Q90R + LGC8 lip sync when Dolby Vision and Dolby Atmos are in use


Deleted member 871284

Hi all, wondered if someone could help me with my setup around some weird lip syncing issues that I’m experiencing.

I recently got the Q90R soundbar to use with my LGC8 and have updated both to the latest firmware.

Initial setup:
AppleTV4K -> LGC8 -> Q90R

Switched the tv setting to dtv auto (from pcm) and hdmi arc output for the q90R to show and use an atmos. I know it’s lossy, that’s fine the tv doesn’t have hdmi 2.1 or eARC.

This worked perfectly for catch-up and streaming non HDR or atmos content until I started some film testing. Using the AppleTV4K and streaming the matrix the lip sync was minor but noticeable.

Tried to sort this via the sync on the bar and av sync in the tv, but didn’t help.

Now I didn’t think that the Q90r could pass atmos and Dolby vision, but changing the setup to be AppleTV -> q90R -> C8 got rid of all sync issues completely and worked flawlessly.

However testing out ReadyPlayerOne is a different story. I get intermittent lip sync, so during the first race for example just before kong appears up to after he goes the sync gets out by almost a second, after the scene it goes back to not having an issue at all when talking at Aich workshop.

I presume that this is just hammering the bandwidth at this point and it just can’t handle it?

I’ve tried messing about with the sync option on the soundbar and the av sync on the tv in many combinations but doesn’t seem to help in this combo either because it’s not constant.

I’ve also run the audio sync calibration on the Apple TV itself and have tried setting match bitrates and audio properties etc

Is this simply a limitation that would be solved if LG released an eARC firmware update for the c8 and have better pass through? I presume not because it won’t be lossless audio anyway.

Is there some setting I’m missing? Any help would be greatly appreciated


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