Ultra HD and 4K explained: Everything you need to know & what you can watch
Find out everything you need to know about 4K, Ultra HD and UHD Blu-ray
While 4K has been with us for a while now, it’s now starting to seep into our homes en masse. With 4K TV prices hitting lows of £500, there’s no better time to make the jump, with more and more people feeling the benefits of Ultra HD and 4K resolution. But what really is 4K and Ultra HD resolution, why should you care and what are the best 4K films to watch right now?
Below you’ll find the definitive guide to Ultra HD and 4K, pointing out the differences between the two, the benefits over Full HD resolution and explaining why High Dynamic Range (HDR) is the hot thing right now.
What’s the difference between Ultra HD and 4K?
The terms Ultra HD and 4K have been used interchangeably, with the latter the more popular term by far. However, in terms of home entertainment, 4K is technically an incorrect term, as it refers to the cinema standard, which has a resolution of 4,096 x 2,160 pixels. The home standard is Ultra HD, which has a resolution of 3,840×2,160 to match the 16:9 aspect ratio of TVs. For the purposes of this article, we’re talking about Ultra HD.
What does Ultra HD give you that Full HD doesn’t?
The simple answer to this question is more resolution. While Full HD TVs have a resolution of 1,920×1,080 (a total of 2,073,600 pixels), Ultra HD TVs have a resolution of 3,840×2,160 (a total of 8,294,400 pixels). In other words, Ultra HD TVs have four times the resolution of standard Full HD TVs, with each picture equivalent to a shot from an 8-megapixel camera. That’s a massive increase of resolution, which means that with the right footage 4K TVs can show more detail than is possible with a Full HD TV.
A couple of images can help show the differences between the various technologies. First, I’ve got the traditional image that shows the difference in size between images, starting with regular PAL TV at the bottom left and moving up to Ultra HD. As you can see Ultra HD is a huge jump from Full HD.
The issue I have with this image is that it shows the differences between images when they’re displayed at full resolution on a 4K TV. Obviously, in real life if you had a 4K TV and watched Full HD content, the image would be full-screen. A better comparison, in my view, is to compare Full HD and 4K TV at the same physical size, which I’ve done in the images below. These are frames pulled from the open source film, Tears of Steel. For these comparisons, I downloaded the rendered frames from the 1080p and cinema 4K versions of the film. I resized the cinema 4K version to fit the Ultra HD standard. I cropped the images at the same point, so that you can see the differences more clearly.
When viewed at the same size, the Full HD version (top) is noticeably softer than the Ultra HD version (bottom). In particular, the Ultra HD version has much better skin texture and you can more clearly read the writing on the carton. You can argue that the differences are subtle, but the effect is greater when watching Ultra HD content: it looks sharper and once you’re used to it, Full HD tends to look soft. Resolution is just one aspect of Ultra HD, though, with the new standard making a few other improvements.
Better colour and a higher frame rate
One of the main things that hasn’t changed with higher resolution TV is the frame rate we watch content at, with films traditionally shot at 24fps and UK TV at 25fps. With Ultra HD that changes and the technology supports up to 60fps (UK TV will most likely come in at 50fps – double the existing frame rate). There may be some naysayers out there saying that a higher frame rate makes footage look wrong and films look as though they’ve been shot on video, but they’re completely wrong. The smoother footage looks a lot better and removes any jerkiness from fast-moving scenes or panning shots. It’s particularly useful in sport, as you can more easily keep up with the action.
On top of that standard gives better colour depth with support for 10-bit and 12-bit colour, rather than the 8-bit colour available at the moment. That means a wider range of colours are available, which gives a more vibrant and realistic colour palette, as well as bringing out subtler detail in images. There’s also the promise of High Dynamic Range (HDR) footage.
Ultra HD and 4K: What is HDR?
The dynamic range in content describes the ratio between the darkest and lightest shades of an image. Typically, an image or a film is shot with a relatively low dynamic range, which means you lose some detail in one part of the image. For example, you may have lots of detail in the shadows of an image, but little detail in the sky; conversely, shadows may appear black, while the brighter part of the image may have lots of detail. With HDR footage, you get all of the detail in the dark parts of the image and all of the detail in the lighter parts of the image. We’ve seen this technique used in photography a lot and now most smartphones even have an HDR photo mode; however, this is the first time that the process has moved into video. We’ve seen some test footage and it’s looking stunning. Find out more by reading our guide to HDR TV.
Ultra HD and 4K: What about sound?
There’s no maximum or minimum sound quality set in the Ultra HD standard, but you can get everything from stereo audio up to 7.1 lossless Dolby TrueHD and DTS-HD Master Audio soundtracks, depending on the source footage. In other words, you can get amazing sound, but the source of the footage defines the quality and type of soundtrack.
Doesn’t Ultra HD footage take up loads of room?
You need a lot more storage space and bandwidth to deliver Ultra HD footage, but not as much as you think. While current Full HD footage generally uses the H.264 codec, Ultra HD content is typically encoded using the H.265 codec, also known as High Efficiency Video Coding (HEVC). It needs a lot more processing power to deal with, but cuts file sizes down: it can make files roughly half the size as when using H.264. Unfortunately, outside of computers, which have powerful processors and are easy to upgrade, HEVC support can’t be added retrospectively to older products. That means, for example, that Ultra HD Netflix support can’t be added to an older TV or media streamer except via an external box.
What are mastered in 4K Blu-rays?
You may have seen that there are a growing number of Sony-produced Blu-ray discs that say Mastered in 4K on them. Given that most films are shot in at least 4K, this sounds like common sense, but there’s actually a couple of differences that are quite important. First, the discs have been created directly from the 4K or higher original masters, which should give a cleaner and clearer picture. Sony has also said that the compression used takes advantage of the X-Reality Pro processors in its TVs to make for better upscaling when you watch the discs on an Ultra HD TV. While you may getter slightly better results than watching a regular disc, the results are still a way off a native Ultra HD image.
More importantly, the new discs use the x.v.YCC colour specification; if you’ve got a TV and Blu-ray player, such as the PlayStation, that support this colour space, you’ll get better colour definition from these discs. Ultimately, Mastered in 4K is really just a method of improving original Blu-ray and you won’t get the full image quality and colour range as with true Ultra HD.
See the next page for the latest info on true Ultra HD Blu-ray.
What do I need to watch Ultra HD content?
This one’s an easy question to answer. First, you need a TV or projector with the correct Ultra HD resolution (3,840×2,160), so that you’ve got something to watch the content on at the correct resolution. I’ve been using the Panasonic AX802 to test Ultra HD in the UK. Make sure that you buy a display with an HDMI 2.0 input (see below for more details). If you use a home cinema amplifier or surround-sound system, it too needs to support HDMI 2.0 and Ultra HD.
Next, you need a method of getting Ultra HD into your display of choice. Since the start of the year, the amount of 4K content has grown massively in the UK and it’s just going to get better. Keep reading below to find out more.
Ultra HD and 4K: HDMI 2.0 is very important
HDMI 2.0 is the updated cable standard, designed specifically for Ultra HD. It’s important that you buy a TV, projector and, if you use one, AV amplifier, that has an HDMI 2.0 port (there’ll usually be only one). You might take that as read that all Ultra HD TVs have this as standard, but the early models didn’t and used HDMI 1.4 instead. This is bad for two reasons. First, it limited Ultra HD to a maximum of 30fps (30Hz refresh rate), so you can’t benefit from the standard’s higher frame rates.
Secondly, TVs without HDMI 2.0 don’t support HDCP 2.2, the new copy protection standard. This is really bad, as newer Ultra HD kit, such as set-top boxes and Blu-ray players will not work.
Don’t get ripped off by HDMI cables and don’t listen to anyone that tries to sell you an Ultra HD cable. Provided the cables you buy are HDMI High Speed (most are), they’ll work just as well with Ultra HD as they do with Full HD.
Where can I get Ultra HD content?
We’ve had the TVs and projectors for a while, but the content has been slow to come in the UK. That is starting to improve, and there’s now a range of decent content available for you to watch. We’ll take you through all of the options available now and coming soon.
Ultra HD and 4K: Blu-ray
Ultra HD Blu-ray is the 4K standard for movies on discs that we’ve all been waiting for and we’re now getting closer to launch, with the Blu-ray Disc Association having agreed upon a specification. This includes discs with 66GB or 100GB capacities, support for Ultra HD resolution obviously, frame rates up to 60fps for smoother motion and HDR technology to provide greater colour depth and contrast.
Samsung demonstrated its first Ultra HD player (the UBD-K8500) a while ago costing a fairly reasonable $400 with hardware available showing up from March 2016. Panasonic also has its Ultra HD Blu-ray player, the DMP-UB900, which is also designed to provide high-end audio thanks to dual HDMI outputs.
Apart from the players being fairly expensive, the catalogue of Ultra HD discs available is pretty good. Traditionally, when a new format is launched, film studios first release a back-catalogue of mediocre films as a way to make cash back on them from early adopters. Thankfully this time around it looks like there’s some pretty strong recent titles getting the Ultra HD treatment.
The Martian, Kingsman: The Secret Service, Wild, Life of Pi, X-Men: Days of Future Past, Mad Max: Fury Road, Chappie and The Lego Movie looking like highlights. There’s some average fare as well of course, but they might appeal to some: Pan, San Andreas, Ender’s Game, Expendables 3 and a handful more.
Unlike with Blu-ray, where releases often had to be scanned digitally from the original prints and then remastered to get them ready for transfer to the format, Ultra HD Blu-ray had a much smoother launch, as practically every film made in the last few years was mastered and distributed digitally, making it a comparably easy task (compared to Blu-ray at least) to transfer these films from cinema 4K to Ultra HD Blu-ray.
Ultra HD and 4K: Netflix
Netflix was one of the first adopters of Ultra HD, delivering its content over the internet. It’s home-grown shows, such as Daredevil, are all shot and delivered in 4K, but it’s also starting to make other content available, such as The Avengers. To get Ultra HD Netflix you, first of all, need a TV with the supported player built-in (you can’t get 4K content through media players or computers at the moment), need to have an internet connection that can deliver a constant 25Mbit/s download speeds and you have to upgrade your plan to the £8.99 a month version, which also lets you have four streams. Quality is excellent, far outstripping that of Full HD and with more titles coming online every month, the catalogue is steadily growing.
Ultra HD and 4K: Amazon Prime Instant Video
Amazon Prime Instant Video has also started to stream in Ultra HD in the UK. As with Netflix, you also need a TV with a built-in app that supports the higher resolution video. Most new TVs do, but it’s worth checking specs before you buy. Amazon’s home-grown content is largely shot and is available in Ultra HD, but there’s a growing catalogue of films available, too. If you’ve got a Prime account, you’ll get a lot of this content included as part of your overall bundle; if you haven’t, some of the films are available to buy or rent in Ultra HD.
Interestingly, Amazon is the first service in the UK to support HDR, with content now available. However, you also need a TV that supports the HDR standard, which currently is just a few Samsung sets. There’s also not a huge amount of HDR content, with only a handful of TV shows, such as its own Mozart in the Jungle, supporting it.
Ultra HD and 4K: YouTube
YouTube has supported Ultra HD for a while now, but I don’t really see it as a primary source for content, as it’s largely user generated. YouTube’s content may be useful for testing purposes, but if you want professional films and TV shows, it’s not the place to watch.
Ultra HD and 4K: TV
The obvious way to get Ultra HD footage is via a regular broadcast system. The DVD-UHD broadcast standard has been approved, but no Ultra HD TV has a compatible tuner, we don’t have any compatible set-top boxes and not one UK broadcaster has committed to using the standard or launching a channel as of yet. The same goes for Sky, which has not committed to launching an Ultra HD service via satellite at the moment.
There are a few barriers to launch, including bandwidth limitations. While the broadcast Ultra HD standards use the HEVC standard, this only currently doubles the compression rate. As Ultra HD uses four times the pixels as Full HD, this means that you still need at least double the bandwidth to deliver Ultra HD. In reality, it’s likely to be more than double, as HD is broadcast at a lower frame rate and is interlaced (every frame gets half the number of lines); Ultra HD has a higher frame rate and every frame is progressive.
Bandwidth pressure could be eased if broadcasters could switch compression to use HEVC on all channels (an HD channel would require half the bandwidth), rather than H.264, but that would require every household to upgrade their existing equipment, so it seems unlikely. A more realistic scenario is that we’ll start slowly, getting one or two Ultra HD channels, with additional content available to stream online. The BBC has already run several trials, as has Sky, so it doesn’t feel as though we’re too far away from a proper launch – I’ll keep you posted.
Ultra HD and 4K: Download services
Being able to download content in Ultra HD makes a lot of sense, as you don’t need the same bandwidth as for streaming: you effectively get rid of buffering as you need to download the entire film or TV show straight away. Sony has the FMP-X10 media player in the US, which lets you download films from the Sony catalogue in Ultra HD; Samsung’s own service, available through MGO, is also only available in the US.
Download services will most likely come to the UK eventually and there are rumours that Sky is working on its own platform that will combine live TV with a download service. I’ll keep you up-to-date with the latest information.
