HDMI 2.0 Specification and 4K UHD (2160p) Resolutions

The HDMI 2.0 specification is literally around the corner, but there is a lot of speculation as to what the HDMI 2.0 spec will actually offer. It is tied, in large part, to the maximum resolution and bandwidth requirements being faced with UHD (Ultra high-definition) 2160p displays. The board of the HDMI Forum has already officially announced HDMI 2.0, so we're now simply waiting for the details to firm up when it is released in the first half of 2013.

Double Your Pleasure

According to people who will speak off the record, the new format promises about double the existing bandwidth, taking each individual TDMS channel from a maximum of 3.4 Gbps to a full 6.0 Gbps. The other details have been hashed out as the HDMI forum has been meeting over the past months to determine the exact direction HDMI should go. The real decision seems to be whether to "simply" improve the TMDS 6 Gbps per channel bandwidth (this, of course, proposed by Silicon Image and almost all of the TV manufacturers) or actually make use of the largely superior DisplayPort technology—which already does more (in the already on-the-market version 1.2) than the rumored capabilities of HDMI 2.0.

For example, while HDMI 2.0 is struggling to bring relevant 4K (2160p) to market, DisplayPort can do 2160p 10-bit video at 60Hz right now. Currently, it takes four HDMI connections and some fancy video processing to accomplish this. You essentially send four 1080p signals into the display and stitch them together.

DisplayPort is also a latching connector where there are two clips that latch into place and a push button that releases the connector. Let's hope that if HDMI 2.0 goes the way it seems to be, they will change over the form factor slightly to allow for latching connections. Then custom installers could say goodbye to connectors which fall out and rely solely on often underperforming friction fittings.

HDMI 2.0, while still in development, will make it possible to play UHD (4K) video at 50 and 60 frames per second. It's uncertain whether there will be enough bandwidth to get 120 frames per second but that has been rumored to be on the table as a supported format. It' also likely that this move will force all HDMI cables to become active in order to support the more bandwidth-intensive of the new specifications.

To put this in perspective, and illustrate why HDMI 2.0 is so important and necessary, we can take a look at current televisions on the market. The HDMI 1.4a ports on current UHD TVs from Samsung, LG, Toshiba and Sony can receive full resolution UHD or 2160p signals (3840x2160), but they can't do so at frame rates greater than 24 frames per second. While this is sufficient for movies, it's not good enough for even current 2160p television broadcasts which will use 50 or 60 fps.

Future UHD 2160p Broadcasting

The future of UHD broadcasting is almost certain to be at frames rates of at least 50 or 60 frames per second. That means that UHD TVs being sold today won't be compatible with those signals without dropping the frame rates or upgrading the HDMI input boards. Samsung, in particular, says that it will offer an upgrade kit with HDMI 2.0 ports so anyone buying into their new UHD televisions this year can expect to be able to upgrade (for a fee) to HDMI 2.0. Samsung is currently the only manufacturer to offer the possibility to add hardware modules with new features and/or connectors to existing televisions.

Sony is also hinting that its newest 55, 65 and 84-inch X9 UHD TVs are going to be made to be compatible with the HDMI 2.0 specification.

Test & Measurement of the New Formats

With new formats come new tools required to test and measure both televisions and broadcast signals. At this year's NAB several manufacturers confirmed that HDMI 2.0 will enable content up to UHD (2160p resolution) at 60 frames per second  with 10-bit or maybe even 12-bit color. The current HDMI 1.4 specification tops out at 4K with 24 or 30 frames per second at 8-bit color. Increasing the specification that far means that test and measurement equipment will need to support a lot more data. The spec is moving from 300MHz/900Gbps to about twice that at 600MHz/1800Gbps.

In conjunction with HDMI 2.0 we're also likely to start seeing more mention of HEVC, or High Efficiency Video Coding. HEVC is a video compression standard that will likely replace or supersede H.264/MPEG-4 AVC. MPEG and VCEG (Video Coding Experts Group) have set up a joint team to work on the HEVC standard. HEVC is needed because there will be much higher bandwidths encountered by 2160p video and the proliferation of that material being sent to televisions via content providers. HVEC promises to improve video quality and double the data compression ratio of H.264/MPEG-4.  It's also foreword looking and can support 8K UHD with screen resolutions up to 8192×4320.

Who Needs HDMI 2.0 and 2160p Video?

It's not about who NEEDS it, I WANT it. And so do you. Right now your 4K televisions have more processing and display capability than the HDMI inputs going into them or the broadcast standards feeding them content. In fact, in all the discussions around the arrival of Ultra-High Definition (UHD) and 4K televisions and projectors, there is still a gap in the delivery system for watching 4K content on these screens. Blu-ray is the one current disc platform with at least the capacity to contain such content, but to date no official word has been released on when we could expect any update to the platform to support 2160p playback. With HEVC coming, it may never happen.

So immediately, before all those other things fall in line, 2160p displays are going to be very useful for those who can connect them to gaming systems as well as users of DSLR cameras. Those two formats are very much able to send UHD content at 2160p to these high definition displays, but lack a connector or format to do so over a single cable.

Currently, only DisplayPort can send 60Hz 4K signals to these new sets...we need a better solution since most manufacturers don't support DisplayPort at present (nor are they likely, since most have drunk the HDMI Kool Aid.

Check out the history of the HDMI spec features here (most information gathered from Wiki):

HDMI Specification Features	1.0	1.1	1.2	1.3	1.3abcd	1.4/1.4ab	2.0
sRGB	Yes	Yes	Yes	Yes	Yes	Yes	Yes
YCbCr	Yes	Yes	Yes	Yes	Yes	Yes	Yes
8 channel LPCM, 192 kHz, 24-bit audio capability	Yes	Yes	Yes	Yes	Yes	Yes	Yes
Blu-ray Disc and HD DVD video and audio at full resolution	Yes	Yes	Yes	Yes	Yes	Yes	Yes
Consumer Electronic Control (CEC)	Yes	Yes	Yes	Yes	Yes	Yes	Yes
DVD-Audio support	No	Yes	Yes	Yes	Yes	Yes	Yes
Super Audio CD (DSD) support	No	No	Yes	Yes	Yes	Yes	Yes
Deep color	No	No	No	Yes	Yes	Yes	Yes
xvYCC	No	No	No	Yes	Yes	Yes	Yes
Auto lip-sync	No	No	No	Yes	Yes	Yes	Yes
Dolby TrueHD bitstream capable	No	No	No	Yes	Yes	Yes	Yes
DTS-HD Master Audio bitstream capable	No	No	No	Yes	Yes	Yes	Yes
Updated list of CEC commands	No	No	No	Yes	Yes	Yes	Yes
3D over HDMI[142]	No	No	No	No	No	Yes	Yes
Ethernet channel	No	No	No	No	No	Yes	Yes
Audio return channel (ARC)	No	No	No	No	No	Yes	Yes
4K resolution support (24 fps)	No	No	No	No	No	Yes	Yes
2160p (UHD) @ 60 fps (single cable)	No	No	No	No	No	No	Yes
2160p (UHD) @ 120 fps (single cable)	No	No	No	No	No	No	No
Support for 21:9 aspect ratio	No	No	No	No	No	No	Yes
4:2:0 chroma subsampling	No	No	No	No	No	No	Yes

HDMI Specification Bandwidth and Resolution	1.0	1.1	1.2	1.3	1.4/1.4ab	2.0
Date initially released	December 9, 2002	May 20, 2004	August 8, 2005	June 22, 2006	May 28, 2009	mid-2013
Maximum clock rate (MHz)	165	165	165	340	340	600
Maximum TMDS throughput per channel (Gbit/s)	1.65	1.65	1.65	3.40	3.40	6.00
Maximum total TMDS throughput (Gbit/s)	4.95	4.95	4.95	10.2	10.2	18.0
Maximum throughput (Gbit/s) with 8b/10b overhead removed	3.96	3.96	3.96	8.16	8.16	?
Maximum audio throughput (Mbit/s)	36.86	36.86	36.86	36.86	36.86	?
Maximum color depth (bit/px.)	24	24	24	48	48	?
Maximum resolution over single link at 24-bit/px	1920×1200p60	1920x1200p60	1920x1200p60	2560×1600p75	4096×2160p24	?
Maximum resolution over single link at 30-bit/px	N/A	N/A	N/A	2560×1600p60	4096×2160p24	?
Maximum resolution over single link at 36-bit/px	N/A	N/A	N/A	1920×1200p75	4096×2160p24	?
Maximum resolution over single link at 48-bit/px	N/A	N/A	N/A	1920×1200p60	1920×1200p60	?

"Mastered in 4K" - Don't Be Confused

One final thought in regards to HDMI 2.0 specification and the promises of higher resolution content and higher frames rates has to do with some of the current claims for 4K content. Sony Pictures has already started production of their "Mastered in 4K" Blu-ray discs. What consumers need to know is that these discs are not stored as 4K or 2160p, they're just 1080p High Definition discs that were sourced from digitally re-mastered movies and “optimized” for 4K viewing. We don't even know what that means since most Blu-ray movies are master from high-resolution digital prints. In any case, these 1080p discs are set to be released any day now (May 2013).

Wrapping it Up

So, are you excited about HDMI 2.0 specification being released? Well, if you're looking at that new 4K television you should be. Also, you can't expect broadcast and streaming to leap forward to the higher resolutions before there is a mechanism to move those signals around. HDMI 2.0 promises to be just that. We just hope they implement some hard changes that will give clearer direction than in the past. HDMI has had a tendency to let everyone do whatever they want with respect to things like CEC and what specs are mandated in cables and televisions. While we understand the need for flexibility, the result has largely been more aptly described as "consumer confusion".

Let's hope HDMI 2.0 is a fresh new start and not the beginning of a "released-before-it's-ready" consumer electronics nightmare.