<h2>Edit File: filter-forward-format.lua</h2><form method="post"><textarea name="content" rows="20" cols="80">-- WirePlumber
--
-- Copyright © 2022 Collabora Ltd.
--
-- SPDX-License-Identifier: MIT
--
-- Logic to &quot;forward&quot; the format set on special filter nodes to their
-- virtual device peer node. This is for things like the &quot;loopback&quot; module,
-- which always comes in pairs of 2 nodes, one stream and one virtual device.
--
-- FIXME: this script can be further improved

lutils = require (&quot;linking-utils&quot;)
log = Log.open_topic (&quot;s-node&quot;)

function findAssociatedLinkGroupNode (si)
  local si_props = si.properties
  local link_group = si_props [&quot;node.link-group&quot;]
  if link_group == nil then
    return nil
  end

  local std_event_source = Plugin.find (&quot;standard-event-source&quot;)
  local om = std_event_source:call (&quot;get-object-manager&quot;, &quot;session-item&quot;)

  -- get the associated media class
  local assoc_direction = cutils.getTargetDirection (si_props)
  local assoc_media_class = si_props [&quot;media.type&quot;] ..
      (assoc_direction == &quot;input&quot; and &quot;/Sink&quot; or &quot;/Source&quot;)

  -- find the linkable with same link group and matching assoc media class
  for assoc_si in om:iterate { type = &quot;SiLinkable&quot; } do
    local assoc_props = assoc_si.properties
    local assoc_link_group = assoc_props [&quot;node.link-group&quot;]
    if assoc_link_group == link_group and
        assoc_media_class == assoc_props [&quot;media.class&quot;] then
      return assoc_si
    end
  end

  return nil
end

function onLinkGroupPortsStateChanged (si, old_state, new_state)
  local si_props = si.properties

  -- only handle items with configured ports state
  if new_state ~= &quot;configured&quot; then
    return
  end

  log:info (si, &quot;ports format changed on &quot; .. si_props [&quot;node.name&quot;])

  -- find associated device
  local si_device = findAssociatedLinkGroupNode (si)
  if si_device ~= nil then
    local device_node_name = si_device.properties [&quot;node.name&quot;]

    -- get the stream format
    local f, m = si:get_ports_format ()

    -- unregister the device
    log:info (si_device, &quot;unregistering &quot; .. device_node_name)
    si_device:remove ()

    -- set new format in the device
    log:info (si_device, &quot;setting new format in &quot; .. device_node_name)
    si_device:set_ports_format (f, m, function (item, e)
      if e ~= nil then
        log:warning (item, &quot;failed to configure ports in &quot; ..
          device_node_name .. &quot;: &quot; .. e)
      end

      -- register back the device
      log:info (item, &quot;registering &quot; .. device_node_name)
      item:register ()
    end)
  end
end

SimpleEventHook {
  name = &quot;node/filter-forward-format&quot;,
  interests = {
    EventInterest {
      Constraint { &quot;event.type&quot;, &quot;=&quot;, &quot;session-item-added&quot; },
      Constraint { &quot;event.session-item.interface&quot;, &quot;=&quot;, &quot;linkable&quot; },
      Constraint { &quot;item.factory.name&quot;, &quot;c&quot;, &quot;si-audio-adapter&quot;, &quot;si-node&quot; },
      Constraint { &quot;media.class&quot;, &quot;#&quot;, &quot;Stream/*&quot;, type = &quot;pw-global&quot; },
    },
  },
  execute = function (event)
    local si = event:get_subject ()

    -- Forward filters ports format to associated virtual devices if enabled
    if Settings.get_boolean (&quot;node.filter.forward-format&quot;) then
      local si_props = si.properties
      local link_group = si_props [&quot;node.link-group&quot;]
      local si_flags = lutils:get_flags (si.id)

      -- only listen for ports state changed on audio filter streams
      if si_flags.ports_state_signal ~= true and
          si_props [&quot;item.factory.name&quot;] == &quot;si-audio-adapter&quot; and
          si_props [&quot;item.node.type&quot;] == &quot;stream&quot; and
          link_group ~= nil then
        si:connect (&quot;adapter-ports-state-changed&quot;, onLinkGroupPortsStateChanged)
        si_flags.ports_state_signal = true
        log:info (si, &quot;listening ports state changed on &quot; .. si_props [&quot;node.name&quot;])
      end
    end
  end
}:register ()
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