Trying to wrap my head around Arc, ARC, Dolby Digital, Dolby Digital Plus and Atmos

Userlevel 4
Badge +8

I have or had every intention of purchasing the Arc and was really excited.

Now that it has been released I have about what it can and can not do with my current setup. It will be replacing my Beam that's connected to my Sony Bravia Android TV that purchase in 2018 though I believe it's a 2017 model.

So it has ARC but not eARC. What does this mean for me. I've been finding conflicting information.

My main concern is will I be able to get Atmos. I've read post that say yes and others that say no.

After spending lots of time googling info for my TV I have found that it supports Dolby Digital and Dolby Digital Plus (and honestly I don't know what it's outputting to my Beam). However no where do I see Atmos support or decoding for it. Will this mean no Atmos for me with the Arc or will the Atmos signals somehow be carried through the Dolby Digital Plus?

Please help... I may need to rethink my purchase. Normally I would speakers for my TV, not the other way around. 

Just FYI, I also have a pair of Sonos One's and a Sub Gen 2.

Thanks in advance for any feedback.


Best answer by Airgetlam 20 May 2020, 15:45

View original

This topic has been closed for further comments. You can use the search bar to find a similar topic, or create a new one by clicking Create Topic at the top of the page.

26 replies

Userlevel 1

I want to chime in and give you my two cents:


It was widely reported in the past (when the new Apple TV 4K was released) that the Apple TV 4K (only the 4K model!) plays Dolby Atmos in a “special” format (DOLBY MAT = “Dolby Metadata-enhanced Audio Transmission”). It looks like the reason for that is, that they want to mix the System Sounds and Siri voice over into the sound mix. By doing that, they have to decode the DD+ w Atmos Singal and put it back together with the System Sounds as a “DOLBY MAT” signal witch is a LPCM signal with Atmos information packed in it. This DOLBY MAT signal cannot be transmitted over regular HMDI ARC but only over eARC.



When “reviewers” are reporting, that they managed to get Atmos from Apple TV over a regular ARC connection out of their TV, the reason is probably their TV. Some TVs are apparently able to convert an DOLBY MAT w/Atmos signal into DD+ w/Atmos and send it via regular ARC to a soundbar.  



Regarding the observations of @jgatie: Could it be that a recent software update for the Apple TV 4K changed anything in that regard (always converting into DOLBY MAT)?