secubox-deb/packages/secubox-fmrelay

secubox-fmrelay

FM broadcast → Icecast2 MP3 mount with live RDS metadata, controlled from the SecuBox dashboard. Closes #377.

What it does

• rtl_fm | ffmpeg -c:a libmp3lame pipes RTL-SDR FM audio into an Icecast2 SOURCE mount. ffmpeg speaks icecast:// natively and handles reconnects, so the runner stays small.
• A parallel rtl_fm | redsea pipeline decodes the 57 kHz RDS subcarrier (PI / PS / RT) and POSTs each RadioText update to icecast2/admin/metadata, so HTTP listeners see Artist - Title change live.
• A small FastAPI on /run/secubox/fmrelay.sock exposes lifecycle
  • introspection endpoints, consumed by the SecuBox admin webui.

The Icecast mount it produces is what the SecuBox webradio module serves and what Lyrion ingests as a Favourite remote URL.

Hardware sharing — RTL-SDR

The dongle is shared with secubox-sentinelle-gsm (GSM scans + RDS sweep). Don't start a relay while a GSM scan is running — the bus contention will crash both. Cross-package device-claim coordination is planned for v0.2.

API

Method	Path	Description
GET	/api/v1/fmrelay/healthz	liveness probe
GET	/api/v1/fmrelay/version	version + build sha
GET	/api/v1/fmrelay/status	overall green / yellow / red
GET	/api/v1/fmrelay/components	per-component state (icecast2 / rtl_fm / lame / redsea / runner)
GET	/api/v1/fmrelay/access	mount URL (lan) + webradio URL (public) — admin UI button reads from here
GET	/api/v1/fmrelay/mounts	active Icecast mounts + listener counts
GET	/api/v1/fmrelay/now-playing	current RDS RadioText (or {})
POST	/api/v1/fmrelay/start	{freq, mount, bitrate?, gain?, ppm?}
POST	/api/v1/fmrelay/stop	stop runner + redsea-icy pusher

All routes are SSO-gated via auth_request /__sbx_auth_verify (Authelia). Per MODULE-GUIDELINES.md §4 the admin webui never hardcodes external URLs — the Open Webradio → button reads its target from /access at runtime (single source of truth).

CLI

fmrelayctl components [--json]
fmrelayctl status     [--json]
fmrelayctl access     [--json]
fmrelayctl mounts     [--json]
fmrelayctl now-playing [--json]
fmrelayctl start FREQ --mount NAME [--bitrate K] [--gain dB] [--ppm N]
fmrelayctl stop
fmrelayctl version

Example:

fmrelayctl start 103.9M --mount savoie --bitrate 128 --gain 49 --ppm 60
fmrelayctl mounts
fmrelayctl stop

Config — /etc/secubox/fmrelay.toml

Seeded from fmrelay.toml.example on first install. Operator only needs to swap the default hackme Icecast2 credentials.

[icecast]
icecast_host         = "127.0.0.1"
icecast_port         = 8000
icecast_admin_pass   = "<change-me>"
icecast_source_pass  = "<change-me>"

[runner]
bitrate_kbps         = 128
gain_db              = 49
ppm                  = 0

[exposure]
webradio_url         = "https://admin.gk2.secubox.in/webradio/"

Dependencies

• rtl-sdr — RTL-SDR userspace + rtl_fm
• ffmpeg — libmp3lame encoder + Icecast SOURCE client
• icecast2 — the streaming server
• curl — used by fmrelayctl mounts against /admin/listmounts
• python3-fastapi, python3-uvicorn — FastAPI host
• secubox-core (≥ 1.0) — shared SecuBox runtime
• redsea — optional, falls back to /usr/libexec/secubox/secubox-redsea if shipped by secubox-sentinelle-gsm

Files installed

/usr/sbin/fmrelayctl
/usr/libexec/secubox/secubox-fmrelay-runner
/usr/libexec/secubox/secubox-fmrelay-icy
/usr/lib/secubox/fmrelay/api/main.py
/usr/share/secubox/www/fmrelay/index.html
/usr/share/secubox/menu.d/72-fmrelay.json
/etc/nginx/secubox.d/fmrelay.conf
/etc/nginx/secubox-routes.d/fmrelay.conf
/etc/secubox/fmrelay.toml.example
/lib/systemd/system/secubox-fmrelay.service

Service

secubox-fmrelay.service runs uvicorn as secubox:secubox on /run/secubox/fmrelay.sock, with NoNewPrivileges, ProtectHome, PrivateTmp and a restricted ReadWritePaths set. The actual rtl_fm/ffmpeg/redsea child processes are spawned by the runner + icy scripts in /usr/libexec/secubox/.