audiod - an elogind-driven audio session manager for Slackware

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The audiod party hub seen live in coppwr's patch-bay view (HP OMEN 16, Slackware64-current). Two independent sources — a HONOR 400 Pro phone over Bluetooth A2DP (bluez_input.CC_62_00_5C_54_9F) and a local Firefox — both feed the virtual hub_combined sink. PipeWire sums them once, and hub_combined mirrors the mix out to every output at the same time: the built-in Speaker, all three HDMI outputs, and a BT Speaker (bluez_output.41_42_E4_0C_EA_BB). Each mirror leg is its own output.hub_combined_ node. The capture devices — the HP Wide Vision HD Camera and the two microphones (Stereo and Digital) — are present in the graph but are deliberately not wired into hub_combined: combine mirrors playback only, so sending music everywhere never routes your microphone anywhere. The profiler on the right shows the whole graph running with essentially zero xruns — clean, glitch-free multi-source, multi-output audio.

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audiod is the small piece that non-systemd Slackware has been missing for years: a per-user audio session manager. It gives the PipeWire stack the ordered startup, readiness gating, per-user lifecycle, and clean teardown that systemd --user provides on systemd distributions — built entirely from elogind + libslack daemon(1) + shell. No systemd. No dinit. No new service manager. elogind is used completely unmodified.

It exists to fix a real, long-standing Slackware bug: after login, PipeWire sometimes takes seconds-to-minutes to produce sound, or comes up muted / as a "Dummy Output". That happens because the stock start scripts fire wireplumber and pipewire-pulse before the PipeWire core is ready and rely on retry/respawn to eventually converge — a race that some machines lose. (Fixed for slackware-current 8/7/26)

On top of the core session manager, audiod has an optional hub mode that turns the machine into a party audio hub: Bluetooth phones play through the box, sound mirrors to every output at once, and you drive it all from the terminal. Hub mode is off by default and changes nothing until you turn it on — see Party hub mode and the companion GAMER-GUIDE.md.

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Table of contents

1. What it does
2. What it does NOT do
3. How it works
4. Requirements
5. Files installed
6. Build & install
7. Enabling it
8. Configuration
9. Using audioctl
10. Going back to PulseAudio
11. Uninstalling / rollback
12. Troubleshooting
13. Design notes & rationale
14. Scope, limitations & known behaviour
15. Party hub mode (optional)

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What it does

• Reacts to login/logout, not to shells. It watches elogind's org.freedesktop.login1 D-Bus interface for UserNew / UserRemoved signals. elogind reference-counts a user's sessions for us, so UserNew fires only on the user's first login and UserRemoved only on their last logout. One PipeWire stack per user, surviving VT switches and multiple concurrent sessions of the same user.

• Starts the stack in dependency order, with a readiness gate. On first login it starts pipewire, waits for its socket to actually appear, then starts wireplumber, then pipewire-pulse. This is the core fix: no race, no retry storm, no "wait a few minutes for sound".

• Supervises the stack. Each service runs under libslack daemon -rB (respawn + stop-when-session-ends) — the exact mechanism Slackware's stock scripts already use, so crash-restart still works.

• Tears down cleanly on last logout. On UserRemoved it stops the user's stack, targeted by name. No orphaned PipeWire processes left behind (a real gap in the stock setup, especially on multi-user machines).

• Handles the D-Bus session bus sensibly. It detects an existing session bus wherever it lives — including the /tmp/dbus-XXXX bus that desktops create via dbus-run-session — by inspecting the session environment (elogind does not track the bus). It reuses that bus and only optionally spawns one for bus-less console/bare-WM logins.

• Respects the system's audio-server choice. If the machine is set to PulseAudio, audiod stands down and does nothing.

• Provides a user tool, audioctl. Any user can check/start/stop/restart their own audio stack without root and without logging out.

• Works regardless of desktop or login path. SDDM+Plasma, lightdm+XFCE, bare WM, startx from runlevel 3, pure console — all covered, because it keys off the elogind session, not the desktop.

What it does NOT do

• It does not replace elogind, logind, seatd, or a service manager. It is only the "launch and supervise the user audio stack" piece. Session/seat tracking, XDG_RUNTIME_DIR, sleep, and ACLs remain elogind's job.

• It does not modify elogind. No patches, no rebuild. It only reads from elogind's public D-Bus interface.

• It does not touch device/channel configuration (in core mode). It starts and stops daemons; it never remaps channels, sets defaults, changes volumes, or edits WirePlumber/PipeWire config. (Hub mode, when explicitly enabled, does create a combine sink and manage Bluetooth on request — but only then.)

• It does not fix kernel-level device enumeration. If the ALSA driver itself takes minutes to expose the card, audiod cannot make the hardware appear sooner — but it makes WirePlumber wait correctly for it instead of timing out, which fixes the common (race-based) form of the delay.

• It does not make two simultaneous desktops share one sound card. With a single card on one seat, only the active session gets the hardware; the other falls back to Dummy Output. This is a fundamental limitation of shared-seat audio and behaves identically under systemd — it is out of scope. (For cross-user sharing over the network see the separate audioshare project.)

• It does not manage system services (bluetoothd, the system D-Bus bus, etc.). Those start at boot, before any login, and audiod relies on them being present.

• It is not strictly required for basic playback — it changes when, how, in what order, and for whom the stack starts and stops.

How it works

        elogind (login1 D-Bus)                 audiod (root daemon)
        ----------------------                 --------------------
  user first login  --> UserNew(uid)  ------>  gate: seat + Class=user + Remote=no ?
                                                 |
                                                 v
                                        ensure session bus (detect/reuse, opt. spawn)
                                                 |
                                                 v   (as the user, via setpriv)
                                        start pipewire  --> wait for socket
                                                 --> start wireplumber
                                                 --> start pipewire-pulse
                                        (each under: daemon -rB, respawn)

  user last logout --> UserRemoved(uid) ----->  stop the stack, targeted by name

• Reactor (/usr/sbin/audiod): a foreground root daemon. On start it reconciles users already logged in, then monitors login1 signals via gdbus monitor, reconnecting if the stream drops.
• Privilege drop: services run as the target user via setpriv --reuid --regid --init-groups with a clean env -i environment (no PAM → it never opens a second elogind session that would corrupt the refcount).
• Shared library (/usr/libexec/audiod/audiod-lib.sh): the gate, audio-server detection, bus detection, and stack operations — sourced by both audiod and audioctl so policy lives in one place.
• Hub library (/usr/libexec/audiod/hub.sh): all optional hub logic, sourced only, inert unless HUB_MODE=yes.
• Single source of truth (/etc/audiod/stack.conf): the ordered service list, read by both tools.

Requirements

• elogind (any reasonably recent version that exposes the login1 D-Bus interface with UserNew/UserRemoved — verified on 257.16).
• psmisc (provides fuser, used for the session-bus liveness check) — part of the Slackware base.
• libslack daemon(1) — already used by Slackware's stock PipeWire scripts.
• PipeWire (pipewire, wireplumber, pipewire-pulse) — the payload.
• pam_elogind must be in the login PAM stacks (Slackware default), so that local logins create elogind sessions and UserNew fires.
• For hub mode only: bluez (BlueZ 5.x) with bluetoothd running and a powered adapter.

Files installed

/usr/sbin/audiod                    root:root 0755  the reactor (system daemon)
/usr/bin/audioctl                   root:root 0755  user control tool
/usr/libexec/audiod/audiod-lib.sh   root:root 0644  shared logic (sourced)
/usr/libexec/audiod/hub.sh          root:root 0644  hub logic (sourced, opt-in)
/usr/libexec/audiod/hub-btwatch.sh  root:root 0755  hub BT VT-switch watcher
/usr/sbin/audiod-takeover.sh        root:root 0755  disable stock autostart
/usr/sbin/audiod-restore.sh         root:root 0755  re-enable stock autostart
/etc/rc.d/rc.audiod                 root:root 0644  init script (0644 = OFF)
/etc/audiod/audiod.conf             root:root 0644  configuration
/etc/audiod/stack.conf              root:root 0644  ordered service list
/usr/doc/audiod-<version>/          root:root 0644  docs

Runtime (not part of the package): /run/audiod.pid (root); and, owned by the user, ~/.run/{pipewire,wireplumber,pipewire-pulse,dbus}.pid plus /run/user/$uid/bus if audiod spawns a bus. Hub mode also uses /run/audiod-hub-owner (auto-owner state, cleared on reboot).

Build & install

cd audiod
bash audiod.SlackBuild                # produces /tmp/audiod-<ver>-noarch-<b>_rtz.txz
sudo installpkg /tmp/audiod-*.txz

To ship the ready-to-go gamer/party preset as the default config, build with GAME=ON:

GAME=ON bash audiod.SlackBuild        # installs the gamer preset (hub + combine on)

The package is noarch (pure shell) and builds from the bundled src/ tree — nothing is downloaded or compiled.

Enabling it

audiod replaces how PipeWire is started, so the stock start mechanisms must be disabled first (this does not switch you to PulseAudio):

sudo /usr/sbin/audiod-takeover.sh     # chmod -x profile.d/pipewire.{sh,csh}
                                      # + Hidden=true on the XDG autostart entries

Note: upgrading the pipewire package can reinstall an executable profile.d/pipewire.sh. If you use install-new, your disabled copy is kept and the new one arrives as .new (no conflict). If in doubt after a pipewire upgrade, re-run audiod-takeover.sh.

Try it in the foreground first (safe: stopping audiod does not stop audio):

sudo sed -i 's/^DEBUG=no/DEBUG=yes/' /etc/audiod/audiod.conf
sudo /usr/sbin/audiod                 # watch the log; Ctrl-C to stop

Once happy, enable it at boot — it must start after elogind:

sudo chmod +x /etc/rc.d/rc.audiod
# add to /etc/rc.d/rc.local, after elogind is up:
#   [ -x /etc/rc.d/rc.audiod ] && /etc/rc.d/rc.audiod start

Control it like any Slackware service:

/etc/rc.d/rc.audiod {start|stop|restart|status}

Configuration

/etc/audiod/audiod.conf — core keys:

Key	Default	Meaning
AUDIO_SERVER	auto	auto detects PipeWire vs Pulse; force with pipewire/pulse. In pulse mode audiod is idle.
MANAGE_DBUS	no	no: never spawn a session bus (desktops bring their own; console basic audio needs none). yes: spawn one at $XDG_RUNTIME_DIR/bus if, after a short wait, none appears.
BUS_WAIT	3	Seconds to wait for a desktop bus before spawning one (when MANAGE_DBUS=yes).
SEAT_WAIT	5	Seconds to wait at login for a valid seat session before deciding the login is not seated.
PIPEWIRE_WAIT	10	Seconds to wait for the PipeWire socket before starting dependent services.
DEBUG	no	Verbose logging to syslog (tag audiod) and stderr in foreground.

Hub keys (all inert unless HUB_MODE=yes) are documented in Party hub mode below.

/etc/audiod/stack.conf — the ordered stack (name binary ready), read by both audiod and audioctl. ready = socket:<name> waits for $XDG_RUNTIME_DIR/<name> before the next service; - means no wait.

Using audioctl

Run as your own user (no root, no logout). It respects the same audio-server gate, so in PulseAudio mode it declines.

audioctl status              # show your stack (dbus + the three services)
audioctl start               # start the stack, ordered
audioctl stop                # stop the stack, targeted
audioctl restart             # restart the whole stack, ordered
audioctl restart wireplumber # restart a single component

This is the easy, discoverable way to do "my sound is stuck, fix it" without a logout — it wraps the same daemon(1) supervisors the stock setup already uses.

The audioctl hub ... subcommands are covered in Party hub mode.

Going back to PulseAudio

audiod never blocks this. Use Slackware's own switch (pipewire-disable.sh), which sets PulseAudio autospawn on; audiod then detects Pulse mode and stays idle automatically. Or set AUDIO_SERVER=pulse in audiod.conf. To fully restore the stock PipeWire start mechanism, run audiod-restore.sh.

Uninstalling / rollback

sudo /etc/rc.d/rc.audiod stop         # (or Ctrl-C if running in foreground)
sudo /usr/sbin/audiod-restore.sh      # re-enable the stock autostart
sudo removepkg audiod                 # removes every packaged file (tracked)
# then remove the rc.local line you added, if any

Nothing runtime survives a reboot (it lives on tmpfs). Edited *.conf files may remain as harmless leftovers.

Troubleshooting

• Nothing starts on login. Confirm elogind is up and pam_elogind is in the login PAM stack (loginctl list-sessions should show your session). Run audiod in the foreground with DEBUG=yes and log in on another VT to watch the events.
• audiod says "PulseAudio mode". The system is set to Pulse. Switch with pipewire-enable.sh or set AUDIO_SERVER=pipewire.
• A second, unused session bus appears. Ensure you are on build 4+ (adds a liveness check so stale/zombie bus sockets from earlier runs are ignored). For desktop systems keep MANAGE_DBUS=no.
• Sound is "Dummy Output" with two desktops open at once. Expected — see Limitations. Only the active session gets the card.
• audioctl restart seems to do nothing. Check you are in PipeWire mode and that ~/.run holds the pidfiles (ls ~/.run).

Design notes & rationale

• Why elogind's UserNew/UserRemoved and not polling loginctl? They are edge-triggered and carry the uid directly; elogind already does the per-user session reference counting, so we get correct first-login / last-logout semantics for free. Verified empirically: a second login on another VT does not re-fire UserNew.
• Why not use the new elogind userdb/varlink features? They are identity only (users/groups) and expose no session-bus or service-control surface; the login1 D-Bus interface (core logind, present in every elogind) is what we need. Verified: elogind does not track the session bus anywhere.
• Why setpriv and not su/runuser login mode? setpriv changes identity without PAM, so it does not open a second elogind session that would corrupt the refcount audiod relies on.
• Why inspect /proc/$pid/environ for the bus? Desktops started via dbus-run-session put the bus in /tmp and advertise it only through DBUS_SESSION_BUS_ADDRESS in the session environment — elogind has no idea where it is, so the environment is the only source of truth.
• Why a liveness check on the standard-path bus? A stale socket left at /run/user/$uid/bus by a dead daemon would otherwise be mistaken for a live bus; fuser confirms something is actually serving it.

Scope, limitations & known behaviour

• Target case (works, verified): one user per seat — the overwhelming majority of real usage, and exactly the forum bug this addresses. Ordered start, readiness gating, per-user lifecycle, clean teardown, bus reuse: all confirmed working, including on a bare console (Type=tty) session.
• Two simultaneous active desktops on one seat/one card: the inactive session's PipeWire falls back to Dummy Output because the active session holds the hardware. This is inherent to shared-seat audio and matches systemd behaviour; it is not something audiod can or should change.
• startx sessions stay Type=tty in elogind (the X server runs inside the console session). audiod starts the stack at console-login time, so audio is ready before the desktop; whether the desktop's later session bus is picked up depends on how it is launched.
• Kernel/hardware-level enumeration delays are outside audiod's control; it makes WirePlumber wait correctly rather than time out.

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Party hub mode (optional)

audiod has an optional hub extension that turns the machine into a party audio hub. It is off by default (HUB_MODE=no) and, when off, changes nothing — audiod behaves exactly as described above. Turn it on only when you want the box to accept Bluetooth phones, take audio from trusted LAN machines, or mirror playback to several outputs. Gamers: see GAMER-GUIDE.md for a task-oriented walkthrough.

What it adds

• Bluetooth speaker. Phones pair (with the normal PIN) and play through the box's speakers, mixed by PipeWire. Paired phones are trusted so BlueZ reconnects them on its own.
• Terminal scan + connect. audioctl hub scan discovers nearby devices (speakers and phones), shows a numbered list with each device's state (connected / paired / new), and lets you connect — or disconnect — by number, so you don't need the desktop's Bluetooth menu.
• Media control from the box. audioctl hub play|pause|next|prev drives the connected phone over AVRCP, so you can control music from the keyboard without touching someone's phone.
• Combine output (sound everywhere). Mirror playback to several outputs at once — built-in speakers, every HDMI output, and any Bluetooth speaker — via a hub_combined sink that becomes the default. HDMI is included on purpose (gamers/AV setups want it).
• Network audio (optional). Trusted LAN machines can stream to the box.
• VT-switch watcher. Stops Bluetooth cleanly on VT switch so the speakers never "drone"; opt-in auto-resume when you return.

Permissions: group-based, per-user

Only members of HUB_GROUP (default audiohub) get hub behaviour; every other user is ignored entirely, so hub mode never touches non-members' sessions.

groupadd audiohub                 # once (Slackware: by hand)
gpasswd -a <user> audiohub        # add each member, then re-login
# in /etc/audiod/audiod.conf:  HUB_MODE=yes

If the group doesn't exist, nobody is allowed (safe default). audiohub is just a permission label for the hub — it is not the system audio group.

Ownership (automatic)

The card and the single system-wide Bluetooth adapter can only be held by one user at a time. The first hub member to log in automatically becomes the owner (recorded in /run/audiod-hub-owner, cleared on reboot); later members are kept from grabbing the shared adapter. You normally set nothing. HUB_OWNER=<user> is an optional override to pin ownership regardless of login order.

Bluetooth pairing & security

Pairing is on-demand and bounded — audioctl hub pair makes the box discoverable for a short window (default 120s) that you trigger, and pairing still requires the normal BlueZ PIN/confirmation. There is no blind auto-accept, and the box is not left discoverable permanently.

VT switching and Bluetooth

Switching to another VT makes the owner's session inactive, and the card/BT handoff would otherwise cut the phone's A2DP stream mid-buffer — the speakers then repeat the last buffer as a loud drone. The per-owner watcher (hub-btwatch.sh) listens to elogind for active-session changes and, when the owner leaves the active VT, pauses the phone and suspends the BT stream cleanly so there is no drone. Plain speaker/HDMI audio is unaffected.

Resuming when you switch back is opt-in, because auto-resume can make the box start music on its own:

• HUB_BT_AUTORESUME=no — reconnect the phone on return (default no).
• HUB_BT_AUTOPLAY=no — also send AVRCP play on reconnect (default no).

With both no, you resume manually with audioctl hub reconnect or by pressing play. (Some phones block remote resume regardless.)

Network audio

Deny-by-default and per-user. NET_TCP=yes alone does nothing; you must also list explicit addresses in NET_ACL (e.g. 192.168.1.0/24). Anyone allowed in can also see that user's microphone and monitors, so only allow machines you trust.

Configuration (hub keys in /etc/audiod/audiod.conf)

HUB_MODE=no              # master switch; yes = enable hub
HUB_GROUP=audiohub       # only members of this group get the hub
HUB_OWNER=               # empty = first login wins; or pin a username
BT_PAIR_SECONDS=120      # length of the 'audioctl hub pair' window

HUB_BT_AUTORESUME=no     # reconnect BT when you switch back to your VT
HUB_BT_AUTOPLAY=no       # also send AVRCP play on reconnect (needs AUTORESUME)

NET_TCP=no               # network audio in (per-user)
NET_ACL=                 # REQUIRED allow-list, e.g. 192.168.1.0/24 (empty=off)
NET_PORT=4713

COMBINE=no               # mirror playback to several outputs, made default sink
COMBINE_SLAVES=          # empty = ALL sinks (Speaker+HDMI+BT); or a,b to restrict

Usage

man audiod, man audiod

audioctl hub status              # HUB_MODE, your role (owner/guest), BT/net/combine
audioctl hub scan [seconds]      # scan + connect/disconnect a device by number
audioctl hub pair [seconds]      # open a bounded Bluetooth pairing window (PIN)
audioctl hub play|pause|next|prev  # control the connected phone (AVRCP)
audioctl hub reconnect           # reconnect BT to you (manual recovery)
audioctl hub combine [off]       # create (or remove) the combine sink
audioctl hub net                 # (re)apply network audio from the config

What it intentionally does NOT do

• It does not leave Bluetooth discoverable permanently, and never auto-accepts unknown devices (PIN/confirm always required).
• It does not open network audio without an explicit allow-list.
• It does not give non-members any hub access.
• It does not manage bluetoothd or the system bus.
• It does not make two different local users share one card at once (kernel/ALSA limit; see the separate audioshare project for host+guests).

Known limitations

• On VT switch, plain speaker/HDMI audio recovers on its own, but Bluetooth resume is best-effort and can depend on the phone (some block remote play).
• audioctl hub scan only finds devices that are actively advertising; a smartwatch already bonded to a phone, for example, won't appear unless you put it into pairing mode.

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Built for Slackware-current. elogind unmodified; no systemd.