There is a serious audio delay issue with the HDMI 2.1 port or anything you want to pass Dolby Atmos through the eArc port with a Samsung Soundbar. It took me a while to troubleshoot and find the root cause on my Samsung Q90t and SAmsung HW-Q70T.
I connected my Xbox One X to the HDMI 2.1 port because it supports VRR. HDMI passthrough is disable on this port and only PCM audio would have 0 delay. Any other series of configuration would add approximately 100 - 200 ms. I tried PCM 2.0 Stereo, to 5.1 Bistream and Dolby Atmos. Only when the TV is set to PCM that I didn't get any audio delay on the soundbar (Samsung HW-Q70T.) When I connect my box to a different HDMI port. HDMI passthrough becomes enable and I can do up to 5.1 Bistream (Dolby Digital) without any delay. If I switch to Dolby Atmos, the delay comes back. I also tried with the Playstation 4 pro. I had 0 delay using Bitstream Dolby 5.1.
Using any Samsung apps have 0 delay. So to me it seems that even if you disable the audio delay from 100 to 0. The Samsung still applies that delay when you are using an external source. The problem is worst when you are using the HDMI 2.1 port with a device that support VRR. It seems like only PCM will work at this point. I bet a lot of Series X or Playstation 5 users are going to be infuriated when they bring home their new and shiny consoles and realize all the audio delay they will experience trying to use Dolby Atmos.
I really hope Samsung does something about this because it's going to get rowdy next month
Same issue, even more prevalent with Atmos enabled 4K Blu-ray - it drives me nuts. I specifically bought the Q70T Soundbar for its Atmos support and am left with a mess. Either disable Atmos or live with cut outs to sound and constant adjusting of lip sync delay...
Happens with both Xbox One X and Switch content, I haven't noticed it on my cable box but it is a mess.
So I have an update. I bought a 48gbps HDMI 2.1 cable from monoprice and replaced the hdmi cable that came with the soundbar. I have 0 delay now and I didn't experience any audio cut out so far. So it seems to me the HDMI cable was the problem all along ?
Your experiences are helpful, I'm shopping for these TVs with a new gaming console. I'm hoping for VRR HDR 4k/120hz from new gaming systems while also using eARC for true Atmos/DTS-X through my receiver.
As I look at the Samsung website images, did you plug your game system into the "gaming" port and a second cable from the "eARC" port to the AV/sound bar system?
I have the same junk delay with my Xbox Series X and HW-Q70T and Q90T. I bought the HDMI 2.1 cable you mentioned for the soundbar and I still have a massive audio delay. Did you do anything special for your settings?
Same issue with my 85" Q80T. I've tried Xbox Series X to the Samsung and eARC to my Denon receiver and get the audio delay. The only sound options the Xbox will let me select are either bitstream Dolby or uncompressed 2 channel PCM. If I plug the Xbox into the Denon, I can choose uncompressed and there's no delay but the Denon isn't HDMI 2.1 so I miss out on the video benefits. I've also tried using the toslink out from the TV to the Denon with the same result. I hope this is fixable with a firmware update.
Man, I'm experiencing audio sync issues with the most basic setup you can have--Xfinity cable box plugged straight into the Q90T. It's frustrating. I'm going to try and use a different HDMI port and see what happens. This is only happening with live TV. I plan to buy a Sonus ARC soon but what good is great sound if the lips move ahead/behind the audio? It's not natural!