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HDMI ARC and eARC: Audio Return Channel for beginners

Reduce wires, clutter, and confusion with HDMI Audio Return Channel. Here's how.

Sarah Tew/CNET

One of the best and yet least-used HDMI features is ARC, or Audio Return Channel. It's a feature that enables you to simplify your system and is compatible with most TVs, receivers and sound bars.

In its most basic form, ARC uses an HDMI cable to send audio from a TV back to a receiver or a sound bar. That means you can use a single cable for both audio and video, for example from the Netflix app built into your TV or from a connected game console, and use your TV for switching.

The upcoming eARC standard, meanwhile, improves on the original in a few key ways, which we'll discuss at the end of this article.

Do you need ARC?

To be fair, many people don't need ARC. If you only listen to audio using your TV's speakers and don't have a receiver or sound bar, then the feature is superfluous. The point of ARC is to send audio created by or switched through your TV to an external audio device, namely a sound bar or receiver.

And because the sound on most TVs is terrible, we strongly recommend getting at least a sound bar to improve the TV experience. Check out our how to buy a sound bar guide and sound bar vs. speakers for more.

If you have a sound bar or receiver of fairly recent vintage that has HDMI, it probably has ARC, too. Here's how it works.

arc-updated

On the left is a traditional non-ARC setup, requiring an HDMI cable from an Xbox to be connected to the audio system, another to send the video to the TV, and an optical cable to send the TV apps audio back to the audio system. With ARC, the HDMI cable connected to the TV can send the TV audio back to the audio system. A two-way street, if you will.

HDMI Licensing/CNET

Can you use ARC?

Check the HDMI connections on the back of your TV, sound bar, or receiver. If the HDMI port has ARC, it should be marked as such. Both your TV and the sound bar/receiver must have ARC for it to work.

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Note the ARC label on the HDMI output of this receiver. An HDMI-equipped sound bar would look similar.  

Onkyo

Setup

Most HDMI cables should work with ARC. Plug one end of the HDMI cable into the ARC-capable HDMI input in your TV and the other into the ARC-capable output on your sound bar or receiver.

There are basically two main ways to connect a system using ARC. For our purposes, we'll assume you have: a TV, a receiver or sound bar, a Blu-ray player and a game console (Xbox/PS4).

Setup 1: Connect the Blu-ray player and game console to the TV, then connect a single HDMI cable from the TV to the sound bar. The TV becomes the central hub of your entertainment system.

This setup lets you use your TV's remote to switch between the Blu-ray player and game console sources, and in most cases, you can use your TV's remote to control the volume.

The potential downside of this setup is you might not be able to get 5.1 surround sound. This is more of an issue if you are using a receiver instead of a sound bar. We'll discuss this more in the next section.

Setup 2: Connect the Blu-ray player and game console to the receiver/sound bar, then a single cable from the receiver/sound bar to the TV. Some budget sound bars might not have enough HDMI inputs for all your sources, in which case you'll have to use Setup 1.

In this setup, your receiver/sound bar is the central hub of the entertainment system. You will switch between your sources and adjust the volume using your receiver/sound bar's remote. You'll only use your TV's remote to turn the TV on, and access any apps built into the TV.

HDMI CEC control

Another HDMI feature is called CEC, or Consumer Electronics Control. Nearly every company has their own name for it, including SimpLink, Anynet+, BRAVIA Sync, and others. In theory, CEC will let the remote from one piece of gear to control another, as long as they're connected with HDMI. For instance, in Setup 1 above, your TV's remote can adjust the volume on your sound bar.

However, there's no guarantee it will work, especially across different brands or ages of gear. If there's any aspect of ARC setup that's going to cause you agony, it's this. You might not be able to realize the dream of using one remote, unless you get a universal remote control. If it doesn't work, though, Google might help. It could be as simple has having to turn on your gear in a certain order. But in the end, this control aspect just might not function.

Troubleshooting

The last setup step is making sure your TV and sound bar/receiver knows to send or look for the audio being sent over the Audio Return Channel. If you've got everything connected correctly, and it's not working, time to dive into the settings. It should be fairly obvious in the setup menus, but if not, all owner's manuals are on the manufacturer's website.

One last thing to check. If everything else seems correct, but you're still not getting audio, or you get audio with some sources but not all, check the audio output settings on the TV or the problematic source. Look for a setting that lets you change "bitstream" to "PCM" or vice versa. Switching to the other might clear up the issue.

sony-ht-st5000-soundbar

Again, note the ARC label on the HDMI connection that would connect to the TV. In Setup 1 mentioned above, you'd connect all your sources to the sound bar, and just run the one cable to the TV. 

Sarah Tew/CNET

Issues with 5.1

As great as ARC can be, there is one big issue: 5.1. Technically, TVs aren't allowed to send 5.1 audio over HDMI. In other words, if you're watching a movie on Blu-ray with 5.1 Dolby Digital or DTS and it's connected directly to your TV (Setup 1, above) your receiver might only be able to get 2.0 audio. TVs that can do this are said to have "5.1 passthrough."

This restriction isn't fully enforced, so some TVs do it anyway. Other TVs will output 5.1 via the optical output, but not ARC.

Our friends over at Rtings.com have an extensive list of what TVs do what, though it only goes back two years.

Keep in mind that this issue is only relevant if you have a 5.1 source, like a Blu-ray player or game console, and you're trying to send that device's audio via ARC from the TV to a receiver. If your TV doesn't support 5.1 passthrough, you can either connect that source to the receiver directly, or you can connect the TV and receiver with an optical cable. Optical cables don't carry Atmos, however.

Connecting a source like Blu-ray directly to the receiver/sound bar has another benefit: Dolby True HD and DTS Master Audio. These higher-fidelity formats can't be sent over ARC. But they will be able to with eARC.

eARC and HDMI 2.1

The latest version of the HDMI interface is 2.1, and it offers numerous important changes. Relevant to us here is eARC, or enhanced Audio Return Channel.

While Dolby Atmos can be passed over regular ARC today (via Dolby Digital Plus) eARC offers improved bandwidth for higher-quality Dolby TrueHD and DTS-HD Master Audio streams, including Atmos.

The new format also has lip-sync compensation built-in. This feature was optional in ARC, but is now required. This lets you more easily line up the sound with the visuals, something that has always been an issue in the modern TV era.

earc
HDMI Licensing

We'll start seeing gear with eARC this year. To take advantage of the new features, both pieces of gear must be eARC compatible. It is backward-compatible with ARC, but not with the new features. Fortunately, eARC should be available in far more gear than just high-end 8K TVs. Even though most TVs don't need the other features of HDMI 2.1, manufacturers will be allowed to implement just the portions of HDMI 2.1 most useful in that TV, i.e. eARC.

You probably don't need new HDMI cables for eARC. Older cables with Ethernet, either Standard or High Speed, will work. The new Ultra High Speed cables will work as well, of course. Chances are your current cables have Ethernet and you didn't even know, so they'll probably work.

ARC reaction

On paper, ARC is a great way to simplify your home theater system. The reality is… complicated. Read any user reviews about any product with ARC and there will be issues getting it to work. Depending on the age of your gear and complexity of your setup, getting ARC running and staying running can be frustrating.

Our advice for most people is to connect your sources to your receiver or sound bar, if they're capable, and only use ARC to get audio from your TV's internal apps. Not every system will work like this, not least if your sound bar doesn't have enough HDMI inputs. However, with infinite setup possibilities, we can't offer perfect idealized advice. Connecting directly to your audio device will, in theory, offer the best chance for the highest quality audio.

Also, even though optical cables and connections are disappearing, they offer a more traditional way to connect audio that might offer fewer issues, at the expense of some sound quality and theoretically less simple usability. 


Got a question for Geoff? First, check out all the other articles he's written on topics like why all HDMI cables are the sameTV resolutions explainedLED LCD vs. OLED and more.

Still have a question? Tweet at him @TechWriterGeoff, then check out his travel photography on Instagram. He also thinks you should check out his best-selling sci-fi novel and its sequel