HDMI 2.0 Is Here…And It’s Not Fast Enough?

This morning, the HDMI Forum announced the release of HDMI 2.0, which was almost two years in the making. The impetus for this new standard was and continues to be 4K, which requires such increases in data rates that the older 1.4 version can’t support it, except at slow frame rates.

Now, HDMI 2.0 has a maximum data rate of 18 gigabits per second (Gb/s), slightly faster than DisplayPort’s 17.2 Gb/s. If you do the math, this should be fast enough to transport 3840×2160 video with frame rates of 50 and 60 Hz, using 8-bit and 10-bit color (at 60 Hz, the clock rate for 8-bit 4K is about 14.9 Gb/s; with 10-bit color, about 17.9 Gb/s).

Here are the highlights from the official press release:

“HDMI 2.0, which is backwards compatible with earlier versions of the HDMI specifications, significantly increases bandwidth up to 18Gb/s and adds key enhancements to support continuing market requirements for enhancing the consumer video and audio experience. New functionality includes:

– Support for 4k@50/60, (2160p: 4 times the clarity of 1080p/60 video resolution)

– Up to 32 audio channels for a multi-dimensional immersive audio experience

– Up to 1536kHz audio sample frequency for the highest audio fidelity

– Simultaneous delivery of dual video streams to multiple users on the same screen

– Simultaneous delivery of multi-stream audio to multiple users (up to 4)

– Support for the wide-angle theatrical 21:9 video aspect ratio

– Dynamic synchronization of video and audio streams

– CEC extensions provides expanded command and control of consumer electronics devices through a single control point

HDMI 2.0 does not define new cables or new connectors. Current High Speed cables (Category 2 cables) are capable of carrying the increased bandwidth.”

After reviewing the specifications, it appears to me that the HDMI Forum was trying to squeeze every last drop of speed out of the existing connector/interface architecture without having to re-engineer the standard. There’s no mention of locking connectors (a bugaboo of the broadcast and AV industries). Nor is there any discussion of speeding up HDCP key exchanges beyond what’s already been accomplished with InstaPort. But an HDMI 2.0 standard should eliminate the need for two or even four separate HDMI ports to playback 4K content (several TV and projector manufacturers currently use this approach).

Adding multiple channels of audio and increasing the sampling frequency is relatively simple stuff, as the bit rates for audio are a small fraction of those needed for 2K and 4K video. And you can already deliver two separate video streams through one HDMI connector – it’s only a bandwidth issue; the new standard just establishes a protocol for doing so. Supporting 21:9 isn’t all that big a deal, either.

I’m not sure what “dynamic synchronization of video and audio streams” means yet and will have to talk to the folks at HDMI Licensing to get a better explanation. As for CEC, it appears that control functionality has been souped-up beyond the basic command sets used to operate AV receivers and Blu-ray players.

What’s clear now is that HDMI 2.0 is NOT going to be the big breakthrough many of us analysts and writers expected, and that it will NOT be able to transport 10-bit and 12-bit 4K video running at higher frame rates (>60 Hz). Both of these specifications are necessary to develop high dynamic range (HDR) video and movie content.

Nor is there any indication of supporting a high-speed data bus overlay like Thunderbolt, which is becoming more important with the growth in popularity of tablets and smart phones, not to mention ultrabooks. These devices are leading the industry changeover to single, dense, multifunction interfaces across all sorts of CE products.

In contrast; over at VESA, they’ve already commenced development of Display Stream, a new interface that will use “light” JPEG compression to push data rates up to 25 Gb/s and beyond over conventional DisplayPort connections. This is a more “future-proof” approach to display connectivity and reflects the current state of 4K and UHDTV product and content development, what with all of the 4K television announcements that have been made this year.

But the reality is that HDMI dominates the CE marketplace and is making major inroads to commercial AV and broadcast installations. The market has largely ignored DisplayPort, despite the facts that (a) there are currently no royalties associated with its use, (b) its connectors come in many different flavors, including support for mobile and fiber optic interfaces, and (c) it already supports a high-speed data bus overlay – the 20 Gb/s Thunderbolt layer.

Maybe they’ll get it right next time..