filter-chain: add dolby surround sink

Encodes a 6 channel surround sound stream into dolby surround.

src/daemon/filter-chain/meson.build

@@ -1,5 +1,6 @@
 conf_files = [
   [ 'demonic.conf', 'demonic.conf' ],
+  [ 'sink-dolby-surround.conf', 'sink-dolby-surround.conf' ],
   [ 'sink-eq6.conf', 'sink-eq6.conf' ],
   [ 'source-rnnoise.conf', 'source-rnnoise.conf' ],
 ]

src/daemon/filter-chain/sink-dolby-surround.conf

@@ -0,0 +1,66 @@
+# Dolby Surround encoder sink
+#
+# start with pipewire -c filter-chain/sink-dolby-surround.conf
+#
+context.properties = {
+    log.level        = 0
+}
+
+context.spa-libs = {
+    audio.convert.* = audioconvert/libspa-audioconvert
+    support.*       = support/libspa-support
+}
+
+context.modules = [
+    {   name = libpipewire-module-rtkit
+        args = {
+            #nice.level   = -11
+            #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-filter-chain
+        args = {
+            node.name =  "dolby_sink"
+            node.description =  "Dolby Surround Sink"
+            media.name =  "Dolby Surround Sink"
+            filter.graph = {
+                nodes = [
+                    {
+                        type = builtin
+                        name = mixer
+                        label = mixer
+                        control = { "Gain 1" = 0.5 "Gain 2" = 0.5 }
+                    }
+                    {
+                        type = ladspa
+                        name = enc
+			plugin = surround_encoder_1401
+                        label = surroundEncoder
+                    }
+                ]
+		links = [
+		    { output = "mixer:Out" input = "enc:S" }
+		]
+		inputs = [ "enc:L" "enc:R" "enc:C" null "mixer:In 1" "mixer:In 2" ]
+		outputs = [ "enc:Lt" "enc:Rt" ]
+            }
+            capture.props = {
+	        media.class = Audio/Sink
+		audio.channels = 6
+		audio.position = [ FL FR FC LFE SL SR ]
+	    }
+            playback.props = {
+	        node.passive = true
+		audio.channels = 2
+		audio.position = [ FL FR ]
+	    }
+	}
+    }
+]