Forget three-disc Blu-ray boxsets stuffed with a digital version and some fancy extras

Without new compression tech the next-gen could see films released in 200+ disc 'shelfset' editions. Such is the leap in quality and detail from simple high definition to so-called 4K – the next big thing in cinema – that home entertainment is set to become a whole lot more demanding.

Also known as Quad Full HD and the slightly catchier Ultra HD, this stunning new video format is better known – in the panel industry at least – as 4K or 4k2k, and it's already been embraced by Hollywood.

"More films than ever are post-produced in 4K, either based on 35mm negative film or digital 4K shoots, which will now be made available to cinemas in 4K," says Oliver Pasch, Head of European Digital Cinema Sales at Sony Professional.

Recent examples included Tinker Tailor Soldier Spy, Moneyball and Girl with the Dragon Tattoo, while The Dark Knight Rises, Men in Black III, Spiderman 4 and Samsara, Ron Fricke's follow-up to 1992's Baraka, will all be filmed with 4K cameras.

Sony's F65 CineAlta, Red's EPIC and JVC's handheld GY-HMQ10 cameras all capture four times more detail – 3840x2160 pixels – than is shown on the two-megapixel resolutions of current Full HD televisions.

Multiplex vs home cinema

"Digital Cinema is slightly different to TV – a 4K frame has 4096 vertical lines of resolution lines compared to 3840 for a 4k TV picture," explains Bill Foster, Senior Technology Consultant at Futuresource Consulting. "It's simple maths – a regular cinema picture measures 2048x1080 pixels, which is slightly wider than a 1920x1080 pixel image we see on a Full HD TV."

Eight-megapixel 4K images are currently a plaything only for top Hollywood directors, but can 4K go mainstream and hit our living rooms anytime soon, either via TV or Blu-ray?

"4K technology is still in its infancy, so like any new technology, initial costs are high," says Glenn Zanoni, TV and Blu-ray Product Marketing Manager, Toshiba UK. "There is a small amount of 4K content available at this stage, which also impacts mass market availability."

A lot of investment would be needed in infrastructure to enable delivery of 4K TV content to homes, and who would be watching?

Equipment that can display 4k material is rare, though the jigsaw is beginning to take shape.

JVC 4K: the £4,340 GY-HMQ10 camcorder from JVC films 4k in 144 Mbps

Though they are theoretically 4K-capable, JVC's DLA-RS55 and DLA-RS65 projectors use Pixel Shift tech to upscale a 2k image to 4k resolution, which is also what some Onkyo AV receivers do.

In terms of displays, Sony sells its £17,000 VPL-VW1000ES SXRD projector, Panasonic's mighty 152-inch TH-152UX1 plasma, and the Toshiba ZL2 TV, both of which is capable of displaying 4K content.

SONY 4K:the F65 CineAlta 4k camera is hard at work in Hollywood

The CES in Las Vegas also saw a flurry of 4K prototype panels from Sharp, LG, Samsung, Panasonic, Sony, and Toshiba. Sony also demoed its BD-S790 Blu-ray player, which can upscale discs to 4K resolution.

How to get 4k to homes?

However, no devices capable of playing native 4K sources currently exist for the home market.

The problem with delivery is the sheer size of 4K's datastream; the infrastructure simply does not exist.

The Digital Cinema Initiatives (DCI) specifications, which are used by Hollywood, use a maximum of 250 Mbits/sec for a JPEG2000 compressed 4K image, though this is set to double to 500 Mbits/sec in the next five years or so.

"In DCI terms, at the highest bitrate of 250 Mbit/sec, a two-hour 4k film would be 225GB for the image only, excluding audio or sub pictures," says Oliver Pasch, Head of European Digital Cinema Sales at Sony Professional.

"However, most films today are compressed at variable bit rates, so in reality, a standard DCP (Digital Cinema Package) used for distribution to cinemas would be smaller, but to what extent would depend on the content of the film."

At a recent Sony event in Tokyo, TechRadar was shown a trailer for The Amazing Spider-Man in 4K using the Sony VPL-VW1000ES projector. The two and a half minute uncompressed trailer weighed in at 500GB.

Pasch underlines the fact that there is a tendency to compress as much as possible to reduce file sizes, and that it's likely to increase; studios and distributors are considering sending 4K films to cinemas via satellite rather than on physical hard disks.

UPSCALING:Onkyo's 4k2k QDEO chip from Marvell, the 88DE2755, can upscale to 4k

How about getting a 4K movie onto a Blu-ray disc?

Actually getting a 4K film onto a Blu-ray disc would be a huge challenge. We asked Sony's Pasch to tell us how many Blu-ray discs it would take to watch a three-hour Lord of the Rings film in 4K?

"On the basis that three hours of 4K video takes up 3.16TB, this would be 212 standard 25GB Blu-rays – although the quality of image and amount of Blu-rays used all comes down to the amount of compression applied."

"Blu-ray has the capability to go beyond what is can do today," says Foster at Futuresource. "Physically it can support up to eight layers – the original specification allowed for 200GB! Whether anyone will want to make one of those is a different story, but it shouldn't be difficult to go to four layers, though even that would require a new player; the electronics in a BD player simply couldn't handle a current BD disc with a 4K resolution."

We asked official industry body the Blu-ray Disc Association (BDA) about 4K.

"There is currently no activity within the BDA to bring 4K into the Blu-ray specs," Victor Matsuda, chairman of the BDA promotions committee, told us.

"That said, I think there is room for it if 4K displays begin to build some momentum in the market and consumer interest in content – as always, the most important driver – becomes apparent. Until then, I think HD-to-4k up-conversion will be the most likely application we'll see from player and TV companies."

Mapping-up

For now, 4K video at home will be seen by only upscaling a Full HD image.

"It's simple to scale a 1920x1080 picture to fill a consumer 4K TV – it maps-up dead easily – hence the promise of some 4K panels to upscale from HD," says Foster. "It's literally four pixels to each picture."

"4K TVs will break cover soon, but the content may be slower in arriving," says Naoki Hamada, Product and Marketing Manager at Onkyo Europe, whose AV receivers already upscale HD to 4K.

"That isn't going to stop people buying the display hardware. With our receivers they'll be able to upscale content to 4k2k from the get-go while they're waiting for true 4K content to arrive."

Hamada also notes that it's especially hard to achieve great looking and smooth moving pictures because 4K scaling needs much, much more CPU power than 1080p upscaling.

If storage of a 4K film on Blu-ray will take some time, delivery over the web seems even more unlikely. It entirely depends on video codec and streaming protocol used, though JVC's GY-HMQ10 camcorder uses a compressed bitrate of 144 Mbps to record in the MPEG-4 AVC/H.264 format.

That could be crucial when it comes to fitting a 4K film onto a Blu-ray disc, but also for web downloads. Broadband speeds in the UK just aren't up to scratch yet – you'd have to have a minimum 144 Mbps broadband line, but preferably 500 Mbps, to stream a 4K film while retaining the detail.

And how about just downloading a 4K film? In its currently uncompressed format, a two-hour film would take somewhere between 1-2 terabytes, which would take between 38-65 hours to download over a maxed-out 7.6 Mbps broadband line (the UK's average speed). A healthy 100 title-strong film library would therefore require a 1-1.5 petabyte hard disk server.

New firmware or new kit?

Big numbers indeed. A new TV or projector will certainly be needed, too, but can some products be upgraded to 4k via firmware updates?

"Interfaces don't currently support 4K, which means that 4K-based products offered today may not necessarily be compatible with 4K content distributed in the future," says Roland Vlaicu, Senior Director Broadcast of Video Ecosystem at Dolby Laboratories. "Consumers will have to decide for themselves whether the investment in a 4k product is justified."

Oddly enough, while 4K sources are scant, the cables to carry these high-data signals to TVs have existed for some time. PNY is one of many manufacturers to have already released 4K-capable HDMI version 1.4 cables.

HDMI: cables like PNY's Active HDMI can already carry 4k data

We asked a spokesperson from PNY why consumers should invest in its high-speed Active HDMI cables before 4K sources even exist?

"For the same reason they invested in a 3D Active TV when 3D content wasn't yet available, or DX11 compliant graphics when games hadn't yet taken advantage of the technology – if you buy our cable today, you won't need to get another when you buy a new screen, Blu-ray player, or games console. Consumers who opt for 4k technology help push the market one step forward – and that's what we're trying to do.

"We like our customers to get as much use out of our products as possible so we try to steal a march on new technologies like 4K, so as not to disappoint them," says Hamada. "If you can see that something's going to be obsolescent in the foreseeable future, why would you buy it?"

The key investment for homes will ultimately be a 4K-capable TV, but how much of an improvement will they bring? A standard 40-inch Full HD telly boasts a pixel density of 52 pixels per inch, with 4k set to bring 80-82 pixels per inch – compare that to the 326 pixels per inch on an iPhone's retina display.

How big is a 4K TV?

So how big must a 4K telly be to appreciate the difference to Full HD?

"60-inch or more ideally, but you can see the difference on anything from a 40-inch display upwards," says Hamada. Toshiba is launching its 55-inch 55ZL2 later this year, so clearly believes that 4K at that size is a worthy upgrade over a Full HD telly, but that set's key claim is that it's the first glasses-free 3D TV.

And 3D could be the key to unlocking a 4K future.

"Manufacturers will need to be to convinced of use cases that support the need for a 4k panel in the home," says Dolby's Vlaicu, "which could well be higher-resolution 3D using passive glasses or even auto-stereoscopic (glasses-free) 3D."

"With 4K displays at home," says Pasch at Sony, "this will allow line-by-line polarization of the images to maintain Full HD resolution to each eye, so avoiding the requirement for active shutter glasses."

Expect your first view of 4K to be in a sports bar – or perhaps on the first truly bigscreen OLED TVs – but it could be a choice between extra detail or more convincing 3D.

Which would you prefer?