feat(tools/nsfv-setup): Move NSFV setup script out of //users r/1082

This program can be used for noise-cancelling in arbitrary audio
streams. See CL/576 and CL/577 for more details.

This moves the script out of my users folder and to //tools, and adds
two changes:

* Existing sinks will be removed & reinitialised
* The sink is changed from stereo->mono (which seems to make little
  difference but is more reliable)
* The parameter has changed from 50 to 42 because I felt like it

Change-Id: Id9ff285fefd682ccc4d9f18e46b5fde9cd056aa7
Reviewed-on: https://cl.tvl.fyi/c/depot/+/578
Reviewed-by: glittershark <grfn@gws.fyi>

1 files changed, 27 insertions, 0 deletions

diff --git a/tools/nsfv-setup/default.nix b/tools/nsfv-setup/default.nix
new file mode 100644
index 0000000000..aa3567c56a
--- /dev/null
+++ b/tools/nsfv-setup/default.nix
@@ -0,0 +1,27 @@
+# Configures a running Pulseaudio instance with an LADSP filter that
+# creates a noise-cancelling sink.
+#
+# This can be used to, for example, cancel noise from an incoming
+# video conferencing audio stream.
+#
+# There are some caveats, for example this will not distinguish
+# between noise from different participants and I have no idea what
+# happens if the default sink goes away.
+#
+# If this script is run while an NSFV sink exists, the existing sink
+# will first be removed.
+{ pkgs, ... }:
+
+let
+  inherit (pkgs) ripgrep pulseaudio nsfv;
+in pkgs.writeShellScriptBin "nsfv-setup" ''
+  export PATH="${ripgrep}/bin:${pulseaudio}/bin:$PATH"
+
+  if pacmd list-sinks | rg librnnoise_ladspa.so >/dev/null; then
+    pactl unload-module module-ladspa-sink
+  fi
+
+  SINK=$(${pulseaudio}/bin/pacmd info | ${ripgrep}/bin/rg -r '$1' '^Default sink name: (.*)$')
+  echo "Setting up NSFV filtering to sink ''${SINK}"
+  ${pulseaudio}/bin/pacmd load-module module-ladspa-sink sink_name=NSFV sink_master=''${SINK} label=noise_suppressor_mono plugin=${pkgs.nsfv}/lib/ladspa/librnnoise_ladspa.so control=42
+''