filter-chain: add mixer sink example

src/daemon/filter-chain/sink-mix-FL-FR.conf

@@ -0,0 +1,39 @@
+# An example filter chain that makes a stereo sink that mixes
+# the FL and FR channels to a single FL channel
+#
+# Copy this file into a conf.d/ directory
+#
+context.modules = [
+    { name = libpipewire-module-filter-chain
+        args = {
+            node.description = "Mix example"
+            media.name       = "Mix example"
+            filter.graph = {
+                nodes = [
+                    {
+                        name   = mix
+                        type   = builtin
+                        label  = mixer
+			control = {
+			  "Gain 1" = 0.5
+			  "Gain 2" = 0.5
+			}
+                    }
+                ]
+                inputs = [ "mix:In 1" "mix:In 2" ]
+                outputs  = [ "mix:Out" ]
+            }
+            capture.props = {
+                node.name       = "mix_input.mix-FL-FR-to-FL"
+                audio.position  = [ FL FR ]
+		media.class     = "Audio/Sink"
+            }
+            playback.props = {
+                node.name        = "mix_output.mix-FL-FR-to-FL"
+                audio.position  = [ FL ]
+                stream.dont-remix = true
+                node.passive = true
+            }
+        }
+    }
+]

src/daemon/filter-chain/source-duplicate-FL.conf

@@ -1,4 +1,4 @@
-# An example filter chain for duplicating the FL channel
+# An example filter chain that makes a source that duplicates the FL channel
 # to FL and FR.
 #
 # Copy this file into a conf.d/ directory
@@ -39,10 +39,12 @@ context.modules = [
                 node.name         = "remap_input.remap-FL-to-FL-FR"
                 audio.position    = [ FL ]
                 stream.dont-remix = true
+                node.passive      = true
             }
             playback.props = {
                 node.name         = "remap_output.remap-FL-to-FL-FR"
                 audio.position    = [ FL FR ]
+                media.class       = "Audio/Source"
             }
         }
     }