SYNOPSIS

$XDG_CONFIG_HOME/pipewire/client.conf

/etc/pipewire/client.conf

/usr/share/pipewire/client.conf

/usr/share/pipewire/client.conf.d/

/etc/pipewire/client.conf.d/

$XDG_CONFIG_HOME/pipewire/client.conf.d/

$XDG_CONFIG_HOME/pipewire/client-rt.conf

/etc/pipewire/client-rt.conf

/usr/share/pipewire/client-rt.conf

/usr/share/pipewire/client-rt.conf.d/

/etc/pipewire/client-rt.conf.d/

$XDG_CONFIG_HOME/pipewire/client-rt.conf.d/

DESCRIPTION

Configuration for PipeWire native clients, and for PipeWire's ALSA plugin.

A PipeWire native client program selects the default config to load, and if nothing is specified, it usually loads client.conf.

The ALSA plugin uses the client-rt.conf file, as do some PipeWire native clients such as pw-cat(1).

The configuration file format and lookup logic is the same as for pipewire.conf(5).

Drop-in configuration files client.conf.d/*.conf can be used, and are recommended. See pipewire.conf(5).

CONFIGURATION FILE SECTIONS

stream.properties: Configures options for native client streams.

stream.rules: Configures rules for native client streams.

alsa.properties: ALSA client configuration.

alsa.rules: ALSA client match rules.

In addition, the PipeWire context configuration sections may also be specified, see pipewire.conf(5).

STREAM PROPERTIES

The client configuration files contain a stream.properties section that configures the options for client streams:

stream.properties = {
    #node.latency = 1024/48000
    #node.autoconnect = true
    #resample.disable = false
    #resample.quality = 4
    #monitor.channel-volumes = false
    #channelmix.disable = false
    #channelmix.min-volume = 0.0
    #channelmix.max-volume = 10.0
    #channelmix.normalize = false
    #channelmix.lock-volume = false
    #channelmix.mix-lfe = true
    #channelmix.upmix = true
    #channelmix.upmix-method = psd  # none, simple
    #channelmix.lfe-cutoff = 150.0
    #channelmix.fc-cutoff  = 12000.0
    #channelmix.rear-delay = 12.0
    #channelmix.stereo-widen = 0.0
    #channelmix.hilbert-taps = 0
    #dither.noise = 0
    #dither.method = none # rectangular, triangular, triangular-hf, wannamaker3, shaped5
    #debug.wav-path = ""
}

Some of the properties refer to different aspects of the stream:

General stream properties to identify the stream.
General stream properties to classify the stream.
How it is going to be scheduled by the graph.
How it is going to be linked by the session manager.
How the internal processing will be done.
Properties to configure the media format.

Identifying Properties

These contain properties to identify the node or to display the node in a GUI application.

node.name: A (unique) name for the node. This is usually set on sink and sources to identify them as targets for linking by the session manager.

node.description: A human readable description of the node or stream.

media.name: A user readable media name, usually the artist and title. These are usually shown in user facing applications to inform the user about the current playing media.

media.title: A user readable stream title.

media.artist: A user readable stream artist

media.copyright: User readable stream copyright information

media.software: User readable stream generator software information

media.language: Stream language in POSIX format. Ex: en_GB

media.filename: File name for the stream

media.icon: Icon for the media, a base64 blob with PNG image data

media.icon-name: An XDG icon name for the media. Ex: audio-x-mp3

media.comment: Extra stream comment

media.date: Date of the media

media.format: User readable stream format information

object.linger = false: If the object should outlive its creator.

Classifying Properties

The classifying properties of a node are use for routing the signal to its destination and for configuring the settings.

media.type: The media type contains a broad category of the media that is being processed by the node. Possible values include "Audio", "Video", "Midi"

media.category

What kind of processing is done with the media. Possible values include:

Playback: media playback.
Capture: media capture.
Duplex: media capture and playback or media processing in general.
Monitor: a media monitor application. Does not actively change media data but monitors activity.
Manager: Will manage the media graph.

media.role

The Use case of the media. Possible values include:

Movie: Movie playback with audio and video.
Music: Music listening.
Camera: Recording video from a camera.
Screen: Recording or sharing the desktop screen.
Communication: VOIP or other video chat application.
Game: Game.
Notification: System notification sounds.
DSP: Audio or Video filters and effect processing.
Production: Professional audio processing and production.
Accessibility: Audio and Visual aid for accessibility.
Test: Test program.

media.class

The media class is to classify the stream function. Possible values include:

Video/Source: a producer of video, like a webcam.
Video/Sink: a consumer of video, like a display window.
Audio/Source: a source of audio samples like a microphone.
Audio/Sink: a sink for audio samples, like an audio card.
Audio/Duplex: a node that is both a sink and a source.
Stream/Output/Audio: a playback stream.
Stream/Input/Audio: a capture stream.

The session manager assigns special meaning to the nodes based on the media.class. Sink or Source classes are used as targets for Stream classes, etc..

Scheduling Properties

node.latency = 1024/48000: Sets a suggested latency on the node as a fraction. This is just a suggestion, the graph will try to configure this latency or less for the graph. It is however possible that the graph is forced to a higher latency.

node.lock-quantum = false

When this node is active, the quantum of the graph is locked and not allowed to change automatically. It can still be changed forcibly with metadata or when a node forces a quantum.

JACK clients use this property to avoid unexpected quantum changes.

node.force-quantum = INTEGER

While the node is active, force a quantum in the graph. The last node to be activated with this property wins.

A value of 0 unforces the quantum.

node.rate = RATE: Suggest a rate (samplerate) for the graph. The suggested rate will only be applied when doing so would not cause interruptions (devices are idle) and when the rate is in the list of allowed rates in the server.

node.lock-rate = false: When the node is active, the rate of the graph will not change automatically. It is still possible to force a rate change with metadata or with a node property.

node.force-rate = RATE

When the node is active, force a specific sample rate on the graph. The last node to activate with this property wins.

A RATE of 0 means to force the rate in node.rate denominator.

node.always-process = false

When the node is active, it will always be joined with a driver node, even when nothing is linked to the node. Setting this property to true also implies node.want-driver = true.

This is the default for JACK nodes, that always need their process callback called.

node.want-driver = true: The node wants to be linked to a driver so that it can start processing. This is the default for streams and filters since 0.3.51. Nodes that are not linked to anything will still be set to the idle state, unless node.always-process is set to true.

node.pause-on-idle = false

node.suspend-on-idle = false

When the node is not linked anymore, it becomes idle. Normally idle nodes keep processing and are suspended by the session manager after some timeout. It is possible to immediately pause a node when idle with this property.

When the session manager does not suspend nodes (or when there is no session manager), the node.suspend-on-idle property can be used instead.

node.loop.name = null

node.loop.class = data.rt

Add the node to a specific loop name or loop class. By default the node is added to the data.rt loop class. You can make more specific data loops and then assign the nodes to those.

Other well known names are main-loop.0 and the main node.loop.class which runs the node data processing in the main loop.

Session Manager Properties

node.autoconnect = true: Instructs the session manager to automatically connect this node to some other node, usually a sink or source.

node.exclusive = false: If this node wants to be linked exclusively to the sink/source.

node.target = <node.name|object.id>: Where this node should be linked to. This can be a node.name or an object.id of a node. This property is deprecated, the target.object property should be used instead, which uses the more unique object.serial as a possible target.

target.object = <node.name|object.serial>: Where the node should link to, this can be a node.name or an object.serial.

node.dont-reconnect = false

When the node has a target configured and the target is destroyed, destroy the node as well. This property also inhibits that the node is moved to another sink/source.

Note that if a stream should appear/disappear in sync with the target, a session manager (WirePlumber) script should be written instead.

node.passive = false

This is a passive node and so it should not keep sinks/sources busy. This property makes the session manager create passive links to the sink/sources. If the node is not otherwise linked (via a non-passive link), the node and the sink it is linked to are idle (and eventually suspended).

This is used for filter nodes that sit in front of sinks/sources and need to suspend together with the sink/source.

node.link-group = ID: Add the node to a certain link group. Nodes from the same link group are not automatically linked to each other by the session manager. And example is a coupled stream where you don't want the output to link to the input streams, making a useless loop.

stream.dont-remix = false: Instruct the session manager to not remix the channels of a stream. Normally the stream channel configuration is changed to match the sink/source it is connected to. With this property set to true, the stream will keep its original channel layout and the session manager will link matching channels with the sink.

Audio Adapter Parameters

An audio stream (and also audio device nodes) contain an audio adapter that can perform, sample format, sample rate and channel mixing operations.

Merger Parameters

The merger is used as the input for a sink device node or a capture stream. It takes the various channels and merges them into a single stream for further processing.

The merger will also provide the monitor ports of the input channels and can apply a software volume on the monitor signal.

monitor.channel-volumes = false: The volume of the input channels is applied to the volume of the monitor ports. Normally the monitor ports expose the raw unmodified signal on the input ports.

Resampler Parameters

Source, sinks, capture and playback streams contain a high quality adaptive resampler. It uses sinc based resampling with linear interpolation of filter banks to perform arbitrary resample factors. The resampler is activated in the following cases:

The hardware of a device node does not support the graph samplerate. Resampling will occur from the graph samplerate to the hardware samplerate.
The hardware clock of a device does not run at the same speed as the graph clock and adaptive resampling is required to match the clocks.
A stream does not have the same samplerate as the graph and needs to be resampled.
An application wants to activate adaptive resampling in a stream to make it match some other clock.

PipeWire performs most of the sample conversions and resampling in the client (Or in the case of the PulseAudio server, in the pipewire-pulse server that creates the streams). This ensures all the conversions are offloaded to the clients and the server can deal with one single format for performance reasons.

Below is an explanation of the options that can be tuned in the sample converter.

resample.quality = 4

The quality of the resampler. from 0 to 14, the default is 4.

Increasing the quality will result in better cutoff and less aliasing at the expense of (much) more CPU consumption. The default quality of 4 has been selected as a good compromise between quality and performance with no artifacts that are well below the audible range.

See Infinite Wave for a comparison of the performance.

resample.disable = false: Disable the resampler entirely. The node will only be able to negotiate with the graph when the samplerates are compatible.

Channel Mixer Parameters

Source, sinks, capture and playback streams can apply channel mixing on the incoming signal.

Normally the channel mixer is not used for devices, the device channels are usually exposed as they are. This policy is usually enforced by the session manager, so we refer to its documentation there.

Playback and capture streams are usually configured to the channel layout of the sink/source they connect to and will thus perform channel mixing.

The channel mixer also implements a software volume. This volume adjustment is performed on the original channel layout. ex: A stereo playback stream that is up-mixed to 5.1 has 2 a left an right volume control.

channelmix.disable = false: Disables the channel mixer completely. The stream will only be able to link to compatible sources/sinks with the exact same channel layout.

channelmix.min-volume = 0.0

channelmix.max-volume = 10.0: Gives the min and max volume values allowed. Any volume that is set will be clamped to these values.

channelmix.normalize = false

Makes sure that during such mixing & resampling original 0 dB level is preserved, so nothing sounds wildly quieter/louder.

While this options prevents clipping, it can in some cases produce too low volume. Increase the volume in that case or disable normalization.

channelmix.lock-volumes = false: Completely disable volume or mute changes. Defaults to false.

channelmix.mix-lfe = true: Mixes the low frequency effect channel into the front center or stereo pair. This might enhance the dynamic range of the signal if there is no subwoofer and the speakers can reproduce the low frequency signal.

channelmix.upmix = true

Enables up-mixing of the front center (FC) when the target has a FC channel. The sum of the stereo channels is used and an optional lowpass filter can be used (see channelmix.fc-cutoff).

Also enabled up-mixing of LFE when channelmix.lfe-cutoff is set to something else than 0 and the target has an LFE channel. The LFE channel is produced by adding the stereo channels.

If channelmix.upmix is true, the up-mixing of the rear channels is also enabled and controlled with the channelmix-upmix-method property.

channelmix.upmix-method = psd

3 methods are provided to produce the rear channels in a surround sound:

none. No rear channels are produced.
simple. Front channels are copied to the rear. This is fast but can produce phasing effects.
psd. The rear channels as produced from the front left and right ambient sound (the difference between the channels). A delay and optional phase shift are added to the rear signal to make the sound bigger.

channelmix.lfe-cutoff = 150: Apply a lowpass filter to the low frequency effects. The value is expressed in Hz. Typical subwoofers have a cutoff at around 150 and 200. The default value of 0 disables the feature.

channelmix.fc-cutoff = 12000

Apply a lowpass filter to the front center frequency. The value is expressed in Hz.

Since the front center contains the dialogs, a typical cutoff frequency is 12000 Hz.

This option is only active when the up-mix is enabled.

channelmix.rear-delay = 12.0

Apply a delay in milliseconds when up-mixing the rear channels. This improves specialization of the sound. A typical delay of 12 milliseconds is the default.

This is only active when the psd up-mix method is used.

channelmix.stereo-widen = 0.0

Subtracts some of the front center signal from the stereo channels. This moves the dialogs more to the center speaker and leaves the ambient sound in the stereo channels.

This is only active when up-mix is enabled and a Front Center channel is mixed.

channelmix.hilbert-taps = 0

This option will apply a 90 degree phase shift to the rear channels to improve specialization. Taps needs to be between 15 and 255 with more accurate results (and more CPU consumption) for higher values.

This is only active when the psd up-mix method is used.

dither.noise = 0

This option will add N bits of random data to the signal. When no dither.method is specified, the random data will flip between [-(1<<(N-1)), 0] every 1024 samples. With a dither.method, the dither noise is amplified with 1<<(N-1) bits.

This can be used to keep some amplifiers alive during silent periods. One or two bits of noise is usually enough, otherwise the noise will become audible. This is usually used together with session.suspend-timeout-seconds to disable suspend in the session manager.

Note that PipeWire uses floating point operations with 24 bits precission for all of the audio processing. Conversion to 24 bits integer sample formats is lossless and conversion to 32 bits integer sample formats are simply padded with 0 bits at the end. This means that the dither noise is always only in the 24 most significant bits.

dither.method = none

Optional dithering can be done on the quantized output signal.

There are 6 modes available:

none No dithering is done.
rectangular Dithering with a rectangular noise distribution. This adds random bits in the [-0.5, 0.5] range to the signal with even distribution.
triangular Dithering with a triangular noise distribution. This add random bits in the [-1.0, 1.0] range to the signal with triangular distribution around 0.0.
triangular-hf Dithering with a sloped triangular noise distribution.
wannamaker3 Additional noise shaping is performed on the sloped triangular dithering to move the noise to the more inaudible range. This is using the "F-Weighted" noise filter described by Wannamaker.
shaped5 Additional noise shaping is performed on the triangular dithering to move the noise to the more inaudible range. This is using the Lipshitz filter.

Dithering is only useful for conversion to a format with less than 24 bits and will be disabled otherwise.

Debug Parameters

debug.wav-path = "": Make the stream to also write the raw samples to a WAV file for debugging purposes.

Format Properties

Streams and also most device nodes can be configured in a certain format with properties.

audio.rate = RATE: Forces a samplerate on the node.

audio.channels = INTEGER: The number of audio channels to use. Must be a value between 1 and 64.

audio.format = FORMAT

Forces an audio format on the node. This is the format used internally in the node because the graph processing format is always float 32.

Valid formats include: S16, S32, F32, F64, S16LE, S16BE, ...

audio.allowed-rates: An array of allowed samplerates for the node. ex. "[ 44100 48000 ]"

STREAM RULES

You can add match rules, see pipewire(1) to set properties for certain streams and filters.

stream.rules and filter.rules provides an update-props action that takes an object with properties that are updated on the node object of the stream and filter.

Add a stream.rules or filter.rules section in the config file like this:

stream.rules = [
    {
        matches = [
            {
                # all keys must match the value. ! negates. ~ starts regex.
                application.process.binary = "firefox"
            }
        ]
        actions = {
            update-props = {
                node.name = "My Name"
            }
        }
    }
]

Will set the node.name of Firefox to "My Name".

ALSA PROPERTIES

An alsa.properties section can be added to configure ALSA specific client config.

alsa.properties = {
    #alsa.deny = false
    #alsa.format = 0
    #alsa.rate = 0
    #alsa.channels = 0
    #alsa.period-bytes = 0
    #alsa.buffer-bytes = 0
    #alsa.volume-method = cubic         # linear, cubic
}

alsa.deny: Denies ALSA access for the client. Useful in rules or PIPEWIRE_ALSA environment variable.

alsa.format: The ALSA format to use for the client. This is an ALSA format name. default 0, which is to allow all formats.

alsa.rate: The samplerate to use for the client. The default is 0, which is to allow all rates.

alsa.channels: The number of channels for the client. The default is 0, which is to allow any number of channels.

alsa.period-bytes: The number of bytes per period. The default is 0 which is to allow any number of period bytes.

alsa.buffer-bytes: The number of bytes in the alsa buffer. The default is 0, which is to allow any number of bytes.

alsa.volume-method = cubic | linear: This controls the volume curve used on the ALSA mixer. Possible values are cubic and linear. The default is to use cubic.

ALSA RULES

It is possible to set ALSA client specific properties by using Match rules, see pipewire(1). You can set any of the above ALSA properties or any of the stream.properties.

Example

alsa.rules = [
    {   matches = [ { application.process.binary = "resolve" } ]
        actions = {
            update-props = {
                alsa.buffer-bytes = 131072
            }
        }
    }
]

ENVIRONMENT VARIABLES

See pipewire(1) for common environment variables. Many of these also apply to client applications.

The environment variables also influence ALSA applications that are using PipeWire's ALSA plugin.

PIPEWIRE_ALSA

This can be an object with properties from alsa.properties or stream.properties that will be used to construct the client and streams.

For example:

PIPEWIRE_ALSA='{ alsa.buffer-bytes=16384 node.name=foo }' aplay ...

Starts aplay with custom properties.

PIPEWIRE_NODE

Instructs the ALSA client to link to a particular sink or source object.serial or node.name.