Snapcast

Synchronised multi-room playback through Snapserver — TCP or FIFO.

Rockbox can feed Snapcast two ways. Both write raw S16LE stereo PCM at 44 100 Hz to snapserver; pick the transport that fits your setup.

	TCP sink	FIFO sink
Filesystem entry required	No	Yes (/tmp/snapfifo)
Snapserver source type	tcp://	pipe://
Startup order	Snapserver first	Rockbox first
Auto-reconnect	Yes (next play call)	n/a — FIFO stays open
Auto-discovery in UI	Yes (_snapcast._tcp.local.)	No — static virtual device
stdout pipe support	No	Yes (fifo_path = "-")

Use TCP for auto-discovery, multiple snapservers, or no filesystem dependency. Use FIFO for stdout piping or the traditional pipe model.

TCP (recommended)

music_dir         = "/path/to/Music"
audio_output      = "snapcast_tcp"
snapcast_tcp_host = "192.168.1.x"   # IP of the snapserver host
snapcast_tcp_port = 4953            # default snapserver TCP source port

Snapserver:

# /etc/snapserver.conf  (or /usr/local/etc/snapserver.conf on macOS)
[stream]
source = tcp://0.0.0.0:4953?name=default&sampleformat=44100:16:2

Auto-discovery: rockboxd scans _snapcast._tcp.local. at startup; discovered servers appear in the web UI device picker. Click to connect — no config file editing required.

Startup order: start snapserver first so it is already listening when rockboxd begins playback. If the connection drops (e.g. snapserver restarts), it is re-established automatically on the next play call.

FIFO / pipe

music_dir    = "/path/to/Music"
audio_output = "fifo"
fifo_path    = "/tmp/snapfifo"   # named FIFO for snapserver; "-" = stdout

Snapserver:

[stream]
source = pipe:///tmp/snapfifo?name=default&sampleformat=44100:16:2

Startup order matters: start rockboxd before snapserver. Rockbox holds a permanent write reference on the FIFO so snapserver never sees a premature EOF between tracks. If snapserver opens the FIFO first it may get EOF and stop reading.

stdout mode

fifo_path = "-" writes raw PCM to stdout — useful for piping into any consumer:

rockboxd | ffplay -f s16le -ar 44100 -ac 2 -

rockboxd | sox -t raw -r 44100 -e signed -b 16 -c 2 - -d

macOS quirk

Snapserver v0.35.0 on macOS ignores the -s sample-format CLI flag. Use the config file at /usr/local/etc/snapserver.conf instead:

[stream]
source = pipe:///tmp/snapfifo?name=default&sampleformat=44100:16:2

Verifying it works

# In one terminal
snapserver --logging.filter "*:debug"

# In another
rockboxd

You should see Stream: 'default' connected in the snapserver logs within a second of starting playback. From a snapclient host:

snapclient -h <snapserver-ip>