AVFD: Rescan audio stream when detecting audio change even when passthrough.
Also don’t drop the audio packet when a change occurs.
AVFD: Do not force the number of channels for AC3

Honestly, I can’t fully recall what it was ever there for. I remember something to do with properly detecting channel changes, but it doesn’t appear to make a difference anymore.
AO: Do not reset audio card if we can continue to passthrough with current configuration.

A channel number change while doing passthrough doesn’t usually require a reset of the audio card. Avoid it if we can.
This could be further extended, so we only reset the card if absolutely necessary
Playback: digital passthrough changes.

We use to always decode stereo so enabling upmixing on the fly was possible.

Change in behaviors and capabilities
* Now will bitstream even stereo signal.
* allows to upmix digital stereo and revert back to bitstreaming once disabled once again