Hi @pauloffduty.

Welcome to the Sonos community and thanks for reaching out to us.

I would like to recommend connecting the Sonos Arc directly to the TV along with the Apple TV and check if the issue persists. I would also like to recommend while the Arc is generating audio from TV and from Apple TV to submit a diagnostic so we can check what signal is being received by the Sonos Arc. Can we also try to reboot both the TV, Sonos Arc, and Apple TV to check if it fixes the issue of a possible glitch with the communication between the TV and the Sonos Arc? Please take note of the confirmation number each time a diagnostic is submitted.

Please let me know how it goes. We are always here to help.

Thanks.

Apparently the Apple TV will send A signal that Sonos cannot yet, updates pending, pass so you end up with stereo 2.0 on Apple content unless you force 5.1. 
 

Switch back from that to get Atmos from Netflix 

Thanks for the reply …

I have submitted the following diagnostic ref: 450659668 whilst playing Netflix 5.1 content with no center audio channel.

The Apple TV is connected to HDMI 4

The Sonos Arc is connected to HDMI 2

Audio Input Format for HDMI 4 is set to Bitstream.

Stereo content works fine.

Dolby Atmos content works fine.

5.1 content (streaming from Netflix, Disney+, etc) is missing the center audio, but other channels are fine. If I look in the app at “About My System”, the Arc shows Stereo 2.0 as Audio In, when it should be 5.1. This is clearly the issue.

Hopefully you can help ...

https://www.reddit.com/r/sonos/comments/h08f9o/testing_arc_with_lg_c9/?utm_source=share&utm_medium=ios_app&utm_name=iossmf

Hi @pauloffduty.

Thanks for submitting a diagnostic and for the immediate response. 

Based on the provided diagnostic, it shows ARC is the disabled meaning you are using the optical to HDMI adaptor that came with the Sonos ARC. The diagnostic still does not contain any information indicating that it is connected to the TV via HDMI ARC, if you may not be using the HDMI to optical adaptor, you may want to consider consulting the owner’s manual of your TV to be sure that the Arc is connected to the TV via HDMI ARC and not the regular HDMI port. 

Please let me know if you still have further questions or concerns. We are always here to help.

Thanks,

That’s super strange - I have it connected to the HDMI ARC (and confirmed). The TV (LG C9) is set up as follows:

HDMI ARC selected

Digital Sound Out set to Passthrough

eARC set to ON

What is also weird is that every other device works fine - supporting stereo, 5.1, Atmos. Also, it seems as I am not alone, as I’m experiencing exactly what is referenced in the Reddit post here:

https://www.reddit.com/r/sonos/comments/h08f9o/testing_arc_with_lg_c9/?utm_source=share&utm_medium=ios_app&utm_name=iossmf

Hi @pauloffduty.

Thanks for the immediate response.

I would like to ask of you can try other sources and see if they have the same audio outcome on the Sonos Arc.

• In app (TV app) movie source like Netflix, Youtube, Amazon Prime, Etc, Submit a diagnostic for us to check what signal the Arc is receiving.
• Regular satellite TV program. Submit a diagnostic for us to check what signal the Arc is receiving.
• Cable Box (if applicable). Submit a diagnostic for us to check what signal the Arc is receiving.
• Try playing music to check if all speakers work. Submit a diagnostic for us to check what signal the Arc is receiving.

Please take note of the confirmation number according to what is the source.

Please let me know how it goes. We are always here to help.

Thanks.

@pauloffduty : Go to the Apple TV settings. Under “Video and Audio” select “Audio Format” and choose convert to Dolby Digital 5.1. 

This should force Apple TV to output DD5.1 signal, which is then passed through the TV’s ARC port to the Sonos Arc. (By default, Apple TV would output an LPCM signal, which the TV converts to stereo over ARC or optical). 

I’m having this same issue with my PS4. 

This was my solution for getting my PS4 to emit DD to my Beam (via my old Smasung TV): https://en.community.sonos.com/setting-up-sonos-228990/samsung-tv-5-1-6839072

Hi 

i have seen this issue once using Netflix, I resolved it by turning everything off and then back on.

However I have recently had the same issue with downloaded movies played through an OPPO 203

Same scenario, some play fine and others have no centre channel and show in the app as stereo 2.0 even though they are 5.1