Signed-off-by: Guido Günther <agx@sigxcpu.org>

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+What if you want to have your phone's alarm clock volume different from your music playback volume
+and have the later go to speakers while alarms should continue to go to the phone's speaker?
+
+While this could be handled via manually set up, per application volume and sink setups this doesn't

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+incoming call while music is playing).
+
+THe modern Linux audio stack uses [pipewire][] and [wireplumber][] and the wireplumber maintainers
+implemented a solution for this called *role* *based* routing. In the following we'll explore how

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+
+THe modern Linux audio stack uses [pipewire][] and [wireplumber][] and the wireplumber maintainers
+implemented a solution for this called *role* *based* routing. In the following we'll explore how
+this works, what is already implemented and what we needs to do before we can enable it by default

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+
+While ducking and corking is being leveraged with pulseaudio to e.g. silence music during phone
+calls on e.g. the Librem 5
+[already](https://source.puri.sm/Librem5/librem5-base/-/blob/pureos/latest/default/audio/pulse/librem5.pa#L26-L31)

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+
+## Media Roles
+
+In order to leverage this applications tag their audio streams with a certain role so wireplumber

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+for alarm clocks, cellbroadcasts incoming calls, etc. is usually emitted by feedbackd these
+applications don't need to anything as feedbackd will set an appropriate role.
+
+The roles are currently not standardized on Linux so we researched a bit what is in use and

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+
+If you want to test this you can build [feedbackd](https://gitlab.freedesktop.org/agx/feedbackd)
+with `-Dmedia-roles`. `meson install` will then put a `media-role-nodes.conf` into
+`/usr/share/wireplumber/wireplumber.conf.d/` enabling media role based

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+with `-Dmedia-roles`. `meson install` will then put a `media-role-nodes.conf` into
+`/usr/share/wireplumber/wireplumber.conf.d/` enabling media role based
+in Wireplumber and feedbackd will then add `media.role` properties to the emitted events ensuring
+that e.g.  incoming calls or emergency alerts will silence any playing music or game output.

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+in Wireplumber and feedbackd will then add `media.role` properties to the emitted events ensuring
+that e.g.  incoming calls or emergency alerts will silence any playing music or game output.
+
+### How do check if role based routing is active

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+
+### How do check if role based routing is active
+
+If role based routing is active the `wpctl status` output should list the known media roles as

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+      { "subject": 0, "key": "current.role-based.volume.control", "type": "Spa:String:JSON", "value": { "name": "input.loopback.sink.role.alarm" } }
+```
+
+We can then use that in Phosh to make the default volume slider operation on this volume control. A

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+
+We can then use that in Phosh to make the default volume slider operation on this volume control. A
+prototype for this can be found
+[here](https://gitlab.gnome.org/World/Phosh/phosh/-/merge_requests/1714))

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+
+## Routing Target
+
+With volume controls sorted out there's still the question where to output to. Mobile phones usually

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+## Routing Target
+
+With volume controls sorted out there's still the question where to output to. Mobile phones usually
+have a speaker and an earpiece and also often Bluetooth headphones are connected to. While the later

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+
+With volume controls sorted out there's still the question where to output to. Mobile phones usually
+have a speaker and an earpiece and also often Bluetooth headphones are connected to. While the later
+might be the right target for music one usually wants emergency alerts and alarms routed to the

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+
+# Trying it out
+
+So how can you try that out. Until more things made it into releases we have to build some

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+So how can you try that out. Until more things made it into releases we have to build some
+components from source:
+
+* [feedbackd][]: The needed changes are merge so you can clone it an run from the working copy

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+_build/run
+```
+
+* [wireplumber][] git has the needed changes merged so you can build and run from the working copy

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+./wp-uninstalled.sh wireplumber
+```
+
+* [phosh-mobile-settings][] has support built in since 0.47, no need to build anything

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+With this you should be able to check if the role based policies are active and e.g. see the volume
+slider in mobile settings.
+
+If you can do without an GUI bits and want to avoid building lots of stuff manually but still want

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+slider in mobile settings.
+
+If you can do without an GUI bits and want to avoid building lots of stuff manually but still want
+to try things out it sufficient to only build wireplumber and add the policy. You can then use