snapcast/doc/configuration.md

Configuration

Sources

source URI of the PCM input stream, can be configured multiple times The following notation is used in this paragraph:

• <angle brackets>: the whole expression must be replaced with your specific setting
• [square brackets]: the whole expression is optional and can be left out
• [key=value]: if you leave this option out, "value" will be the default for "key"

Format:

TYPE://host/path?name=<name>[&codec=<codec>][&sampleformat=<sampleformat>][&chunk_ms=<chunk ms>]

parameters have the form key=value, they are concatenated with an & character parameter name is mandatory for all sources, while codec, sampleformat and chunk_ms are optional and will override the default codec, sampleformat or chunk_ms settings. Non blocking sources support the dryout_ms parameter: when no new data is read from the source, send silence to the clients

Available types are:

pipe

pipe:///<path/to/pipe>?name=<name>[&mode=create][&dryout_ms=2000], mode can be "create" or "read"

librespot

librespot:///<path/to/librespot>?name=<name>[&dryout_ms=2000][&username=<my username>&password=<my password>][&devicename=Snapcast][&bitrate=320][&wd_timeout=7800][&volume=100][&onevent=""][&normalize=false][&autoplay=false]

note that you need to have the librespot binary on your machine sampleformat will be set to 44100:16:2

file

file:///<path/to/PCM/file>?name=<name>

process

process:///<path/to/process>?name=<name>[&dryout_ms=2000][&wd_timeout=0][&log_stderr=false][&params=<process arguments>]

airplay

airplay:///<path/to/airplay>?name=<name>[&dryout_ms=2000][&port=5000]

note that you need to have the airplay binary on your machine sampleformat will be set to 44100:16:2

tcp server

tcp://<listen IP, e.g. 127.0.0.1>:<port>?name=<name>[&mode=server]

default for port (if omitted) is 4953, default for mode is server

mopidy.conf (running GStreamer in client mode)

[audio]
output = audioresample ! audioconvert ! audio/x-raw,rate=48000,channels=2,format=S16LE ! wavenc ! tcpclientsink

tcp client

tcp://<server IP, e.g. 127.0.0.1>:<port>?name=<name>&mode=client

mopidy.conf (running GStreamer in server mode)

[audio]
output = audioresample ! audioconvert ! audio/x-raw,rate=48000,channels=2,format=S16LE ! wavenc ! tcpserversink

alsa

alsa://?name=<name>&device=<alsa device>

Snapcast v0.21 can capture audio from alsa, and to capture the output of a player, an alsa loopback device can be used:

1. setup the alsa loopback device by loading the kernel module:

   sudo modprobe snd-aloop
   

2. the loopback device should show up in aplay -l

   aplay -l
   **** List of PLAYBACK Hardware Devices ****
   card 0: Loopback [Loopback], device 0: Loopback PCM [Loopback PCM]
   Subdevices: 8/8
   Subdevice #0: subdevice #0
   Subdevice #1: subdevice #1
   Subdevice #2: subdevice #2
   Subdevice #3: subdevice #3
   Subdevice #4: subdevice #4
   Subdevice #5: subdevice #5
   Subdevice #6: subdevice #6
   Subdevice #7: subdevice #7
   card 0: Loopback [Loopback], device 1: Loopback PCM [Loopback PCM]
   Subdevices: 8/8
   Subdevice #0: subdevice #0
   Subdevice #1: subdevice #1
   Subdevice #2: subdevice #2
   Subdevice #3: subdevice #3
   Subdevice #4: subdevice #4
   Subdevice #5: subdevice #5
   Subdevice #6: subdevice #6
   Subdevice #7: subdevice #7
   card 1: Intel [HDA Intel], device 0: CX20561 Analog [CX20561 Analog]
   Subdevices: 1/1
   Subdevice #0: subdevice #0
   card 1: Intel [HDA Intel], device 1: CX20561 Digital [CX20561 Digital]
   Subdevices: 1/1
   Subdevice #0: subdevice #0
   card 2: CODEC [USB Audio CODEC], device 0: USB Audio [USB Audio]
   Subdevices: 0/1
   Subdevice #0: subdevice #0
   

   On my system it's card 0 with devices 0 and 1, each having 8 subdevices. You can address them with hw:<card idx>,<device idx>,<subdevice num>, i.e. hw:0,0,0. If a process plays audio using hw:0,0,x, then this audio is looped back to hw:0,1,x, so

3. Configure your player to use a loopback device.

   For mopidy (gstreamer) it should be something like this (not tested):

   output = audioresample ! audioconvert ! audio/x-raw,rate=48000,channels=2,format=S16LE ! wavenc ! alsasink device=hw:0,0,0
   

   For mpd: in mpd.conf

   audio_output_format            "48000:16:2"
   audio_output {
           type            "alsa"
           name            "My ALSA Device"
           device          "hw:0,0,0"      # optional
   #       auto_resample   "no"
   #       mixer_type      "hardware"      # optional
   #       mixer_device    "default"       # optional
   #       mixer_control   "PCM"           # optional
   #       mixer_index     "0"             # optional
   }
   

4. Configure Snapserver to capture the loopback device:

   [stream]
   stream = alsa://?name=SomeName&sampleformat=48000:16:2&device=hw:0,1,0