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. Sometimes your audio source might insist in creating the pipe itself. So the pipe creation mode can by changed to "not create, but only read mode", using the mode option set to 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

TODO: description of the parameters

file

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

TODO: description of the parameters

process

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

TODO: description of the parameters

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

TODO: description of the parameters

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