I have a Sonos Arc, Sub (gen 3) and a pair of OneSL speakers. Connected to an LG C9 OLED TV with eARC enabled. Much Dolby 5.1 content (specifically e.g. Friends on Netflix and Iron Man 2 on Disney+ but there is more) has inaudible dialog when played from an Apple TV 4K. Dolby Atmos is fine. Also the same content is fine when played from the television’s in-built Netflix and Disney+ apps. My previous soundbar, also eARC, was fine so it seems to be something to do with the Arc.
Can anyone else try this and let me know if you have the same problem? Anyone have any suggestions?
Best answer by Ken_Griffiths
This is because the Apple TV is sending the audio in multichannel LPCM format, which the C9 TV now supports with its latest firmware update v04.80.03, but the ARC doesn’t (at the moment) support that codec.
Sonos have said they will be adding the codec to the Arc, but not sure when that will be, so you could change the output/codec within the Apple TV audio settings to Dolby Digital 5.1 for example, when watching/listening to such problematic sources on ATV.