feat(tazjin/nsfv-setup): Add script for noise-cancelling others r/1080

This script creates a pulseaudio sink that will cancel noise in audio
streams sent to it, and then move it on to the default sink.

This means that other people's crackling, static background, gulping,
keyboard sounds, fan whirring, construction noise etc. are removed.

Some preliminary tests on TVL suggest that this actually works. The
parameter might need some tweaking ("50" is just the default value),
as there is some occasional crackling at the beginning/end of a speech
segment, but this is already *much* better than before.

Change-Id: I9d4e2b39cfc2b878b4b7c5458788b8d46fb801af
Reviewed-on: https://cl.tvl.fyi/c/depot/+/577
Reviewed-by: nyanotech <nyanotechnology@gmail.com>

1 files changed, 18 insertions, 0 deletions

diff --git a/users/tazjin/nsfv-setup/default.nix b/users/tazjin/nsfv-setup/default.nix
new file mode 100644
index 000000000000..65f94034da42
--- /dev/null
+++ b/users/tazjin/nsfv-setup/default.nix
@@ -0,0 +1,18 @@
+# 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.
+{ pkgs, ... }:
+
+let
+  inherit (pkgs) ripgrep pulseaudio nsfv;
+in pkgs.writeShellScriptBin "nsfv-setup" ''
+  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_stereo plugin=${pkgs.nsfv}/lib/ladspa/librnnoise_ladspa.so control=50
+''