proper pipewire setup to utilize DAC

computational/configuration.nix

@@ -20,6 +20,30 @@
       devices=/dev/sda1,/dev/sdb1
   '';
 
+  # [AUDIO]
+  environment.etc."pipewire/media-session.d/alsa-monitor.con".text = ''
+    enabled = true
+
+    rules = {
+      {
+        matches = [
+          {
+            node.name = "alsa_output.usb-SMSL_SMSL_USB_AUDIO-00.analog-stereo"
+          }
+        ]
+     
+        actions = {
+          update-props = {
+            audio.format = "S32_LE"
+          }
+        }
+      },
+    }
+  '';
+
+  environment.etc."pipewire/pipewire.conf".text = builtins.readFile ./pipewire.conf;
+  
+
   # [NETWORKING]
   networking.hostName = "computational";
   networking.networkmanager.enable = true;

computational/pipewire.conf

@@ -0,0 +1,308 @@
+context.properties = {
+    ## Configure properties in the system.
+    #library.name.system                   = support/libspa-support
+    #context.data-loop.library.name.system = support/libspa-support
+    #support.dbus                          = true
+    #link.max-buffers                      = 64
+    link.max-buffers                       = 16                       # version < 3 clients can't handle more
+    #mem.warn-mlock                        = false
+    #mem.allow-mlock                       = true
+    #mem.mlock-all                         = false
+    #clock.power-of-two-quantum            = true
+    #log.level                             = 2
+    #cpu.zero.denormals                    = false
+
+    core.daemon = true              # listening for socket connections
+    core.name   = pipewire-0        # core name and socket name
+
+    ## Properties for the DSP configuration.
+    # default.clock.rate          = 48000
+    default.clock.allowed-rates = [ 44100 48000 88200 96000, 176400 192000 352800 384000 705600 768000 ]
+    default.clock.quantum       = 1024
+    default.clock.min-quantum   = 128
+    default.clock.max-quantum   = 2048
+    #default.clock.quantum-limit = 8192
+    #default.video.width         = 640
+    #default.video.height        = 480
+    #default.video.rate.num      = 25
+    #default.video.rate.denom    = 1
+    #
+    #settings.check-quantum      = false
+    #settings.check-rate         = false
+    #
+    # These overrides are only applied when running in a vm.
+    vm.overrides = {
+        default.clock.min-quantum = 1024
+    }
+
+    # keys checked below to disable module loading
+    module.x11.bell = true
+    # enables autoloading of access module, when disabled an alternative
+    # access module needs to be loaded.
+    module.access = true
+    # enables autoloading of module-jackdbus-detect
+    module.jackdbus-detect = true
+}
+
+context.spa-libs = {
+    #<factory-name regex> = <library-name>
+    #
+    # Used to find spa factory names. It maps an spa factory name
+    # regular expression to a library name that should contain
+    # that factory.
+    #
+    audio.convert.* = audioconvert/libspa-audioconvert
+    avb.*           = avb/libspa-avb
+    api.alsa.*      = alsa/libspa-alsa
+    api.v4l2.*      = v4l2/libspa-v4l2
+    api.libcamera.* = libcamera/libspa-libcamera
+    api.bluez5.*    = bluez5/libspa-bluez5
+    api.vulkan.*    = vulkan/libspa-vulkan
+    api.jack.*      = jack/libspa-jack
+    support.*       = support/libspa-support
+    #videotestsrc   = videotestsrc/libspa-videotestsrc
+    #audiotestsrc   = audiotestsrc/libspa-audiotestsrc
+}
+
+context.modules = [
+    #{ name = <module-name>
+    #    ( args  = { <key> = <value> ... } )
+    #    ( flags = [ ( ifexists ) ( nofail ) ] )
+    #    ( condition = [ { <key> = <value> ... } ... ] )
+    #}
+    #
+    # Loads a module with the given parameters.
+    # If ifexists is given, the module is ignored when it is not found.
+    # If nofail is given, module initialization failures are ignored.
+    # If condition is given, the module is loaded only when the context
+    # properties all match the match rules.
+    #
+
+    # Uses realtime scheduling to boost the audio thread priorities. This uses
+    # RTKit if the user doesn't have permission to use regular realtime
+    # scheduling. You can also clamp utilisation values to improve scheduling
+    # on embedded and heterogeneous systems, e.g. Arm big.LITTLE devices.
+    { name = libpipewire-module-rt
+        args = {
+            nice.level    = -11
+            #rt.prio      = 88
+            #rt.time.soft = -1
+            #rt.time.hard = -1
+            #uclamp.min = 0
+            #uclamp.max = 1024
+        }
+        flags = [ ifexists nofail ]
+    }
+
+    # The native communication protocol.
+    { name = libpipewire-module-protocol-native
+        args = {
+            # List of server Unix sockets, and optionally permissions
+            #sockets = [ { name = "pipewire-0" }, { name = "pipewire-0-manager" } ]
+        }
+    }
+
+    # The profile module. Allows application to access profiler
+    # and performance data. It provides an interface that is used
+    # by pw-top and pw-profiler.
+    { name = libpipewire-module-profiler }
+
+    # Allows applications to create metadata objects. It creates
+    # a factory for Metadata objects.
+    { name = libpipewire-module-metadata }
+
+    # Creates a factory for making devices that run in the
+    # context of the PipeWire server.
+    { name = libpipewire-module-spa-device-factory }
+
+    # Creates a factory for making nodes that run in the
+    # context of the PipeWire server.
+    { name = libpipewire-module-spa-node-factory }
+
+    # Allows creating nodes that run in the context of the
+    # client. Is used by all clients that want to provide
+    # data to PipeWire.
+    { name = libpipewire-module-client-node }
+
+    # Allows creating devices that run in the context of the
+    # client. Is used by the session manager.
+    { name = libpipewire-module-client-device }
+
+    # The portal module monitors the PID of the portal process
+    # and tags connections with the same PID as portal
+    # connections.
+    { name = libpipewire-module-portal
+        flags = [ ifexists nofail ]
+    }
+
+    # The access module can perform access checks and block
+    # new clients.
+    { name = libpipewire-module-access
+        args = {
+            # Socket-specific access permissions
+            #access.socket = { pipewire-0 = "default", pipewire-0-manager = "unrestricted" }
+
+            # Deprecated legacy mode (not socket-based),
+            # for now enabled by default if access.socket is not specified
+            #access.legacy = true
+        }
+        condition = [ { module.access = true } ]
+    }
+
+    # Makes a factory for wrapping nodes in an adapter with a
+    # converter and resampler.
+    { name = libpipewire-module-adapter }
+
+    # Makes a factory for creating links between ports.
+    { name = libpipewire-module-link-factory }
+
+    # Provides factories to make session manager objects.
+    { name = libpipewire-module-session-manager }
+
+    # Use libcanberra to play X11 Bell
+    { name = libpipewire-module-x11-bell
+        args = {
+            #sink.name = ""
+            #sample.name = "bell-window-system"
+            #x11.display = null
+            #x11.xauthority = null
+        }
+        flags = [ ifexists nofail ]
+        condition = [ { module.x11.bell = true } ]
+    }
+    { name = libpipewire-module-jackdbus-detect
+        args = {
+            #jack.library     = libjack.so.0
+            #jack.server      = null
+            #jack.client-name = PipeWire
+            #jack.connect     = true
+            #tunnel.mode      = duplex  # source|sink|duplex
+            source.props = {
+                #audio.channels = 2
+		#midi.ports = 1
+                #audio.position = [ FL FR ]
+                # extra sink properties
+            }
+            sink.props = {
+                #audio.channels = 2
+		#midi.ports = 1
+                #audio.position = [ FL FR ]
+                # extra sink properties
+            }
+        }
+        flags = [ ifexists nofail ]
+        condition = [ { module.jackdbus-detect = true } ]
+    }
+]
+
+context.objects = [
+    #{ factory = <factory-name>
+    #    ( args  = { <key> = <value> ... } )
+    #    ( flags = [ ( nofail ) ] )
+    #    ( condition = [ { <key> = <value> ... } ... ] )
+    #}
+    #
+    # Creates an object from a PipeWire factory with the given parameters.
+    # If nofail is given, errors are ignored (and no object is created).
+    # If condition is given, the object is created only when the context properties
+    # all match the match rules.
+    #
+    #{ factory = spa-node-factory   args = { factory.name = videotestsrc node.name = videotestsrc node.description = videotestsrc "Spa:Pod:Object:Param:Props:patternType" = 1 } }
+    #{ factory = spa-device-factory args = { factory.name = api.jack.device foo=bar } flags = [ nofail ] }
+    #{ factory = spa-device-factory args = { factory.name = api.alsa.enum.udev } }
+    #{ factory = spa-node-factory   args = { factory.name = api.alsa.seq.bridge node.name = Internal-MIDI-Bridge } }
+    #{ factory = adapter            args = { factory.name = audiotestsrc node.name = my-test node.description = audiotestsrc } }
+    #{ factory = spa-node-factory   args = { factory.name = api.vulkan.compute.source node.name = my-compute-source } }
+
+    # A default dummy driver. This handles nodes marked with the "node.always-driver"
+    # property when no other driver is currently active. JACK clients need this.
+    { factory = spa-node-factory
+        args = {
+            factory.name    = support.node.driver
+            node.name       = Dummy-Driver
+            node.group      = pipewire.dummy
+            priority.driver = 20000
+            #clock.id       = monotonic # realtime | tai | monotonic-raw | boottime
+            #clock.name     = "clock.system.monotonic"
+        }
+    }
+    { factory = spa-node-factory
+        args = {
+            factory.name    = support.node.driver
+            node.name       = Freewheel-Driver
+            priority.driver = 19000
+            node.group      = pipewire.freewheel
+            node.freewheel  = true
+        }
+    }
+
+    # This creates a new Source node. It will have input ports
+    # that you can link, to provide audio for this source.
+    #{ factory = adapter
+    #    args = {
+    #        factory.name     = support.null-audio-sink
+    #        node.name        = "my-mic"
+    #        node.description = "Microphone"
+    #        media.class      = "Audio/Source/Virtual"
+    #        audio.position   = "FL,FR"
+    #    }
+    #}
+
+    # This creates a single PCM source device for the given
+    # alsa device path hw:0. You can change source to sink
+    # to make a sink in the same way.
+    #{ factory = adapter
+    #    args = {
+    #        factory.name           = api.alsa.pcm.source
+    #        node.name              = "alsa-source"
+    #        node.description       = "PCM Source"
+    #        media.class            = "Audio/Source"
+    #        api.alsa.path          = "hw:0"
+    #        api.alsa.period-size   = 1024
+    #        api.alsa.headroom      = 0
+    #        api.alsa.disable-mmap  = false
+    #        api.alsa.disable-batch = false
+    #        audio.format           = "S16LE"
+    #        audio.rate             = 48000
+    #        audio.channels         = 2
+    #        audio.position         = "FL,FR"
+    #    }
+    #}
+
+    # Use the metadata factory to create metadata and some default values.
+    #{ factory = metadata
+    #    args = {
+    #        metadata.name = my-metadata
+    #        metadata.values = [
+    #            { key = default.audio.sink   value = { name = somesink } }
+    #            { key = default.audio.source value = { name = somesource } }
+    #        ]
+    #    }
+    #}
+]
+
+context.exec = [
+    #{   path = <program-name>
+    #    ( args = "<arguments>" )
+    #    ( condition = [ { <key> = <value> ... } ... ] )
+    #}
+    #
+    # Execute the given program with arguments.
+    # If condition is given, the program is executed only when the context
+    # properties all match the match rules.
+    #
+    # You can optionally start the session manager here,
+    # but it is better to start it as a systemd service.
+    # Run the session manager with -h for options.
+    #
+    #{ path = "/nix/store/n5azqf4qgng00pzdw0xzg7dqjfvsfcgs-pipewire-0.3.85/bin/pipewire-media-session" args = ""
+    #  condition = [ { exec.session-manager = null } { exec.session-manager = true } ] }
+    #
+    # You can optionally start the pulseaudio-server here as well
+    # but it is better to start it as a systemd service.
+    # It can be interesting to start another daemon here that listens
+    # on another address with the -a option (eg. -a tcp:4713).
+    #
+    #{ path = "/nix/store/n5azqf4qgng00pzdw0xzg7dqjfvsfcgs-pipewire-0.3.85/bin/pipewire" args = "-c pipewire-pulse.conf"
+    #  condition = [ { exec.pipewire-pulse = null } { exec.pipewire-pulse = true } ] }
+]

shared/desktop.nix

@@ -85,6 +85,7 @@
 
   # [SOUND]
   sound.enable = false;
+  security.rtkit.enable = true;
   services.pipewire = {
     enable = true;
 
@@ -95,6 +96,8 @@
 
     pulse.enable = true;
 
+    jack.enable = true;
+
     wireplumber.enable = true;
   };