Ahh okay - that makes since 
Youāre right, I was searching quickly and didnāt read all the specs. There is a 4K version from the same vendor for $28. There seem to be many vendors of these types of devices, so you may want to do your own search for a better deal.
I got my C7 up and running over the weekend. Iām using the optical out port on the back straight to a Playbar. Was having sync issues, but I went into the LGās audio settings and changed the Audio Out from Auto to PCM and its been fine since.
The playbar doesnāt have HDMI so I havenāt been able to try ARC yet.
Interesting. PCM only does 2channel/Stero correct? So by changing it on the LG, youāre not able to have 5.1 for the other apps on AppleTV, including iTunes, Netflix, etc.
I would rather NOT give up 5.1 in all of the other apps just to get Channels working the way it should 
Iām willing to give up 5.1 within the app however if thatās what it takes.
No, PCM can easily do 5.1 as well.
@Maddox told me how to check the Playbar input in the Sonos app, and it looks like the TV is only sending Stereo over optical in PCM mode.
Iāve switched it back to Auto and the sync is fine on the Olympics but Iāll keep testing and see what I can figure out about the sync issue.
OP here. I generally find that NBC, PBS and CNN have pretty good sync in 5.1 on the ATV4k.
In Philadelphia we have a local NBC SportsNet that show 76ers games. The sound comes considerably later than the ball hitting the court or swishing thru the netin 5.1, but stereo is right on. USA, TNT, AMC, Comedy Central, CBS and ABC each look like the video is ahead of audio in 5.1 on the 4k.
I also have a non-4k ATV4 connected to a 7-8 year old Sony soundbar receiver and a 1080p Samsung LCD as well. Last night I tried Channels both in stereo and 5.1 on that combo. Every station looked the same to me on either setting - pretty good sync!
I obviously donāt pretend to know how you guys work your magic, but may I suggest that there could be something involved in the 4k upscale thatās throwing the sync off?
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Iām seeing the same issue. Just set this up.
I have FIOS, ATV4K, LG C7 TV (2017), Onkyo Receiver
Chain: ATV4K -> TV -> Onkyo Receiver via ARC
Seeing same delay as folks up here are seeing.
Turning ATV4K to stereo fixes sync.
Strangely I havenāt had any sync problems again since that first day when I set it up. Iām back to using Audio Out: Auto, and I also went into About and upgraded firmware from webOS 3 to webOS 4.
Iāve added a Surround Sound Off option to the latest TestFlight beta for experimentation.
Awesome! Iāll download it and give it a test.
Hey thanks a million! I downloaded TestFlight and the beta tonight. Switched off surround sound and boom! Every channel is perfectly in sync!
FYI My system is : Verizon Fios > HDHomeRun Prime > ATV4k > LG B7 > ARC to Vizio Sound Bar
Thanks guys!!!
Downloaded the beta this evening. Seems to fix the issue. Curious why 5.1 recorded programs w/Plex donāt see this. I have seen this is a widely experienced issue with LG OLED TVs from 2016/2017. Thanks for creating this option. Hope LG can release a SW updated to fix.
Looks like the stero setting on the beta fixes the sync issue. Thank you!
Is this going to be fixed? Iāve just realised it was when bbc 1hd was broadcasting in 5.1 that i had really noticable lip sync and when i switched surround off in channels it corrected itself.
I would like to benefit from the surround sound when on offer, is this still being looked at?
Atv 4k, sony a1, yamaha sound bar.
If i switch to the tvās tuner on for bbc 1hd on 5.1 no lip sync, yamaha fed by optical from tv.
Regards
Gary
If thereās lip sync issues its because your TV is introducing a delay before feeding to your sound bar. You need to check the settings on your TV to see if thereās a switch for the ARC audio format.
Not using arc! As per post
It sounded like you were using ARC over optical, which means the TV is still in the middle and performing extra processing.
So what is the setting iām looking for here, as not sure what the aditional setting is that iām looking for
It depends on the TV. Some have settings to fix the issue and others donāt. Hereās a similar report: https://en.community.sonos.com/home-theater-228993/if-you-re-experiencing-audio-delay-issues-read-this-6793458#post16189185