HDMI 2.1, ARC, and eARC explained

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The difficulty of trying to figure out which cable to choose and what HDMI, ARC, and eARC have to do with connecting your TV and soundbar is a common complaint these days. So, if you feel confused when you see these acronyms, don’t be. They are actually pretty easy to understand once you take a closer look. So, let’s get into it.

A closer look at HDMI

HDMI (High-Definition Multimedia Interface) is a technology used to pass high-definition video and audio between multimedia devices (like a TV and a soundbar). HDMI 2.0 can carry up to 18 Gigabytes per second (Gbps). More data translates into higher resolution (better picture) and clearer, more in-depth sound.

The next evolutionary step in this technology was a real game-changer though — HDMI 2.1 can transmit up to 48 Gbps. This increase in bandwidth capacity makes some pretty amazing things possible in the world of audiovisual technologies.

For many users, gamers in particular, the jump from HDMI 2.0 to HDMI 2.1 brings with it some highly anticipated features. Where HDMI 2.0 was limited to 4K resolution at 60 frames per second, HDMI 2.1 increases that anywhere from 4K at 120 frames per second, or 8K at 60 frames per second, or all the way up to 10K resolution at lower frame rates.

The increased bandwidth also brings with it support for the new eARC standard, affording you greater audio format compatibility. Just make sure all your devices support HDMI 2.1 and that you're using a HDMI 2.1 “ultra-high-speed” cable to take full advantage of all these great features. 

ARC and eARC: what’s the difference?

ARC and eARC are both powerful features of HDMI.

ARC (Audio Return Channel) allows you to send audio from your TV to your soundbar or AVR using a single HDMI cable.

eARC (or (Enhanced Audio Return Channel) builds on this technology, leveraging the increased bandwidth of HDMI 2.1 to support a wider range of audio formats as well as expanded features such as automatically correcting processor delays so that your audio and video always match, as well as lip sync correction.

Gaming and HDMI 2.1

If your TV supports eARC, and you love to game, then you’ll want to hear about these new features. HDMI 2.1 has been a particular boon for gamers as it offers several features that have improved the gaming experience. These include Auto Low Latency Mode (ALLM), Quick Frame Transport (QFT), and Variable Refresh Rate (VRR) all of which lead to a more fluid and seamless game play. Let’s look at them one by one.

Auto Low Latency Mode (ALLM) needs to be turned on manually in the settings of your TV display. When you set your TV display on Game Mode it activates this feature which sends a signal from your console to your TV that reduces lag time so that game play is seamless.

Before a visual frame can be displayed it first needs to be processed. If the frame is not fully processed before it is displayed a lag occurs (like when a character seems to get stuck for a second) and can also lead to decreased responsiveness (you smash a button, but your character doesn’t move in time with your action). Quick Frame Transport (QFT) solves for this by quickly transporting the frames once they have been processed.

Similar to QFT, Variable Refresh Rate (VRR) increases the speed in which frames are displayed so that there is reduced latency in the picture (your character goes from one environment to another and there is no lag between scenes, for example.)

Do I need to buy a special cable for HDMI 2.1?

The good news is that HDMI 2.1 is backwards-compatible with any HDMI cable that you already own, meaning you will still be able to use your new TV or soundbar if it doesn’t come with the cable and you already own an HDMI cable of a previous standard.

However, they may not allow for the optimal frame rate that an HDMI 2.1 cable can deliver, so for the best possible viewing experience, we recommend that you use your device with the new standard of HDMI 2.1 cable.

Final recommendations

To make sure you get the most out of your entertainment setup, we recommend pairing TV and soundbar devices that support eARC. This will give you the broadest format support so that all your favorite Dolby Atmos content will play back like it should.

Don't worry, if your TV supports eARC but your soundbar or AVR only supports ARC you will still be able to enjoy spectacular audio, however due to bandwidth limitations playback support for certain audiovisual formats may be reduced. To check if the devices you already own support ARC or eARC just look for the label on your device's HDMI ports.

How to find entertainment in Dolby

To get the full Dolby experience, brought to you in Dolby Vision and Dolby Atmos, you need to first make sure you are engaging with content created in Dolby. You can find entertainment in Dolby on any number of popular streaming services such as Apple TV+, Netflix, HBO Max (US), Paramount+ (US), Amazon Prime Video, and Disney+. As well as cable services such as Sky and BT Sport in the UK and Comcast in the US. Be sure to look for the Dolby Vision and Dolby Atmos badges on the title pages of your favorite entertainment.

Many services will offer Dolby Vision and Dolby Atmos as part of their standard subscription. If not available, check with your service provider as you may need to upgrade to a different subscription plan.