Back in September 4th 2013, HDMI Forum released the new version of HDMI, which was upgraded to version 2.0. This new version brought some very necessary upgrades in terms of supported bandwidth and the much needed new 4K resolutions. Also, as an added bonus, existing 1.4 category 2 cables would be compatible with the new standard and resolutions.
On the other hand, people learned to put some salt on some technological breakthroughs and product launches, with some call vapourware or paperware. Anyways, HDMI 2.0 would have no reason to diverge from the rest of the industry best practices, and as such it brings some much needed goodies, technological gimmicks and a few less publicised restrictions. From those, the cable compatibility claim seems to be the one causing more fuss, even for those more literate on electronics. There no more free upgrades as free lunches, so what’s the catch?
What is new today, it that finally there are some real HDMI 2.0 and 4K Ultra High Definition products on the market, both TVs and set top boxes, so we can really find out what was all the hype about and if all claims where in fact due. In fact, after some digging, we can now say that HDMI 2.0 is not completely what was expected, starting with the so much publicised legacy cable compatibility. At the end get ready for real HDMI 2.1 cables in order to fully take advantage of HDMI 2.0 new capabilities, but will it be worth it?
Well, fist of all let’s see what was presented to the public, as visible on the HDMI.org website.
The new HDMI 2.0 brings a lot new enhancements, but can one use all of them?
NO NEW CABLES! Current cables “are capable of carrying the increased bandwidth.
On thing which was NOT announced was the availability of the Compliance Test Specification (CTS), which allows manufacturers to market HDMI 2.0 equipments. In fact, this was just released in April 2014, a full 7 months later (or late, depending on who to do work for 🙂 ). This is also the reason why products only arrived at the market 7 months later than the announcement. As only after the CTS specs are published equipment manufacturers (both client equipment and test equipment) can be certified and thus, sold as HDMI 2.0 compliant.
It’s the last feature which deserves questions: free current HDMI 1.4b cable compatibility. Since electronic communications began people acknowledge it is not physically possible to arbitrarily add bandwidth to an already existing medium. From 10Base-T to 100Base-T new cables were required (cat.5) and the same happened with 1000Base-T (cat.5e) and again with 10G Base-T (cat.6e). The same happens on DSL connections, although higher bandwidth was attained from 8Mbps up to 24Mbps, it did not came at the expense of higher frequencies, but with higher modulations and better error correction. It is simply not possible to increase the used frequency and expect everything works.
Also, note that even if the publicized maximum new bandwidth is 16Gbps, actually only around 14.4Gbps is actually usable due to 8b/10b encoding.