Turn off output on idle

[jens1608]

Awesome job mill1000!
It works flawlessly on my setup :)

I ran into some small problem in my setup:
I'm using active speakers for a multi room setup.
SnapCast-Server -> SnapCast Client on Raspberry Pi Zero -> raspdif -> LED -> Toslink to my speakers.
My speakers are able to automatically activate on Toslink signal and deactivate themselves after 10s without signal.
BUT no signal means Toslink being turned off completely.
I realized in standard configuration, even with "no-keep-alive" the output never turns off, so my speakers are never going to sleep.

I've added a few lines to turn of PCM completely during buffer underrun, this solves my issue and my speakers are going to sleep.
Maybe this might help somebody else with a similar setup.

Thanks again for your amazing work, I really appreciate it!

Regards
Jens

[mill1000]

Thanks for the contribution! Glad it's working well for you.

If you can fix the minor formatting issues reported by the checks I'll get this merged.