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 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
               }
           }
       }
       ]

SEE ALSO

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