If you want the whole story, read this: https://www.avforums.com/threads/lg-43uj630v-audio-output-delay-gets-worse-the-longer-tv-is-on-arc-digital-optical.2138124/
Otherwise, here's the relatively short and sweet version:
I bought an LG 43UJ630V and a Samsung HW-K450 2 weeks ago.
When connected to the soundbar (either digital optical or HDMI ARC), they are in sync.
When left on for around 2 hours though, I'll start noticing the lips are not correctly syncing up with the words.
By the 3-4 hour mark being left on, it's atrocious.
I expect to have to have to set the av sync initially, but changing it every hour as it slowly drifts out of sync - this is clearly a technical fault.
When I plug the soundbar directly into my Sky box (set-top box) there are no issues of drifting audio sync.
Changing settings, updating firmware, using different wires, nothing makes a jot of difference unfortunately.
I determined the problem was with the processing of the digital output audio signal in the TV's internals.
I returned my TV for a replacement, and bought a new sound bar to go with it - an LG SH4D 2.1 - figuring that the samsung soundbar may have been incompatible.
Yesterday I set it all up, but found after 3-4 hours of being left on, the audio was wildly out of sync again. https://youtu.be/hmH5jsu20AQ
In this example I set the audio so it would output via digital output and internal speakers. The latency between the 2 is so bad you can't even call it echo. This demonstrates how badly out of sync the soundbar output gets compared to the internal speaker.
Remember - this is my second 43UJ630V and a different soundbar, and yet the problem returned in exactly the same way.
After recording that video I tried connecting my Samsung soundbar instead and it was exactly the same.
There is clearly a fault with this model or the entire UJ630V range.
I hope it can be fixed in a firmware update.
Ignoring momentarily the fault, and the countless hours and stress this has caused - I rather like this model. I'd prefer to fix it instead of sending it back for a refund.
I don't understand why I cannot find anyone else reporting the same problems. When I spoke to LG a week ago describing the problem, they told me a fault like this hadn't been reported before... But I've proven beyond a doubt that the problem is there, and probably afflicts a great number of people.
I've emailed LG but I'm sure they'll just fob me off again. I plan to give them a ring later, but again, I'm not sure what good this will do.
I've diagnosed the problem, and I cannot be the only one experiencing this problem. It is probably addressable in a firmware update if I can bring it LG's attention.
Any help or suggestions would be appreciated.
