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A brief overview of HDMI 2.0 and 2.0a: made for 4K and HDR

by on July 23, 2015

Stephan Jukic – July 23, 2015

As data, images and particularly video keep increasing the data load they consume, the difficulty in transporting them only grows, and this is where HDMI 2.0 and HDMI 2.0a come into the picture. In particular, they’re part of the future of 4K video content.

The video production industry, consumers with their TVs and PC monitors, gamers with their 4K-capable games and almost everyone in between keep piling on the demand for more pixels, more frames per second, more dynamic range, more colors and more whatever will make digital video look so much cooler. Meanwhile all this extra data has to get transported somehow and not just from A to B but from A to B at the speeds and smoothness we’ve all become accustomed to.

This is where HDMI 2.0 and its cousin 2.0a come into the picture. As our daily content loads become ever more difficult to squeeze through the same piping we’ve been using for some years smoothly, the two new versions of the ubiquitous HDMI have become vitally necessary.

HDMI 1.4 is currently still the most common video transmission cable standard on the market and to be honest, it is quite capable as far as it goes. With a capacity to handle 10.2 gigabits per second at 3.4 gigabits per channel, HDMI 1.4 has served HD video honorably and effectively for years now. However, as 4K video and its now arriving variations with HDR, wider color gamut and other data-intensive aspects arrive on the market, the HDMI 1.4 of HD electronics has suddenly become woefully inadequate for the growing body of consumers who are switching to 4K in PC displays, TVs, PC gaming and video media players.

The fundamental problem with 1.4 is that, in order to transmit data at lightning fast speeds, it has to perform quite a bit of electronic acrobatics. Multiple (dual) channels inside the HDMI 1.4 cables themselves mitigate some of the speed problems in doing this but complexity grows as content resolution expands and with 1.4, resolutions that go well beyond 1080p HD (Full HD) simply can’t be handled at transmission speeds beyond roughly 24 to 30 frames per second.

This frame rate isn’t enough for full 4K smoothness in fast action video and things like sportscasts. Furthermore, it’s also not enough for seriously decent 4K gaming or for other more exotic things like UHD stereoscopy or certain aspects of HDR and color gamut enhancement.

The evolution of HDMI from SD to 4K ultra HD

The evolution of HDMI from SD to 4K ultra HD

Thus, with the race to achieve more speed on and advanced in semiconductor technology to help it out, HDMI 2.0 emerged. This new version of HDMI has been the standard since 2013 but only very recently has it come into play with the development of ultra HD video, TVs, media players and PC gaming too even. In fact, the deployment of HDMI 2.0 has been so slow even where it was badly needed that many earlier (2013 to early 2014) 4K TV models didn’t even include it and offered only the 1.4 variant. For 4K PCs, the latency in adoption has been slower still and only in the last couple of months have we really seen a number of PC models emerge with 2.0 built into them. 4K-capable gaming GPUs only started to offer HDMI 2.0 connectivity only recently too in the form of the Nvidia GTX 900+ cards and the company’s Titan X GPU but here at least the delay is understandable since most GPUs use DisplayPort 1.2 for their connections to PC monitors.

Overall, the new numbers that come with HDMI 2.0 are great for 4K and other complex video content. The standard offers a 6Gbps per-channel data flow rate, a doubling from the 3.4 of HDMI 1.4. This totals out to throughputs of 18Gbps or more than enough for 4K video at a smooth 60 frame per second, for gaming, TV or media player use. Furthermore, HDMI 2.0 supports the Rec. 2020 colorspace for much broader, richer color gamuts and also comes with other goodies like cinema-like 21:9 aspect ratio and augmentations in multichannel audio and 3D handling. These benefits also don’t just translate to 4K content exclusively, they also mean heavy improvements for HD content, in the form of things like 1080p60 stereoscopy, for HD at 120 frames per second.

Then there’s the HDMI 2.0a addition to HDMI 2.0, which was delivered to manufacturers in April of 2015. This additional improvement to the already augmented standard further introduced high dynamic range support, for the next generation of 4K content from media players and 4K Blu-ray devices. HDMI 2.0a is also certainly going to be a facilitator of the adoption of Dolby’s Vision technology.

Future developments for HDMI 2.0 or possibly its successor include the potential adoption of a highly ambitious (for now) plan to deliver 120-frame 4K content, or 2160p120. This however still requires some much great bandwidth and technical expansions in HDMI since even the current 2.0 could only deliver such a signal if four cables had their throughput combined.

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  • Adi
    September 16, 2015 at 10:17 am

    Can a 4K TV with HDMI 2.0 accept signals from a device that outputs via HDMI 2.0a? I’m pretty sure it won’t hon the HDR stuff, but will it at least display the image without issues?


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