What’s the Difference Between HDMI ARC and eARC?

Q I want to get the highest possible audio quality from my home theater system when using the streaming apps on my new Samsung QN90A Neo QLED 4K smart TV. I have a Denon AVR-A100 A/V receiver that has an HDMI ARC port. My previous TV only had an optical digital output, and I used that to connect it to the Denon, but I’m now ready to use the Samsung’s HDMI eARC connection to get sound from the TV. Here’s my question: Is my Samsung TV’s eARC port compatible with my Denon receiver’s ARC port? By compatible, I mean will the Denon “understand” the Dolby Digital Plus bitstream coming from the apps and just ignore any Atmos metadata? —George Perkins / Madison, WI

A Unlike a standard HDMI ARC (Audio Return Channel) connection, the HDMI eARC (enhanced Audio Return Channel) connection found on more recent TVs and audio gear fully supports Dolby Atmos. Another audio benefit specific to HDMI eARC is that it supports the high-resolution Dolby True HD and DTS-HD Master Audio soundtracks found on Blu-ray discs. In your setup, however, you’ll be getting sound from the Samsung TV’s built-in apps, and in the streaming world Atmos information is conveyed as an extension to Dolby Digital Plus, a lossy bitstream format that nonetheless uses a higher data rate than standard Dolby Digital soundtracks.

The good news here is that an HDMI eARC connection like the one on your new TV is backward compatible with a regular HDMI ARC connection like the one on your Denon receiver. The bad news — as you’re already aware — is that your Denon receiver doesn’t support Dolby Atmos processing. Fortunately, Dolby Digital Plus bitstreams can be conveyed over regular HDMI ARC connections, so you will be able to get higher-quality 5.1 soundtracks from compatible streaming apps.

Note that I said “compatible.” Unfortunately, not all streaming apps on all TVs deliver Atmos, or even regular 5.1 Dolby Digital soundtracks. And since your goal is to get the highest possible audio quality from your home theater system, I’d recommend trying out various streaming apps on the Samsung to see which ones provide 5.1-channel sound. Those specific services should be the ones you commit your subscription dollars to.

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