Demystifying 4K UHD: What Does it All Mean?

Ultra High Definition is finally starting to take hold in the market with equipment prices that are beginning to drop into the price range for buyers of normal means and more content is starting to become available for everyone’s viewing enjoyment.  But what does the new technology entail and how does one navigate all the new specifications, acronyms, and jargon along with all the recycled, updated, and bastardized terminology from the previous generation of HDTV.  That is where Audioholics comes in to do some critical review to help you, the reader, sort through it all.

We will start our journey of discovery in this first article by initially attempting to identify both the wheat and chaff so that we can later separate them to establish what defines Ultra High Definition TV.  This will involve trying to determine standards and specifications used for UHD TV.  We will then move through definitions and explanations of some of the relevant technology and hardware performance in a subsequent article.  Finishing up, we will discuss what sorts of performance characteristics to look for in your own personal quest for UHD as well as how the consumer electronics and film industries work against the owners of slightly less recent gear that could still otherwise function in this new UHD environment and how one might go about defying this built in obsolescence in our final article.

Muddled Definitions, Partial Specifications, and Marketing BS

There is plenty of potential for confusion in the marketplace for UHD TV that is built upon the previous generation of confusion about HDTV.  This confusion is generated by liberally applied marketing jargon from manufacturers attempting to create brand distinction between one another for features that are otherwise functionally identical, a multitude of specifications and specification bodies, some of which feature optional specifications, and changing terminology for effectively the same performance characteristics.  All of this is further exacerbated by manufacturers who don’t provide standardized or complete technical information about their products, sometimes even using marketing jargon to obfuscate performance deficiencies, exaggerate the actual performance, or to suggest functionality that is not there, and retail sales workers that are confused themselves.  Taken all together, this makes it difficult for most consumers to navigate the growing plethora of new products and make informed buying choices.

There are numerous examples of these sources of confusion occurring over time that consumers have to wade through.  One such example caused by manufacturers, marketers, and retailers who made an effort when LED backlighting for LCD televisions were first introduced to refer to the new LED backlit LCD displays as LED TVs while continuing to refer to the older Cold Cathode Fluorescent (CCFL) backlit models as LCD TVs.  Both CCFL and LED are backlight technologies used for LCD displays, but the sales staff at your local Best Buy would argue that point with you with all of the flexibility of thought and understanding of a rock.  Elsewhere, they will likely just look at you funny and carry on as if you had not said anything.

Another example is HDMI where portions of the specification are optional, and up until recently, products were labeled by HDMI version number, but were not required to even list supported portions of the specification by the HDMI licensing body.  Let me be very clear about this: optional specifications are not specifications and referring to them as such is inherently an oxymoron, with emphasis on the moronic.  Further, with the increasing bandwidth of each version of the HDMI specification, the qualitative descriptions of High Speed and Standard HDMI cables have been sliding with the specifications.  The good news for cables is that you can use any cable that can transmit a picture with equipment of any HDMI version number: either the cable works, or it does not, and only have to replace the cable if needed.  The bad news is with the equipment where you often have to have the matching standards.  Even if the device is built such that it could support the signal processing involved, provide the necessary bandwidth, or if functionality is renamed and/or regrouped in a subsequent specification, an older feature treated as a new feature, the device will not work because everything is digital and the devices can be programed with which features they are allowed to support.

The Blu-ray specification is yet another example.  Between being released before it was completed to compete with the now defunct HD-DVD standard, and rolling out the parts that did not make the original standard piecemeal using a band aid referred to as profiles, it also allows partial compliance.  Features such as audio codecs, secondary decoders, internet connectivity, built in local storage, and even compatibility with preceding formats, such as DVD and CD, were all optional.  The absence of many of these optional features became the bane of early adopters who found that not only would their expensive players be unable to support all the features later available on cheaper players, but that they eventually would be unable to play the latest movies when they were no longer being updated by manufacturers with the latest Hollywood mandated copy protection revisions.  AV gear that was released in the earliest days of Blu-ray supported uncompressed LPCM audio decoding as the only mandatory high resolution audio encoding available.  What some still do not realize is that the optional Dolby TrueHD and DTS Master Audio codecs that arrived on later AV gear are just a lossless compression of LPCM encoding which is always included on every Blu-ray.  With the Blu-ray specification, even backwards compatibility with CD and DVD playback is optional, but is usually supported.

The latest example is, of course, 4K TV which is now also being called Ultra High Definition (UHD) TV.

The Easy Part: The Resolution

In defining what exactly is 4K/UHD, this is the easy part: at 3840 x 2160 pixels, 4K Ultra High Definition provides a picture with twice as many pixels, both horizontally and vertically, of what has come to be called Full HD (FHD) at 1920 x 1080 pixels, which is also known as 1080p.  This means the picture has four times the overall resolution of FHD with more than 8.29 mega pixels to approximately 2.07 mega pixels and an enormous jump over traditional 480i SDTV with a mere 0.307 mega pixels, only half of which are actually lit up on any given frame thanks to interlacing.

From here, it gets a bit more murky.

The Less Easy Part: The Resolution, and Some Other Stuff Thrown In

The latest form for the type of confusion discussed above is with ultra-high definition television which has been called many things in the marketing and product literature: 4K TV, 4K HDTV, Ultra HD, UHD, 4K UHD, UHD TV, UHD Premium, etcetera.  Initially, the most prominent terminology was to call the increased resolution 4K followed by TV or HDTV.

So why 4K rather than 2160p, which most consumers are familiar with and can related to at this point in time?

Apparently, in search of hyped up ways to describe the improved resolution, the marketing types initially seemed to latch onto 4K cinema.  But, while both 4K cinema and UHD TV both happen to have 2160 vertical pixels, not being technical, the marketers apparently were unaware that 4K HDTV does not actually have 4000 pixels in the other direction, the one responsible for the 4K nomenclature.

The difference here is that cinema presentations and HDTVs are not at the same aspect ratio, so the resolutions are inherently different.  Cinema 4K resolution is 4096 x 2160 pixels, an aspect ratio of about 1.89:1 while a 4K HDTV is at a resolution of 3840 x 2160 pixels, which is 1.78:1, commonly referred to as 16:9, and obviously does not actually have 4000 (i.e. 4K) pixels in the horizontal direction.   Added to this confusion is the fact that the 4K specified screen dimensions in UHD switches from vertical lines of resolution, like 720p and 1080i/p HDTV or the traditional 480i SDTV, to horizontal lines of resolution.  At least the now superfluous p has been dropped because there is no more i in the current video standards as there is only 2160p in 4K.

As of late, the various manufacturers associations seems to have settled on Ultra HD or UHD although the 4K moniker has been retained in some form or another in the marketing of many products by individual manufacturers.  Now that High Dynamic Range (HDR) is being thrown into the mix mid cycle, so to speak, you will find all of the above variations on UHD Premium, the name now intended to separate HDR capable TVs from those not capable of HDR playback, which is also not followed by marketing from various manufacturers in any consistent sort of way.  HDR also has nothing to do with 4K TV resolution, it is simply that 4K is the latest commonly available resolution that happened to coincide with the introduction of HDR.  There is no reason one could not have a HDR 1080p FHDTV, or even a HDR 480i SDTV, other than no one is currently making them, although that could change with current bandwidth limits on broadcast TV, digital encoding, and some of the specifications floating around, as discussed below.  One should also keep in mind that the definition of UHD also includes the forthcoming 8K resolution, meaning that UHD as defined can run the gamut of 1080p (i.e. 2K) to 8K resolution as long varying amounts of HDR are thrown into the mix.

Speaking of HDR, this acronym is its own muddle of rearranged definitions that covers more than just dynamic range.  In addition to setting limits for the minimum range for the brightness and darkness of screen output, i.e. dynamic range, competing standards, HDR10 and Dolby Vision, based on the STMPE Perceptual Quatizer (PQ) transfer function, also include increased color bit depth and Wide Color Gamut (WCG), both of which are an optional part of some of the base UHD TV specifications; again, more on that below.

Editorial Note: Deep Color & Extended Gamut

Back in the day, Deep Color and Extended Gamut YCC, also known as xvYCC as well as by Sony’s proprietary name for the format, x.v.Color, were once the terms de Jour.  Deep Color specified an increase in color bit depth from the standard 8 bits per color to either 10 or 12 bits.  This is now included in HDR10 at 10 bits or Dolby Vision at 12 bits.  While not exactly the same color space as that used in xvYCC, HDR10 and Dolby Vision specify the Rec. 2020 color space, all of which are improvements on the older Rec 709 color space that was constrained by the limitations of CRT RGB saturation, which interestingly, current TVs cannot meet.  More on that below as well.  With xvYCC now apparently abandoned, the extra color gamut available in an older xvYCC compatible devices will not be of any benefit with sources following the newer standards.

To add in just a bit more confusion, a third HDR standard is floating around called Hybrid Log Gamma (HLG) that was developed by the BBC.  HLG makes use of a modified Gamma Curve developed from the standard Gamma Curve used by most, if not all, current video display devices.  This makes UHD content encoded with HLG backwards compatible with commonplace SDR equipment and content, but is not yet common place itself.

Standards and Standards Bodies Galore

So how did we get to this semantic quagmire?

Standards bodies seem to be a dime a dozen in consumer electronics.  Consumer Technology Association, the UHD Alliance/Ultra HD Forum, DigitalEurope, and God knows how many others.  It seems as soon as one group tries to decide on and set some sort of standards, another group comes along that thinks that they can come up with something better.  Usually, they cannot, it is just different, and likely incompatible; sometimes deliberately.  And when not going defunct or rearranging themselves into new forms, these organizations also seem to like to change their names periodically for some reason just to keep consumers guessing.

Myriad consumer electronics organizations and standards bodies exist all over the world, and all are pushing their own standards, many of which are at least partially overlapping in actual functionality if not implementation, and worse still is when several separate standards bodies join Voltron like into a giant meta standards body to publish standards of standards.  Television broadcast standards, television manufacturer standards, digital cinema standards, video recording standards, video playback standards, digital encoding/decoding standards, international standards, regional standards, open standards, proprietary standards… the list goes on and on.

Let’s just say that, worldwide, consumer electronics standards are a cluster…

Broadcast TV has historically had a hand in some of this mess.  Around the world, numerous broadcast standards were developed independently over time which drive the basic design of TVs in their respective regions that are then layered with the requirements of both the current standards and compatibility with legacy standards.  So even if current standards do somewhat converge, the legacy requirements keep the underlying variation in play.

In North America, digital television broadcasting conforms to the Advanced Television Standards Committee (ATSC), based largely on recommendations from the International Telecommunications Union (ITU), but is still confined by legacy analog broadcast standards requirements of the National Television Standards Committee (NTSC).  In Europe, the European Telecommunications Standards Institute (ETSI), the European Broadcasting Union (EBU), formerly the International Broadcasting Union (IBU), and the European Committee for Electromechanical Standardization (CENELEC) all morphed together into the Digital Video Broadcasting (DVB) standards that still have to make do with the detritus of all of the legacy analog broadcasting standards such as Phased Alternating Line (PAL) and Sequential Color with Memory (SECAM, acronym  derived from the original French).  Then there are the Integrated Services Digital Broadcasting (ISDB) standard in Japan, the Digital Terrestrial Multimedia Broadcast (DTMB) standard in China, just to name a few, along with each of their legacies.

To be fair, some of the differences in broadcast standards were driven by outside factors.  Different screen refresh rates between North America at ratios of 30/60 Hz and Europe at ratios of 25/50 Hz were driven by local AC power generation at those corresponding frequencies.  Other differences have come about from the independent development of technologies inevitably exacerbated by a lack of communication, particularly in the past, local preference, national pride, and good old corporate desire of control for profit.

Piled on top of all of this are the additional standards from other industries such as movie production and cinema projection required to actually get content onto a TV.  This means an infusion or overlap with other standards to comply with motion picture production, such as the Society of Motion Picture and Television Engineers (SMPTE) and the Digital Cinema Initiative (DCI) specifications.

In more recent times, many newer standards accumulating in the actual video products making their way into consumer’s homes have at least been somewhat unified by recommendations from the International Telecommunications Union, a UN body responsible for worldwide coordination of information and communication technologies including global use of shared electromagnetic radio spectrum, communication satellite orbits, and communications infrastructure which develops and promotes corresponding technical standards.  ITU membership is open to UN member states as well as private corporations such as telecom carriers, regional telecommunications agencies, and research organizations who act as nonvoting members.

Documents from organizations like the ITU can be thought of along the lines of worldwide model codes that, in turn, are followed and adapted to differing extents by other organizations closer to the actual product manufacturing or content production along with the necessary recording, broadcasting, and reproduction devices.  It is at this level that new organizations spring up every time there is a change in technology, in an attempt to usurp the previous standards group, usually in an effort to control licensing fees.

Case in point would be the Consumer Technology Association (CTA), formerly the Consumer Electronics Association (CEA), which originally was an independent branch of the Electronics Industries Alliance (EIA), an American National Standards Institute (ANSI) accredited standards body that dates back to the 1920’s that seems to now be in competition with the more recent UHD Alliance/Ultra HD Forum that sprung up in 2015.  Both are now decreeing standards for UHD TV in the United States that are fairly similar based on ITU recommendations, but for some reason, someone felt we needed another organization, apparently one that does not have roots directly in communications infrastructure engineering.

Editorial Note: History of Standards

The EIA has a long history of producing legally recognized standards that have been used in the electronics and communications industries for decades, many of which are American National Standards Institute (ANSI) recognized documents.  From power distribution infrastructure to broadcast and cellular telephone infrastructure to electronic and microelectronic components, the various branches to the EIA, such as the TIA, ECA, and JEDEC, have been active in setting technology standards.  While the EIA as an overall organization ceased operations in 2011, the various sections still exist to support their particular industries.

The significance of ANSI accreditation is that it was founded as an interdisciplinary standards body in 1918 by five professional engineering societies: the Institute of Electrical and Electronics Engineers (IEEE), the American Society of Mechanical Engineers (ASME), the American Society of Civil Engineers (ASCE), the American Institute of Mining, Metallurgical, and Petroleum Engineers (AIME), and the American Society of Testing and Materials (ASTM).  Many of these societies produce model codes and standards that have been incorporated into law as manufacturing, production, and building codes.

Unfortunately, this model of standards producing bodies does not seem to hold sway in consumer electronics.  Standards do not come from professional organizations formed by independent engineers and academics with joint input from manufacturers to solve problems, they come from organizations formed by corporations to control profits.  The altruism of solving common problems in the name of progress is supplanted by the desire for licensing fees as frequently, the majority of engineers involved are employed by those corporations and likely operate under pressure to represent corporate interests over their profession as a whole.

This fundamental difference can be seen in the standards produced by ANSI and other legally recognized and accredited bodies which may cost money to obtain copies of the actual standards, but there is no money grab to make users of the standards pay for what they create based upon said standards.  If such were the case, most of the infrastructure and facilities that we depend on in our daily lives, including our homes, would likely cost much more than they do now to cover those additional licensing fees and they would be an absolute mess of incompatibility and cost to either maintain or improve over the usable service life for these types of projects.

On the other hand, the CTA does not seem to really be following this more engineering orientated model, if it ever did, and of late, it does not even seem to be able to muster a comprehensive set of recommendations for the future of UHD but it is offering licensing.  The CTA, which claims to represent over 2200 member companies, initially developed a somewhat limited set of recommendations for UHD TV in 2012 with some subsequent extensions, only to be upstaged by the recently formed, initially several dozen member strong Ultra HD Forum, many of whom likely overlap with CTA membership, that seems to have taken the lead with more substantial requirements.

To make matters more confusing about who exactly is in charge, the Ultra HD Forum seems to also have a parallel, complimentary organization called the UHD Alliance with many of the same members.  The arrangement seems to be something along the lines of the Forum setting standards, particularly for video production and distribution, and the Alliance maintaining consumer marketing logos, product certification, and such, along with collecting the licensing fees, to produce TV sets capable of displaying Forum specification content.  The UHD Alliance is behind the UHD Premium branding per the Ultra HD Forum specifications, which mostly separates HDR from non-HDR capable consumer UHD video equipment via this specification.  Why two separate but apparently intertwined groups are required to do this is anyone’s guess.  Maybe it is to pretend that the standards portion is somehow independent of the money grabbing portion.

The Ultra HD Forum states that its purpose is to assist in solving real world deployment issues of UHD video including HDR, HFR, WCG video, and next generations object based audio.  Seems that could have been covered with some sort of existing group to which the members of the newly formed group likely already belong.  But hey, what’s one more organization added to the mix?

In the meantime, the CTA has taken a yea, what they said stance, rather than updating their own standards, by announcing that they agree with and share the goals, along with a few member companies, of the UHD Alliance and its new UHD Premium standard shortly after it was announced.  Or maybe it was the Ultra HD Forum?  UHD Forum?  Ultra HD Alliance?  One of those.

Furthering their push for legitimacy in their specifications, the UHD Alliance/Ultra HD Forum is actually requiring independent testing to receive certification for meeting their standards and to be able to use their logos on products.  Seems that should have already been happening with some specification somewhere all along, but apparently wasn’t.

4K UHD: What Does it All Mean? p2

Definitions and Guidelines for UHD: CTA (CEA) vs. Ultra HD Forum/UHD Alliance

The original CEA announcement in October of 2012 by the 4K Working Group defined Ultra HD TV as displays with the following characteristics:

• At least 8 million pixels at 3840 pixels wide by 2160 pixels tall.
• An aspect ratio of at least 16:9 or wider, length to width.
• At least one input capable of displaying native 4K video without upscaling.

The remaining components necessary to the specifications such as color space (ITU-R Rec. 709), bit depth (8 bit) , and ATSC broadcast tuning would remain as they had with HDTV.

The CTA’s UHD requirements have since been updated several times to accommodate subsequent developments in available technology.  These updates have brought requirements for 4K upscaling by TVs in addition to the one input capable of native UHD resolution, High Frame Rate (HFR) up to 60 Hz, and HDCP 2.2 compatibility.  The updates also provide an allowance, but not a requirement, for WCG spaces greater than Rec. 709, additional bit depth, and the inclusion of HDR in the form of HDR10 per CTA and STMPE standards.  But remember that optional standards are not really standards, kind of by definition.

The newer Ultra HD Forum, an organization with a stated mission to further UHD deployment, seems to have taken their UHD definitions a step or two further.  They even have phases, but at present, only one phase, A, is in effect.  They are still working on B, as are those still working to develop the requisite technology.

Phase A UHD Recommendations:

The Ultra HD Forum’s current recommendations are at version 1.5, published in September of 2018, and include the following:

• Display resolutions greater than or equal to 1080 and less than or equal to 2160p.
• HFR up to 50/60 Hz with integer frame rates preferred.
• Display bit depth of at least 10 bit.
• High Efficiency Video Coding (HVEC) decoding capability.
• WCG greater than Rec. 709 with colorimetry based on Rec. 2020 with conversion from Rec. 709.
• HDR light output range of at least 13 f-stops supporting SMPTE ST 2084 Perceptual Quantizer (PQ10)/HDR10 or BBC Hybrid Log Gamma (HLG10).
• One of two HDR brightness standards: 1000 nits peak brightness, 0.05 nits minimum brightness or 540 nits peak brightness, and 0.0005 nits minimum brightness, with the difference presumably to accommodate differences in LED and OLED light output capabilities.
• Implementation of immersive audio such as Dolby Atmos in addition to legacy stereo and multi-channel (AC-3) 5.1 sound.
• Support for live and prerecorded video production combing HDR and SDR along with conversion between Rec. 709 and Rec. 2020 color spaces and conversion between different HDR formats.
• Recommendation to recognize 1080p resolution content with WCG and HDR to be UDH TV.

Makes the CTA UHD requirements seem a bit sparse, but they at least stick to 4K resolutions in their UHD.  It is the Ultra HD Forum specifications where UHD gets decoupled from a purely screen resolution definition and good old 1080p gets grouped into UHD as long as it supports HDR.  This does provide some justification for manufactures to keep the 4K branding on their UHD sets that the Forum is trying to discourage.

But the truth be told, even the guys coming up with the definitions and specifications don’t seem to have all of their terminology and facts straight.

There is a potential internal contradiction in the UHD Phase A specification which seems to require HDR to be considered UHD but then later says that SDR is acceptable for Phase A.  This contradiction occurs according to section 4.1, page 17/89, where it says pretty clearly that to be considered UHD that HDR is required, but then a couple of pages later it seems to say SDR is included in Phase A per Table 3, page 18/89.  See the circle there?  Along with some talk about HDR 1080p being UHD in the footnotes, it seems Ultra High Definition does not require higher definition than Full High Definition 1080p as long as the colors are richer and the screen brighter.

In another apparent bit of confusion, this time about color spaces, the Ultra HD Forum actually does not require full Rec. 2020 color space performance to satisfy Phase A requirements.  When reading through the numerous articles on UHD, a significant number of the third party commentary that I have seen seems to be taken in by the idea that the Rec. 2020 color gamut is what is being provided by TV manufacturers when claiming UHD Premium.  In reality they are not, nor are they required to.

From the Ultra HD Forum Guidelines, version 1.3:

6.1 HDR/WCG Technologies

There  are many terms  in  use  in  the  field  of  HDR  television.  This  section  explains  the  existing terminology and how terms are used in these Guidelines.

Note that currently some UHD displays are capable of accepting BT.2020 [4] content, but as of this publication, no direct view display is available that is capable of rendering the full gamut of colors in the BT.2020 [4] color space.  It is assumed that in these cases, the device employs “best effort” gamut mapping tailored to its particular display characteristics, and thus these devices are considered BT.2020 [4]-compatible.

Color space and gamut are related, overlapping concepts, but they are not fully synonymous in a very subtle way.  In practice, using the Rec. 2020 color space really means fitting the available gamut inside the primaries from the Rec. 2020 color space, it does not mean that the full available gamut from that space can be reproduced.  This is also tacitly acknowledged in several other sections such as:

6.2.1.2 Imaging Devices: Resolution, Dynamic Range and Spectral Characteristics

In the area of color space and spectral characteristics, the more advanced sensing devices will exhibit characteristics approaching the color gamut of BT.2020 [4], while more typical devices will produce acceptable color performance approximating the DCI-P3 gamut or just beyond the gamut of BT.709 [3].

6.2.2 Reference Monitor

For UHD Phase A, a reference monitor can ideally render at least the following: resolutions up to 3840x2160, frame rates up to 60p, BT.2020 [4] color space (ideally at least the P3 gamut), and HDR (i.e., greater than or equal to the contrast ratio that could be derived from 13 f-stops of dynamic range).

9.3.1 Bit Depths (under Table 14, Existing Practices for Real-Time Program Service Distribution Formats)

In Cases 3 and 4, SMPTE ST 2086 can be used to signal Peak White. It should also be noted that in Cases 3 and 4, the color gamut can be up to BT.2020 color primaries; however, in current practice the gamut does not exceed DCI P3 primaries.

Actually, UHD Premium branded TVs are only required to display 90% of the much smaller DCI-P3 color space, which happens to fit inside the Rec. 2020 color space.  This is because the best current UHD TVs cannot display full Rec. 2020 colors, but it is better for marketing to keep citing the more impressive Rec. 2020 in the specifications.  More on that to come.

The Future: Phase B Recommendations:

Phase B is presently in flux with many of the technologies need still in development, but consists, at present, of a list of candidate technologies expected to launch in 2018 and later including:

• Implementation of UHD 8K resolution.
• Increased HFR exceeding Phase A 50/60 Hz.
• Increased color bit depth to 12 bits.
• ICtCp color space per Rec. 2100.
• Color remapping information (CRI)
• Scalable coding of spatial, temporal, color gamut, dynamic range information.
• Dynamic metadata for HDR with per scene metadata coding per STMPE 2094 in addition to HDR single layer (HDR10) and HDR dual layer (Dolby Vision).
• Next generation object based audio codecs including Dolby AC-4, DTS:X, and MPEG-H.

Phase B is made up of technologies that are not yet practical enough to deploy, but are on the horizon.  The goal is to have single program streams that are backwards compatible based on scalable video coding that embeds multiple resolutions, 1080p/2K, 2160p/4K, and 4320p/8K at different frame rates, color encoding, i.e. Rec. 709 and 2020, and mixed SDR and HDR content all with shiny new audio codecs.

For those paying attention, Phase B will include Dynamic High Dynamic Range, DHDR.  Using the associative property, this becomes: DHDR = HDDR = HD^2R, which just has to be better because they have Dynamic to the second power in the name, right?  Who comes up with these crap naming schemes anyways?  Oh, that’s right... the marketing guys.

UHDTV Specifications

So now that we have discussed several versions of UHD guidelines from the various manufacturer’s organizations that produce them, we are onto the actual technical standards to which the guidelines refer.

Keep in mind that this list is in no way comprehensive as I am quite sure there are more standards lurking about.  I have, however, included links to the actual documents where they are available for viewing or download, if one is so inclined.

Warning: a significant number of acronyms to follow.

International Telecommunications Union

The ITU is broken into three sectors responsible for different areas of overall ITU responsibility.  The Radiocommunication division, known as the ITU-R, handles broadcast spectrum communications and satellite orbital resources.  The Standardization division, ITU-T handles all non-broadcast telecommunications.  The third section, Development, ITU-D, promotes development and access to communications technologies.
Standards developed by the ITU for UHD TV span across the ITU-R and ITU-T and are developed jointly with several other standards bodies.

ITU-R Approved Standards

Standards for TV themselves have traditionally fallen under the ITU-R as originally, before the advent of home video cassettes and subsequent developments in home video, TV was principally a broadcast medium.

• Rec. ITU-R BT.1201-1 (2008) Extremely High Resolution Imagery
• Rec. ITU-R BT.1769-0 (2008) Parameter values for an expanded hierarchy of LSDI image formats for production and international programme exchange (Withdrawn)
• Rec. ITU-R BT.2020-2 (2015) Parameter values for ultra-high definition television systems for production and international programme exchange
• Rec. ITU-R BT.2035-0 (2013) A reference viewing environment for evaluation of HDTV program material or completed programmes
• Rec. ITU-R BS.2051-0 (2014) Advanced sound system for programme production
• Rec. ITU-R BT.2100-0 (2016) Image parameter values for high dynamic range television for use in production and international programme exchange
• Report ITU-R BT.2390-2 (2017) High Dynamic range television for production and international programme exchange

Other ITU-R Reports and In Progress

• Report ITU-R BT.2246-3 (2014) The present state of ultra-high definition television
• Draft new Report ITU-R BT.[UHDTV-DTT TRIALS] Collection of field trials of UHDTV over DTT networks

ITU-T Standards

Standards produced by the ITU-T that relate to UHD TV have been in video encoding schemes through the Video Coding Experts Group (VCEG, ITU-T Q.6/SG 16) in conjunction with the International Standards Organization (ISO) Moving Pictures Experts Group (MPEG, ISO/IEC JTC 1/SC 29/WG 11).  The combined efforts of the two organizations has resulted in the H.26x series of video encoding standards.

Standards developed by the  ITU-T VCEG and ISO/IEC JTC1 MPEG used in support of UHD TV concern video encoding and include:

• H.264/MPEG-4 AVC (v4, 2016) Advanced Video Coding
• H.265/MPEG-H HEVC (v11, 2016) High Efficiency Video Coding

You may recall H.264 from the early days of HDTV, but it has now been supplanted by the newer H.265, also known as MPEG-H.  The MPEG-H standard is actually more comprehensive than the portion listed above, which relates specifically to video.  Known as ISO/IEC 230008 – High efficiency coding and media delivery in heterogeneous environments is broken into a number of parts representing different aspects of digital content delivery:

• Part 1: MPEG Media Transport (MMT) - a network adaptable media streaming format.
• Part 2: High Efficiency Video Coding – a data compression standard that doubles the compression performance of the previous standard, MPEG-4, and support up to 8192 x 4320 (8K) resolutions that is jointly developed with the ITU-T VCEG.
• Part 3: 3D Audio – an audio compression standard supporting 3D multichannel audio.
• Parts 4-6: Reference software corresponding to parts 1-3.
• Parts 7-9: Conformance testing standards corresponding to parts 1-3.
• Part 10: MMT FEC Coding.
• Part 11: MMT Composition Coding.
• Part 12: High Efficiency Image File Format developed from the ISO base media file format.
• Part 13:  MMT Implementation Guidelines.

As can be seen above, the full standard describes encoding/decoding for both video and audio along with defining a transmission medium, implementation guidelines, reference software, and a conformance testing regimen.

In theory, H.265 has a 2:1 compression ratio advantage over the older H.264 for the supposed same picture quality.  In practice, that is likely to be somewhat less when used with real world video content and not theoretical calculations and idealized test files.  Regardless, it is a significant jump.

Standardization in SMPTE

The Society of Motion Picture and Television Engineers (SMPTE) produces standards and engineering guidance for motion imaging including the obvious film and television production industries, as well as in digital cinema, audio recording, information technologies, and even medical imaging.  These standards include film and broadcast formats, storage media, physical transmission interfaces, video test patterns, and data exchange formats.  The pertinent contributions related to UHD TV include:

• ST 2036-1:2014 - Ultra High Definition Television — Image Parameter Values for Program Production

• ST 2036-2-2008 - Ultra High Definition Television1 — Audio Characteristics and Audio Channel Mapping for Program Production

• ST 2036-3:2015 - Ultra High Definition Television — Mapping into Single-link or Multi-link 10 Gb/s Serial Signal/Data Interface

• ST 2036-4:2015 - Ultra High Definition Television — Multi-link 10 Gb/s Signal/Data Interface Using 12-Bit Width Container

• ST 2084:2014 - Dynamic Range Electro-Optical Transfer Function of Mastering Reference Displays

• ST 2086:2014 - SMPTE Standard - Mastering Display Color Volume Metadata Supporting High Luminance and Wide Color Gamut Images

• OV 2094-0:2017 -  SMPTE Overview Document - Dynamic Metadata for Color Volume Transformation — Overview for the SMPTE ST 2094 Document Suite

• RP 431-2:2011 - SMPTE Recommended Practice - D-Cinema Quality — Reference Projector and Environment

Note that the links are not to the actual documents, as is the case in some of the other sections, as STMPE is looking for some cash to allow you to see these.

The last item included describes the characteristics of the reference digital projector, which plays into the next section, the Digital Cinema Initiative specifications and is a limiting metric on colorimetry for cinema and, incidentally, the Ultra HD Forum.

4K UHD: What Does it All Mean? p3

Other Standards: Digital Cinema Specification

Another set of standards that is mentioned in discussions of UHD TV, which have some bearing, are those of the Digital Cinema Initiative, a group formed by the major Hollywood movie studios to define standards for digital cinema to insure interoperability and consistency among studios, distributors, exhibitors, and digital cinema equipment manufacturers and vendors.  The first efforts resulted in the 2005 Digital Cinema Specification (DCI), a guide to producing the Digital Cinema Package (DCP) from files known as the Digital Cinema Distribution Master (DCDM), and how the DCP is to be decoded and presented in theaters.

The DCI does not create technical standards directly, but establishes specifications for which standards will be followed by the movie production chain in addition to setting requirements for the presentation of films and the theater environment as well as content protection.  DCI specifications typically refer to technical standards that are drawn from sources including SMPTE and ISO.  The current version of the specification is in several parts:

• Digital Cinema System Specification Version 1.3 with Errata as of 27 June 2018
• Digital Cinema Object-Based Audio Addendum, dated September 9, 2013
• DCI Stereoscopic Digital Cinema Addendum, Version 1.0, dated July 11, 2007

In addition to specifying ambient light levels and projection luminosity in the theater environment, the DCI specifies technical details for the film imagery and audio in terms of pixels, aspect ratio, frame rates, audio channels, bit depth, sample rates, as well as compression requirements and total data rates:

2D Imagery

• 2048x1080 (2K) total pixel image at 24 or 48 frames/second in two aspect ratios:

      CinemaScope (2.39:1) at 2048x858 pixels used

      Masked/Flat (1.85:1) at 1998x1080 pixels used

• 4096x2160 (4K) total pixel image at 24 frames/second

      CinemaScope (2.39:1) at 4096x1716 pixels used

      Masked/Flat (1.85:1) at 3996x2160 pixels used

• 12 bit color required for all formats except 2K at 48 frames/second at 10 bits

• International Commission on Illumination (CIE) CIE XYZ color space

• JPEG2000 image compression with wavelet decompositions of either 0-5 at 2K or 1-6 at 4K

Stereoscopic 3D Imagery

• 2048x1080 (2K) total pixel image at 24 or 48 frames/second in two aspect ratios:

      CinemaScope (2.39:1) at 2048x858 pixels used
      Masked/Flat (1.85:1) at 1998x1080 pixels used

• 10 bit per color chroma subsampled to 4:2:2 with a separate stream for each eye

High Frame Rate

• Recommended practice for HFR imagery

      2D 2K resolution at 60, 72, 96, and 120 frames per second
      2D 4K resolution at 48 and 60 frames per second
      3D 2K resolution at 48 and 60 frames per second

• Maximum compressed bit rate of 500 Mbits/second

Audio

• WAV container for uncompressed PCM audio
  
• 24 bits/sample at 48 and 96 kHz
• Up to 16 discrete channels

Details of the ITU-R Recommendations

There are several of the above listed documents from the ITU-R that are frequently brought up in discussions and marketing around UHD TV.  One of the most commonly mentioned is Rec. 2020, and more recently, Rec. 2100, both of which are referred to against the previous standard for HDTV, Rec. 709.  We will, of course, talk about the latter first to give context to the newer UHD standards.

The ITU recommendations get deep into the technical weeds in specifying not just display resolution and aspect ratios, but colorimetry RBG points, reference white, signal format transfer functions, and quantization of luminance levels to relate to bit values at different bit rates.  If such is your cup of tea, the links to the actual documents are included in the ITU section above.

ITU-R Rec. 709

Rec. 709 (BT.709) is an ITU standard dating back to 1990 that defines the basis used for HDTV:

• Displays with roughly 2 million pixels and a 16:9 aspect ratio, including the current 1080i and 1080p standards, as well as several defunct vertical resolutions that did not use square pixels.
• Frame rates 24, 25, 30, 50, 60 Hz and fractional rates at a ratio of 1.001, leading to 23.976, 29.97, 59.94 Hz fractional frame rates consistent with legacy analog televisions broadcast standards such as NTSC and its digital replacement, ATSC.
• Interlaced or progressive image capture and transport, with requirements that progressive images sent over segmented interlaced transport be sent at twice the captured frame rate.
• Color encoding at 8 and 10 bit depth and a color space the encompasses 35.9% of the visible spectrum.

ATSC digital broadcasting standards largely conform with Rec. 709 as does the original Blu-ray Disc specifications.  The Rec. 709 standard comes from a time when the picture tube was king and reflects many of the limits of that technology.  The more recent Rec. 2020 moves to take advantage of newer display technologies that do not have the constraints of CRT.

ITU-R Rec. 2020

Rec. 2020, introduced in 2012, is the ITU standard that defines the basis of UHD televisions.

• Two square pixel resolutions specified at 3840 x 2160 pixels (4K) and 7680 x 4320 (8K) pixels, both at a 16:9 aspect ratio.
• Frame rates of 24, 25, 30, 50, 60, 100, and 120 Hz with fractional rates at 1.001.
• Progressive scan frame rates only, no interlaced frame rates.
• Color encoding at 10 and 12 bit depth and a color gamut encompassing 75.8% of the light spectrum visible to the human eye.

For comparison, note that a digital cinema reference camera based on the DCI-P3 color space, as published in the SMPTE 431-2 and 432-1, only covers 45.5% of the visible spectrum per the CIE 1931 XY Chromacity Diagram.  So while all that color gamut sounds nice, just remember that all those movies you will be watching on that TV will still be constrained by the limits of their DCI compliant source material.  Also, while all the UHD TV manufacturers are still trying to upstage each other about which display type produces the greatest amount of the specified color gamut,  we have to remember that they are talking about the DCI-P3 gamut and that most current TVs still mostly display less than 100% of that except for the latest high end TVs.  Remember, UHD Premium only requires 90% of the DCI-P3 color space and 90% of 45.5% of the visible spectrum is not anywhere near 75.8% of the visible spectrum per Rec. 2020.

But invoking the Rec. 2020 color space sure does sound more impressive in the marketing.  The operative word used here is that UHD premium sets have to be compatible with the Rec. 2020 color space.  Think of it akin to the UHD Premium TV set being able to down convert wider color source content when it becomes available to match the TVs actual capability.

The reality here is a bit of a subtle trick: the manufacturers keep saying Rec. 2020 color space, but they say DCI-P3 color gamut.  This means that the DCI-P3 represents the upper bound color gamut that can be reproduced, just within the Rec. 2020 color space, which the DCI-P3 does fit completely within.  The difference is less color in a bigger space defined by different vertices and white point between the two standards.

ITU-R Rec. 2100

Rec. 2100 figures into the new UHD Premium moniker being fielded by the Ultra HD Forum and it defines the parameters of HDR television images using two methods, Picture Quantization (PQ) and Hybrid Log Gamma (HLG).  Specifics on PQ and HLG can be found in the aforementioned ITU-R 2390 Report.  Both of these methods rely on nonlinear transfer functions defined in the standard to allow for greater picture detail at lighting extremes, but PQ, which includes both HDR10 and Dolby Vision, break compatibility with SDR TV while HLG allows SDR and HDR imagery to coexist in the same broadcast and to be displayed on traditional SDR displays, albeit with HDR as SDR.  PQ basically uses an additional metadata signal along with the picture that sets specific values for brightness while HLG is an extension of the standard gamma curve that allows for greater levels of brightness differentiation when a display is capable of such.

• Resolution, frame rates, colorimetry, and color bit depth encoding as in Rec. 2020.
• Peak display luminance of 1000 cd/m2, over a small area, but not of the full display.
• Minimum display luminance of 0.005 cd/m2.
• Parameters for the reference viewing environment such as ambient lighting and distance.
• Nonlinear electro-optical/opto-electrical transfer functions for PQ and HLG.
• Signaling schemes and color subsampling for those schemes.
• Integer and floating point representation settings for 10 and 12 bit color depths.

The recommendation does make note that the each of the two systems to capture and present HDR video content have different advantages.  PQ is noted to be finely tuned to human visual acuity while HLG maintains a degree of backwards compatibility with legacy content and displays.  The recommendation also provides guidance on converting between the two formats in an annex (appendix) at the end of the document.

Sources for UHD Video

Ultra HD Blu-ray

First introduced in September of 2014 by the Blu-ray Disc Association, Ultra HD Blu-ray is the successor to the Blu-ray.  With the highest available bit rates, Ultra HD Blu-ray is your best bet for the highest quality 4K picture and immersive lossless audio currently available.

• 4K 3840 x 2160 luminance resolution at 23.97p, 24p, 25p, 50p, 59.94p, 60p
• Chroma subsampling 4:2:0, half 4K color resolution
• 10 bit color and Rec. 2020 color space
• Mandatory HDR support for HDR10
• Optional support for Dolby Vision HDR
• HVEC encoding
• Three disk storage sizes with corresponding data rates:

•       50 GB at 82 Mbit/s
•       66 GB at 108 Mbit/s
•       100 GB at 128 Mbit/s

• No region coding
• No 3D support
• Mandatory HDCP 2.2
• Dolby Atmos/DTS:X multichannel audio

Region coding is gone, 3D is gone, so some definite improvements, but support for the highest performing specifications requires HDMI 2.0/HDCP 2.2 for the 60 Hz frame rate and HDMI 2.0a for HDR support.  But also remember that most of the content available is movie based and will be a 24 Hz so HDMI 1.4 is adequate and technically will have enough bandwidth available to allow the necessary metadata stream to support HDR, although it is likely that this will not be allowed and disabled by the manufacturers of the players.

Broadcast TV Standards

Broadcast TV is likely limited to FHD picture resolution and frame rates at best for the time being due to physical limitations of the broadcast standards currently in use around the world.  The ITU-R BT.2246-3 (2014) report discusses the current limits on the amount of data transmission that can be achieved with the regimen of legacy broadcast channel widths and at the current state of data compression technology.  These physical limits of broadcasting will likely leave use watching 1080 content for the time being, but there is enough room to potentially move 1080 resolution images to WCG and HDR, which is considered by some to be of greater improvement than simply increasing to 4K picture resolution.  This correlates with the push by a number of standards organizations to consider FHD resolution TV with WCG and HDR as UHD TV and the general trend of replacing the 4K designation with UHD for that reason.

Despite these limitations, in North America there is an ATSC 3.0 standard which does include 4K UHD with HDR with HFR and WCG.  Using the signaling methods in the standard, traditional 6 MHz channels can produce up to 57 Mb/s total bandwidth with 4 sub channels that can be independently allocated with bandwidth.  This would allow everything from SD and HD to UHD HDR video to be sent out on a single channel with the sub channels used as layers for additional picture quality using Scalable Video Coding over a larger sub channel.  Audio in the standard would be either Dolby AC-4 or MPEG-H 3D Audio.

The ATSC 3.0 standard has undergone some limited testing, both by LG Electronics in in Korea in early 2016 and in the states by WRAL in Raleigh, NC, in mid-2016 that broadcast a demo ATSC 3.0 channel in 1080p and a 4K demo loop.  At a policy and implementation level, the current FCC is suggesting voluntary support for broadcasters that want to start using ATSC 3.0 but there are still quite a few technical hurdles including a dearth of TVs with the appropriate tuners, although the FCC is considering making tuners mandatory. FCC support so far has only come in the form of an op-ed by Chairman Pai in February 2017, so the FCC is, at best, really just starting on this proposal with Pai’s public support.

Interestingly, the CTA, in a bold forward looking move, has subsequently gone on record as opposing possible mandatory FCC requirements for ATSC 3.0 tuners on UHD TVs.   I guess you cannot sell as many TVs if you future proof them too much, but I digress.

In Europe, 4K terrestrial broadcasting appears to still in the trial phase.  The DVB has been working on various standards necessary to implement UHD TV broadcasts, but this also appears to be nescient.  One such standard being developed by the DVB is the TS 101 154 V2.3.1, with the latest version approved at the end of 2016, published in the DVB Blue Book A157 Specification for the use of Video and Audio Coding in Broadcasting Applications based on the MPEG-2 Transport Stream.  It seems there is still some work to be done there as well.

Cable and Satellite TV

Similar to broadcast TV, legacy cable and satellite sources will be constrained on bandwidth to support UHD video service.  HVEC encoding can solve some of this problem, but as with HDTV over these sources, you can expect more significant compression and somewhat reduced quality from the best available.

Currently, DirectTV offers limited 4K service.  Initially, the service was limited to a small library of on demand content that could be downloaded to certain Direct TV receivers, but has since been expanded to some live sports broadcasting.  The first such live 4K transmission was for several holes of the 2016 Masters golf tournament.  I say transmission rather than broadcast, because there are no over the air broadcasts currently.

At least one other operator is offering 4K, a smaller regional cable outfit called Layer 3 TV.  Not being a legacy player, Layer 3 seems to have some technological advantages that some of the older operators do not have, such as mixing IP based streaming in with standard cable channel bundles all squeezed with the latest HEVC encoding.  However, the service the Denver company offers is limited in footprint with Chicago and a few other cities on the coasts as their initial markets.  According to an article in Wired, Layer 3 apparently has their own fiber backbone, but partner with ISPs to deliver last mile service.

Technical details for cable and satellite based UHD TV, such as actual bit rates and how much compression and color subsampling is being used, are thin on the ground.  It is probably best to expect that compression will be high for the foreseeable future.

Streaming

Many streaming services have started to make UHD available, the most familiar general platforms being Amazon, Netflix, Hulu, Vudu, and YouTube, although a number of specific content providers have their own UHD streaming apps.  Generally accepted wisdom is that at least 15 Mb/s of dedicated bandwidth is required to steam at 4K, strongly suggesting that many streaming services are, at best, near, but very likely, below that number.  Keep in mind that at the minimum bandwidth, 4K steaming will probably barely work, likely resulting in some time spent watching video buffering, and it also does not account for any other simultaneous uses of that available bandwidth by others sharing the same connection.

Theoretically, steaming 4K should only be limited by available internet bandwidth, but short of having something like Google fiber service available, the limited bandwidth provide by most US ISPs to consumers leave streaming unable to provide content that is anywhere near the bit rate of Ultra HD Blu-ray.  Also, it is not just the receiver’s bandwidth that will limit quality, the services providing streaming will be limited by bandwidth and the associated costs on the sending end of the steams.

This list is not intended to be an exhaustive list by any means, and it focuses on UHD streaming subscription services rather than ala cart purchasing options.  Specifics on the technical details of the various streaming services are hard to come by reliable numbers, but I have attempted to list what I could find below:

Amazon Video

• 4K UHD with HDR
• HDR10 and Dolby Vision
• Dolby Digital 5.1/Dolby Digital Plus 7.1/Dolby Atmos depending on device

Netflix

• 4K UHD with HDR at 15.6 Mb/s
• HDR10 and Dolby Vision
• Dolby Digital 5.1/Dolby Digital Plus 5.1
• 25 Mb/second connection recommended

Hulu

• 4K UHD with HDR
• Dolby Digital Plus 5.1

Vudu

• MPEG4 video up to 4K resolution
• Dolby Digital Plus audio source output as DD 5.1 or stereo

YouTube

• 4K UHD with HDR
• Recently added 8K support
• PG of HLG HDR support with Rec. 2020 color space
• Open source VP9 video and Opus audio default encoding more common to web browsers
• H264/MPEG4 and AAC audio if default is not supported

The Ultra HD Forum guidelines suggest 15-20 Mbps for 3840x2160 60 Hz Adaptive Bit Rate (ABR) streams for Over the Top (OTT) streaming services under section 9.3.3.  Most of these services are, at best, hitting the lower end of the recommendation.

On the other hand, it is likely far more bandwidth than traditional paid TV operators, such as Comcast, will likely provide UHD TV channels on their service and at present, they are hard at work trying to gut any protections consumers might have when trying to avoid their service by going the streaming route.  Using high Internet access prices, particularly when you don’t pay to bundle their TV service with Internet access, usage caps, and slow deployment of higher speed service, particularly to less profitable areas such as rural and poor sections of the country, the traditional paid TV providers are making full use of the uncompetitive market that they have fostered through government lobbying and regulatory capture.  Streaming may be the future, but those who benefit from the status quo will fight it all the way to the bitter end.

As you also should have noticed, total bit rates and audio formats are considerably more limited than what is available with Ultra HD Blu-ray.  Even the 15.6Mb/s UHD stream available from Netflix is less than 1/5 of what can be provided by UHD disc based media and is also substantially lower than standard Blu-ray which can deliver up to 54 Mb/s.  Even considering the 2:1 theoretical HVEC codec efficiency improvement over AVC, the Blu-ray data rate is approximately equivalent to a 27 Mb/s HVEC stream which is nearly twice as much data, and it is not at all clear that any of the providers use HVEC with some specifying AVC/MPEG4.

All of this also means that the video is actually compressed to something below the recommended connection speed, and for those caught up in color resolution, expect chroma subsampling to be used and to certainly be no better than 4:2:0 used on 4K Blu-ray.  Additionally, most of the audio formats offer fewer output channels and are rarely, if ever, lossless, even if lossless audio is theoretically supported.  The convenience of streaming does have its price.

So What Have We Learned So Far?

So now, let us summarize what have we learned about 4K UHD TV so far:

• The idea of standards in the consumer electronics industry is just short of being a complete oxymoron:

•       When there are multiple competing standards, effectively there is not a standard.
•       When standards contain optional components, this also is effectively not a standard.

• The CTA (CEA) and the Ultra HD Forum/UHD Alliance are trying to one up each other on who dictates UHD TV standards for design and performance parameters.

• ITU-R Rec.2020 is used as the basis of most UHD TV, but other standards crop up such as DCI-P3.

• 4K TVs are not actually 4K, but 4K cinema is, hence, part of the reason for the shift from calling TVs 4K to UHD.

• UHD TVs are also not necessarily required to have 4K resolution based on the predominant recommendations, and hence the rest of the reason for the shift.

• Why the consumer electronics industry decided to go with 4K in the first place rather than with the more widely familiar vertical resolution designation, 2160p, which would have reduced consumer confusion…  ¯\_(ツ)_/¯.

• Remember that movies are filmed at 24 Hz and they represent a significant chunk of the currently available 4K content.  In other words, the need for 60 Hz HFR is mostly BS at present unless you are a fan of Soaps.

• Most, if not all, available 4K content uses color subsampling, likely to be at least 4:2:0, to further help with data size and bandwidth limitations beyond just straight up data compression.

• So videophiles, don’t get all uptight just yet about 60 Hz, 4:4:4 color sampling 4K content as there really is not much, if any, that is actually available meaning that any you are watching involves your UHD TV and other AV gear faking it with interpolation and upscaling.  I personally prefer to watch what was actually filmed/recorded/produced rather than what my TV concocts on the fly while I am watching it.

• Ultra HD Premium TVs are supposed to be compatible with the Rec. 2020 color space, but they currently are only required and able to produce 90% of the 30% smaller DCI-P3 color space currently used in the film industry.  The best UHD TV’s are just getting to where they are able to display all of DCI-P3 color space, so at this point, Rec. 2020 color is a goal, not really a feature, and it is likely not just around the corner.

• HDR includes a lot of other things that have nothing to do with dynamic range and is in the early stages of a potential format war between HDR10 and Dolby Vision with HDR10+ and HLG10 waiting in the wings.  Once again, none of them are really a standard at this point, by definition.

• Most current TVs that support HDR only support one format, some support two, but I do not think there are any available yet that support all three formats.

• The HDR format that your TV most likely does not support, HLG10, is the best way to provide backwards compatibility with the oodles of legacy SDR content and to minimize bandwidth necessary to supply both.

• Don’t expect over the air UHD TV broadcasts any time soon due to legacy bandwidth limits and the fact that the ATSC 3.0 specification to broadcast that UHD TV with was just recently released, which leads to a distinct lack of ATSC 3.0 tuners on the currently available UHD TVs.

• Baring a jump in the efficiency of encoding technology, 1080p HDR broadcasting is way more likely than 4K broadcasting in the near future.  Good thing it is all called UHD now.

• Satellite and cable TV have more 4K content than broadcast TV, but not by much.

• Streaming is a serviceable way to get a fair amount of 4K TV, but that may change if the current FCC allows the existing uncompetitive ISP environment to flourish having revoked Net Neutrality thereby allowing ISPs to choke customers on the price and bandwidth for the necessary internet connection speeds.

• Ultra HD Blu-ray, while less convenient than streaming, assuming you even have the Internet connection speeds required for it, produces the best available 4K picture and the number of movies and TV shows available is only increasing.

Stay tuned for the next part where we dig in a little more into the terminology and technology associated with UHD and what to look for in the televisions themselves.