The next time you set up a TV or connect a soundbar, you might notice that one of your HDMI inputs is labeled "ARC." Though you may not realize it, those three letters indicate one of the best home-theater features — one that can save you money, reduce your cable clutter and simplify your home-theater setup.
What is ARC?
The often-overlooked ARC stands for "Audio Return Channel," and ever since the HDMI 1.4 standard was introduced, ARC has been available on TVs, soundbars and receivers. This protocol offers two-way communication between devices over a single HDMI connection. Essentially, the HDMI ARC port lets you use HDMI as both an input and an audio output.
Since ARC was introduced in 2009, it has become a very common standard, and you'll find it on virtually all TVs, soundbars and receivers sold in recent years. Anything that works with the HDMI 1.4 standard should support ARC, but check the documentation for your specific devices to be sure.
What can you do with ARC?
That two-way flow of sound means that you can do some things that used to require extra cables.
First, you can connect your audio system with a single HDMI cable. Connect your soundbar to the TV using the designated ARC-capable port, and you can use it for every device that connects to the TV, including Blu-ray players, game consoles and other devices. And it does that through the TV itself, instead of requiring a separate audio receiver.
Second, you can run these connections through the soundbar itself, letting you shift the multiple HDMI connections from the TV to the soundbar without requiring any additional setup. This is especially helpful for instances in which your TV is wall mounted and you either don't have access to all of the HDMI ports or simply want a cleaner look with fewer cables running to and from the TV. It also means fewer cables to install.
When your TV is connected to a soundbar or speaker system, you can also use the ARC connection to deliver TV audio to your speakers. Audio going to the TV from an antenna, for example, can also be output over HDMI and piped through the soundbar instead of just the TV's built-in speakers. This is especially important for smart TVs, for which streaming services deliver all content via Wi-Fi, with nothing to feed into a receiver. Instead, the ARC connection lets you output that sound to your soundbar without having to connect with a dedicated audio cable.
You can also use this in conjunction with another HDMI standard, called Consumer Electronics Control (HDMI-CEC), which lets you control external devices – like Blu-ray players or satellite boxes – using you TV remote. By using the ARC connection for audio and the HDMI-CEC functionality (this should be enabled on your TV by default), you can reduce both the number of cables used and the number of remote controls needed for your home theater.
Setting up for sound
It may take a couple of extra steps to get everything activated and set up for ARC, depending on your TV's manufacturer and the specific model.
First, determine which port(s) have ARC support. Most TV manufacturers offer ARC output over only one HDMI port instead of all three or four ports on the set. This is usually indicated by a label on the set itself. If the HDMI ports aren't clearly labeled, you can check the TV manual, which should indicate which HDMI port to use.
Second, you may need to activate ARC output on the TV. You will generally find this feature in the Settings menu, under Audio. While many TVs auto-detect devices with ARC capability, others require you to turn on the feature manually.
Finally, just plug in your stuff. This is dead simple; any HDMI cable will work. The only thing to keep in mind is that the ARC-enabled port needs to be connected to your external audio device.
While the simplicity of ARC and audio-over-HDMI is great, it's not entirely perfect. The ARC standard was designed specifically to replace S/PDIF digital audio outputs (also called TOSLINK), and thus supports every audio format that would normally pass through S/PDIF: Dolby Digital, DTS and PCM audio. It can handle both the TV's regular two-channel audio and 5.1 surround sound without any trouble.
But it also has the same limitations as the S/PDIF standard it replaces. Namely, it can't send HD or high-bit-rate audio used by standards like Dolby Atmos and DTS:X. This is especially irritating because downstream audio over HDMI can carry the signal with no problem; it's purely a limitation of the ARC spec.
Even more irritating, some TVs actually downgrade the audio output over ARC, converting everything to two-channel sound even if it originated as 5.1 audio. It's not common, but depending on your make and model of TV, you might actually wind up with lower sound quality over ARC. In these instances, connecting an extra audio cable or two may be worth the trouble.
What comes next: HDMI 2.1 with eARC
In 2018, HDMI 2.1 will begin showing up on TVs and sound equipment, and with it will come a new and improved audio technology, called Enhanced Audio Return Channel, or eARC. The biggest improvement eARC offers is support for full-resolution audio signal, meaning that it will support Dolby Atmos and similar uncompressed sound.
Unlike the original HDMI ARC, which works with all HDMI cables, eARC will require new cables that meet the 2.1 spec. And if you're looking to upgrade your TV early next year, be ready to shop for a new soundbar, too.
Credit: Tom's Guide