Running Channels on ATV 4K. When using a 30hz connection to my 4K TV (Vizio) I have no audio issues. Tried moving to a 60Hz HDMI port today and found significant lip sync issues. Other apps (iTunes, PLEX) show no such issues. Using with Connect Quatro, Connect Extend and Prime. Issue exists on all sources.
Huh, that’s weird. So your TV has two different types of HDMI ports??
Are you using the TV speakers? Or HDMI ARC to different speakers?
Usually audio sync problems occur when the TV is using ARC but isn’t fast enough to deal with surround sound, and introduces some delay. You can try switching your Apple TV’s audio settings to Stereo to see if it goes away.
Yes, TV has 1 HDMI for 4K @60Hz. All rest are 4K @30Hz. Sound is ARC to Denon receiver. Note issue does not exist for other video sources, only Channels.
I would still like to know whether Stereo fixes the issues or not. Other apps may not be using surround sound in the same codec as OTA/Cable broadcasts, so that might be why they are not affected.
Please try the InstaTV app to compare as well.
Something weirder yet. I switched Apple TV to stereo output (was on best quality available) and sync issue resolved. Moved to Dolby Digital 5.1 and still no issues. Back to Best Quality Available and problem did not return. I’ll have to track this down further. Using 60Hz input on TV and Apple TV 4K has video as 4K SDR 60Hz.
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What make and model of HDMI cable are you using?
Tmm1 already figured it out, but basically boils down to this:
- TV is doing additional processing on the audio signal for the ARC output. It is not just a bitstream in/out.
- TV is not fast enough to do the 5.1 decoding. If true 5.1 is desired, better to run hdmi through the receiver and have that do the decode.
- OP changed ATV output to stereo. In turn, TV changes processing mode for the ARC output to PCM stereo.
- OP changed ATV back to 5.1, but TV stays in PCM and is not doing 5.1 decode anymore. Now there is no delay.