Did you change this in the Template for your Denon device.
I have no Ruby snippets in my template for the Denon.
That's strange. Mine definitely does.
So basically LMCE is sending out the string every so often to see if we are still on that input.
I've only confirmed that it sends 'SIDVD' once a few seconds after playback starts. I did not have the same issue you described where audio cuts out throughout a movie for example.
I see it do this all the time with the TV as well. I will get a 1080P window with the input listed in the top right corner of the Sharp TV screen.
I have seen the '1080P' window on my Sharp TV at odd times too, but I'm not sure if the two are the same root cause.
I looked through my GSD log as well and it seems to be polling the input at Random.
What do you mean by 'polling the input at Random'? i.e. What do you see in the log?
I think we need some kind of ruby mute circuit so it does this and we cannot tell. I have multiple inputs used on my Denon so a global fix is needed.