New tv audio/video sync problems

[zarniwoop]

I have a new LG 55" Oled tv and I've had some problems with syncing audio and video.

The set-up I've had for a while was using a Sony bluray player for all discs and also to stream Neflix, Prime etc. From the bluray player I ran Video only to the 720p tv and audio to the hifi and there were no sync problems with any source. I tried the same approach with the new 4k set and the first film I watched was absolutely fine. Other films and tv shows have varying degrees of lag, with the video lagging behind the audio. I gather this is due to the greater length of time required to process higher res video, which wasn't a problem with the old 720p set, although it's a puzzle that a relatively recent film is fine and a lower res tv show from the 90s has a problem.

I've resorted to running audio & video to the tv (HDMI) and taking digital audio (optical) out of the tv and back to the hifi. If I set the tv audio output to "optical only" I still have the lag but if I set to "tv speaker & optical" it syncs. This means, though, that the tv is converting the original audio to red book and I'd rather avoid having the tv do any audio processing.

I've ordered a cheap HDMI de-embedder with ARC support which should arrive tomorrow, and then I'll see if I can connect that to the HDMI ARC port on the tv and get the higher res audio into my DAC.

Does anyone have any alternative suggestions? I'm using the streaming apps on the tv now, so this is mainly about discs.

 

[alcarmichael]

This is why AV amplifiers/processors have time delay adjustment. If you have the space, a nice legacy AV processor would be a great addition to your set up.

 

[ShadowWarrior]

If your video is lagging behind the audio then you're in luck. Most issues I see are the audio lagging the video.... for which there isn't a lot that can de done.

There should be a setting on your TV to allow you to delay the audio by varying steps to sync them up.

 

[zarniwoop]

Thanks both for your responses.

In the end I discovered that if I set all i/o to use PCM explicitly rather than bitstream, auto or pass through I was able to get sync'd audio and video using optical out. I thought I'd tried that earlier but with multiple places to set options the number of possible combinations of settings quickly rises. I'm having to run the audio via the tv for this to work which I'd prefer not to do but keeping it separate would require an external audio delay varying with source so it just isn't practical.

I experimented with an HDMI ARC audio extractor which worked also, but it isn't reliable and needs to be power-cycled every few hours. The tv appears to be down-sampling the audio even through this route so with a functioning optical solution there is no point. I've had a look for a similar device supporting eARC but they are thin on the ground and it's not certain they'd be any better.