These days it is very difficult to buy a TV or Smart TV that is not 4K. They are everywhere, and even the cheapest models of just 400 Pounds already include panels of this resolution because of how quickly they have become cheaper to manufacture. Let’s explain what differences there are with previous resolutions, their technical characteristics, what we need to watch 4K, and where to watch 4K content.
What is 4K? Is it the same as UHD?
Until the arrival of 4K, resolutions have usually been named by the vertical pixels (720p or 1080p). However, it was decided to name new one 4K for the horizontal resolution above 4,000 pixels to simplify and make it easier. The “original” 4K resolution used in cinema, known as DCI 4K, was 4096 x 2160 pixels, with an aspect ratio of 17:9. However, in our televisions or monitors, the one we find is 3840 x 2160 pixels, which has an aspect ratio of 16:9 to fit the content we normally see, and whose full and correct name is 4K UHDV, although we know it more as 4K UHD (Ultra HD), or even 2160p.
Although the resolution we commonly use as 4K is less than 4000 horizontal pixels, manufacturers started using this term, and it is finally the one that has remained. Thus, 4K UHD, with 3840 x 2160 pixels (8,294,400 pixels), is four times the resolution of 1080p (1920 x 1080 pixels, or 2,073,600 pixels).
HD vs Full HD vs WQHD vs 4K UHD: resolution differences
The evolution of resolutions has brought us better image quality. With HD we had 1280 x 720 pixels, although most HD Ready TVs were 1366 x 768 pixels. Later came Full HD, taking the resolution 1920 x 1080 pixels worldwide and still has a large presence in our country.
Next came WQHD, or 2560 x 1440 pixels, which is widely used today in gaming monitors, although no such TV was ever released. Finally, we reached 4K UHD, with 3840 x 2160 pixels. Therefore, the pixels and resolution of each one are as follows:
- HD: 1280 x 720 pixels
- Full HD: 1920 x 1080 pixels
- WQHD: 2560 x 1440 pixels
- 4K UHD: 3840 x 2160 pixels
Distance to watch a 4K TV
There is a clear difference in resolution when switching from Full HD to 4K. By quadrupling the resolution, we also decrease the distance at which we can see a screen before we start to distinguish individual pixels. By sitting closer, we will have a greater immersion in the image given the same screen size.
The viewing distance depends on the size of the TV. For example, a 55-inch 4K TV can start to be seen properly at 1 meter, and a 65-inch TV at 1.2 meters. To see the same quality as a 55-inch 4K on a Full HD, you need to sit at least 2 meters away. In other words, if you already have a Full HD TV and you have it more than 2 meters away, and you want to buy another one of the same size, you won’t notice the difference in resolution, although you will be able to perceive other elements such as color or brightness.
4K content: where can I watch 4K movies and series?
The first 4K movies could be seen in 2011 in movie theaters in the United States, even though Sony had been offering movie projectors in that resolution since 2004. The first home projector was launched in 2012.
YouTube has supported 4K video since 2010 because there were already camera manufacturers that allowed recording in that resolution. They use the VP9 codec, which is open and developed in part by Google, instead of HEVC because they say it’s “better” for the platform. Since 2017, however, they have been able to upload videos recorded directly in HEVC.
The first paid streaming platform that started having 4K content natively and stably was Netflix, which in 2014 added House of Cards, Breaking Bad and some documentaries in that resolution. At that time they used the HEVC codec, where practically no 4K TVs sold in 2013 natively supported that codec. It was from that 2014 onwards that compatible televisions began to be launched, forcing those who had bought it before to buy separate players.
The first UHD 4K Blu-Ray players were released in 2016, along with Xbox One S consoles in 2016, PS4 Pro later that year, and then Xbox One X. Today, any TV over ?500 released after 2017 can play 4K without problems thanks to the ability to decode the HEVC codec in hardware.
Since then, the amount of content has not stopped growing. Nowadays we can watch movies and series in 4K on Netflix and Amazon Prime Video, as well as on the platforms of operators such as Movistar, Vodafone or Orange, which have a multitude of movies and series in their video store. In them we can also find linear channels in 4K, including those of football, in which LaLiga and Champions League matches are broadcasted in 4K. As for the satellite, in Spain there are no 4K channels, although there are a few in Europe. To watch them, it is necessary to have a DVB-S2 decoder.
As for Blu-ray, there are currently almost 1,000 movies available in this resolution on Blu-ray, although getting hold of some of them is difficult in Spain, in addition to the fact that their price is usually high. That’s why many users choose to download them from P2P networks in many occasions, where they also upload the discs as they are, or recompress them to 8 bits for those who don’t have panels compatible with 10 bits, or even switch to using H.264 codec instead of native H.265, which brings us to our next point.
HEVC: the codec used for 4K
As we said, all 4K UHD Blu-ray movies use the HEVC codec to compress video. This is because H.264 does not compress well enough, and HEVC (H.265), is much more efficient, being able to maintain the same quality as H.264 in half the space, or double the quality in the same space. This is achieved by increasing the number of blocks into which an image is divided, and it does so dynamically, by better adjusting the compression of a content.
It is possible to view 4K content compressed in H.264 or in the format we want, but it is much more inefficient and the file will take up more space. Therefore, we will almost always see these files with HEVC, or with VP9 if we download it from YouTube.
Most devices decode HEVC in hardware, but in some cases, like in Windows 10, it is necessary to download the HEVC extension from the Microsoft Store. There is also DRM that encrypts media content. For example, Netflix uses PlayReady 3.0 in Windows, while Blu-ray uses AACS 2.0 and AACS 2.1, which was cracked a couple of years ago, allowing you to get your Blu-ray movie content just as it is.