HDMI connections came almost 20 years ago to facilitate the connection between video sources and displays . The evolution has come to the "new" HDMI 2.1 that was presented in 2017 and which will be a strong point of the new PS5 or XBOX Series X consoles . And it is now when we begin to see televisions equipped with this connection and home theater receivers also arrive with it. The highlight is that it supports 8K video at 60 Hz and also 4K at 120Hz (smooth fast images). Its speed of communication will allow previously unheard of features thanks to the fact that the sources and the screen exchange information. Let's see what all this implies ...
HDMI 2.1: what resolutions does it support and how it compares in data flow with the previous
Seventh generation HDMI
As we said above, HDMI is already almost two decades old: in a single cable and for the first time audio and video traveled digitally, already in the 21st century. The first standard (HDMI 1.0) was released in 2003 and already allowed “Full HD” video (1080p at 60 Hz) with high resolution audio as well (up to 8 channels at 24 bit and 192 kHz). The next two evolutions (1.1 and 1.2) were small adaptations to allow higher quality sound to be transmitted, from DVD-Audio (almost disappeared) first and Super Audio CD (only for very amateurs) later.
The fourth version of HDMI, 1.3, arrived in 2006 and marked a change by increasing the data rate up to 10 Gb / s. Support was added for the new cinema sound formats (Dolby True HD and DTS-HD) for HD-DVD (defunct) and Blu-ray (new standard). It was carried by the Playstation 3 or the Xbox 360 . More innovative was the HDMI 1.4 (2009) capable of supporting video resolutions higher than Full HD 1080p and 3D images. In addition, on the same cable, it established an Ethernet connection between the components: one less cable.
In 2013 HDMI 2.0 was introduced , with a data rate of 18 Gb / s and that "jumps" from version to become the necessary standard for 4K . The sound can reach 32 channels, ideal for "3D" sound systems such as Dolby Atmos or DTS: X among others, and improves communication aspects between source and screen. Now, 2.1 takes another step in that direction.
HDMI 2.1 and resolution
The bandwidth jumps up to 48 Gb / s , ten times what USB 3.0 and more than double that of the latest USB 3.2. In video it is capable of supporting 10K resolution, but in practice it matters that it will allow the use of 8K sources and displays, or consoles with 4K120 resolution.
Video resolution, from Full HD to 10K
Speaking of resolutions , let's remember how many pixels each represents : the "high resolution" or Full HD came with 1,980 x 1,080 dots on the screen, which was followed by 4K with its 3,840 x 2,160 pixels . Most television channels broadcast in HD through their channels with this name, and some services such as Netflix already offer 4K images, available with UHD Blu-ray as well. The 8K resolution, present in some current televisions, is four times higher than 4K, going up to 7,680 x 4,320 points . The 10K is nothing less than 10,240 × 4,320 , still far from being everyday ... but this new HDMI already supports it.
Consoles and speed
Besides “how many dots” our images have, there are two other factors in the quality of the images. How fast these images are refreshed is one, and with what colors and dynamics, the other. That is precisely why it is necessary to increase the speed of the connection: HDMI 2.1 will allow 8K images to be transmitted up to 60 Hz, and what is surely more important now 4K images up to 120 Hz. Each “Hz” is a refresh per second, the minimum to see continuous movements are 24-25 (like cinema) and the higher it is, the more fluid we perceive the images.
When there are fast movements, like in games, speed is key to a perfect experience . The new generation of consoles (PS5 and XBOX X Series) will use those resolutions (8K60 or 4K120) and for them, among other things, comes HDMI 2.1. Something new will be the "VRR" (" Variable Refresh Rate ", variable refresh rate): the console or graphics card will adjust the frequency of the TV on the fly depending on the scene. Goodbye to stutter , tearing, and other out- of-sync effects . Goodbye also to delays, because HDMI 2.1 allows low latency modes to be automatically activated. It will take a compatible monitor or television to take full advantage of these new technologies.
We have already seen the importance of resolution and speed. One other key factor remains: colors and their dynamics… HDR . It is about being able to present colors on the screen with maximum precision of tone and luminosity.
Standard video dynamic range (left) compared to HDR (right)
The more advanced HDR modes are dynamic, that is, they allow the source and the screen to exchange information and adjust to each “frame” (screenshot or basic image). That's what HDMI 2.1 will allow with 4K and 8K images, as well as greater color depth (greater basic palette and more precision).
Until now, when connecting the TV with a home theater amplifier, it could pass the sound through the ARC (Audio Return Channel) of the HDMI. With eARC (“ enhanced Audio Return Channel ”) this takes a significant leap: ARC only supported basic digital sound (up to Dolby Digital + with compression). But eARC will support advanced formats like Dolby Atmos or DTS: X that until now had to be sent independently with another HDMI cable to the amplifier from the source. Now they can go straight from the TV to the bar or stereo.