This repository has no description
configs.gg23.audio: low-latency ROC/AirPlay hub on acheron with room selection
acheron gets a minimal system-wide pipewire with a virtual "hub" sink.
Any LAN machine sends into it via ROC while `gg23-audio` from
tools/gg23-audio runs (ROC sink loaded into pipewire-pulse, removed again
on Ctrl-C), barnacle via AirPlay 1 (shairport-sync, "gg23", pipewire
backend, mDNS on int0 only).
The hub monitor is linked to ROC sinks for shodan and icarus (room.nix),
chosen with `audio-room shodan|icarus|both|off` or from Home Assistant via
MQTT discovery (select + buttons). Retained MQTT commands restore the choice
after pipewire restarts.
The rooms have no stable LAN address, so the hub sends to their retiolum IPs
and they accept the ROC ports only from acheron on retiolum.
author
Hermes
date
(Oct 13, 2026, 3:40 PM CEST)
commit
697ad8c8
697ad8c80dee29ebc96570407ea80f9ae5607af2
parent
c196454d
c196454dd303ea587a346cb6e66d4885a50a921e
+304
+1
machines/acheron/config.nix
+1
machines/acheron/config.nix
+1
machines/icarus/config.nix
+1
machines/icarus/config.nix
+1
machines/shodan/config.nix
+1
machines/shodan/config.nix
+17
tools/gg23-audio/flake-module.nix
+17
tools/gg23-audio/flake-module.nix
···
1
+
{ ... }:
2
+
{
3
+
perSystem =
4
+
{ pkgs, ... }:
5
+
{
6
+
packages.gg23-audio =
7
+
(pkgs.writeShellApplication {
8
+
name = "gg23-audio";
9
+
runtimeInputs = [
10
+
pkgs.pulseaudio
11
+
pkgs.gawk
12
+
];
13
+
text = builtins.readFile ./gg23-audio.sh;
14
+
}).overrideAttrs
15
+
{ passthru.usage = builtins.readFile ./usage.kdl; };
16
+
};
17
+
}
+46
tools/gg23-audio/gg23-audio.sh
+46
tools/gg23-audio/gg23-audio.sh
···
1
+
#!/usr/bin/env bash
2
+
# Send audio to the gg23 audio hub on acheron (configs/gg23/audio/hub.nix)
3
+
# via ROC while running: loads a ROC sink into pipewire-pulse and makes it the
4
+
# default. Ctrl-C / SIGTERM unloads it (streams move back) and restores the
5
+
# previous default sink.
6
+
7
+
set -euo pipefail
8
+
9
+
SINK=roc-gg23
10
+
11
+
if [ "$#" -gt 0 ]; then
12
+
echo "usage: gg23-audio (runs until Ctrl-C)" >&2
13
+
exit 1
14
+
fi
15
+
16
+
if pactl list short modules | awk -v s="sink_name=$SINK" '$2 == "module-roc-sink" && index($0, s) { f = 1 } END { exit !f }'; then
17
+
echo "gg23-audio: $SINK is already loaded (another gg23-audio running?)" >&2
18
+
exit 1
19
+
fi
20
+
21
+
prev=$(pactl get-default-sink)
22
+
23
+
id=$(pactl load-module module-roc-sink \
24
+
sink_name="$SINK" \
25
+
"sink_properties='node.description=\"gg23 (acheron hub)\"'" \
26
+
remote_ip=10.42.0.1 \
27
+
remote_source_port=10001 \
28
+
remote_repair_port=10002 \
29
+
remote_control_port=10003 \
30
+
fec_code=disable)
31
+
32
+
cleanup() {
33
+
if [ -n "${sleeper-}" ]; then kill "$sleeper" 2>/dev/null || true; fi
34
+
pactl unload-module "$id" || true
35
+
pactl set-default-sink "$prev" || true
36
+
}
37
+
trap cleanup EXIT
38
+
trap 'exit 130' INT
39
+
trap 'exit 143' TERM
40
+
41
+
pactl set-default-sink "$SINK"
42
+
echo "sending audio to gg23 hub, Ctrl-C to stop" >&2
43
+
44
+
sleep infinity &
45
+
sleeper=$!
46
+
wait
+3
tools/gg23-audio/usage.kdl
+3
tools/gg23-audio/usage.kdl
+202
configs/gg23/audio/hub.nix
+202
configs/gg23/audio/hub.nix
···
1
+
# Low-latency audio hub on acheron: everything received plays into the
2
+
# virtual "hub" sink, whose monitor is linked to the ROC sinks of the rooms
3
+
# selected with `audio-room` or from Home Assistant (MQTT). Senders: any LAN
4
+
# machine via ROC (while `gg23-audio` from tools/gg23-audio runs), barnacle
5
+
# via AirPlay (shairport-sync). Rooms run ./room.nix.
6
+
{
7
+
self,
8
+
config,
9
+
lib,
10
+
pkgs,
11
+
...
12
+
}:
13
+
let
14
+
# shodan and icarus have no stable LAN address (dynamic DHCP leases), so
15
+
# send to their static retiolum IPs; tinc's LocalDiscovery keeps that on the
16
+
# LAN.
17
+
kartei = import (self.inputs.kartei + "/modules/retiolum/hosts.nix") { inherit lib; };
18
+
ip4 = n: (kartei.own.${n} or self.retiolum.own.${n}).ip4;
19
+
20
+
rooms = [
21
+
"shodan"
22
+
"icarus"
23
+
];
24
+
choices = rooms ++ [
25
+
"both"
26
+
"off"
27
+
];
28
+
29
+
mqtt = "-h localhost -u gg23 -P gg23-mqtt";
30
+
31
+
# Home Assistant picks these up via MQTT discovery: a select showing the
32
+
# current room plus one button per choice (dashboard / phone shortcuts).
33
+
# Commands are retained, so the bridge restores the last choice on start.
34
+
discovery = [
35
+
{
36
+
topic = "homeassistant/select/audio_room/config";
37
+
config = {
38
+
name = "Audio room";
39
+
unique_id = "acheron_audio_room";
40
+
command_topic = "gg23/audio-room/set";
41
+
state_topic = "gg23/audio-room/state";
42
+
options = choices;
43
+
retain = true;
44
+
icon = "mdi:speaker-multiple";
45
+
};
46
+
}
47
+
]
48
+
++ map (c: {
49
+
topic = "homeassistant/button/audio_room_${c}/config";
50
+
config = {
51
+
name = "Audio ${c}";
52
+
unique_id = "acheron_audio_room_${c}";
53
+
command_topic = "gg23/audio-room/set";
54
+
payload_press = c;
55
+
retain = true;
56
+
icon = "mdi:speaker-multiple";
57
+
};
58
+
}) choices;
59
+
in
60
+
{
61
+
services.pipewire = {
62
+
enable = true;
63
+
systemWide = true;
64
+
audio.enable = true;
65
+
extraConfig.pipewire."10-audio-hub" = {
66
+
"context.properties"."default.clock.quantum" = 256;
67
+
"context.objects" = [
68
+
{
69
+
factory = "adapter";
70
+
args = {
71
+
"factory.name" = "support.null-audio-sink";
72
+
"node.name" = "hub";
73
+
"node.description" = "Audio hub";
74
+
"media.class" = "Audio/Sink";
75
+
"audio.position" = [
76
+
"FL"
77
+
"FR"
78
+
];
79
+
};
80
+
}
81
+
];
82
+
"context.modules" = [
83
+
{
84
+
# from any LAN sender (`gg23-audio`); roc mixes concurrent
85
+
# sender sessions. Only reachable via int0, et0 is closed.
86
+
name = "libpipewire-module-roc-source";
87
+
args = {
88
+
"local.ip" = "0.0.0.0";
89
+
"local.source.port" = 10001;
90
+
"local.repair.port" = 10002;
91
+
"local.control.port" = 10003;
92
+
"fec.code" = "disable";
93
+
"sess.latency.msec" = 30;
94
+
"source.name" = "roc-lan";
95
+
"source.props" = {
96
+
"node.description" = "LAN (ROC)";
97
+
"target.object" = "hub";
98
+
};
99
+
};
100
+
}
101
+
]
102
+
++ map (r: {
103
+
name = "libpipewire-module-roc-sink";
104
+
args = {
105
+
"remote.ip" = ip4 r;
106
+
"remote.source.port" = 10001;
107
+
"remote.repair.port" = 10002;
108
+
"remote.control.port" = 10003;
109
+
"fec.code" = "disable";
110
+
"sink.name" = "roc-${r}";
111
+
"sink.props"."node.description" = "${r} (ROC)";
112
+
};
113
+
}) rooms;
114
+
};
115
+
};
116
+
117
+
services.shairport-sync = {
118
+
enable = true;
119
+
# AirPlay 1: the default package has no AirPlay 2 (no nqptp needed)
120
+
settings = {
121
+
general = {
122
+
name = "gg23";
123
+
output_backend = "pipewire";
124
+
# play early by about the hub -> room ROC hop, so AirPlay video
125
+
# stays in sync in the rooms
126
+
audio_backend_latency_offset_in_seconds = -0.04;
127
+
};
128
+
pipewire.sink_target = "hub";
129
+
};
130
+
};
131
+
users.users.shairport.extraGroups = [ "pipewire" ];
132
+
133
+
# mDNS for AirPlay on the LAN only; int0 is trusted, et0 must stay closed
134
+
services.avahi = {
135
+
allowInterfaces = [ "int0" ];
136
+
openFirewall = false;
137
+
};
138
+
139
+
# MQTT -> pipewire links, so Home Assistant (in podman) needs no access to
140
+
# pipewire. Restarted with pipewire, the retained command restores the room.
141
+
systemd.services.audio-room = {
142
+
wantedBy = [
143
+
"multi-user.target"
144
+
"pipewire.service"
145
+
];
146
+
bindsTo = [ "pipewire.service" ];
147
+
after = [
148
+
"pipewire.service"
149
+
"mosquitto.service"
150
+
];
151
+
path = [
152
+
config.services.pipewire.package
153
+
pkgs.mosquitto
154
+
];
155
+
script = ''
156
+
${lib.concatMapStrings (d: ''
157
+
mosquitto_pub ${mqtt} -r -t ${d.topic} -m ${lib.escapeShellArg (builtins.toJSON d.config)}
158
+
'') discovery}
159
+
route() {
160
+
for r in ${toString rooms}; do
161
+
pw-link -d hub "roc-$r" 2>/dev/null
162
+
case "$1" in "$r" | both)
163
+
i=0
164
+
until pw-link hub "roc-$r"; do
165
+
i=$((i + 1))
166
+
[ "$i" -lt 10 ] || return 1
167
+
sleep 1
168
+
done
169
+
;;
170
+
esac
171
+
done
172
+
}
173
+
mosquitto_sub ${mqtt} -t gg23/audio-room/set | while read -r room; do
174
+
case "$room" in
175
+
${lib.concatStringsSep " | " choices}) ;;
176
+
*) echo "ignoring $room" >&2; continue ;;
177
+
esac
178
+
route "$room" && mosquitto_pub ${mqtt} -r -t gg23/audio-room/state -m "$room"
179
+
done
180
+
'';
181
+
serviceConfig = {
182
+
DynamicUser = true;
183
+
SupplementaryGroups = [ "pipewire" ];
184
+
Restart = "always";
185
+
RestartSec = 2;
186
+
};
187
+
};
188
+
189
+
environment.systemPackages = [
190
+
(pkgs.writers.writeDashBin "audio-room" ''
191
+
case "''${1-}" in
192
+
${lib.concatStringsSep " | " choices})
193
+
exec ${pkgs.mosquitto}/bin/mosquitto_pub ${mqtt} -r -t gg23/audio-room/set -m "$1"
194
+
;;
195
+
*)
196
+
echo "usage: audio-room ${lib.concatStringsSep "|" choices}" >&2
197
+
exit 1
198
+
;;
199
+
esac
200
+
'')
201
+
];
202
+
}
+33
configs/gg23/audio/room.nix
+33
configs/gg23/audio/room.nix
···
1
+
# Room speaker for the acheron audio hub (./hub.nix): plays what the hub
2
+
# sends via ROC on the default output.
3
+
{ self, lib, ... }:
4
+
let
5
+
kartei = import (self.inputs.kartei + "/modules/retiolum/hosts.nix") { inherit lib; };
6
+
acheron = (kartei.own.acheron or self.retiolum.own.acheron).ip4;
7
+
in
8
+
{
9
+
services.pipewire.extraConfig.pipewire."10-audio-room"."context.modules" = [
10
+
{
11
+
name = "libpipewire-module-roc-source";
12
+
args = {
13
+
"local.ip" = "0.0.0.0";
14
+
"local.source.port" = 10001;
15
+
"local.repair.port" = 10002;
16
+
"local.control.port" = 10003;
17
+
"fec.code" = "disable";
18
+
"sess.latency.msec" = 30;
19
+
"source.name" = "roc-hub";
20
+
"source.props" = {
21
+
"node.description" = "Audio hub (acheron)";
22
+
# keep the graph quantum small while the hub plays here
23
+
"node.latency" = "256/48000";
24
+
};
25
+
};
26
+
}
27
+
];
28
+
29
+
# the hub sends over retiolum (see ./hub.nix), accept only acheron
30
+
networking.firewall.extraInputRules = ''
31
+
iifname "retiolum" ip saddr ${acheron} udp dport 10001-10003 accept
32
+
'';
33
+
}