modules: Add module-rt

Add a module to set thread priorities without using rtkit.

src/daemon/pipewire.conf.in

@@ -73,6 +73,17 @@ context.modules = [
         flags = [ ifexists nofail ]
     }
 
+    # Set thread priorities without using RTKit.
+    #{   name = libpipewire-module-rt
+    #    args = {
+    #        nice.level   = -11
+    #        rt.prio      = 88
+    #        rt.time.soft = 200000
+    #        rt.time.hard = 200000
+    #    }
+    #    flags = [ ifexists nofail ]
+    #}
+
     # The native communication protocol.
     {   name = libpipewire-module-protocol-native }
 

src/daemon/systemd/system/pipewire.service.in

@@ -22,6 +22,7 @@ RestrictNamespaces=yes
 SystemCallArchitectures=native
 SystemCallFilter=@system-service
 Type=simple
+AmbientCapabilities=CAP_SYS_NICE
 ExecStart=@PW_BINARY@
 Restart=on-failure
 RuntimeDirectory=pipewire