Audio Stereo PCM 2.0 only: Infuse 7, AppleTV 4K (2nd gen), LG C9, Sonos Beam

I am quite happy with the Apple TV 4K (2nd gen), except that for some reason I cannot get Infuse to play Dolby 5.1 in the recommended settings. I am following all advice on the support pages of Infuse and Apple. Sonos doesn’t provide meaningful support and LG is patchy.

Sonos Beam connected to LG C9 eArc (HDMI 2), running on Sonos S2.
Apple TV connected to LG C9 HDMI 1. Audio set to “Auto, Dolby Atmos available” or just “Auto” - same result.
LG C9: Sound out to “HDMI Arc”, Digital Sound out set to “Passthrough”, eArc set to “On”.

This set-up should assure that Apple automatically selects the right format and sends uncompressed multi-channel PCM (5.1 or 7.1).

However, only (!) when I play Dolby 5.1, Dolby Atmos from Netflix, Disney etc. there is actually 5.1 sound on my Sonos Beam. When I play from Infuse it becomes Stereo PCM 2.0.

I read a lot about Apple’s implementation of Dolby Atmos, why it only works with streaming. But I am in a different situation because my Sonos Beam would only accept 5.1 anyways, and Apples “automatic” setting is supposed to achieve this.

For now the solution is setting the Apple TV audio to “Dolby 5.1”, leave all other connections and setting equal. When I do this all sources work in Dolby 5.1 on my Sonos Beam. I would like to make the “Automatic” setting work, so that there is no conversion happening anywhere except the Sonos Beam.

I can leave it like this but seek help from readers who can explain to me what is going on. For some reason I have the impression that Apple TV HD (my prior Apple TV) worked swimmingly with the automatic setting, and the change happened with Apple TV 4K.

Thanks for reading and if you have guidance then please reply.

According to sonos only the sonos Arc supports multichannel PCM. All other products are stereo pcm and Dolby digital

https://support.sonos.com/s/article/4945?language=en_US

1 Like

Correct Jarvis. Thanks for taking the time to write. Dolby Digital includes 5.1, Beam+2 satellite+sub, which is my configuration. I re-confirm that Dolby 5.1 on Sonos Beam works when streaming Netflix etc via Apple TV but does not work (becomes 2.0) when using Infuse. That’s why I posted in the Infuse community. I try to find out 1/ if I made a mistake in my configuration, 2/ if forcing Dolby 5.1 on Apple TV has disadvantages for my set-up?

Hi there!

  1. No, your config is 100% correct. I run an ATV 4K, LG OLED C9 & Sonos Playbar and MUST use the same settings.

  2. No, you don’t have any disadvantages, since the Sonos Beam (as well as the playbar) can only output Dolby Digital 5.1 anyways.

Btw: It did work on ATV 4K set to „automatic“ quite a while ago. What happened then - at least to my observation - were 1-2 FW updates on my LG OLED. I wasn’t careful enough and suddenly I was required to use the DD 5.1 setting on ATV 4K to continue watching my contents in Dolby Digital 5.1.

Regards!

Hi Tbor, thank you for confirming that you chose the same approach. I didn’t notice the LG update and didn’t connect it to the changed behavior. Audio appears to be complicate, so many players in the chain: The source, Infuse, Apple TV, the TV set, the home cinema speakers. I would have preferred that compression happens at only one place, ie speakers. I would have preferred that Apple TV does automatic decompression and delivery of uncompressed audio, no decompression and reencoding. I just hope that neither TV set nor speakers repeat the exercise which would at least theoretically impact sound. Anyways, unless somebody has a better idea, this topic will be closed. I still don’t quite understand why it works but not with Infuse. Thank you again.

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