LG TV with HDMI ARC to Pioneer amp - jittery audio with SD video?

[davelondon]

I have an LG 75UM7110PLB TV and a Pioneer SC-LX79 receiver. The TV is used as the audio source, and feeds the receiver by HDMI ARC.

When viewing HD content everything works flawlessly. However when I watch an SD broadcast, the audio is jittery. When I switch to internal TV speaker the jitter disappears and the audio is perfect.

I've updated the firmware on both the TV and the receiver.

Any ideas?

 

[davelondon]

Here's a demo: https://photos.app.goo.gl/Ap44Sdp39pKj8ytp6