If you're experiencing audio delay issues, read this

SOLVED ????

I was looking in the wrong spot.   My LG OLED menu under audio had a choice between AUTO and PCN for optical out

But looking under the Lip Sync adjustments in another menu, there is a BYPASS OPTION !!!

When I chose it, all seems OK now.    

My setup:

LG OLED 55C8

Sonos Beam Connected via HDMI ARC

2x Sonos One SL (5.1) connected via WiFi

Chromecast Ultra, Sony PS4 Pro, Nintendo Switch

I read through about 5 pages of this thread. I really don't wanna go out and buy anything like a HDMI audio extractor to fix it. Tried a few things and the only way I could get rid of the delay is physically bypassing my TV with the provided HDMI-Optical cable to get a Digital 5.1 signal from my PS4 straight to the beam. HDMI ARC, optical/HDMI thru TV all produce a slight ~250ms lag. Linear PCM has no delay, only when the beam is running in Digital 5.1 do I notice the issue. I've tried LG's sync delay bypass to no avail as well... Beginning to think there's no fix here. 

Ah well. Maybe they'll announce a new soundbar on the 6th and I'll just buy that, or just use something else. If anyone thinks there's a solution though I'd love to hear it. For those of you who have had luck with the LG Bypass option I'm glad, but no dice for me.

The problem isn’t in the Sonos, so a new version of one of their sound bars won’t change anything. 

Let me modify that. If the TV has a separate process for handling eARC, and the new Sonos sound bar accepts such a signal, it might make a difference. Right now, it appears that any HDMI input on several TVs is impacted by this delay. Until there is a Sonos or other speaker that works via this third output method, we have no real proof if it is an issue on input to the TV, or an output issue. 

@Airgetlam I don't fully understand the fundamental issue with HDMI ARC and the sound signals, but I was thinking perhaps a new product would bring a solution some other way. Thinking.only about the issues I've noticed... I don't get any lag over the PS4 with Linear PCM (but it's a Stereo 2.0 signal). I don't know if somehow the soundbar just doesn't do 5.1 unless it's Bitsteam, but my hope is for PCM 5.1 essentially, over HDMI ARC. Maybe it's a pipe dream, but I've got my fingers crossed something will get sorted out.

I’m not an electrical engineer, so take my assumptions as such, but it’s pretty clear to me that if stripping out the audio before it reaches the TV using an HDMI switch, it’s evident that there is an issue with the handling of the Dolby Digital signal inside the electronics of the TV. I’d expect that a stereo (PCM) signal gets handled by different electronics, which is why the Dolby Digital signal is delayed, and the stereo signal is not. I think that’s a fair indicator that the issue isn’t on input, as I suggested in my previous post, but there must be some additional processing / pathway occurring when the signal is Dolby Digital. 

But yes, if and when Sonos adds more options for encoding to the audio stream for their home theater products, it’s possible that the TV will not delay that stream, and present it at the same speed that they do the stereo stream. But that still depends on the capability of the electronics in the TV, and has nothing to do with Sonos, for all practical purposes. 

So far, the only mention I’ve seen from Sonos is inferred to be about music encoding, nothing but speculation, including my own, about the Home Theater stream getting extra codec interpretation. 

And even if that occurs, there will be a significant amount of frustration from owners who currently use optical, as most other codecs are not able to be carried by optical due to limitations in bandwidth. I’m not looking forward to the posts of condemnation for Sonos having chosen such a transport method, although I suspect at the time that the PLAYBAR was designed, HDMI-ARC didn’t exist, or if it did, it wasn’t in wide enough use to make sense from a cost perspective to put it in to Sonos, and it wouldn’t have sold because, at the time, the majority of TVs wouldn’t have supported it.

But certainly, if the maker of the TV set handles the new codec stream in a different manner than they do for Dolby Digital, you’re absolutely correct. I have my doubts that they do/will, but who knows, other than the folks who created the TV set. 

We’ll have to see. My crystal ball seems to be broken ;)
 

Makes sense to me. It's a tough thing to get right. I hope LG, Sonos and Samsung can implement firmware or software solutions that work for the stuff everyone's already bought. I did some more googling and found a rather interesting blog from Dolby in 2018 that explains a lot of these troubles quite well. Worth a read for anyone else who winds up here.

Dolby blog link:

https://developer.dolby.com/blog/dolby-audio-over-hdmi-part-3-reality/

The blog has a sentence that makes for a decent tldr;

"Decoding audio and video in devices requires some processing time, and each process introduces different time delays, or latencies, in each device."

Couldn’t agree more. I’m certain that Sonos isn’t instantaneous, either, but given how well it works in other TVs, as well as if you pull the audio out before it hits the TV, it’s hard to imagine anything other than the TV is the issue here. 

I appreciate the discussion from someone who is interested in the discussion, and is willing to consider all aspects of the situation. Rather frequently in these forums, people have decided that Sonos is the issue, and are not dissuaded by other perspectives. Sonos isn’t perfect, IMHO, but the fault on this issue is not them. But I’ve not found a better system out there, Sonos certainly meets the needs I have for now. Would love it to do more, and I hope in time, the opportunity for them to continue evolving will happen.

Stay safe, and have a lovely weekend!

I am very much in the same boat as you! I’ve found the following on the LG forums

https://lgcommunity.us.com/discussion/4423/oled-c9-edid-limitation-regarding-hdmi-earc-pass-through

“LG will be introducing PCM Multi-channel support when using eARC in the 2 quarter of 2020. This will be possible via a software update for 2019 & 2020 TV that support eARC.”

Not sure but wonder if this will mean that the LG following update will pass a 5.1 LPCM signal? Also not sure how the Sonos soundbar will use it if it does...

I have a 4 year old Panasonic dx902b. When I connect my beam via arc I seems to get a 250ms delay from externally connected hdmi DD 5.1 sources, however, internal TV apps will output DD5.1 perfectly in sync. 
 

At the moment I am running everything into the beam using an optical connection via a hdmi switch with optical output. The beam will now play audio with no sync issues. Bypassing the TV audio processing seems to solve the problem but this also means that I can not upgrade to the new Arc until I:

a) upgrade my TV as I will not be able to get atmos via optical input. 
b) accept the 250ms audio delay. 
 

Neither of these options seem likely. Does anyone know of an hdmi Splitter that can split the audio and video via hdmi rather than optical so it can be fed into the beam/Arc directly ?