[pulseaudio-discuss] Add a way to override priority of sinks - mostly for module-combine-sinks

[Tanu Kaskinen]

On Fri, 2017-05-26 at 06:41 -0700, Myst Fox wrote:
> This is a bit hard to describe. I'd really like to see a way to manually
> set priorities on sinks. I recently got a portable DAC, and I wanted to
> use it when plugged in and fall back on module-combine-sink otherwise -
> mostly because I often use a program that cannot handle changing sinks.
> This however means I needed my priorities to be correctly ordered. After
> fixing the identification of my DAC on the udev side, and switching to
> running a git build to have recent fixes like
> https://bugs.freedesktop.org/show_bug.cgi?id=99222, I ran into that I
> wanted the module-combine-sink sink to be above my internal card but
> below my DAC. I solved this for now with `load-module
> module-combine-sink sink_properties='device.class="sound"
> device.form_factor="speaker"'
> `, but that's faking out the priority setting to get the right order,
> not doing it any sort of "right".
> 
> I'm imagining adding a proplist entry of some naming that lets you
> outright set the priority, and there would be a check at the start of
> pa_device_init_priority in sink.c that would outright set the priority
> if it was a valid value. I'd like to know, though, how that sounds, what
> people think, ideas about the name, if there's anything big I might be
> missing, before I try to work on a patch.

I wouldn't mind making it possible to configure the sink priority. I
don't really like using the property list for this, though. pa_sink
already has a priority field, duplicating the same information in the
property list doesn't seem like a good thing. module-combine-sink could
take a separate sink_priority argument and use that to override the
default priority after the pa_sink_new() call.

I'm cc'ing Arun, because we recently had a discussion[1] about maybe
removing sink priorities altogether and prioritizing sinks only based
on the active port priority. That would break this use case, so I think
it's best to keep the sink priorities.

[1] https://lists.freedesktop.org/archives/pulseaudio-discuss/2017-February/027493.html

-- 
Tanu

https://www.patreon.com/tanuk