Question Dolby Atmos AV Sync when using eARC?

Thortok2000

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Feb 3, 2016
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This is a follow up to my last question https://forums.tomshardware.com/threads/split-dolby-atmos-and-4k120-without-earc.3710768/

Since then, I've bought an eARC converter (didn't help), and then gave in and bought a HW-Q700A soundbar, and surprisingly still had issues, until then I got a displayport-HDMI adapter.

Currently I'm able to connect PC > soundbar (via displayport adapter) and PC > TV simultaneously, and I get atmos and 4K/120Hz/VRR just fine.

If I instead connect it what should be the 'proper' way where it's PC > TV > Soundbar (via eARC), then stereo works great, but 'atmos' does not. It seems to be a 3.1 channel sound (sound only comes from or is mixed with the front, but the subwoofer channel works). But worse than that, there's a HUGE av-sync issue where video happens before audio, significantly, like almost half a second difference. The AV sync adjustment on TV/soundbar connection only goes the other way, making the sound happen even later.

I'm at my wit's end trying to figure out why this is happening and what the fix is to get an eARC setup working so my PC can do atmos without having to have the soundbar separated from the TV.

Again, mentioned it in old thread, but current hardware is:
RTX 3080 PC
QN55QN90A samsung TV
HW-Q700A samsung soundbar
SWA-9500S (rear speakers for soundbar, sold separately)

Supposedly the exact same setup, swap out the PC for some other atmos source, like a blu-ray player, works. So Samsung blames the PC for the issue. Dolby and nvidia have ignored any request to contact them for help. Haven't bothered with Microsoft.

Although I have a working setup, I'm still super frustrated I can't get eARC working, because if I could then I could enable q-symphony (as well as not have to juggle sources and connections when watching anything directly from the TV or any other source connected to it).

Also, the only form of dolby the PC seems willing to be set to is atmos. I can't find any way to set to a lesser version of dolby like 'dolby digital plus' which may be more compatible with the TV/soundbar. As long as I'm getting discrete positional audio I don't really care if it goes all the way to the quality of atmos or not. I'm not sure I could really tell the difference.

Windows seems to resist/ignore setting sound to anything except stereo or atmos. Setting it to 5.1 doesn't seem to stick, keeps reverting to stereo.

Help! Please!
 

Thortok2000

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Feb 3, 2016
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As an update, when the TV "Digital Audio Output format" is set to pass-through, and I do a soundtest, then all the sound that's supposed to come from the front, is completely silent, and the sound that's supposed to come from rear speakers, comes from the front.
 

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