NAME

       libpipewire-module-loopback - Loopback

DESCRIPTION

       The loopback module passes the output of a capture stream unmodified to a playback stream.

       It can be used to construct a link between a source and sink but also to create new virtual sinks or
       sources or to remap channel between streams.

       Because both ends of the loopback are built with streams, the session manager can manage the
       configuration and connection with the sinks and sources.

MODULE NAME

       libpipewire-module-loopback

MODULE OPTIONS

       • node.description: a human readable name for the loopback streams

       • target.delay.sec: delay in seconds as float (Since 0.3.60)

       • capture.props = {}: properties to be passed to the input stream

       • playback.props = {}: properties to be passed to the output stream

GENERAL OPTIONS

       Options with well-known behavior. Most options can be added to the global configuration or the individual
       streams:

       • remote.name

       • audio.rate

       • audio.channels

       • audio.position

       • media.name

       • node.latency

       • node.description

       • node.group

       • node.link.group

       • node.virtual

       • node.name : See notes below. If not specified, defaults to 'loopback-PID-MODULEID'.

       Stream only properties:

       • media.class

       • node.name  : if not given per stream, the global node.name will be prefixed with 'input.' and 'output.'
         to generate a capture and playback stream node.name respectively.

CHANNEL HANDLING

       Channels from the capture stream are copied, in  order,  to  the  channels  of  the  output  stream.  The
       remaining  streams are ignored (when capture has more channels) or filled with silence (when playback has
       more channels).

       When a global channel position is set, both capture and playback will  be  converted  to  and  from  this
       common channel layout. This can be used to implement up or downmixing loopback sinks/sources.

EXAMPLE CONFIGURATION OF SOURCE TO SINK LINK

       This  loopback  links  a source node to a sink node. You can change the target.object properties to match
       your source/sink node.name.

       # ~/.config/pipewire/pipewire.conf.d/my-loopback-0.conf

       context.modules = [
       {   name = libpipewire-module-loopback
           args = {
               capture.props = {
                   #  if you want to capture sink monitor ports,
                   #  uncomment the next line and set the target.object
                   #  to the sink name.
                   #stream.capture.sink = true
                   target.object = "alsa_input.usb-C-Media_Electronics_Inc._TONOR_TC-777_Audio_Device-00.mono-fallback"
                   node.passive = true
                   node.dont-reconnect = true
               }
               playback.props = {
                   target.object = "alsa_output.usb-0d8c_USB_Sound_Device-00.analog-surround-71"
                   node.dont-reconnect = true
                   node.passive = true
               }
           }
       }
       ]

EXAMPLE CONFIGURATION OF A VIRTUAL SINK

       This Virtual sink routes stereo input to the rear channels of a 7.1 sink.

       # ~/.config/pipewire/pipewire.conf.d/my-loopback-1.conf

       context.modules = [
       {   name = libpipewire-module-loopback
           args = {
               node.description = "CM106 Stereo Pair 2"
               #target.delay.sec = 1.5
               capture.props = {
                   node.name = "CM106_stereo_pair_2"
                   media.class = "Audio/Sink"
                   audio.position = [ FL FR ]
               }
               playback.props = {
                   node.name = "playback.CM106_stereo_pair_2"
                   audio.position = [ RL RR ]
                   target.object = "alsa_output.usb-0d8c_USB_Sound_Device-00.analog-surround-71"
                   node.dont-reconnect = true
                   stream.dont-remix = true
                   node.passive = true
               }
           }
       }
       ]

EXAMPLE CONFIGURATION OF A VIRTUAL SOURCE

       This Virtual source routes the front-left channel of a multi-channel input to a  mono  channel.  This  is
       useful  for  splitting up multi-channel inputs from USB audio interfaces that are not yet fully supported
       by alsa.

       # ~/.config/pipewire/pipewire.conf.d/my-loopback-2.conf

       context.modules = [
       {   name = libpipewire-module-loopback
           args = {
               node.description = "Scarlett Focusrite Line 1"
               capture.props = {
                   audio.position = [ FL ]
                   stream.dont-remix = true
                   node.target = "alsa_input.usb-Focusrite_Scarlett_Solo_USB_Y7ZD17C24495BC-00.analog-stereo"
                   node.passive = true
               }
               playback.props = {
                   node.name = "SF_mono_in_1"
                   media.class = "Audio/Source"
                   audio.position = [ MONO ]
               }
           }
       }
       ]

EXAMPLE CONFIGURATION OF AN UPMIX SINK

       This Virtual sink has 2 input channels and 6 output channels. It will  perform  upmixing  using  the  PSD
       algorithm on the playback stream.

       # ~/.config/pipewire/pipewire.conf.d/my-loopback-3.conf

       context.modules = [
       {   name = libpipewire-module-loopback
           args = {
               node.description = "Upmix Sink"
               audio.position = [ FL FR ]
               capture.props = {
                   node.name = "effect_input.upmix"
                   media.class = Audio/Sink
               }
               playback.props = {
                   node.name = "effect_output.upmix"
                   audio.position = [ FL FR RL RR FC LFE ]
                   node.passive = true
                   stream.dont-remix = true
                   channelmix.upmix = true
                   channelmix.upmix-method = psd
                   channelmix.lfe-cutoff = 150
                   channelmix.fc-cutoff = 12000
                   channelmix.rear-delay = 12.0
               }
           }
       }
       ]

EXAMPLE CONFIGURATION OF A DOWNMIX SOURCE

       This  Virtual  source has 2 input channels and a mono output channel. It will perform downmixing from the
       two first AUX channels of a pro-audio device.

       # ~/.config/pipewire/pipewire.conf.d/my-loopback-4.conf

       context.modules = [
       {   name = libpipewire-module-loopback
           args = {
               node.description = "Downmix Source"
               audio.position = [ AUX0 AUX1 ]
               capture.props = {
                   node.name = "effect_input.downmix"
                   target.object = "alsa_input.usb-BEHRINGER_UMC404HD_192k-00.pro-input-0"
                   node.passive = true
                   stream.dont-remix = true
               }
               playback.props = {
                   node.name = "effect_output.downmix"
                   media.class = Audio/Source
                   audio.position = [ MONO ]
               }
           }
       }
       ]

SEE ALSO

       pw-loopback : a tool that loads the loopback module with given parameters.

PipeWire                                              1.4.5                       libpipewire-module-loopback(7)