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What is 4K TV and Ultra HD?

John Archer by

Sky Sports

Everything you need to know about 4K and UHD

With 4K TVs now arriving in numbers and at increasingly affordable prices it’s no longer just a technology for the tech-minded early adopter market. So we thought we’d have a crack at answering some of the most commonly asked 4K-realated question to save you a load of time and effort.

Q: What exactly is 4K?

A: 4K – also known as UHD (more on this in the next answer!) – is a picture technology that quadruples the number of pixels found in a full HD picture. These pixels are usually arranged in a 3,840 x 2,160 configuration, compared with the 1920x1080 you get in a full HD TV.

Q: What is the difference between 4K and Ultra HD?

A: While 4K is the most commonly used name for content and screens that use 3,840 x 2,160 pixels, some brands prefer the term Ultra HD – or UHD for short.

While confusing, there is actually some logic to the new UHD term. That's because it provides a way of distinguishing between the 3,840 x 2,160 resolution adopted by 16:9-ratio TVs and the slightly different 4096x2160 resolution first introduced in digital cinemas (and actually employed by Sony’s domestic 4K projector range).

However, 4K is used so widely to describe 3,840 x 2,160 displays and content now that the roots of the technical distinction between the 4K and UHD terms have been all but lost outside of the projection world. In other words, for most people the two terms have become interchangeable.

What is 4k TV Ultra HD?

Q: Is 4K actually any good?

A: While 4K has its detractors, we’re big fans. The extra resolution of 4K images adds more detail, more depth and more colour resolution to the picture, resulting in images that look incredibly life-like – more like looking through a window than watching TV.

4K is especially effective on very large screens – so ideally you’ll go for a 65-inch set or even bigger. That said, we’d argue that 4K resolution clearly improves picture quality at pretty much any screen size.

An interesting point about 4K that may help you appreciate its importance to image quality is the fact that 4K is considered by the film-making community as being able to reproduce in pixel form the sort of resolution and ‘finish’ you get with 35mm film. Though that hasn’t stopped some films studios from starting to remaster film prints in 8K!

So far as we’re concerned the only problems with 4K from a picture quality perspective are likely to be caused by video compression applied to its distribution, motivated by the difficulties involved in distributing the huge quantities of data associated with 4K masters.

Q: Do I need to sit nearer my TV to benefit from 4K?

A: To get the best from 4K, it is recommended that you sit closer to your screen than is recommended with HD TVs. This is partly so you can most clearly appreciate the extra resolution, but also because it makes the 4K image fill more of your field of view, making for a more immersive experience.

There are also ‘scientific’ charts in circulation suggesting that you need to sit extremely close to 4K TVs in order to appreciate the extra resolution at all.

However, while we’d agree that you get the most impact from 4K if you sit close to it, we reject the notion that you get no benefit at all from more distant viewing positions. You still perceive more depth, colours still look more smoothly rendered, and objects within the picture still look more solid and three-dimensional.

4K packs in four times the number of pixels as Full HD / 1080p.

Q: Is a 4K TV all I need to start watching 4K?

A: No. While your 4K TV will use processing to upscale HD and even standard definition pictures to its 4K pixel count, if you want to watch 4K at its best you will also need a native 4K source. Which brings us neatly to our next Q&A…

Q: What 4K content can I watch?

A: The short answer to this at the time of writing is ‘not a lot’. While we’ve now got a few 4K video servers set up in our test rooms, 4K content that’s accessible by the general public is still rather limited - though things are improving.

The most important 4K option is Netflix. The subscription on-demand service currently carries a growing library of TV series and films you can stream in 4K for £8.99 per month (up from £5.99). In terms of TV, Breaking Bad and House of Cards have been joined by the likes of Marco Polo and The Blacklist. UHD films include The Amazing Spider-Man, Crouching Tiger Hidden Dragon and Jerry Maguire, among others. You also get a few nature documentaries.

Amazon Prime Instant Video also offers some 4K content free of charge, including original Amazon series Alpha House, Extant, and Transparent, though only on select TV sets from Sony, LG and Samsung.

Otherwise your main source of 4K content is the internet, predominantly via YouTube and a handful of dedicated 4K sites such as hd-trailers.net and demo-uhd3d.com. You can download files from these, transfer them to USB drive, and play them directly into your TV (so long as your TV is compatible with the video encoding format of the clip you want to watch).

BT has also just announced that it will become the first broadcaster to have a 4K channel - BT Sport Ultra HD. As the name suggests, this is sports channel (read further down for more information about sports) and it will show Premier League, FA Cup and Champions League football along with Aviva Premiership rugby. You'll one of BT's new Ultra-HD boxes to take advantage of the service though, but we've haven't got confirmed pricing yet.

There are a couple of other boxes too that'll help fill your screen with glorious 4K. The most notable is the Android TV toting Nvidia Shield. This box will stream 4K Netflix and retails for $199, though it's currently available in the States.


The Sony KD-75X9405C is about as good as TV gets at the moment.

Q: Do all 4K TVs support 4K streaming?

A: No, not all of the older ones do. None of 2013’s 4K TVs can handle Netflix’s 4K streams, due to them not being able decode the HEVC video format Netflix has adopted. Not all of 2014’s 4K TVs can handle Netflix 4K either, with sets from Philips and Toshiba unable to cope with Netflix 4K (Panasonic added such support for its AX802 range late in the year).

The majority of 4K TV sets from reputable manufacturers released in 2015 support Netflix 4K streaming, however, so if you've bought one recently you should be okay.

Philips (a manufacturer that hasn't been great with Netflix 4K support) also supplies the UHD 880 4K, a media streamer that adds such support to its non-compatible TVs. Sony has one too in the Sony FMP-X5, which can enable Netflix 4K streaming on older Sony 4K TV sets for around £350.

Indeed, Sony is one of the biggest supporter of 4K so far, with an available library of a couple of hundred 4K films.

It must be stressed that not being able to play Netflix 4K doesn’t automatically preclude a TV from being able to play future alternative 4K streaming services that might emerge. But it doesn’t exactly fill us with confidence…

Q: What broadband speed do you need to stream 4K?

A: We’ve only got Netflix to go on here, but for that you’ll need a minimum of 15Mbps. And your speeds need to remain consistently at or above that figure. As soon as you drop lower – due to high contention rates at peak usage times, say – the picture will slip back into HD mode.

To try and cover itself for this eventuality, Netflix actually says on its website that you need 25Mbps minimum. But we’ve confirmed with Netflix that a consistent 15Mbps is enough.

Compression techniques improve all the time, so it’s possible you may in the future need slightly lower broadband speed to experience 4K on Netflix or other rival 4K streaming platforms. But bear in mind that high levels of compression inevitably negatively affect picture quality, so if you’re serious about 4K a fast broadband connection is a must.

What is 4k TV Ultra HD?

House of Cards was the first 4k series available made available to stream, via Netflix.

Q: What connections do I need to watch 4K?

A: We’d love to say ‘an HDMI socket’ and leave it at that, but wouldn’t you know it, it’s just not that simple.

The issue here is that not all HDMI sockets are equal. There have been multiple versions/standards of HDMI since the digital connection first appeared, with the latest v2.0 HDMI specification being defined specifically with 4K feeds in mind.

The most significant advantage of v2.0 HDMIs from a 4K perspective is that they support increased data bandwidth, and so enable playback of 4K feeds with full (so-called 4:4:4) colour sampling at frame rates of up to 60fps. The previous v1.4 HDMIs only support 4K feeds up to 30fps.

HDMI sockets made to the v2.0 level have only really entered the TV manufacturing stream last year. Some older 4K sets were able to upgrade their v1.4 HDMIs via firmware to permit 4K streams at higher than 30fps frame rates, but only with reduced colour sampling.

Most of the major 4K TV brands now carry HDMI 2.0 in their current TVs – LG, Sony, Panasonic and Samsung are all onboard with it now, as is (finally) Philips.

Rather scarily, there’s talk of adding other picture quality ‘boosters’ to the 4K spec, such as much greater colour bandwidth and much higher frame rates. Content mastered with High Dynamic Range is also seen as a big future move, but if these come to pass the data rates involved will almost certainly require yet another HDMI upgrade, or maybe a new connection altogether.

With all this in mind it’s easy to understand why Samsung has opted to go with an external ‘One Connect’ connections box for its flagship UHD TVs, since these can be upgraded in future years as connectivity requirements change.

Because of the ongoing TV connection issues, don't rule out seeing more of those external 4K ‘receivers’ able to decode 4K streams and even download 4K titles on your TV’s behalf.

Q: Can I make my own 4K content?

A: Indeed you can. There are now domestic cameras out there capable of producing startlingly good 4K quality without costing the earth. Two of the best examples are the £1,500 Sony FDR-AX100 camcorder and the £1,750 (with lens) Panasonic DMC-GH4 camera.

Many modern Android-powered smartphones are also capable of capturing 4K video, including the Samsung Galaxy S6, HTC One M9, and the Nexus 6.

What is 4k TV Ultra HD?

Want the ultimate in sound quality as well as a 4k picture? The Sony KDL-65X9005B set the standard.

Q: When will more commercial 4K content become available?

A: The good news is that more and more films and TV shows are now being made in 4K. So the source content is at least being created. It’s just a pity that distributing it seems so difficult.

The big 4K hope for many home cinema enthusiasts is some kind of 4K disc format. Sure enough, a standard for 4K Blu-ray players was agreed back in February, and the Ultra HD Blu-ray format was officially announced a couple of months later.

However, you won't see Ultra HD Blu-ray players hitting shops until some time towards the end of the year.

What of 4K broadcasts? BBC technology chief Matthew Postgate recently told the FT that the broadcaster was looking to offer 4K programming by 2016, but other comments from the BBC (and the simple reality of the standard's lack of progress) suggest that this will be in limited form rather than a widespread or comprehensive rollout. BT and Sky are also rumoured to be readying their own 4K boxes, but there's been nothing concrete.

Other 4K options include the likes of the Ultraflix service. Launched in the US at the turn of the year, and available across a number of 4K TV brands (including Sony and Samsung), it offers hundreds of hours of 4K content containing a mix of sports, concert, documentary and film. It's not the most polished or comprehensive of offerings, however.

Next, read our pick of the Best TVs 2015

One final potential 4K source to look out for are external HDDs, to which you can download 4K films. These are likely – in the short term, at least – to be offered as add-ons to specific brands of TV. Sony has had such boxes available for purchase with its 4K TVs in the US since 2013, offering a series of preloaded titles and the facility to download other titles later.

Samsung has launched a similar box into the UK. This box offers owners of Samsung UHD TVs (it won’t work with other brands of TV) three pre-installed 4K movies and a bunch of demo material for £150.

Q: What's this about older 4K TVs not being able to handle sport?

A: Yes, about that. As is probably becoming eminently clear to you by this point in the article, anyone who became an early adopter of the 4K standard is, well, a little screwed. The constantly shifting goalposts of this new standard have rendered 2013 sets all but obsolete, and that's particularly the case if you watch a lot of sport.

Because early 4K TV sets can only render UHD content at 25fps, they won't be suitable for future 4K sports broadcasts. At least, not on Sky's service anyway.

Speaking at a recent conference in London, Sky's Chris Johns supplied the brutal truth: "If you bought a [4K] set in 2013 and early 2014, then sorry, it won't do sport. It'll only go up to 25 frames per second."

25fps is just peachy for most Hollywood films, which are shot at that frame rate. But sporting broadcasts benefit from the smoother action that much higher frame rates bring about, with 100fps here stated as the ideal.

Such a boost in frame rate requires newer, faster hardware - a software update simply won't cut it. Hence the reason that your 2013 or even 2014 4K TV might not play future sporting content.

Samsung is one company that has provided a way out for 4K early adopters, but it involves plugging yet another box into your TV set. The UHD Evolution Kit costs around £400, and essentially acts as a hardware upgrade complete with quad-core processor and HDMI 2.0 connectivity.

Having said that, with standards still not settled, there's no guarantee that this expensive sticking plaster will actually solve the issue. It's all a bit of a mess, really.

Sky Sports

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