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majelbstoat
Contributor I
November 14, 2020

PS4 Pro outputting PCM via LG CX shows Multichannel PCM 7.1 for Sonos Arc, but rear surrounds have no audio

I have the Arc, Sub, and Sonos 1 in a surround setup, connected to an LG CX via eArc. Previously I had the PS4 outputting Bitstream (Dolby), and Sonos reported Dolby Digital 5.1.

The fix that added LPCM to Sonos Arc recently went live, so I updated PS4 Pro to output PCM, and the HDMI input on the TV to PCM. (The output remained Passthrough). After doing this, the System Status page for Sonos shows Multichannel PCM 7.1.

However, I now get no rear surround audio in games like Assassin’s Creed Valhalla. (It’s not faint, there’s really none.) I get the full surround experience if I change it back to getting Dolby Digital 5.1. On the PS4 Home screen, I do get sound from the rears in PCM 7.1, albeit very faintly, compared to Dolby Digital 5.1.

Does Sonos not downmix the extra channels properly? It’s kinda bad that a higher fidelity signal sounds worse.

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    127 replies

    majelbstoatAuthor
    Contributor I
    November 14, 2020

    So, it looks like this might be the reason: https://en.community.sonos.com/home-theater-228993/lpcm-eta-for-arc-6842558?postid=16488286#post16488286

     

    TL:DR, it looks like LPCM 7.1 is downmixed incorrectly with side channels coming out the rear and rear channels not coming out at all. Back to Dolby Bitstream it is. (And back to having to switch modes between Atmos and non-Atmos on Apple TV 4k too.) Sigh.

     

    I know Sonos doesn’t do ETAs, but can we at least get an official acknowledgement of this problem?

      Whistler
      Enthusiast II
      November 14, 2020

      Yeah, something is definitely wrong with the channels on Multichannel PCM. Sound coming out the wrong channels or not at all.

        Naekyr
        Enthusiast II
        November 14, 2020

        So, it looks like this might be the reason: https://en.community.sonos.com/home-theater-228993/lpcm-eta-for-arc-6842558?postid=16488286#post16488286

         

        TL:DR, it looks like LPCM 7.1 is downmixed incorrectly with side channels coming out the rear and rear channels not coming out at all. Back to Dolby Bitstream it is. (And back to having to switch modes between Atmos and non-Atmos on Apple TV 4k too.) Sigh.

         

        I know Sonos doesn’t do ETAs, but can we at least get an official acknowledgement of this problem?


        can you make the PS4 output lpcm 5.? 


        When I first started the ps5 it was set to “TV sound” lpcm 7.1 and while the number of channels can be changed it was greyed out. I changed the output type to “AV Receiver” and then it let me change the channel to 5.1. After doing that I confirmed in the Sonos app that the Arc was getting “Multichannel 5.1”. After doing this the sound output is correct.

         

        Unfortunately i no longer have a PS4 to test but hopefully it has the same options.

         

        Ive also got a PC and Nintendo Switch. The Switch asked me if I'd like 5.1 or 7.1 so I selected 5.1. The PC was a little tricky, on the PC I can output Lpcm or Atmos but it was defaulting to 7.1.2 or 7.1 for both - I found an option in Windows that let me disabled the SR and LR channel so now the PC outputs 5.1.2 or 5.1 only 

        SONOS ARC | SONOS Sub | SONOS Play 1 x 2 | LG C9 OLED | PS5 | RTX3090 Gaming PC | Sennheiser GSP600 Headset | Audio Pro T8L Desktop Monitors
        Funkalicious
        Lyricist I
        November 14, 2020

        I am having this same issue on the PS5.  I tried selecting the PS5 option of connecting to an AV receiver and using a 5.1 setup but I am still missing audio channels.  Anyone know what the exact issue is?

          billiejoe87
          Chromatic Producer I
          November 15, 2020

          For those having issues with the LG CX outputting MultiChannel 7.1 to the Sonos ARC, have you tried changing the sound output to Auto instead of passthrough? This fixed the issue and changed it to Multichannel 5.1 for me.

          1 x Arc, 1 x Beam Gen 2, 1 x Amp, 2 x Sonos In Ceiling Speakers, 2 x Sub, 4 x Sonos Ones, 2 x Sonos Era 100, 5 x Symfonisk Lamp (Gen 2)
          billiejoe87
          Chromatic Producer I
          November 15, 2020

          I have the Arc, Sub, and Sonos 1 in a surround setup, connected to an LG CX via eArc. Previously I had the PS4 outputting Bitstream (Dolby), and Sonos reported Dolby Digital 5.1.

          The fix that added LPCM to Sonos Arc recently went live, so I updated PS4 Pro to output PCM, and the HDMI input on the TV to PCM. (The output remained Passthrough). After doing this, the System Status page for Sonos shows Multichannel PCM 7.1.

          However, I now get no rear surround audio in games like Assassin’s Creed Valhalla. (It’s not faint, there’s really none.) I get the full surround experience if I change it back to getting Dolby Digital 5.1. On the PS4 Home screen, I do get sound from the rears in PCM 7.1, albeit very faintly, compared to Dolby Digital 5.1.

          Does Sonos not downmix the extra channels properly? It’s kinda bad that a higher fidelity signal sounds worse.

          It’s counterintuitive but leave the PS4 Pro/PS5 on PCM and change the HDMI Input on the TV to bitstream and the output to Auto. This fixed the issue for me.

          1 x Arc, 1 x Beam Gen 2, 1 x Amp, 2 x Sonos In Ceiling Speakers, 2 x Sub, 4 x Sonos Ones, 2 x Sonos Era 100, 5 x Symfonisk Lamp (Gen 2)
          Whistler
          Enthusiast II
          November 15, 2020

          For those having issues with the LG CX outputting MultiChannel 7.1 to the Sonos ARC, have you tried changing the sound output to Auto instead of passthrough? This fixed the issue and changed it to Multichannel 5.1 for me.

          Changing it to Auto changes the output to Dolby Multi-channel PCM 5.1, which is not the same as Multichannel PCM (LPCM)  as far as I know.

          billiejoe87
          Chromatic Producer I
          November 15, 2020

          For those having issues with the LG CX outputting MultiChannel 7.1 to the Sonos ARC, have you tried changing the sound output to Auto instead of passthrough? This fixed the issue and changed it to Multichannel 5.1 for me.

          Changing it to Auto changes the output to Dolby Multi-channel PCM 5.1, which is not the same as Multichannel PCM (LPCM)  as far as I know.

           

          It shows in the Sonos App as Multichannel PCM 5.1 when playing Dolby 5.1 content and shows as Dolby Atmos when playing Atmos content (Not DD+ Atmos). From my understanding this is what you would expect to see, since Sonos doesn’t do 7.1.

          1 x Arc, 1 x Beam Gen 2, 1 x Amp, 2 x Sonos In Ceiling Speakers, 2 x Sub, 4 x Sonos Ones, 2 x Sonos Era 100, 5 x Symfonisk Lamp (Gen 2)
            Whistler
            Enthusiast II
            November 15, 2020

            For those having issues with the LG CX outputting MultiChannel 7.1 to the Sonos ARC, have you tried changing the sound output to Auto instead of passthrough? This fixed the issue and changed it to Multichannel 5.1 for me.

            Changing it to Auto changes the output to Dolby Multi-channel PCM 5.1, which is not the same as Multichannel PCM (LPCM)  as far as I know.

             

            It shows in the Sonos App as Multichannel PCM 5.1 when playing Dolby 5.1 content and shows as Dolby Atmos when playing Atmos content (Not DD+ Atmos). From my understanding this is what you would expect to see, since Sonos doesn’t do 7.1.

            Ok that is nice, unfortunately not in my case. I’m using an Apple TV 4K and not a PS4 so perhaps there is a difference there. Have to do some more experimenting. 

            billiejoe87
            Chromatic Producer I
            November 15, 2020

            For those having issues with the LG CX outputting MultiChannel 7.1 to the Sonos ARC, have you tried changing the sound output to Auto instead of passthrough? This fixed the issue and changed it to Multichannel 5.1 for me.

            Changing it to Auto changes the output to Dolby Multi-channel PCM 5.1, which is not the same as Multichannel PCM (LPCM)  as far as I know.

             

            It shows in the Sonos App as Multichannel PCM 5.1 when playing Dolby 5.1 content and shows as Dolby Atmos when playing Atmos content (Not DD+ Atmos). From my understanding this is what you would expect to see, since Sonos doesn’t do 7.1.

            Ok that is nice, unfortunately not in my case. I’m using an Apple TV 4K and not a PS4 so perhaps there is a difference there. Have to do some more experimenting. 

            I’m using an Apple TV 4K as well at the moment on an LG CX and getting these results. I’ve left the Apple TV on Auto, Atmos Available for Audio and I have set HDMI Input Audio on the TV to Bitstream and Audio Output to Auto. It’s really weird how so many of us are getting different results.

            1 x Arc, 1 x Beam Gen 2, 1 x Amp, 2 x Sonos In Ceiling Speakers, 2 x Sub, 4 x Sonos Ones, 2 x Sonos Era 100, 5 x Symfonisk Lamp (Gen 2)
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