modules/pipewireLowLatency: use modular config files

Fixes breakage caused by NixOS/nixpkgs#220332.

modules/pipewireLowLatency.nix

@@ -1,92 +1,85 @@
 {
   config,
   lib,
+  pkgs,
   ...
 }:
 # low-latency PipeWire configuration
 # extends the nixpkgs module
 let
   cfg = config.services.pipewire.lowLatency;
+  qr = "${toString cfg.quantum}/${toString cfg.rate}";
+  json = pkgs.formats.json {};
 in {
   options = {
     services.pipewire.lowLatency = {
-      enable = lib.mkEnableOption "Enable low latency";
+      enable = lib.mkEnableOption (lib.mdDoc "Enable low latency");
+
       quantum = lib.mkOption {
-        description = "Minimum quantum to set";
+        description = lib.mdDoc "Minimum quantum to set";
         type = lib.types.int;
         default = 64;
         example = 32;
       };
+
       rate = lib.mkOption {
-        description = "Rate to set";
+        description = lib.mdDoc "Rate to set";
         type = lib.types.int;
         default = 48000;
         example = 96000;
       };
     };
   };
 
-  config = let
-    qr = "${toString cfg.quantum}/${toString cfg.rate}";
-  in
-    lib.mkIf cfg.enable {
-      services.pipewire = {
-        config = {
-          # pipewire native config
-          pipewire = {
-            "context.properties" = {"default.clock.min-quantum" = cfg.quantum;};
-          };
-
-          # pulse clients config
-          pipewire-pulse = {
-            "context.properties" = {};
-            "context.modules" = [
-              {
-                name = "libpipewire-module-rtkit";
-                args = {
-                  "nice.level" = -15;
-                  "rt.prio" = 88;
-                  "rt.time.soft" = 200000;
-                  "rt.time.hard" = 200000;
-                };
-                flags = ["ifexists" "nofail"];
-              }
-              {name = "libpipewire-module-protocol-native";}
-              {name = "libpipewire-module-client-node";}
-              {name = "libpipewire-module-adapter";}
-              {name = "libpipewire-module-metadata";}
-              {
-                name = "libpipewire-module-protocol-pulse";
-                args = {
-                  "pulse.min.req" = qr;
-                  "pulse.min.quantum" = qr;
-                  "pulse.min.frag" = qr;
-                  "server.address" = ["unix:native"];
-                };
-              }
-            ];
+  config = lib.mkIf cfg.enable {
+    # pipewire native config
+    environment.etc = {
+      "pipewire/pipewire.d/99-lowlatency.conf".source = json.generate "99-lowlatency.conf" {
+        context.properties.default.clock.min-quantum = cfg.quantum;
+      };
 
-            "stream.properties" = {
-              "node.latency" = qr;
-              "resample.quality" = 1;
+      # pulse clients config
+      "pipewire/pipewire-pulse.d/99-lowlatency.conf".source = json.generate "99-lowlatency.conf" {
+        context.modules = [
+          {
+            name = "libpipewire-module-rtkit";
+            args = {
+              nice.level = -15;
+              rt.prio = 88;
+              rt.time.soft = 200000;
+              rt.time.hard = 200000;
             };
-          };
-        };
-        # lower latency alsa format
-        media-session.config.alsa-monitor = {
-          rules = [
-            {
-              matches = [{node.name = "alsa_output.*";}];
-              actions = {
-                update-props = {
-                  "audio.format" = "S32LE";
-                  "audio.rate" = cfg.rate * 2;
-                  "api.alsa.period-size" = 2;
-                };
-              };
-            }
-          ];
+            flags = ["ifexists" "nofail"];
+          }
+          {
+            name = "libpipewire-module-protocol-pulse";
+            args = {
+              pulse.min.req = qr;
+              pulse.min.quantum = qr;
+              pulse.min.frag = qr;
+              server.address = ["unix:native"];
+            };
+          }
+        ];
+
+        stream.properties = {
+          node.latency = qr;
+          resample.quality = 1;
         };
       };
+
+      "wireplumber/main.lua.d/99-alsa-lowlatency.lua".text = ''
+        alsa_monitor.rules = {
+          {
+            matches = {{{ "node.name", "matches", "alsa_output.*" }}};
+            apply_properties = {
+              ["audio.format"] = "S32LE",
+              ["audio.rate"] = ${toString (cfg.rate * 2)},
+              ["api.alsa.period-size"] = 2,
+            },
+          },
+        }
+      '';
     };
+  };
 }