First generation HDMI 1.4 spec UHD 4K, next-generation HDMI 2.0 spec UHD 4K and what integrators need to know.

An analysis of 4K Interim vs 4K Proper by Chris Pinder, Founder and MD of HDanywhere, June 2015.


4K is a complicated subject matter. 4K isn’t one format, it’s an umbrella term for many combinations of resolutions, frame rates and colours. Talking about 4K in too generalised a way is dangerous. When I discuss 4K with anyone, in as non-patronising a way as possible to simplify and aid understanding, I refer to ‘i’ and ‘p’, (like 1080i and 1080p) but my ‘i’ and ‘p’ doesn’t mean interlaced and progressive, I mean first generation 4K and next-generation 4K, or in other words  ’interim’ and ‘proper’. P could also quite easily stand for ‘premium’.

This is my take on the two-speed world of 4K UHD devices at the moment. It may be labelled and marketed as 4K, it may even support HDCP 2.2 – but is it 4Ki or 4Kp?

Proper 4K (4Kp) is next-generation HDMI 2.0 spec 4K, it’s what Ultra HD Blu-ray is and what premium 4K content will be. Ultra HD video refreshes at a smooth 60 frames per second in amazing 10-bit 4:2:0 colour (or if your display doesn’t support 10-bit) 8-bit 4:4:4 colour – basically hugely superior colours than what we have seen before over HDMI. 4Kp can also support HDR content and runs at very high 18Gbps data rates and, as a result, will require all new high-bandwidth HDMI 2.0a* spec electronics.  4Kp will also have HDCP 2.2 copy protection encrypting the content, which I’ll touch on later.

What is most important from integrator perspective is that single-cable HDBaseT DOES NOT carry 4Kp. It will only carry 4Ki because HDBaseT is max 10.2Gbps and 4Kp requires 18Gbps.

Most devices out there today labelled as ’4K’ do not support 4Kp, they only support 4Ki. And by most, I mean over 95%. But this is improving, more and more displays are coming out now that support HDMI 2.0 and have a 10-bit panel. Ultra HD Blu-ray is likely going to be the first 4Kp source device we see. So what is 4Ki?

Interim 4K (4Ki) runs at a 9G data rate (half that of 4Kp) and doesn’t necessarily require new HDMI 2.0 electronics. It will work on older HDMI 1.4 spec devices. It may or may not have HDCP 2.2 encryption. And colour-wise if it’s running at 60fps it can only be the lesser 8-bit 4:2:0 quarter colours. For 4:4:4 a lower 30fps refresh rate is used instead and smooth panning shots are sacrificed. 10-bit colour content just flatly isn’t supported full stop.


What is so important about colours?

4Kp/60 and 4Ki/60 if watched in black and white are EXACTLY the same. The same number of pixels wide and high, refreshing at 60 times per second, with the same pixel data for light and dark contrast. So no difference in sharpness, motion or contrast.

Where they differ is with a compromise on colour. The resolution of the colour layer that gets laid over the top of the black and white frame when combined to make the final image. With 8-bit 4:4:4 each pixel can choose a colour, whereas with 4:2:0 every 4 pixels have to share a single colour choice. Even though a cluster 4 pixels are sharing the same colour, the overlay of the black and white image creates different shades. The resulting 4:2:0 video content, although a lesser quality, is not as substantially different from 4:4:4 as you might think. In fact, when viewing the two from a couple of metres away, the human eye really struggles to differentiate them.

OK, now that you’re thinking is in tune with there being two primary types of 4K material and you understand the difference between the two.

You also NEED to be aware of a couple of associated meteors about to hit the AV side of the CI industry that relate to the facilitation of working 4K HDMI systems. (Remember HDMI is a system, NOT a cable) One is called ‘HDMI 2.0′ and the other is ‘HDCP 2.2′. The two meteors should really hit simultaneously, but not necessarily.

Meteor 1: HDMI 2.0 is the new twice-as-big digital pipeline to accommodate the higher data rates of proper 4K jumping from 9G to 18G bandwidth. Its not a new cable design, its new electronics at either end of the existing (short) HDMI cable we use. So that is new source devices (Ultra HD Blu-ray players for example) and new displays (10-bit SUHD Samsung panels for example). However for longish cable distances, say 3m and over, current passive cables may struggle with the higher data rates. We’ll begin to see some new breeds of HDMI cable types appear to solve this. Some will use integrated active/powered boosting chips and others are likely to be a copper/fibre hybrid cable. Existing long length HDMI cables, that may be buried in walls for example will be able to be utilised through the use of restorative dongles that can be placed at the start and end of the cable run. I expect to see this HDMI cable rescue/fixer market grow over the coming years sharply.

Meteor 2: HDCP 2.2 is the new 128 bit encryption designed to secure 4K content from being pirated. It is the same level of security encryption as credit card issuers use for internet transactions. Unless every device in the signal path is HDCP 2.2-capable, theoretically the content will not be shown. Source, matrix, AVR, balun, display, projector must all support HDCP 2.2. One weak link means black screen. The thing about HDCP 2.2 support is that it’s essential to ensure the best chance of displaying 4K content from your favourite content providers (i.e Hollywood and sports). The HDCP 2.2 event horizon will largely be determined by the release of Ultra-HD 4K Blu-ray and 4K content being delivered via our set-top-boxes.


In summary, until more next-gen 4Kp source devices, like Ultra HD Blu-ray, set-top-boxes, and media players are released we live in a kind of interim 4K limbo land, a phoney, interim 4K world with no proper, premium 4K content to enjoy. In addition to this, more displays with HDMI 2.0, HDCP 2.2 and 10-bit panels need to be released so that users can take full advantage of the advancements in picture quality offered by 4Kp. Month-on-month this situation improves.

From an integrator perspective, quite rightly there is a lot of emphasis currently on HDCP 2.2 support within matrixes. But even when HDCP 2.2 compliant, single-cable HDBaseT is a bottleneck in many video distribution systems, which will result in premium 4K content video quality being downgraded when distributed. There is a quality compromise currently in order to deliver a distributed solution over a single network cable.

SIDELINE RED HERRING: What about 4K streaming like Netflix?

Well it’s not 4Kp and it’s not 4Ki… It’s dynamically compressed, streamed 4K content using AVC H.264 and HEVC H.265 codecs with varying quality from home to home according primarily to the speed and quality of their network. For the purposes of this article, I am talking about uncompressed 4K content.

More info here:



Answers to various 4K / Ultra HD questions we’ve been asked recently…

What is the content availability for Ultra HD/4K currently?
Very limited right now. In the US, Sony are shipping pre-loaded media servers with their 4K panels (in what seems to be a stop-gap measure) until an industry-ratified medium comes along. This will most likely be answered by Blu-ray, with the BDA working on defining a new expanded and elevated specification right now, expected for release later this year.

Why do home technology professionals need to be aware of Ultra HD/4K? Are consumers buying into this new technology?
The need to be aware because it’s happening now. It’s possible some are thinking of it as 3D – a passing fad or a peripheral feature. In reality it is similar to the leap we made from SD to 1080p; it’s being supported by SMPTE, studios and vendors alike to such a high level that most in the community are not yet aware. Consumers will inevitably buy into the technology, but it will take time. Serious penetration won’t happen until prices come right down and content is broadly available. Ten years ago you could only get 1080p by upscaling before Blu-ray (and HD-DVD) came along in 2006, but look at it now – 1080p is ‘normal’. The 4K path will be the same, albeit in a much shorter timeframe.

What are some common misconceptions about Ultra HD/4K?
Misconception one – there’s no content. OK, it’s true right now – but it’s close. There is actually already an impressive back catalogue of movies in 4K – but the new BD spec needs to be released (and new players to implement it) before we’ll be able to truly tap in.
Misconception two – it will deliver no benefit: The resolution would exceed our own visual acuity. Look back through recent history – there was a time that an 34” TV (not rear pro) was regarded as HUGE. Now 42” is small, 50-60′ is normal, and even sizes up to 84” are gaining popularity. However we’re not sitting further away than we used to. IMAX cinemas allow a much bigger picture with relatively close seating by increasing picture resolution. 4K panels and content will do the same.

Can you suggest one way Ultra HD/4K will help the bottom line?
There are a few opportunities for 4K to help drive business:
Old install refurbishments: all-new hardware and possibly even new cabling.
New 4K sales and installation requirements.
It defers cloud based delivery methods and in-home wireless technologies (for AV), reducing the DIY plug-n-play capability of consumers. That is, the high bandwidth specialty installation of 4K sustains the need for a professional integrator, with a chance for more hardware sales.
It will even help software (BD disc) sellers as 4K reduces the threat of downloads due to sheer file size and delivery bit rates.

On the technical side, where will the common mistakes be made?
Cables mislabelled: 4K is deliverable via HDMI at one fixed clock speed of 297MHz (up to 30 frames). This equates to an aggregate data rate nearing 9Gbps, which before the year is out will double again with an upcoming new HDMI spec. Although the existing ‘High Speed’ HDMI cable spec technically has this 9Gbps rate covered, many HDMI cables are possibly not accurately labelled.

Devices simply not capable: The big ‘gotcha!’ is with devices and the HDMI silicon they contain. Currently most devices employ HDMI chipsets (transmitters & receivers) that are limited to 225MHz, or 6.75Gbps, emanating from 2006 specifications. This is clearly insufficient for 4K, even with firmware upgrades. The pipe simply isn’t big enough. Many HDMI extenders, switchers, splitters, matrix switchers etc, on the market also contain this restricted silicon, and so are not adaptable to 4K applications. Even if the silicon is upgraded, length potential will be much reduced, perhaps by more the half. CATx cable has become a favourite choice for installers for HDMI extension but 4K fundamentally challenges the limits of this cable type. Technologies like HDBaseT already address this through proprietary firmware driven timing technologies, but it’s no longer native HDMI. Matrix switchers with HDBaseT will generally still perform the cross-point switching in the HDMI space, so they may still be restricted even though the HDBaseT stage is capable of more.

Do you have a final comment?
4K is not only coming, it’s here. We’ll exist in a world of upscaling and some proprietary file delivery for perhaps a year or two, then things will turn very quickly to more mass-market. The challenge for the custom installer is that they are expected to pre-wire jobs for future 4K support NOW, even though they can’t yet even test what they’re putting in for validation. They will need to rely on their product suppliers and a leap of faith that the products will deliver as expected, when expected. The phrase ‘futureproof’ is scarier and more difficult to define than ever.
The new HDMI spec will push data rates up to at least 18Gbps, driving the need for all-active connectivity and pretty much wiping out CATx cable as a viable extension cable option (other than possibly HDBaseT).

It’s exciting times ahead with the best sales opportunities opening-up to those that learn the basics NOW and stay ahead of the curve.

A quick introduction to Ultra HD 4K

Ultra HD began its life known as ‘4K’. The term 4K was officially adopted by the HDMI® organisation in 2009. In October 2012, the 4K working group of US-based organisation CEA renamed 4K to Ultra HD.

Regardless of its title, Ultra HD it is a video format offering four times the resolution of what is known as 1080p. Ultra HD has been also referred to as ‘4Kx2K’, ‘4K/2K’, and ‘Quad HD’. In simple terms, 1080p video (what is called ‘Full HD’) is actually like viewing a 2 megapixel photo. 4K, however, is the equivalent of viewing an 8 megapixel photo. 1080p = 1920 x 1080 pixels. 4K = 3840 x 2160 pixels (consumer version)

What are the requirements for viewing Ultra HD?

1. Displays:
Ultra HD is initially dominating the high-end purist projector format, where it is most beneficial to improving the viewing experience. Sony have already shipped their first 4K projector. As of November 2012, it is appearing in flat panel displays due to consumer demand and/or manufacturers value-adding.

2. Sources:
The Blu-ray disc format is compatible with Ultra HD content once enough layers to hold the data are incorporated into the disc. A new ‘Ultra HD capable’ BD player will be required, of course.

3. Content:
As of November 2012, the movie industry is gearing up for Ultra HD content. James Cameron’s Avatar 2 will be filmed in Ultra HD and other high profile directors are working with Ultra HD cameras now. Back catalogue film negatives are being transferred to Ultra HD digital masters.

4. Cables:
From a cabling point of view, Ultra HD video will actually be the first true technical/performance challenge to many long length HDMI cables which claim to be High Speed.

HDMI 2.0 – key features of the new specification.

HDMI 2.0 was unveiled to the world at IFA Berlin in September.  Following this, Aussie company Kordz, stocked in the UK by HD Connectivity, became the first approved HDMI 2.0 Adopter in the world, outside of the HDMI Forum, and is the only HDMI 2.0 Adopter in Australia.  Founder David Meyer lifts the lid on the key features, inner workings and potential pitfalls of this new specification.

Each time a new version of HDMI is announced, there follows a buzz of new features and formats, but also a groan from the custom installation community as to what the implications may be.  HDMI 2.0 paves the way for some fantastic new video and audio capabilities, but no need to panic – the changes may not run as deep as you might think.  Ultimately HDMI 2.0 will settle into a place of normality, as has happened with every iteration before it.

So what does HDMI 2.0 offer, how is it different, and what are the headline features that you need to know about?  Let’s take a look.

Development of HDMI 2.0

HDMI 2.0 is the first major HDMI specification release since version 1.4 back in 2009, so it’s fair to say a lot has changed, and it needs to.  There are now two HDMI organisations;

  • HDMI Licensing, LLC, with its seven founder companies.  Developers and managers of the HDMI 1.x generations, and now also appointed licensing, marketing and compliance managers of HDMI 2.0,
  • HDMI Forum, Inc., a non-profit corporation founded in 2011, with more than 80 member companies for broader market development of future versions of HDMI,

An important point to note is that HDMI 1.4b remains as an ongoing specification, with HDMI 2.0 running concurrently with its subset of additional optional features and enhancements.  Existing HDMI Adopters do not automatically get an upgrade; they must sign an addendum and be accepted before they can become adopters of HDMI 2.0.

Key Features of HDMI 2.0

Here’s a summary of some of the key new features of HDMI 2.0;


  • 2160p/60 (4K) 8-bit 4:2:0 in the existing 9Gbps data rate (previously 30fps limited),
  • 2160p/60 (4K) 10 or 12-bit 4:2:2 colour at a new higher speed of 18Gbps,
  • Anamorphic video modes for 2.37:1 picture,
  • New ‘Dual View’ video mode for two simultaneous full screen 1080p images (on 3D backbone),


  • Up to 32 channels of One Bit audio to 192kHz, and up to 1536kHz sampling in 2-channel mode,
  • New 10.2, 22.2 and 30.2 channel modes for ‘3D Audio’ speaker placement,
  • Up to 4 simultaneous audio streams to accompany Dual View video or multi-language,


  • New 2.0 clock mode, EQs and data scrambling for transmission robustness,
  • New improved CEC 2.0, HDCP 2.2 support, and expanded applications for DDC.

In this article we’ll focus on 2160p, touching on anamorphic, but coming back to explore audio some other day.

Emerging Trends – 4K TV Firmware upgrade to “HDMI 2.0”

The first key new feature of HDMI 2.0 out of the gate is the upgrade of 2160p (4K) to 60 frames per second within the existing defined HDMI bandwidth, where previously it was limited (under HDMI 1.4) to 30fps.  Both Sony and Panasonic have recently announced firmware updates for their existing 4K TVs to enable this feature, indicating that there is no new hardware (aka ‘speed’) required.  As an aside, they tend to tout this upgrade as “HDMI 2.0”, but that’s a non-compliant practice as it’s actually just one of a multitude of new features of HDMI 2.0 that they’re talking about.  What they really mean is that the firmware just adds newly defined support 2160p/60, 8-bit 4:2:0… assuming the existence of content.

So how is it possible to double the frame rate without doubling the bandwidth?  The answer lies in the ‘…8-bit 4:2:0’ reference; save on colour data, give back in frame rate.

Chroma subsampling and pixel data packing

Chroma subsampling is a process of compressing, or rather stripping out colour data to reduce file size &/or video transmission bandwidth load.  The premise is that the human eye is far less sensitive to colour than in is to brightness and grayscale, by a factor of 20, in fact.  As such, the amount of colour information in video can potentially be reduced without us really noticing… or that’s the plan.

The trick is to leave the resolution and gray scale untouched, which is why it’s only applicable to Component video (YCbCr) signalling, where the separate luminance (Y) channel can be left intact.  The most common chroma subsampling methodologies are 4:2:2 with half colour data when compared to 4:4:4 original, and then there’s 4:2:0 (as used with DVD & Blu-ray) with just one quarter of the original colour data.

The sampling commonly occurs over a 2×2 pixel array, where each pixel comprises a Luminance channel (Y) and two Chrominance channels (Cb & Cr).  Fig.1 below shows a simplified depiction of the uncompressed array before any subsampling, called 4:4:4.  Fig.2 shows how HDMI 1.4 (and prior) handles YCbCr, where everything from 8-bit 4:2:0 to 12-bit 4:2:2 produces precisely the same bandwidth at a constant 96 bits per array (same as 8-bit 4:4:4).  Fig.3 depicts 4:2:0 as it really should be, being how HDMI 2.0 handles it; with 8 bits of ‘Y’ per pixel, and just one of each 8-bit colour component Cb & Cr across the whole 2×2 array.

What they’ve done with HDMI 2.0 is recognise that 8-bit 4:2:0 natively nets 48 bits per sample array, and they’ve actually passed on the savings.  That is, they halve the bandwidth, which enables them to then double it again with frame rate.  Voila, 30fps goes to 60fps in the same bandwidth as before.  Note this is ONLY applicable to 8-bit 4:2:0.  This is not where HDMI 2.0 stops – there’s even better formats on the horizon.

HDMI 2.0 Need for speed

There are several formats of 2160p (4K) that are included in the HDMI 1.4 specification, all of which run at 8.91Gbps, the specification then capping out at 10.2Gbps.   HDMI 2.0 introduces some more at this legacy level, and several superior combinations at double this rate, being 17.82Gbps (rounded to 18Gbps, 6Gbps/ch).  This is well beyond the limits of HDMI 1.4, and defines the top end of HDMI 2.0.  The range above 10.2Gbps is referred to as “HDMI 2.0 mode”, whereby the TMDS Clock is slowed to 1/40th of the data rate to counter the effects of EMI at such high speeds.  Other techniques like data scrambling are also employed to improve stability.

HDMI 2.0 Cables

Right off the bat – THERE IS NO SUCH THING!  If anyone offers you so-called “HDMI 2.0 cables”, turn and run.  It will be either a marketing tactic, or expression of ignorance.  Either way it’s non-compliant.  When the HDMI 2.0 specification was first announced, it was accompanied by this statement;

“..Current High Speed cables (category 2 cables) are capable of carrying the increased bandwidth.”
– HDMI Licensing, LLC, Press Release, 4 Sep 2013

There is no new speed, no new cable.  Does it make sense that a cable rated to 10.2Gbps can then carry up to 18Gbps?  Logically no, but they have some tricks up their sleeve.  2.0 introduces a parametric-like new sink EQ system which supposed to make a 10.2Gbps tested cable perform up to 18Gbps.  It can’t however fully compensate for the collapsing effect of cable length, and will be expected to cap out at around 3m with a decent cable.  Beyond that, it’s all bets off and there is no new cable spec, speed or directive.  My prediction – HDMI cables will have to turn active, as some already have.

2.37:1 Cinemascope

Another fantastic feature of HDM I 2.0 is the ability for it to support different pixel aspect ratios, namely 4:3 (nothing to do with 4:3 TV, by the way).  Eg; a 1080p image is comprised of 1,920 pixels wide and 1,080 pixels high.  Every pixel is square, so content is fed to each pixel in 1:1 ratio.  The array of 1:1 pixels then determines overall image aspect ratio, being 1.78:1, or 16:9.

What HDMI 2.0 has introduced is the ability for content to be formatted using 4:3 pixel ratio.  Every pixel in a supporting display could potentially be fed 4:3 anamorphic content, even though the pixel is still 1:1 square.  In practice, a projector with a matching anamorphic lens will horizontally stretch the image by 1/3 (4:3).  The result is 2.37:1 picture aspect ratio (1.78/3)x4 = 2.37.

No more encoded black bars.  It means we can look forward to maximising image resolution for cinemascope 2.37:1 in a standardised format.


HDMI 2.0 brings many benefits and some exciting new features, paving the way for a level of AV immersion the likes of which we’ve never seen.  Yes it means new hardware, but that points to opportunity for the custom AV dealer/installer.  HDMI speeds are ever increasing, and that means more demand on quality infrastructure to ensure everything works as planned.

Imagine a premium 2160p/60 2.37:1 aspect home cinema projection system with brilliant 12-bit 4:2:2 colour and 10.2 audio system.  How about dual-view gaming with 2 players each experiencing their own full screen 1080p image on the same TV, with separate audio tracks being fed to their headphones?   Or to really make your head spin, imagine an IMAX Private Theater ™ with 30.2 channel 3D digital sound.  Phwoah!