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michary
Contributor I
June 9, 2020

Arc + ATV + Non Atmos Content

  • June 9, 2020
  • 50 replies
  • 4442 views

Hello,

 

just received the Arc and so far loving my first Sonos device :relaxed:

 

I have an Apple TV 4K, LG OLED B9 (eARC support) and now the Sonos Arc.

When I play normal DD-Content on the ATV, the Arc only outputs Stereo. (The TV also says PCM)..

 

Is there anything I can do besides force the ATV to output DD? Because it would be not so nice to switch between the audio settings if I want to watch Atmos or DD-Content.

 

Thanks

Michael

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    50 replies

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    Marc_51
    Enthusiast II
    June 9, 2020

    I don’t exactly know how Dolby MAT works, but can’t the Apple TV always send LPCM, and add MAT for an ATMOS signal ? 

    And signal received by the ARC could be only PCM Stereo, plus MAT infos, resulting in “Dolby Atmos” indicated by the ARC ? 

    This would explain the PCM Stereo for a DD signal, and Atmos (but just stereo Atmos) for an Atmos signal.

     

     

    I don’t think there is a thing like stereo Atmos. If the ATV received Atmos it will stream it in a MAT container which the Arc can decode. Everything else is streamed as LPMC. Depending on your TV it will either pass it through or change it into something else (PCM or DD). Anyway, this won’t be an issue when the Arc gets enabled for LPMC. Then the bitstream can get straight pass through via eARC and the Arc can play it. 

      micharyAuthor
      Contributor I
      June 10, 2020

      I’m getting my C9 and my Arc delivered tomorrow so I’m guessing I’ll have all that fun over the weekend. Do you get DD when you’re using the internal apps ?

      For privacy purposes the TV is not connected to the internet.. so I cannot test this.

        mucullus
        Contributor I
        June 10, 2020

        How do you verify the Arc is receiving Dolby Atmos? I also have a LG C9 and with the internal Netflix app I only see “Dolby Digital Plus 5.1” in the about my sonos System screen. Should it state “Dolby Atmos”?

        psathionoukous
        Lyricist I
        June 11, 2020

        Hey, what firmware are you running on your TV? I have a C9 and I have not updated to the newest firmware that includes multi-channel LPCM support and I am not experiencing this issue. My Apple TV 4K is set to Auto and Dolby Atmos on, and when I play Atmos content it is output as Atmos and when I play a 5.1 movie it plays as 5.1, no downmixing to stereo.

         

        However, I have seen someone else with your issue and their C9 was updated to the latest firmware. Based on this I suspect that the inclusion of multi-channel LPCM in the LG C9/B9 series has caused the Apple TV to output everything as LPCM and the TV now sends it straight through instead of converting it like it used to. Of course the Arc can’t handle multi-channel LPCM yet so it downmixes it to stereo.

         

        So to get a better idea, what firmware are you rocking?

        topilouf1
        Contributor I
        June 11, 2020

        Received my Arc today and have just few minutes to do some test with my Apple TV

        I although have Dolbiy Atmos (regarding to Sonos App) for Atmos contents, and PCM Stereo for non Atmos, when configuring the Apple TV with the auto / Atmos Settings, 

        And DD 5.1 when changing audio settings to DD5.1

        My TV (Panasonic GZ1000) is ARC only, I’ll be forced to switch the audio parameters each time I want to watch Atmos / non Atmos content, frustrating...

        and I still don’t understand what signal the Apple TV actually sends for Atmos Content. I thought the Dolby MAT signal was only metadatas, “real” sounds being transmitted in LPCM.

         

         

         

          msalisbu
          Contributor I
          June 11, 2020

          Just wanna chime in, I got DD+ this working on my X900E via AppleTV after having issues with the audio in being Stereo 2.0.

          In your TV’s sound settings, there should be a setting for digital audio out, and it should be set to “Auto 1”.

          On the AppleTV, go to settings, Audio format, Set “Change format” to On, and new format: Dolby Digital 5.1.

          This enabled DD+ for compatible content over ARC (not eARC) on my TV.

          nbgr
          Contributor I
          June 11, 2020

          Sounds like you’re running the latest LG firmware that introduced LPCM and this issue. The workaround is to go into the Apple TV settings and turn off Atmos when you want to watch DD 5.1 content. This will most likely go away once the Arc is updated to support multichannel LPCM.

            JRO594
            Lyricist III
            June 17, 2020

            Oh sorry, I should have make it a little clearer..

             

            I only use the Apple TV 4K:

            • Track in Dolby Atmos → I get Atmos on the Arc
            • Track in Dolby Digital 5.1 → I get PCM (2.0) on the Arc

            Yep! I experienced the same issue. I also ran into an issue where I would get no sound at all until I change the settings within the tv from auto to pass through. Annoying when switching back and forth. 

            JRO594
            Lyricist III
            June 17, 2020

            How do you verify the Arc is receiving Dolby Atmos? I also have a LG C9 and with the internal Netflix app I only see “Dolby Digital Plus 5.1” in the about my sonos System screen. Should it state “Dolby Atmos”?

            When playing content hop on to the Sonos app-Settings-System-About my system- Search for your Arc and look for Audio in. That will tell you what content you are getting. 

            batsabode
            Lyricist III
            June 19, 2020

            I have the new LG 75NANO90UNA tv which has an EARC hdmi 2.0 I have that sending the signal to the Sonos Arc and I have the Apple TV connected to a regular hdmi 2.1 but it refuses to play a sound when it goes into a movie that has atmos. When I go to the menu for the movie the theme music plays and when I play a non atmos movie the sound goes through fine but the minute I play an atmos movie from atv it has no sound.  I can play atmos from the Netflix app on the tv (Space Force) and it does show on the Sonos App that it is in Dolby Atmos. I am now at a complete loss as to what else to try as the entire reason I bought a brand new tv and the Sonos Arc was to be able to play my atmos movies I bought that are on my Apple TV. If anyone has any ideas I would love to hear them, I have tried every setting I can think of, and the tv has arc set to on and passthrough enabled also. The Apple TV is set to bitstream on the lg tv. The lg app for appletv+  doesn't play atmos but it is not supported as yet apparently but will be updated FYI  but the LG  Netflix app plays atmos perfectly. 

            ARGHHHHHH

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