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What is 4K TV and Ultra HD?

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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 painfully limited.

The most important 4K option is Netflix. The subscription on-demand service currently carries two key TV series you can stream in 4K - Breaking Bad and House of Cards - plus a few nature documentaries. Otherwise your only other 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).

There are no 4K broadcasts right now, and nor is there any 4K disc format. Basically, it’s online or nothing. Unless you make your own 4K content (more on this later).

What is 4k TV Ultra HD?
The curvy Samsung UE65HU8500 is about as good as TV gets at the moment.

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

A: No. 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. And actually not all of 2014’s 4K TVs can handle Netflix 4K either. The only ones that can that we’ve seen to date are the latest models from Sony, Samsung and LG. The current 4K sets from Philips, Toshiba and Panasonic cannot cope with Netflix 4K (though the Panasonic AX9 series due for launch later in the year will do Netflix 4K).

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 and Breaking Bad are currently the only widely available programs in 4k, 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.

However, HDMI sockets made to the v2.0 level have only recently entered the TV manufacturing stream, meaning that only one of last year’s 4K TVs, the Panasonic TX-L65WT600, carried a full 2.0 implementation. Some other 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.

There are more 4K TVs in 2014’s ranges that carry HDMI 2.0 – LG, Sony, Panasonic and Samsung are all onboard with it now. But frustratingly we’re still seeing some new models, like the recently reviewed Philips 55PUS7809, that don’t carry HDMI 2.0 ports.

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. 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, it’s possible we’ll eventually see an influx of 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. The two best examples are the £1,500 Sony FDR-AX100 camcorder and the £1,750 (with lens) Panasonic DMC-GH4 camera.

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 – probably 4K Blu-ray. But while the AV industry’s Blu-ray working group is beavering away at coming up with a suitable format for 4K discs, it’s taking its own sweet time about it, with nothing confirmed as yet. We’re hoping something might emerge at the Las Vegas Consumer Electronics Show in January 2015 – but then we held out the same hopes this year!

The best case scenario/guess is that the first 4K disc releases – and the new players they’ll require! - may appear next spring or summer, but this may be the optimist in us getting carried away…

It’s similarly impossible to say for sure when the first 4K broadcasts may happen. The BBC trialled 4K broadcasts of the Commonwealth games, and we know that Sky has been trialling 4K sports content internally. But neither platform has announced a formal launch date for a consistent consumer service. In Sky’s case a new 4K platform would require a new set top box.

As for other streaming services beyond Netflix, Amazon has announced that it is now shooting all of its original content (including TV series Extant) in 4K and intends to launch 4K streaming before the end of 2014.
But what about streamed films? Why can’t you get any of these in 4K from Netflix or Amazon yet?

According to Netflix’s VP of Product Innovation, Todd Yellin, the chief reason is that the film studios don’t want to go through the actually quite arduous process of preparing 4K masters of its film catalogue until some way is found of monetizing the 4K streams – maybe through extra per purchase costs, or a higher Netflix subscription for a 4K service.
Yellin made it clear that such options were under discussion, but there was certainly no sniff of a date when some kind of 4K movie service might launch.

A potentially more imminent ray of 4K movie streaming light could be the Ultraflix service. This is launching in the US any day now, offering more than 350 hours of 4K content containing a mix of sports, concert, documentary and film. At the time of writing, though, we’ve only been able to get confirmation that the films will include family, horror, sci-fi, comedy and drama options; exact film names have not been made available…

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. But nothing similar has been available to UK buyers.

Samsung is launching a similar box into the UK. This box was supposed to have launched already, actually, offering owners of Samsung UHD TVs (it apparently won’t work with other brands of TV) the facility to download up to 50 big-name movie titles at no extra charge beyond the box’s £300 up-front cost.

Next, read our pick of the Best 4K TVs

Disappointingly, though, the box seems to have disappeared from Samsung’s launch radar following its initial announcement back in May. Hopefully it will be resurrected at some point, and hopefully Sony will finally find a way, too, of launching its own 4K download box - even if it was only able to download 4K movies from Sony’s own film studio!

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