PipeWire Module: Combine Stream

The combine stream can make:

• a new virtual sink that forwards audio to other sinks
• a new virtual source that combines audio from other sources

Module Options

• node.name: a unique name for the stream
• node.description: a human readable name for the stream
• combine.mode = capture | playback | sink | source, default sink
• combine.props = {}: properties to be passed to the sink/source
• stream.props = {}: properties to be passed to the streams

General options

Options with well-known behavior.

• PW_KEY_REMOTE_NAME
• PW_KEY_AUDIO_CHANNELS
• SPA_KEY_AUDIO_POSITION
• PW_KEY_MEDIA_NAME
• PW_KEY_NODE_LATENCY
• PW_KEY_NODE_NAME
• PW_KEY_NODE_DESCRIPTION
• PW_KEY_NODE_GROUP
• PW_KEY_NODE_VIRTUAL
• PW_KEY_MEDIA_CLASS

Stream options

• audio.position: Set the stream channel map. By default this is the same channel map as the combine stream.
• combine.audio.position: map the combine audio positions to the stream positions. combine input channels are mapped one-by-one to stream output channels.

Example configuration

context.modules = [
{   name = libpipewire-module-combine-stream
    args = {
        combine.mode = sink
        node.name = "combine_sink"
        node.description = "My Combine Sink"
        combine.props = {
            audio.position = [ FL FR ]
        }
        stream.props = {
        }
        stream.rules = [
            {
                matches = [
                    # any of the items in matches needs to match, if one does,
                    # actions are emited.
                    {
                        # all keys must match the value. ~ in value starts regex.
                        #node.name = "~alsa_input.*"
                        media.class = "Audio/Sink"
                    }
                ]
                actions = {
                    create-stream = {
                        #combine.audio.position = [ FL FR ]
                        #audio.position = [ FL FR ]
                    }
                }
            }
        ]
    }
}
]

Below is an example configuration that makes a 5.1 virtual audio sink from 3 separate stereo sinks.

context.modules = [
{   name = libpipewire-module-combine-stream
    args = {
        combine.mode = sink
        node.name = "combine_sink_5_1"
        node.description = "My 5.1 Combine Sink"
        combine.props = {
            audio.position = [ FL FR FC LFE SL SR ]
        }
        stream.props = {
                stream.dont-remix = true      # link matching channels without remixing
        }
        stream.rules = [
            {   matches = [
                    {   media.class = "Audio/Sink"
                        node.name = "alsa_output.usb-Topping_E30-00.analog-stereo"
                    } ]
                actions = { create-stream = {
                        combine.audio.position = [ FL FR ]
                        audio.position = [ FL FR ]
                } } }
            {   matches = [
                    {   media.class = "Audio/Sink"
                        node.name = "alsa_output.usb-BEHRINGER_UMC404HD_192k-00.pro-output-0"
                    } ]
                actions = { create-stream = {
                        combine.audio.position = [ FC LFE ]
                        audio.position = [ AUX0 AUX1 ]
                } } }
            {   matches = [
                    {   media.class = "Audio/Sink"
                        node.name = "alsa_output.pci-0000_00_1b.0.analog-stereo"
                    } ]
                actions = { create-stream = {
                        combine.audio.position = [ SL SR ]
                        audio.position = [ FL FR ]
                } } }
        ]
    }
}
]

Below is an example configuration that makes a 4.0 virtual audio source from 2 separate stereo sources.

context.modules = [
{   name = libpipewire-module-combine-stream
    args = {
        combine.mode = source
        node.name = "combine_source_4_0"
        node.description = "My 4.0 Combine Source"
        combine.props = {
            audio.position = [ FL FR SL SR ]
        }
        stream.props = {
                stream.dont-remix = true
        }
        stream.rules = [
            {   matches = [
                    {   media.class = "Audio/Source"
                        node.name = "alsa_input.usb-046d_HD_Pro_Webcam_C920_09D53E1F-02.analog-stereo"
                    } ]
                actions = { create-stream = {
                        audio.position = [ FL FR ]
                        combine.audio.position = [ FL FR ]
                } } }
            {   matches = [
                    {   media.class = "Audio/Source"
                        node.name = "alsa_input.usb-046d_0821_9534DE90-00.analog-stereo"
                    } ]
                actions = { create-stream = {
                        audio.position = [ FL FR ]
                        combine.audio.position = [ SL SR ]
                } } }
        ]
    }
}
]