@@ 0,0 1,68 @@
+---
+title: "How to Loopback Application Sound as an Input Source with PulseAudio"
+date: 2021-05-03
+---
+
+This guide will show you how to loopback your computer's application sound as a
+source in your meeting or calling software. There is probably a way to automate
+or make this setup permanent, which is something I'd like to later figure out.
+
+We'll first make a sink, we'll name `sink_mix`. This sink would mix mic and
+application sound. This is done by loading the `module-null-sink`, with some
+arguments (providing the name and properties).
+
+```
+pactl load-module module-null-sink sink_name=sink_mix sink_properties=device.description=sink_mix
+```
+
+We'll then loopback the mic sound into this new sink, this is done using the
+`module-loopback`. We first need to find the source of the microphone, you can
+list sources with:
+```
+pactl list sources
+```
+
+If you'd like to know what are the difference between sinks, sources, etc. I
+recommend you check out Victor's post regarding [PulseAudio under the
+hood](https://gavv.github.io/articles/pulseaudio-under-the-hood/#key-abstractions).
+
+After finding the name, in my case, this is
+"alsa_input.usb-BLUE_MICROPHONE_Blue_Snowball_797_2020_07_29_83297-00.mono-fallback".
+In the next command, replace `<source>` with the name of your source.
+
+```
+pactl load-module module-loopback latency_msec=60 adjust_time=6 source=<source> sink=sink_mix
+```
+
+Using PulseAudio Volume Control (`pavucontrol`), we can see we can now set the
+playback of specific applications to `sink_mix` instead of your default output
+source. You can also under recording, set your source to "Monitor of sink_mix".
+
+The issue now is that you are not able to listen to the playback, as it is only
+sent to `sink_mix`, which you cannot hear without listening to yourself.
+
+To solve this, we can use `module-combine-sink`, which allows us to direct any
+output of this sink to multiple sinks (defined as "slaves").
+
+We first have to find the name of your output (speakers) sink, this can be done
+with:
+
+```
+pactl list sinks
+```
+
+In my case, this was "alsa_output.pci-0000_00_1f.3.analog-stereo", and was
+listed as the first sink in the list. But this might vary depending on your
+setup.
+
+In the next command, replace `<speaker>` with the name of your output sink.
+
+```
+pactl load-module module-combine-sink slaves=<speaker>,sink_mix
+```
+
+When directing the playback of an application, make sure to select
+"Simultaneous output to ..., sink_mix". Where the ellipsis would match your
+speaker.
+
+If you have any suggestions, please let me know in the mailing list below!