Some modules may only be loaded once, and trying to load them
twice from default.pa makes PulseAudio startup fail. While that could
be considered a user error, it's nicer to not be so strict. It's not
necessarily easy to figure what went wrong, if for example the user
plays with RAOP and adds module-raop-discover to default.pa, which first
works fine, but suddenly stops working when the user at some point
enables RAOP support in paprefs. Enabling RAOP in paprefs makes
module-gconf load the module too, so the module gets loaded twice.
This patch adds a way to differentiate module load errors, and
make cli-command ignore the error when the module is already
loaded.
For various use-cases a passthrough stream should have priority over all
other streams and get exclusive access to the sink regardless of whether
any other streams are playing.
An example use-case is ensuring Kodi can successfully start video
playback (with passthrough) even if an external notification sound
happened to be playing at the same time.
Signed-off-by: Arun Raghavan <git@arunraghavan.net>