Human like compressor

01-pipewire.conf

context.modules = [
  {
    name = libpipewire-module-filter-chain
    args = {
      node.name = "eq_before_comp"
      node.description = "Human-like compressor chain (entry eq_before_comp)"
      media.name       = "HCL out"
      audio.format = "S32BE"
      audio.rate   = 48000
      # ? del:
      target.object = "hcl_compressor"
      capture.props = {
        media.class    = "Audio/Sink"
        node.name      = "eq_before_comp"
        audio.channels = 6
        audio.position = [ FL FR FC LFE SL SR ]
      }

     # And sends *stereo out* to your actual HDMI device
      playback.props = {
        node.target    = "hcl_compressor"
        audio.channels = 2
        audio.position = [ FL FR ]
      }

      # Main filter graph
      filter.graph = {
        nodes = [
          # Duplicate the C
          {
            type  = builtin
            name  = dupeC
            label = copy
          }
          # Duplicate the LFE
          {
            type  = builtin
            name  = dupeLfe
            label = copy
          }
          # Build LEFT output from FL + C + LFE + SL
          {
            type    = builtin
            label   = mixer
            name    = mixL
            control = {
              "Gain 1" = 1.0   # FL
              "Gain 2" = 0.0   # FR
              "Gain 3" = 0.7   # FC  (center into left)
              "Gain 4" = 0.5   # LFE
              "Gain 5" = 0.3   # SL
              "Gain 6" = 0.0   # SR
            }
          }

          # Build RIGHT output from FR + C + LFE + SR
          {
            type    = builtin
            label   = mixer
            name    = mixR
            control = {
              "Gain 1" = 0.0   # FL
              "Gain 2" = 1.0   # FR
              "Gain 3" = 0.7   # FC  (center into right)
              "Gain 4" = 0.5   # LFE
              "Gain 5" = 0.0   # SL
              "Gain 6" = 0.3   # SR
            }
          }

          {
            type = builtin
            label = param_eq
            name = eq_before
            config = { filename = "/home/tomfun/prj/tomfun/infrastructure/pulse_audio/eq_comp.txt" }
          }

          {
            type = ladspa
            name = compressor
            plugin = sc4_1882
            label  = sc4
            # https://github.com/swh/ladspa/blob/master/sc4_1882.xml#L116
            control = {
              "0" = 0.5
              "1" = 20
              "2" = 250
              "3" = -30
              "4" = 6
              "5" = 4
              "6" = 13
            }
          }

          {
            type = builtin
            label = param_eq
            name = eq_after
            config = { filename = "/home/tomfun/prj/tomfun/infrastructure/pulse_audio/eq_after_comp.txt" }
          }
        ]

        inputs = [
          "mixL:In 1"  # FL
          "mixR:In 2"  # FR
          "dupeC:In"  # FC
          "dupeLfe:In"  # LFE
          "mixL:In 5"  # SL
          "mixR:In 6"  # SR
        ]

        # Wire EQ outputs into the L/R mixers
        links = [
          { output = "dupeC:Out" input = "mixL:In 3" }
          { output = "dupeC:Out" input = "mixR:In 3" }
          { output = "dupeLfe:Out" input = "mixL:In 4" }
          { output = "dupeLfe:Out" input = "mixR:In 4" }
          # FL -> L mixer
          { output = "mixL:Out" input = "eq_before:In 1" }
          # FR -> R mixer
          { output = "mixR:Out" input = "eq_before:In 2" }

          { output="eq_before:Out 1" input="compressor:Left input" }
          { output="eq_before:Out 2" input="compressor:Right input" }

          # compressor -> EQ(after)
          { output="compressor:Left output" input="eq_after:In 1" }
          { output="compressor:Right output" input="eq_after:In 2" }
        ]

        # Final graph outputs: stereo
        outputs = [
          "eq_after:Out 1"  # Left
          "eq_after:Out 2"  # Right
        ]
      }
    }
  }
  {
    name = libpipewire-module-filter-chain
    args = {
      node.name = "eq_sven"
      node.description = "EQ Sven + LFE"
      audio.format = "S32BE"
      audio.rate = 48000
      audio.channels = 2
      audio.position = [ FL FR ]
      capture.props = { "media.class": "Audio/Sink" }
      filter.graph = {
        nodes = [
          {
            type = builtin
            label = param_eq
            name = eq_sven_lfe
            config = { filename = "/home/tomfun/prj/tomfun/infrastructure/pulse_audio/eq_sven.txt" }
          }
        ]
      }
    }
  }
  { name = libpipewire-module-zeroconf-discover flags=[ "nofail" ] }

  {
    # https://docs.pipewire.org/devel/page_module_roc_source.html
    name = libpipewire-module-roc-source
    args = {
        fec.code = rs8m

        local.ip = 10.50.10.8

        # These must match whatever ports you configure on the desktop's roc-source
        remote.source.port  = 10001
        remote.repair.port  = 10002
        remote.control.port = 10003

        #roc.resampler.profile = high
        sess.latency.msec = 120

        source.name = "ROC-Source"

        #sink.props = {
        #   node.name = "input.eq_before_comp"
        #}
    }
  }
  #{
  #  name = libpipewire-module-rtp-source
  #  args = {
  #      #local.ifname = eth0
  #      local.ifname = enp3s0
  #      #local.ifname = wg0
  #      #source.ip = 224.0.0.56
  #      #source.ip = 10.50.10.6
  #      #source.ip = 192.168.0.108
  #      source.ip = 0.0.0.0
  #      source.port = 26864
  #      sess.latency.msec = 200
  #      sess.ignore-ssrc = true
  #      #sess.ignore-ssrc = false
  #      node.always-process = true
  #      sess.ts-direct = true
  #      sess.media = "audio"
  #      #audio.format = "S16LE"
  #      audio.format = "S16BE"
  #      audio.rate = 48000
  #      audio.channels = 2
  #      audio.position = [ FL FR ]
  #      stream.props = {
  #         media.class = "Audio/Source"
  #         node.name = "RTP_from_Laptop"
  #         node.description = "RTP audio from laptop mic"
  #      }
  #  }
  #}
  #{
  #  name = libpipewire-module-rtp-sap
  #  args = {
  #      #local.ifname = "enp3s0"
  #      sap.ip = "10.50.10.6"
  #      sap.port = 26864
  #      #sap.cleanup.sec = 5
  #      source.ip = "0.0.0.0"
  #      #net.ttl = 1
  #      #net.loop = false
  #      stream.rules = [
  #          {   matches = [
  #                  # any of the items in matches needs to match, if one does,
  #                  # actions are emitted.
  #                  {   # all keys must match the value. ! negates. ~ starts regex.
  #                      #rtp.origin = "wim 3883629975 0 IN IP4 0.0.0.0"
  #                      #rtp.payload = "127"
  #                      #rtp.fmt = "L16/48000/2"
  #                      #rtp.session = "PipeWire RTP Stream on fedora"
  #                      #rtp.ts-offset = 0
  #                      #rtp.ts-refclk = "private"
  #                      sess.sap.announce = true
  #                  }
  #              ]
  #              actions = {
  #                  announce-stream = {
  #                  }
  #              }
  #          }
  #          {   matches = [
  #                  {   # all keys must match the value. ! negates. ~ starts regex.
  #                      #rtp.origin = "wim 3883629975 0 IN IP4 0.0.0.0"
  #                      #rtp.payload = "127"
  #                      #rtp.fmt = "L16/48000/2"
  #                      #rtp.session = "PipeWire RTP Stream on fedora"
  #                      #rtp.ts-offset = 0
  #                      #rtp.ts-refclk = "private"
  #                      rtp.session = "~.*"
  #                  }
  #              ]
  #              actions = {
  #                  create-stream = {
  #                      #sess.latency.msec = 100
  #                      #sess.ts-direct = false
  #                      #target.object = ""
  #                  }
  #              }
  #          }
  #      ]
  #  }
  #}
  {   name = libpipewire-module-pulse-tunnel
      args = {
          tunnel.mode = source
          # Set the remote address to tunnel to
          pulse.server.address = "tcp:10.50.10.6"
          #pulse.latency = 200
          reconnect.interval.ms = 1000
          audio.rate=48000
          audio.channels=2
          audio.position=[ FL FR ]
          target.object=alsa_input.pci-0000_00_1f.3.analog-stereo
          stream.props = {
            media.class = "Audio/Source"
            node.name = "pa_from_Laptop"
            node.description = "audio from laptop mic"
          }
      }
  }
]

question.md

❓ PipeWire filter-chain works for 1 node, but fails with 2+ node chain (EQ → Compressor → EQ)

Hi all 👋 I'm using PipeWire master (1.5.0) and WirePlumber 0.5.8 on LinuxMint. I'm building a modular DSP setup using libpipewire-module-filter-chain from config files.

---

✅ What works

The following simple 1-node filter-chain works fine:

{
  name = libpipewire-module-filter-chain
  args = {
    node.name = "eq_from_fly_plate"
    filter.graph = {
      nodes = [
        {
          type = builtin
          label = param_eq
          name  = eq_from_fly_plate_lfe
          config = { filename = "/.../eq_from_fly_plate.txt" }
        }
      ]
    }
  }
}

This node shows up properly and I can manually patch it to HDMI using Helvum or pw-link, and it passes audio.

---

❌ What doesn’t work

When I try to load a more complex filter-chain with 3 nodes:

• EQ → LADSPA (sc4) → EQ

...the node loads, but no audio goes through. It seems to be silently broken. Nothing shows up in Helvum/patchbay output for this sink.

{
  name = libpipewire-module-filter-chain
  args = {
    node.name = "eq_hl_comp"
    ...
    filter.graph = {
      nodes = [
        { type = builtin, name = eq_before_comp, ... }
        { type = ladspa,  name = compressor, plugin = sc4_1882, label = sc4, control = { "0"=..., ... } }
        { type = builtin, name = eq_after_comp, ... }
      ]
    }
    links = [
      { output = "eq_before_comp:Out" input = "compressor:In" }
      { output = "compressor:Out"     input = "eq_after_comp:In" }
    ]
    inputs  = [ "eq_before_comp:In 1", "eq_before_comp:In 2" ]
    outputs = [ "eq_after_comp:Out 1", "eq_after_comp:Out 2" ]
  }
}

I verified that control = { "0" = ..., ... } is required format. Still no audio or output appears.

Attempts

I've verified that the graph loads and nodes are created by PipeWire — they appear in pw-cli and can be manually routed to HDMI via Helvum. However, even when simplified to a two-node chain (e.g. param_eq → param_eq, skipping the LADSPA compressor entirely), the result is the same: audio flows through the graph virtually, but no actual DSP is applied. The output signal is either silence or an unmodified passthrough, even though all links appear visually correct.

I also ensured that input/output port names, channel layouts, and formats are correctly defined and that filter.graph.inputs/outputs match the final node. I restarted PipeWire and WirePlumber with clean state, tested multiple EQ config files, and even moved the failing part into a working structure. Still, any multi-node graph (even very basic ones) silently fails to apply DSP, unlike the one-node version which works reliably.

---

🔧 My setup

$ wireplumber --version
WirePlumber 0.5.8
# master

$ pipewire --version
PipeWire 1.5.0 (compiled and linked)
# master

$ systemctl --user restart wireplumber.service pipewire.{service,socket} pipewire-pulse.{service,socket}

Config is loaded via:

$ pw-config
{
  "config.path": "/usr/share/pipewire/pipewire.conf",
  "override.3.0.config.path": "/home/tomfun/.config/pipewire/pipewire.conf.d/01-pipewire.conf"
}

---

Does anyone know why a multi-node filter-chain graph would silently fail, while a 1-node version works? Thanks a lot 🙏

restart-sound.sh

#!/usr/bin/env bash
set -e
script_dir="$(cd -- "$(dirname -- "${BASH_SOURCE[0]}")" &> /dev/null && pwd)"
export script_dir

sudo cp custom.pa /etc/pulse/default.pa.d/custom.pa
sudo systemctl daemon-reload
sudo apt install libasound2-dev libbluetooth-dev libsbc-dev libudev-dev doxygen
sudo apt install \
  libgstreamer1.0-dev \
  libgstreamer-plugins-base1.0-dev \
  gstreamer1.0-plugins-base \
  gstreamer1.0-plugins-good \
  gstreamer1.0-plugins-bad \
  gstreamer1.0-plugins-ugly \
  gstreamer1.0-libav \
  gstreamer1.0-tools \
  gir1.2-gstreamer-1.0 \
  python3-gi
#sudo apt install gstreamer1.0-plugins-bad gstreamer1.0-plugins-good gstreamer1.0-plugins-base gstreamer1.0-plugins-ugly
rm -f ~/.config/systemd/user/stick_hard_eq.service
mkdir -p ~/.config/pipewire/pipewire.conf.d/
mkdir -p ~/.config/pipewire/pipewire-pulse.conf.d/
mkdir -p ~/.config/wireplumber/wireplumber.conf.d/
rm -f ~/.config/pipewire/pipewire.conf.d/pipewire.conf \
  ~/.config/pipewire/pipewire.conf.d/* \
  ~/.config/pipewire/pipewire-pulse.conf.d/pipewire-pulseaudio.conf \
  ~/.config/wireplumber/wireplumber.conf.d/01-wireplumber.conf

ln -sv "$script_dir/stick_hard_eq.service" ~/.config/systemd/user/
ln -sv "$script_dir/pipewire-pulseaudio.conf" ~/.config/pipewire/pipewire-pulse.conf.d/
ln -sv "$script_dir/01-pipewire.conf" ~/.config/pipewire/pipewire.conf.d/
ln -sv "$script_dir/01-wireplumber.conf" ~/.config/wireplumber/wireplumber.conf.d/

cd pipewire
git pull
rm -rf builddir
meson setup builddir \
  --prefix=/usr \
  --libdir=/usr/lib/x86_64-linux-gnu \
  -Dalsa=enabled \
  -Dspa-plugins=enabled \
  -Dsystemd=enabled \
  -Dgstreamer=enabled \
  -Dbluez5=enabled \
  -Dudev=enabled \
  -Dpipewire-alsa=enabled \
  -Dsession-managers=wireplumber \
  -Dman=enabled \
  --buildtype=release

ninja -C builddir
sudo ninja -C builddir install
sudo ldconfig

sudo apt-mark hold pipewire pipewire-bin pipewire-audio-client-libraries pipewire-pulse wireplumber pulseaudio

sudo rm -f /etc/systemd/user/pipewire.{service,socket}
sudo rm -f /etc/systemd/user/pipewire-pulse.{service,socket}
sudo rm -f \
  /usr/local/lib/x86_64-linux-gnu/libpipewire-0.3.so* \
  /usr/local/lib/x86_64-linux-gnu/libwireplumber-0.5.so*

systemctl --user daemon-reload

systemctl --user --now enable wireplumber.service pipewire.{service,socket} pipewire-pulse.{service,socket}

#systemctl --user enable stick_hard_eq.service
#systemctl --user restart pipewire.service stick_hard_eq.service

Also I've tried:
https://pipewire.pages.freedesktop.org/wireplumber/policies/software_dsp.html
Inspired by:
https://forum.artixlinux.org/index.php/topic,6668.0.html
Main doc seems missing simple and concise example of 2 nodes example (eq + eq):
https://docs.pipewire.org/page_module_filter_chain.html

The same thing with pulse audio: https://github.com/tomfun/eq-pulse-audio

Usefull https://gitlab.freedesktop.org/pipewire/pipewire/-/wikis/Migrate-PulseAudio#set-card-profile