So my LG LED uses a Beam with Arc and a gen 3 Apple TV and with 2 Play 1s it shows Dolby Digital 5.1 as it should. When I watch the exact same content on my LG OLED with eArc surround and an Apple TV 4k (old version) I get the MC LPCM 7.1. Why the difference? I haven’t made any major setting changes on the led setup and it’s fine.
Best answer by GuitarSuperstar
The Beam/Apple TV Gen 3 setup only supports up to Dolby Digital 5.1 audio. The Arc/Apple TV 4K setup supports up to Dolby Atmos and multichannel LPCM audio when connected to a TV with HDMI eARC. Also the Apple TV 4K uses Dolby MAT which will play all Dolby Digital Plus audio as multichannel PCM through the Arc.