What Are HDMI ARC and eARC and How Do They Work

What Are HDMI ARC and eARC and How Do They Work?

In Cables, General by Jonah MatthesLeave a Comment

HDMI has greatly reduced the number of cables necessary to set up your home theater system, and ARC and eARC are just one way it does that. The HDMI ARC or audio return channel and eARC (enhanced audio return channel) allows for audio signals to be passed in both directions, allowing you to reduce the number of cables you need to set up an A/V receiver.

HDMI ARC and eARC allow audio channels to travel in both directions simultaneously. This allows you to cut the number of cables you have to use, particularly when you are using an A/V receiver as the center of your home theater set-up. It also allows you to control the volume with one remote. Where HDMI ARC is capable of transmitting stereo sound and compressed 5.1 sound on the return channel, HDMI eARC allows for up to 8 channels of audio to be sent and returned over a single cable.

HDMI ARC and eARC are fairly straightforward to take advantage of if you have the right equipment. Using this technology will allow you to use one remote to control your home theater system’s audio volume. It will also allow you to reduce the number of cables you will have to use. As such, set-up is a breeze once you know what you are doing.

What Is HDMI ARC?

What is HDMI ARC

HDMI combines audio and video channels into one cable. This is convenient because it reduces the number of cables you have to plug between the same two devices, however, it makes it impossible to split the audio signal from the video without special equipment (and more cables).

This means that if you want to hook up an auxiliary device such as a DVD player to your TV through your A/V receiver, you would have to hook up your TV twice: once for the video signal being sent from your DVD player through your A/V receiver to your TV, and one for the audio signal coming from your TV when you aren’t using your DVD player.

HDMI ARC allows for the transmission of audio in both directions, allowing you to combine both of these signal paths into a single cable. This allows you to control your TV and A/V receiver with a single volume control.

How Does HDMI ARC Work?

How Does HDMI ARC Work - Smaller?

An HDMI connection has 19 pins, each sending a digital signal describing some component of the video, audio, or device information. HDMI ARC is transmitted over two of those pins.

If you are familiar with how analog audio and video work, that won’t help you here. Two pins don’t mean two channels of audio.

When devices connect via HDMI, they do a digital handshake, exchanging device information which becomes the basis for a shared key passed between the devices. This key is used to encrypt all the data being transferred between the devices. This ensures, among other things, that unauthorized devices do not intercept the signal. This was designed as an anti-piracy measure.

What’s important to note here, however, is that HDMI connections are inherently designed to send information in both directions. In this way, the two-way capability enabled by HDMI ARC isn’t actually that incredible.

What is incredible is that by transferring data at up to 1 Mbps, HDMI ARC can transmit uncompressed stereo sound and compressed surround sound.

When Would You Use HDMI ARC?

When to Use HDMI ARC - HDMI ARC Diagram

The most common application of HDMI ARC is when you connect all your devices through an A/V receiver or soundbar. In this case, it would pass any video signals from, for example, a BluRay player to your display device.

However, if your display device is broadcasting, for instance, the cable that’s plugged into the TV, the HDMI ARC channel will send audio from your display device to your sound system or soundbar.

HDMI ARC is also useful because it enables the Consumer Electronics Control (CEC) feature that had gone largely unused before the intervention of HDMI ARC.

CEC allows you to control both devices connected on an HDMI ARC channel with a single remote. This allows you simultaneous power and volume control. In this way, HDMI ARC is still useful even if you are plugging all of your devices directly into the display device rather than your A/V receiver or soundbar.

What Equipment Do You Need for HDMI ARC?

For starters, all of the equipment you intend to hook up via HDMI ARC needs to be capable of sending and receiving HDMI ARC signals. HDMI ARC has been available since HDMI 1.4 was released in 2009, so almost all TVs and most soundbars and A/V receivers will come equipped to use it.

Further, you will need an HDMI cable that is version 1.4 or better and capable of high-speed data transfer. Since HDMI 1.4 has been around since 2009, it would be pretty difficult to find an HDMI cable that doesn’t match these specs.

How to Set Up HDMI ARC

To set up the hardware connection, simply plug the HDMI cable into the HDMI port on your devices that indicate HDMI ARC capability (they’ll usually be labeled ARC).

To enable HDMI ARC, you will need to turn your display device’s internal speaker off and enable both HDMI ARC and CEC controls. This is usually found in the settings menu under system settings, audio settings, or something similar.

To make things more confusing, different brands have trade names for what they call CEC. Check out our list of the different commercial names for HDMI CEC. Consult your devices’ manuals for how to enable it on each device.

What Is HDMI eARC?

HDMI eARC is a newer technology released in 2017 with HDMI version 2.1. HDMI eARC works a lot like HDMI ARC, except, as the name Enhanced Audio Return Channel implies, the technology is much improved.

Like HDMI ARC, eARC works on two pins, but unlike HDMI ARC, it also uses the ground signal of a third pin. HDMI eARC is also used to reduce cables between display devices and A/V receivers or soundbars.

Set-up is largely the same as it is for HDMI ARC, but you will need newer cables. One distinct advantage is that the combined HDMI and ethernet that makes HDMI eARC work allows you to skip the step of setting up your devices to enable HDMI eARC. It’s plug and play!

Unfortunately, because the technology is so new, it’s not yet widely available in new home theater equipment. LG was an early adopter among TV manufacturers, and Onkyo, Pioneer, and Sony all issued HDMI eARC firmware updates on select A/V receivers and soundbars. More devices equipped with HDMI eARC are slowly entering the market.

What Makes HDMI eARC Stand Out?

There are a number of features that make HDMI eARC stand out from HDMI ARC or its predecessors. As just mentioned, HDMI eARC improves on set-up. It also improves on sound quality.

HDMI eARC Advantages:

  • 37 Mbps (megabits per second)
  • Uncompressed surround sound
  • Plug and play

HDMI eARC allows for a maximum bandwidth of 37 Mbps enabling the handling of better quality audio. Because it is 37 times faster than HDMI ARC, it is able to handle both uncompressed 5.1 and 7.1 surround sound, but also object-based audio formats like Dolby Atmos and DTS:X.

With HDMI eARC, device discovery is automatic. This means you don’t have to page through the settings to set your display device to discover your sound system manually. Just connect the HDMI eARC ports with an HDMI 2.1 ultra-high-speed cable and you’re good to go.

What Equipment Do You Need for HDMI eARC?

HDMI eARC requires HDMI 2.1 or higher hardware. This may be a rarity still as device manufacturers are still adopting the HDMI 2.1 protocol. However, that’s expected to accelerate over time.

Second, you need an ultra-high-speed HDMI 2.1 or higher cable to connect your devices. HDMI 2.1 has been on the market for two years, so it’s unlikely you’ll find an HDMI cable that isn’t an ultra-high-speed HDMI 2.1 but check the packaging just to be sure.

Like with HDMI ARC, you can use either your display device, your A/V receiver, or soundbar to be the central hub for all of your devices with HDMI eARC. As long as your display device and your sound system are hooked up via the HDMI eARC ports.

Is HDMI eARC Backwards Compatible with HDMI ARC?

This depends on what you mean by backwards compatible. HDMI eARC has ARC fallback, meaning that if you hook up one device with HDMI eARC with another device that doesn’t support it, the devices will fallback to broadcasting an HDMI ARC signal instead.

This means your audio device will not be automatically discovered, and you will have to initiate the digital handshake manually. This also means it will be broadcasting with a maximum bandwidth of 1 Mbps rather than 37 Mbps, meaning no lossless surround sound.

If, however, you are connecting two HDMI eARC capable devices with an HDMI 2.0 or lower cable, you might not get it to work. The results of doing so are unclear and may depend on the devices themselves, though it is unlikely you will damage your equipment by using the wrong HDMI cable since the pin configuration and plug shape are the same.

Your best bet, as always, is to make the inexpensive upgrade to an ultra-high-speed HDMI 2.1 or higher cable.

Set Up Your System

As you can see, using HDMI ARC and eARC is fairly straightforward and will reduce the number of cables and remotes you need to use.

HDMI eARC improves upon HDMI ARC by supporting lossless surround sound formats and discovering devices automatically. HDMI eARC hasn’t saturated the market yet, but it is expected to do so soon.

In the meantime, we hope this guide can help you navigate HDMI ARC until you decide to upgrade.

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