This is complex and I have read every post imaginable. I hope someone can help.
I've got a PC with an Nvidia 4070 Super connected directly to the HDMI 4 2.1 (Gamepad icon) port of my Samsung Frame 55 inch. I have a verified 8K / 4k HDMI 2.1 cable.
The TV is connected to my Denon AVR X2700H receiver via the HDMI 3 eARC port.
The TV is in Game mode, with 120hz and VRR, from a visual perspective everything is working.
If I play content on the TV via Disney Plus that supports Dolby Atmos, the AVR displays that it is using Atmos and the sound works.
In the sound settings on the TV I have it set to output to eARC, HDMI sound is set to passthrough and Dolby Atmos is showing as active.
On the PC I can select 5.1 surround in sound settings and that plays via the AVR amp correctly. I have the Dolby Atmos app installed in Windows. I cannot select Dolby Atmos for home theatre in the sounds settings.
If I plug the PC directly into the eARC port, I can then use Game mode, with 120hz and VRR select Dolby Atmos for home theatre in the sounds settings, but I cannot then get the sound to come from the TV to the AVR.
If I plug the PC into the 8K port of the AVR, then the AVR into the HDMI 4 2.1 (Gamepad icon) port of the TV and make sure all the setting are correct with 8K passthrough, I cannot get the TV to display 4K 120hz with VRR, but I can then select Dolby Atmos for home theatre in the PC settings and get it to output Atmos via the AVR amp. I can get it to work with 1080p 120hz with VRR.
So, is this a problem with the HDMI 4 2.1 (Gamepad icon) port?
My setup is a bit different but I haven't had any issues getting Dolby Atmos to work. I am using the Demon X1800H AVR and my GPU is a PowerColor 7900XT. My HDMI 2.1 cables are full 48Gbps from Monoprice and connected to the game labeled port on the AVR in passthrough. You should have the option to select Dolby Atmos at the bottom of your audio configuration in the Windows Sound output. You will not get Atmos sound on the desktop. Whatever you are doing has to be Atmos enabled and outputting in Dolby Atmos. Windows no longer outputs in Atmos but VLC, games, etc., will trigger Atmos if the content supports it.
