HDMI 2.1

HDMI 2.1 is the new standard of Image and sound transmission. How important is an HDMI 2.1 connection when buying a TV set? What advantages does it have compared to an HDMI 2.0 connection? What improvements in sound and picture can be expected thanks to HDMI 2.1? This article answers these questions.

The new HDMI standard

HDMI 2.1
Data rate up to 48 GBit/s
14 and 16 Bit colour depth
Variable Refresh Rate (VRR),
4K with 120 Hz and 8K with 60 Hz
Quick Media Switching (QMS)
Quick Frame Transport (QFT)
Auto Low Latency Mode (ALLM)
Display Stream Compression (DSC)
Enhanced Audio Return Channel (eARC)

Big differences to HDMI 2.0?

There are already televisions that have the (supposedly) new functions such as ALLM, eARC or VRR despite HDMI 2.0 connection. However, HDMI 2.1 makes the innovation of combining all these features in one connection for the first time. Thanks to HDMI 2.1, these functions will no longer be isolated, but will be combined into a new, uniform standard. An HDMI 2.1 connection therefore gives the customer the guarantee that the television he is buying has all the features listed in the table above. This provides more clarity and overview when purchasing a TV set and also creates a guarantee that the TV purchased is suitable for watching films as well as for gaming.

Data transfer rate of up to 48 Gigabit per second

HDMI 2.1 allows a data transfer rate of up to 48 Gigabit per second. This is a significant leap over the previous model HDMI 2.0, which can only transfer 18 gigabits per second. HDMI 2.1 also outshines Displayport 1.4, which has a transfer rate of 32.4 gigabits per second.

14 and 16 bit color depth

Thanks to HDMI 2.1 it will be possible to reproduce up to 16 bits of colour depth. The problem is that current TV sets support a maximum of 10 bits. In addition, the majority of visual content currently available has a color depth of only 8 bits. This applies not only to TV shows and Blu-Rays, but also to all PC and console games. To get 10 bit, you not only need a compatible TV, but also compatible content. All stages of production, as well as the hardware for playback, must be coordinated to get ”real” 10 bit color depth. A prerequisite that is currently not given. 16 bit colour depth sounds good in itself. The problem is that, due to the current state of technology, you even can get 10 bits in the rarest cases. That means that about the quality differences between 14 and 16 bit colour depth there can’t be nothing said at this point.

4K, 8K and even 10K with HDMI 2.1

For the regular user, the question arises as to how this enormous data transmission rate contributes to the picture and sound quality. The answer is quite simple: 48 gibabits per second means that 4K in 120 Hz and 8K in 60 Hz can be reproduced. With the HDMI 2.0 connection, only 60 Hz was possible at 4K. An uncompressed 8K signal could not be played at all. Apart from the lossless transmission of 4K and 8K signals, HDMI 2.1 has a Display Stream Compression function (DSC), which can reproduce a compressed 10K signal in 120 Hz.

Dynamic HDR formats in 4K and 8K for the first time

With Static HDR, static data from the player (Blu-ray player, receiver or console) is transmitted once to the TV set. The TV device applies the data for depth, detail, brightness, contrast and color space and uses these for the entire playback time. With dynamic HDR formats, such as HDR10+, each picture is calibrated individually so that every moment can be given the maximum visual expression. Thanks to HDMI 2.1, it will now be possible to play back 4K at 120 Hz and 8K at 60 Hz, when using dynamic HDR formats. With the HDMI 2.0 connection, it was also possible to play back dynamic HDR formats, but not with such high frame rates.

Automatic adjustment of the refresh rate with QMS

The Quick Media Switching Function (QMS) of HDMI 2.1 allows for the first time that TV sets can switch between different frame rates without delay. The TV automatically detects which frame rate the content being played back has and adjusts the refresh rate accordingly. QMS thus enables a smooth transition between 24 Hz, 60 Hz or 120 Hz. This eliminates picture drop-outs or annoying delays that can occur when switching. The constant change from Game to Film Mode is obsolete, as the TV will be able to make this change automatically and find the appropriate frame rate for each signal.

HDMI 2.1 – Perfect for gamers

HDMI 2.1 supports VRR. This means that the television can immediately match the refresh rate from the panel with that of the source device. This results in a strong reduction of frametearing and judder, as well as a reduction of the input lag. VRR is an essential feature for gamers and is already included in HDMI 2.0, but not in the higher resolutions and refresh rates. The Samsung Q70R for example, which has an HDMI 2.0 input, has a VRR range of 48-60Hz at 4K. With HDMI 2.1, VRR will also be possible at 4K with 120 Hz and 8K with 60 Hz. However, if the connection from the TV does not have the necessary bandwidth, an update to HDMI 2.1 will unfortunately not be possible.

HDMI 2.1 also has a Quick Frame Transport function (QFT). QFT significantly reduces the input lag and takes VR gaming to a new level by eliminating any delays between input and playback. Thanks to HDMI 2.1, the player’s movements can be captured and displayed immediately.

Thanks to the Auto Low Latency Mode function (ALLM), manual switching to gaming mode is a thing of the past. As soon as you switch on your console, ALLM automatically selects the ideal mode that guarantees the lowest latency. There are already some TVs that have this function. Despite their HDMI 2.0 connection. However, thanks to HDMI 2.1, ALLM will become the new standard for all TV sets.

HDMI 2.1 unfortunately only allows VRR, QFT and ALLM if the source device also has these functions. Currently there is no console on the market that offers all of the above features. However, the new generation of consoles will have the necessary equipment.

Enhanced Audio Return Channel (eARC)

ARC (Audio Return Channel) is part of the HDMI standard since HDMI 1.4. With ARC you can connect all source devices, such as consoles or Blu-Ray players directly to the TV and connect the TV to the receiver with a single HDMI cable. This enables bidirectional communication between the receiver and the TV set.

The limited bandwidth of the current ARC standard (1 Mbps) limits the quality of the audio that can be sent over the return channel. This makes it impossible to send high quality uncompressed audio to the receiver. The new ARC standard, which will be part of HDMI 2.1 and is called eARC, increases the bandwidth of the ARC channel from 1 Mbps to 37 Mbps. This significant increase in bandwidth allows the transmission of uncompressed 5.1 and 7.1 sound, such as DTS-HD or Dolby TrueHD, which are often the carrier signals for Dolby Atmos and DTS:X. In short, thanks to HDMI 2.1, consumers who use a high-quality soundbar or hi-fi system can expect a significant increase in audio quality.

The right cable

Even if you have an HDMI 2.1 capable TV and a compatible source device, you won’t get any advantages of HDMI 2.1 if you don’t have an ”Ultra High Speed” cable. The predecessor model ”Premium High Speed” is used with HDMI 2.0 and is characterized by a data rate of 18 GBit/s. The maximum picture format that could be transferred with the Premium High Speed cable was 4K at 60 Hz. This is no longer sufficient for HDMI 2.1. You need the Ultra High Speed cable to be able to use all the functions and play back 4K at 120 Hz and 8K at 60 Hz. If you want to upgrade to HDMI 2.1, you have to make sure that you are equipped with the appropriate cables.

For whom is HDMI 2.1 worthwhile?

If you look closely, you quickly realize that HDMI 2.1 doesn’t offer that many new features. The big difference to HDMI 2.0 is that HDMI 2.1 makes all the features of its predecessor much better and combines them in one connection. The almost threefold increase in data transfer rate enables a huge leap forward in terms of resolution, refresh rates and audio and picture quality. A leap that is so great that there is no adequate hardware and content basis for it. There are currently no movie and video game players that can take advantage of the massive bandwidth and all the features of HDMI 2.1. The HDMI 2.1 connection will therefore only be able to develop its full potential over time. Whether HDMI 2.1 and the associated playback of 8K is even reasonable for the regular consumer is explained in our article about the double-blind study.

Many of the features that HDMI 2.1 offers are primarily beneficial to gamers. Apart from eARC, customers who want to use their TV to watch TV or movies only need HDMI 2.1 to a limited extent. Those who are hesitant about buying a TV because it doesn’t got a HDMI 2.1 connection need not worry. Non-gamers can choose a high-quality TV like the Q90R, as it has almost all the features that HDMI 2.1 is expected to provide in the future. However, if you insist that the TV has to have HDMI 2.1 and don’t want to be patient, you can confidently purchase an LG C9 OLED.

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