pipewire: added different loopback devices

wiki/linux/pipewire.md

@@ -15,11 +15,12 @@ Make sure to restart to be sure everything is running correctly.
 
 ## Usage
 
-For simple sound processing in the form of volume adjustment as well as setting
-the default input and output devices
+This section will focus on the usage of Pipewire.
 
-### Volume Control
+### Mixing
 
+For simple sound processing in the form of volume adjustment as well as setting
+the default input and output devices
 [`pavucontrol`](https://freedesktop.org/software/pulseaudio/pavucontrol/) can be
 used as a simple mixer.
 
@@ -72,14 +73,25 @@ pw-loopback -C <id>
 
 ### Virtual Devices
 
-The source for this section of the entry is derived by
-[Pipewire Gitlab site](https://gitlab.freedesktop.org/pipewire/pipewire/-/wikis/Virtual-Devices#behringer-umc404hd-speakersheadphones-virtual-sinks).
+This section focusses on the temporary and permanent creation and removal of virtual devices like
+virtual sinks and sources aswell as coupled nodes like loopbacks.
 
 #### Creating a Null Device
 
+This section will focus on the creation of a dummy device.
+That is a virtual device that can be selected as output but is not used by default.
+This can be useful to record applications as their sound can cleanly be passed to the dummy device
+which will eliminate other applications sounds.
+If the goal is to record and listen to an application at the same time navigate to
+[the application loopback section](#creating-an-application-loopback)
+
+The source for this section of the entry is derived by
+[Pipewire Gitlab site](https://gitlab.freedesktop.org/pipewire/pipewire/-/wikis/Virtual-Devices#single-nodes).
+
 A dummy device, or null sink, can be created permanently by creating a `.conf` file inside the
 `~/.config/pipewire/pipewire.conf.d` directory with the following lines.
 
+
 ```txt
 context.objects = [
     {   factory = adapter
@@ -116,3 +128,94 @@ This will return an id that can be used to remove the sink with the following co
 ```sh 
 pactl unload-module <id>
 ```
+
+#### Creating a Device Loopback
+
+In this section a device loopback is defined as a loopback that takes a device as input.
+This can be useful to listen to input devices, such as audio interfaces with connected microphones,
+instruments, etc.
+
+The source for this section of the entry is derived by
+[Pipewire Gitlab site](https://gitlab.freedesktop.org/pipewire/pipewire/-/wikis/Virtual-Devices#single-nodes)
+and [the official website](https://docs.pipewire.org/page_module_loopback.html).
+
+A device loopback can be created permanently by creating a `.conf` file inside the
+`~/.config/pipewire/pipewire.conf.d` directory with the following lines.
+
+```txt
+context.modules = [
+  {
+    name = libpipewire-module-loopback
+    args = {
+      audio.position = [ FL FR ]
+      capture.props = {
+        media.class = "Stream/Input/Audio"
+        node.name = "device-loopback-1-recording"
+        node.description = "Device-Loopback 1 Recording"
+      }
+      playback.props = {
+        media.class = "Stream/Output/Audio"
+        node.name = "device-loopback-1-playback"
+        node.description = "Device-Loopback 1 Playback"
+      }
+      audio.volume = 0.5
+      audio.mute = true
+    }
+  }
+]
+```
+
+The created device loopback is made up by two parts that can be found in different places inside a
+mixer like [pavucontrol](#volume-control).
+The part called `Device-Loopback 1 Recording` in the example config can be found in the `Recording`
+tab.
+There the device to loopback can be selected.
+The second part called `Device-Loopback 1 Playback` is available under the `Playback` tab and
+allows to switch the selection of the output device.
+
+#### Creating an Application Loopback
+
+This section will focus on the creation of an application loopback.
+In this section an application loopback is defined as a loopback that takes an application as input.
+This can be useful to record applications as their sound can cleanly be passed to the sink sink of
+the applicatino loopback which will eliminate other applications sounds.
+If the goal is to record and not listen to the application at the same time navigate to
+[the null device section](#creating-a-null-device).
+Alternatively the null device can also be selected as a output device for the playback part of the
+application loopback which makes it easily and seemlessly possible to switch between listening in
+and not listening without changing the device that is recorded by the capturing program.
+
+The source for this section of the entry is derived by
+[Pipewire Gitlab site](https://gitlab.freedesktop.org/pipewire/pipewire/-/wikis/Virtual-Devices#single-nodes)
+and [the official website](https://docs.pipewire.org/page_module_loopback.html).
+
+An application loopback can be created permanently by creating a `.conf` file inside the
+`~/.config/pipewire/pipewire.conf.d` directory with the following lines.
+
+```txt 
+context.modules = [{
+    name = libpipewire-module-loopback
+    args = {
+        audio.position = [ FL FR ]
+        capture.props = {
+            media.class = "Audio/Sink"
+            node.name = "application-loopback-1-sink"
+            node.description = "Application-Loopback 1 Sink"
+        }
+        playback.props = {
+            media.class = "Stream/Output/Audio"
+            node.name = "application-loopback-1-playback"
+            node.description = "Application-Loopback 1 Playback"
+        }
+    }
+}]
+```
+
+The created device loopback is made up by two parts that can be found in different places inside a
+mixer like [pavucontrol](#volume-control).
+The part called `Application-Loopback 1 Sink` in the example config can be found in the `Output
+Devices` tab.
+The second part called `Application-Loopback 1 Playback` is available under the `Playback` tab and
+allows to switch the selection of the output device.
+Also in the `Playback` tab `Application-Loopback 1 Sink` can be selected as an output for currently
+running applications which will loopback the sound to the selected output device.

wiki/linux/pulseaudio.md

@@ -6,8 +6,10 @@
 
 ## Usage
 
+This section will discuss the usage of PulseAudio.
+
 ### Mixing
 
 For simple sound processing in the form of volume adjustment as well as setting
-the default input and output devices `pavucontrol` can be used as a simple
-mixer.
+the default input and output devices [`pavucontrol`](/wiki/linux/pipewire.md#mixing) can be
+used as a simple mixer.