Can I Get Atmos From an HDMI ARC Connection?
We’ve talked extensively about HDMI ARC and eARC. The biggest difference is that eARC can carry full lossless audio while ARC can only carry lossy codecs. You can read more about this in detail here. Dolby Atmos and DTS:X are often spoken in conjunction with lossless codecs like Dolby TrueHD or DTS:MA. Does that mean that an ARC connection can’t carry Atmos and DTS:X? Let’s discuss.
The Simple Answer
Some of you have come here because you are confused. You’ve sometimes been able to pass an Atmos or DTS:X signal through your HDMI ARC connection. Other times it hasn’t. You aren’t sure why. The simple answer is that it depends. It will sometimes work, other times it won’t. If all you wanted was someone to tell you that you weren’t doing anything wrong when it wasn’t working, go with our blessing. It isn’t your fault that it doesn’t always work.
The Longer Explanation
As we’ve explained before, Dolby Atmos and DTS:X are object-based audio formats. These formats are layered on top of an existing audio codec as metadata. This is great for backward compatibility. Older gear can still decode the base layer of audio while newer gear can recognize the metadata and give you the object-based audio.
The reason why you can sometimes realize Atmos through your ARC connection is because of this layering. If the base layer is a lossy codec that can pass through an HDMI ARC connection, then you’ll see “Atmos” on your receiver. If the base layer isn’t compatible (usually connected to a lossless codec), then you’ll get a lossy version of the audio. Remember that all lossless codecs contain a lossy version for backward compatibility. This allows your ARC connection to pass audio but will likely be without the Atmos or DTS:X metadata.