protection for consumers.

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4K is like standing at the seashore and watching waves coming in one after the other. Waves… that’s the reality of 4K. We are currently experiencing the first wave of 4K – “Basic 4K.” My designation for the next 4K wave is “4K v2.0.”

The first wave is video under the HDMI v1.4 spec with a resolution of 3840 x 2160 (4K), 24 or 30 frames per second (also known as refresh rate), 8-bit color and 4:2:0 color sub-sampling. The data rate for a 3840×2160/30f/8-bit/4:2:0 is about 4Gbps. That’s pretty easy for a well-made HDMI cable at most any length.

The second wave of 4K started when HDMI v2.0 was introduced last year. My first reaction was how will this new spec affect the performance of our then current selection of Tributaries HDMI cables? With HDMI v2.0 expanding the bandwidth/data rate maximum to 18Gbps, I knew our cables, except for a number of shorter lengths, would not be able to successfully transport the dramatic required increase of data. That would also be true for other manufacturer’s longer length HDMI cables.

Then, HDMI LLC announced that any cable that was rated “High-Speed” would successfully pass 4K. Without any further explanation of what that statement meant, I began a journey of discovery to understand how a “High-Speed” cable rated at 10.2Gbps (some, just barely) could now pass 18Gbps.

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First, there was the question of the meaning of “High-Speed.” When an Authorized Testing Center (ATC), the testing facilities of HDMI LLC, certifies a cable as “High-Speed” does that mean it will successfully pass an “Eye Pattern” test at 10.2Gbps?  Or, does it have to do with compliance to the “Feature Sets” described by HDMI LLC in v1.4, the original HDMI version where “High Speed” was defined? If an HDMI cable will support 4K/24, Ethernet, ARC, Dolby and DTS Lossless Audio, etc., can it be considered “High-Speed” even if it only passes a maximum of 6Gbps? HDMI furnishes no guidance as to the answer of these questions. 

Second, if a cable is labeled “High-Speed” how would anyone know if it is actually “High Speed,” that is, has been tested and certified by an ATC. HDMI LLC states that if the cable or connector has the HDMI logo it is a certified product. However, having the HDMI logo may not be the answer. Interestingly, on January 8, 2013, HDMI Licensing, LLC announced that over 3 billion HDMI devices had been shipped since the launch of the HDMI standard. Also, according to industry sources, only about 200 million cables were certified by ATC. That means there are millions of counterfeit cables on the market which were never certified by an ATC. 

Speed Ratings on Cables Not Being Monitored
Another issue is “Speed” ratings. According to a 2008 directive by HDMI LLC, the only speed ratings that were permitted to be used on the cable, connector, packaging, product literature or advertisements was “High Speed,” “High Speed with Ethernet,” “Standard,” “Standard with Ethernet” or “Standard Automotive.”  All other “Speed” ratings were forbidden under threat of legal action by HDMI LLC for infringement of trademark and copyright issues. Yet, you can go into any store or distributor and see labeling on HDMI packaging such as “Supersonic Speed,” “Ultra High Speed,” “Super High Speed,” etc.

This has been going on for years with no visible action by HDMI LLC to clean it up. I’ve seen packaging declaring “21Gbps” on a bagged passive 6-meter HDMI cable. No other spec was given, so it could be the signal was down 50dB (unrecognizable). Inside the bag was a piece of paper with an “eye pattern” printed on it implying that the packaged cable produced the printed “eye pattern.” 

There was no explanation of what testing protocol was used or what length of cable was actually tested or whether the “eye pattern” on the paper was the test result of the cable in the bag. Theoretically, it is possible to produce a 6-meter HDMI cable to “successfully” pass 21Gbps but it would probably need to be made with 12AWG conductors making it the size of a garden hose. 

Of course, it should be noted that there is no testing protocol available for an HDMI cable being tested above 18Gbps. The question then becomes, “How does one know when purchasing an HDMI cable the ‘true’ performance specifications of the product?” The answer is that unless the company making the cable supplies that information you’ll never know.

Effect of Ultra HD Blu-ray Discs
For today’s available consumer video content, most HDMI cables work fine. However, that will soon change. On May 15, 2015, the Blu-ray Disc Association (BDA) announced the completion of the specifications of the UltraHD Blu-ray Disc; 3840×2160 (4K), 60fps, 10-bit color (Deep Color), High Dynamic Range (HDR) with 4:2:0 color sub-sampling. The BDA expects new UHD Blu-ray Players and discs to be available before the end of 2015. You can bet we will see demos at CEDIA Expo in October.

This new disc will require HDMI cable capability of at least 11Gbps which is higher than the HDMI v1.4 “High-Speed” spec of 10.2Gbps. I believe this will cause many already installed HDMI cables to fail. The reason many cables won’t work with this new content is that they were only designed to work with content up to 1080p/60 or possibly 4K/30.

So, the answer to the question, “Will your customers be ready for 4K v2.0?” can only be answered by you. Are you purchasing HDMI cables from a reputable supplier that will furnish cables which will successfully pass 4K v2.0 content? Is the performance properly certified by a legitimate testing facility? Are the certified test results available for public viewing for each length of cable?

In 2014, Tributaries, along with the support and expertise of Jeff Boccaccio of DPL Labs, decided to design a new line of HDMI cables with an abundance of “headroom”—that is, cables that would exceed ATC’s testing specifications by a minimum of 20 percent. With DPL’s highly advanced test equipment we were able to measure the performance of each internal conductor at various wire gauges and lengths. This took almost one year but the result was flexible HDMI cables with small O.D.s, excellent performance and small, tight fitting connectors.

To support our product claims, Tributaries displays on www.tributariescable.com, the specific Eye Patterns, Insertion Loss graphs and the DDC channel (transports the HDCP keys) rise-time oscillographs for each length of the models UHDS and UHDP cables. For the basic UHD cables, the Eye Patterns are displayed. Insertion Loss and DDC channel’s rise-time specifications are additional tests Tributaries requested to give a more complete picture of each cable’s “real-world performance.”

So, the next question is when do we expect 4K v3.0; 2160p/60/12-bit color with 4:2:2 or 4:4:4 color sub-sampling requiring 12Gbps to 18 Gbps? My prediction is that we will see hardware by 2016 but we won’t see content until at the earliest 2017. And, maybe 8K by 2020.