Everything you need to know about HDMI 2.0, 2.0a, 2.0b and 2.1

It wasn't too long ago that HDMI 2.0 was announced. Shortly thereafter, the HDMI 2.0a, HDMI 2.0b and HDMI 2.1 versions followed. What confusion had settled in the past regarding the HDMI standard is now boiling up again - more complicated than ever. So: what should you know about these connections now? Let's try to explain it in simple terms:

HDMI 2.0, HDMI 2.0a, or HDMI 2.0b - simply explained!

What is the relevance of new HDMI versions in general?
HDMI versions were and are basically designed as internal version designations for manufacturers of HDMI-compatible devices and should not really matter to the end user. The HDMI Licensing Org. itself has pointed out several times that the use of version designations is more likely to irritate consumers than help them. TV manufacturers have recognized this and are often very reluctant to provide detailed version designations for HDMI inputs. Cable manufacturers, on the other hand, often just flaunt supported HDMI versions.

So why should you care?

Especially if you want to use modern devices like a 4K HDR TV with a new 4K HDR video player or a 4K game console smoothly, it's worth taking a look at the HDMI versions used to ensure the best possible signal transmission. Even with modern 4K TVs, the HDMI version often differs depending on the connection and thus influences the transmission properties!

To avoid nasty surprises, it pays to roughly know and understand the HDMI versions of existing devices.

What do the HDMI versions mean?
If you buy new devices with HDMI connection, you should make sure that they are at least equipped with HDMI 2.0. This ensures 4K resolution at 60Hz. More importantly, HDCP 2.2 is included as a copy protection protocol so that 4K content can be played from an external device like a 4K Blu-Ray player.

Any device connected between two HDMI 2.0 interfaces must also be equipped with at least HDMI 2.0 / HDCP 2.2. This means that an HDMI 2.0 4K player and an HDMI 2.0 TV cannot be combined with an HDMI 1.4 soundbar in between, for example.

Info: Of course, all versions are backwards compatible, so an HDMI 1.4 Blu-Ray player can be connected directly to an HDMI 2.0b TV.

The HDMI 2.0 updates a and b contain various refinements; especially with regard to the HDR standard. For example, HDMI 2.0b is the first to support Hybrid Log Gamma (HLG) transmission, which is required for advanced HDR images. Currently, this support is still quite irrelevant. HDMI 2.0b is currently especially interesting because many modern TVs come with this connection as standard. HDMI 2.0b is often installed instead of HDMI 2.1 connections. Which raises the question:

What are HDMI 2.1 connectors?
HDMI 2.0b and HDMI 2.1 are worlds apart. With HDMI 2.1, 10K resolutions and 120 Hz transmissions are suddenly possible. Just to put things in perspective, industry heavyweight Apple only recently introduced support for 4K and HDR on its Apple TV. And streaming heavyweights like Netflix are also currently keeping busy with the smooth delivery of 4K content. It will likely be many months if not a few years before there are enough devices and (more importantly) content to max out the HDMI 2.1 standard. A switch to HDMI 2.1 would mean a complete renewal of cables and connection sockets - currently an unnecessary expense.

So for the use of modern devices, the HMDI-2.0b standard is the definitive one. Here is an overview of its performance compared to HDMI 2.0, 2.0a and HDMI 1.4, and the differences:

HDMI Version Max. Resolution Max. 4K Frequency HDCP 2.2 HDR HLG
1.4 4K 30Hz No No
2.0 4K 60Hz Yes No No
2.0a 4K 60Hz Yes Yes No
2.0b 4K 60Hz Yes Yes Yes
2.1 10K 120Hz Yes Yes Yes

Does HDMI 2.0 require special HDMI cables?
Whether a new HDMI cable is necessary depends on several factors. The 4K transmission standard has already been supported in theory for HDMI cables of all kinds for many years (keyword: highspeed). However, it can always happen that the cable is not able to transmit the high resolutions. Contrary to popular belief, this has little to do with price. This fate can strike expensive as well as cheap cables and is rather due to the cable specification used by the manufacturer. If you want to make sure your cable works smoothly with HDMI 2.0b (4K at full 60Hz and HDR10+), reach for an HDMI cable with the Premium label. The Premium Label was developed in 2017 by the HDMI Licensing Organization specifically for HDMI cable 4K and smooth operation of HDMI 2.0 features.

HDMI Cable with Premium Label for HDMI 2.0 Features

Which version should new devices support?
Currently, the credo is: HDMI 2.0! Regardless of the device type, at least this standard should be present. Whether the port is a or b is not always specified by the manufacturer. However, if the product claims HDR, it is probably at least 2.0a and possibly 2.0b.

Are subsequent updates from HDMI 2.0 to 2.1 possible?
In the future, the question will arise whether a product can be updated to "a", "b" or ".1" via a firmware update. There is no clear answer to this yet. The HDMI Forum, the developers of the HDMI standards, are understandably keeping mum with information. They don't like to reveal early on how manufacturers are preparing for a possible coming changeover. The important question for us users is: can HDMI 2.0b features theoretically be retrofitted via firmware update if HDMI 2.0 or even just HDMI 1.4 is already in place? The answer: Theoretically, yes, at least for devices from the last 2 years or so, since they usually have the necessary hardware. In practice, however, this is unlikely to happen, because experience shows that manufacturers have little interest in retrofitting their old devices with new functions.

And what about HDMI 2.1? Can a jump from HDMI 2.0 to HDMI 2.1 be retrofitted via a software update? The answer here: Clearly no, at least according to the current state of the art. HDMI 2.1 requires much more powerful hardware (note 10K@120Hz vs. 4K@60Hz) and currently no devices are being shipped with HDMI 2.1 capable hardware just on spec.

Conclusion: HDMI 2.0 is the current standard
Although there are a variety of options for the HDMI standard, the main focus is currently on the HDMI 2.0 standard. Whether this includes a or b is only relevant when the device is used for transmitting HDR pictures with HLG - which, by the way, is still a real rarity, even among current top devices. It is important that all intermediate devices comply with the same standard - otherwise the TV will remain dark.

HDMI 2.1 is not completely a dream of the future, but it is not a modern necessity either. Currently, the appropriate end devices and content in 10K quality are still missing. Realistically speaking, the market is still a good two years away from corresponding devices. So there is no need to worry about this standard at the moment. We will have to wait and see what compatibility with existing standards will look like.

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