Hi @chromos, thanks for reaching out with the Sonos Community! I appreciate you sharing this with us and I’m thinking why you’re getting that Atmos signal is because your Arc is connected to your TV physically using the HDMI cable and when you are streaming AirPlay audio to Sonos Arc using your phone and you open the Sonos app, are you still seeing within the Sonos App on the "Now Playing" screen, that the Arc is receiving an Atmos signal? Keep us posted here. We and the community are always here to help.

Hi Krishma, after doing a bit more research, it looks like the ‘'Play Purchases from iCloud’ option has been removed from tvOS14. I used to keep that OFF to force the Apple TV to use the stream from the device, instead of getting the stream from the internet. 

Now with the option removed, it is entirely possible that the Atmos signal I saw was because the Apple TV was streaming from the internet instead of my device.

That being said, I’m only interested in this topic because I’m anxiously waiting for the Arc firmware to support LPCM over eARC (hint hint). 

Hi @chromos, thanks for letting us know about that and yes, we are committed to adding support for uncompressed McLPCM to Arc, but that we don’t have any time frame to share as to when. I'll make sure your voice is heard with the team. 
Please let us know if there’s anything else we can help you with. We and the community are always here.

Education question.  I do see a lot of talk about the LPCM.  May I as what is it and why does everyone want it?  Is it going to make something work better for everyone, or just some people in certain configurations?

Hi @Immersive, Xbox and Apple TV 4K encode Dolby Atmos metadata using the multichannel LPCM codec to deliver Atmos (the other codecs for that can carry Atmos are Dolby Digital Plus and Dolby TrueHD). 

Currently the Sonos Arc doesn’t decode multichannel LPCM, and previously I couldn’t get Dolby Atmos from my Apple TV 4K. 

However, something has changed and now I find that I can, even without the promised Arc firmware update. As mentioned, tvOS 14 came out last week, and there was also a recent update for my LG OLED TV, so a combination of those somehow has made it possible.

Hi @Immersive, thanks for reaching out with the Sonos Community and for the assistance, @chromos.

Yes, uncompressed MultiChannel PCM is the highest quality that can be obtained for surround audio.

As such users who have TVs that support Uncompressed MultiChannel LPCM and compatible content and playback devices will want to use this setting. 

If users use a TV that supports Uncompressed Multichannel LPCM and a source device that too outputs Uncompressed Multichannel LPCM  like Apple TV 4K in combination with a Sonos Arc, they won't receive a center channel.

This is because the Sonos Arc does not yet support Uncompressed MultiChannel Linear PCM signals. 

A few weeks back, updates to the top line LG TV's fixed an issue whereby LG's 2019 & 2020 TV's didn't pass Uncompressed McLPCM.

This now means using these TV's have the capability to playback Uncompressed MultiChannel PCM same with @chromos.

Will update this thread when we do.

Please let us know if there’s anything else we can help you with. We and the community are always here.

chromos… thanks.  Weird.  I have the LG OLED B8 and have ATV4K connected to TV via HDMI. And HDMI ARC to Sonos Arc.  I have been receiving DA.  I seem to have a center channel.  I will receive Arcana on Wednesday which I planned on using it without a switcher with just 100% streaming through ATV4K.  The way it sounds, I may not get DA this way until LPCM support?  Or it will work without a center channel?

appreciate you and krishma taking the time out to respond.

Hi @Immersive, thanks for your response and for letting us know here about your case. If you’re good with the setup, you should be okay but if you will try to use LPCM if your TV has that feature, it won’t work until the Sonos Arc supported it. 

Just let us know if you need anything. We and the community are always here to help.

So this post got me curious to do my own testing with my setup and was actually able to get atmos sound through my arc over airplay!!! These are my devices:

1. 2020 Vizio V-Series V585-H11 (Airplay 2 compatible) with the latest Smartcast OS firmware version
2. Apple iPad Pro 10.2” with iOS 14.2
3. Sonos Arc connected via eARC to the vizio using the provided sonos branded hdmi cable

A bit of background. I have ONLY been able to output an Atmos signal to the Sonos Arc using the Vizio Smartcast Netflix app (I have the 4k tier), Vizio Smartcast Apple TV app, and Vizio Smartcast Movies Anywhere app with some titles I’ve purchased over the years. The Disney+ pre-installed Vizio Smartcast app despite outputting a Dolby Digital Plus signal (which as I understand it, should allow for atmos through DD+), has NEVER been able to send Atmos.

Motivated by your post, I found Dolby’s Nature’s Fury trailer in DD+ Atmos through some forums and airdropped it to my iPad, opened it in the VLC app, checked the settings to make sure audio passthrough was enabled in the app, connected via Airplay to my Vizio and VOILÁ to my surprise, the Sonos app indicated it was receiving an Atmos signal!!!!! So I started playing around with my apps. I opened the TV app in the iPad and played Home Before Dark from Apple TV+ over airplay to the Vizio… SURPRISE! The Vizio info bar indicated it was displaying the series in 4K Dolby Vision and ATMOS, AND the sonos app indicated it was outputting ATMOS! I tried Spider-Man Homecoming which I had a digital copy in my library (upgraded automatically to 4k Dolby Vision & Atmos) and I ALSO got both 4K dolby vision & atmos OVER AIRPLAY from the iPad.

So I got to the ultimate test… since I knew that the native Vizio Disney+ app could display 4k dolby vision but NOT play Atmos, I tried The Mandalorian over airplay from the iPad app and this is where things got interesting. With the Vizio native app when I play the Mandalorian, I get 4K dolby vision picture with Dolby digital plus 5.1 audio. With the D+ app over airplay I get… 1080p Dolby Vision picture with Dolby ATMOS audio… and OUT OF SYNC SUBTITLES. All the other apps sync the subs perfectly and were able to send the highest possible resolution. I checked the app settings to see if there was some setting to modify but no. The highest quality it could send was 1080p over airplay. I even checked with Rogue One which I have purchased from iTunes and also is available in D+ and I got the same results: Dolby atmos from airplay and the native Vizio Apple TV app, 4k resolution from the D+ app & the native apple TV app, but 1080p only over airplay...  

So this leads me to believe Disney+ definitely has some software issues they need to work out over MULTIPLE platforms (I’ve read samsung has the same issue as vizio with their native apps), but the bottomline is that something DID change with iOS 14 because I am DEFINITELY getting atmos (and dolby vision) over airplay!

As a note, when using the Chromecast feature of some of these apps (HBO MAX & D+) I only got STEREO 2.0 audio, vs with airplay I was able to get ATMOS with D+, and Dolby Digital + with HBO MAX. It seems HBO MAX does not have Atmos encoded titles (although it did send 4k resolution over airplay)...