filter-chain: add nofail flags

Add nofail flags to some filter-chain examples to avoid aborting on
startup and leaving the system in a silent state.

Add some more comments to guide people to change the paths to the
filters and config files where needed.

src/daemon/filter-chain/demonic.conf

@@ -4,8 +4,9 @@
 # ~/.config/pipewire/filter-chain.conf.d/
 #
 context.modules = [
-    { name = libpipewire-module-filter-chain
+  { name = libpipewire-module-filter-chain
-        args = {
+    flags = [ nofail ]
+    args = {
             #audio.format    = F32
             #audio.rate      = 48000
             audio.channels   = 2

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

@@ -5,6 +5,7 @@
 #
 context.modules = [
     { name = libpipewire-module-filter-chain
+        flags = [ nofail ]
         args = {
             node.description = "Dolby Surround Sink"
             media.name       = "Dolby Surround Sink"

src/daemon/filter-chain/sink-matrix-spatialiser.conf

@@ -8,6 +8,7 @@
 
 context.modules = [
     { name = libpipewire-module-filter-chain
+        flags = [ nofail ]
         args = {
             node.description = "Matrix Spatialiser"
             media.name       = "Matrix Spatialiser"

src/daemon/filter-chain/sink-virtual-surround-5.1-kemar.conf

@@ -3,8 +3,11 @@
 # Copy this file into a conf.d/ directory such as
 # ~/.config/pipewire/filter-chain.conf.d/
 #
+# Adjust the paths to the convolver files to match your system
+#
 context.modules = [
     { name = libpipewire-module-filter-chain
+        flags = [ nofail ]
         args = {
             node.description = "Virtual Surround Sink"
             media.name       = "Virtual Surround Sink"

src/daemon/filter-chain/sink-virtual-surround-7.1-hesuvi.conf

@@ -3,8 +3,11 @@
 # Copy this file into a conf.d/ directory such as
 # ~/.config/pipewire/filter-chain.conf.d/
 #
+# Adjust the paths to the convolver files to match your system
+#
 context.modules = [
     { name = libpipewire-module-filter-chain
+        flags = [ nofail ]
         args = {
             node.description = "Virtual Surround Sink"
             media.name       = "Virtual Surround Sink"

src/daemon/filter-chain/source-rnnoise.conf

@@ -3,8 +3,11 @@
 # Copy this file into a conf.d/ directory such as
 # ~/.config/pipewire/filter-chain.conf.d/
 #
+# Adjust the paths to the rnnoise plugin to match your system
+#
 context.modules = [
     { name = libpipewire-module-filter-chain
+        flags = [ nofail ]
         args = {
             node.description = "Noise Canceling source"
             media.name       = "Noise Canceling source"
@@ -13,7 +16,13 @@ context.modules = [
                     {
                         type   = ladspa
                         name   = rnnoise
-                        plugin = librnnoise_ladspa
+			# The path to the plugin. The suffix .so is appended to
+			# this string and then the file is then located in the directories
+			# listed in the environment variable LADSPA_PATH or 
+			# /usr/lib64/ladspa, /usr/lib/ladspa or the system library directory
+			# as a fallback.
+			# You might want to use an absolute path here to avoid problems.
+                        plugin = "librnnoise_ladspa"
                         label  = noise_suppressor_stereo
                         control = {
                             "VAD Threshold (%)" 50.0

src/daemon/filter-chain/spatializer-7.1.conf

@@ -3,8 +3,11 @@
 # Copy this file into a conf.d/ directory such as
 # ~/.config/pipewire/filter-chain.conf.d/
 #
+# Adjust the paths to the sofa file to match your system.
+#
 context.modules = [
     { name = libpipewire-module-filter-chain
+        flags = [ nofail ]
         args = {
             node.description = "Spatial Sink"
             media.name       = "Spatial Sink"

src/daemon/filter-chain/spatializer-single.conf

@@ -4,8 +4,11 @@
 # Copy this file into a conf.d/ directory such as
 # ~/.config/pipewire/filter-chain.conf.d/
 #
+# Adjust the paths to the sofa files to match your system
+#
 context.modules = [
     { name = libpipewire-module-filter-chain
+        flags = [ nofail ]
         args = {
             node.description = "3D Sink"
             media.name       = "3D Sink"