A new start

lib/audio/default.nix

@@ -0,0 +1,65 @@
+{ lib }:
+
+rec {
+  ## Renames an alsa device from a given `name` using the new `description`.
+  ##
+  #@ { name: String, description: String } -> { matches: List, apply_properties: Attrs }
+  mkAlsaRename = { name, description }: {
+    matches = [
+      [
+        [ "device.name" "matches" name ]
+      ]
+    ];
+    # actions = { "update-props" = { "node.description" = description; }; };
+    apply_properties = {
+      "device.description" = description;
+    };
+  };
+
+  ## Create a pipewire audio node.
+  ##
+  #@ { name: String, factory: String ? "adapter", ... } -> { factory: String, args: Attrs }
+  mkAudioNode = args@{ name, factory ? "adapter", ... }: {
+    inherit factory;
+    args = (builtins.removeAttrs args [ "name" "description" ]) // {
+      "node.name" = name;
+      "node.description" = args.description or args."node.description";
+      "factory.name" = args."factory.name" or "support.null-audio-sink";
+    };
+  };
+
+  ## Create a virtual pipewire audio node.
+  ##
+  #@ { name: String, ... } -> { factory: "adapter", args: Attrs }
+  mkVirtualAudioNode = args@{ name, ... }:
+    mkAudioNode (args // {
+      name = "virtual-${lib.toLower name}-audio";
+      description = "${name} (Virtual)";
+      "media.class" = args.class or args."media.class" or "Audio/Duplex";
+      "object.linger" = args."object.linger" or true;
+      "audio.position" = args."audio.position" or [ "FL" "FR" ];
+      "monitor.channel-volumes" = args."monitor.channel-volumes" or true;
+    });
+
+  ## Connect two pipewire audio nodes
+  ##
+  #@ { name: String?, from: String, to: String, ... } -> { name: "libpipewire-module-loopback", args: Attrs }
+  mkBridgeAudioModule = args@{ from, to, ... }: {
+    name = "libpipewire-module-loopback";
+    args = (builtins.removeAttrs args [ "from" "to" "name" ]) // {
+      "node.name" =
+        if args ? name then
+          "${args.name}-bridge"
+        else
+          "${lib.toLower from}-to-${lib.toLower to}-bridge";
+      "audio.position" = args."audio.position" or [ "FL" "FR" ];
+      "capture.props" = {
+        "node.target" = from;
+      } // (args."capture.props" or { });
+      "playback.props" = {
+        "node.target" = to;
+        "monitor.channel-volumes" = true;
+      } // (args."playback.props" or { });
+    };
+  };
+}