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# PipeWire

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[PipeWire](https://pipewire.org) is a server and user space API to
deal with multimedia pipelines. This includes:
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  - Making available sources of video (such as from a capture devices or
    application provided streams) and multiplexing this with
    clients.
  - Accessing sources of video for consumption.
  - Generating graphs for audio and video processing.

Nodes in the graph can be implemented as separate processes,
communicating with sockets and exchanging multimedia content using fd
passing.

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## Building and installation
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The preferred way to install PipeWire is to install it with your
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distribution package system. This ensures PipeWire is integrated
into the rest of your system for the best experience.

If you want to build and install PipeWire yourself, refer to
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[install](INSTALL.md) for instructions.
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## Usage

The most important purpose of PipeWire is to run your favorite apps.

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Some applications use the native PipeWire API, such as most compositors
(gnome-shell, wayland, ...) to implement screen sharing. These apps will
just work automatically.
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Most audio applications can use either ALSA, JACK or PulseAudio as a
backend. PipeWire provides support for all 3 backends. Depending on how
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your distribution has configured things this should just work automatically
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or with the provided scripts shown below.

PipeWire can use environment variables to control the behaviour of
applications:

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* `PIPEWIRE_DEBUG=<level>`         to increase the debug level (or use one of
                                   `XEWIDT` for none, error, warnings, info,
                                   debug, or trace, respectively).
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* `PIPEWIRE_LOG=<filename>`        to redirect log to filename
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* `PIPEWIRE_LOG_SYSTEMD=false`     to disable logging to systemd journal
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* `PIPEWIRE_LATENCY=<num/denom>`   to configure latency as a fraction. 10/1000
                                   configures a 10ms latency. Usually this is
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				   expressed as a fraction of the samplerate,
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				   like 256/48000, which uses 256 samples at a
				   samplerate of 48KHz for a latency of 5.33ms.
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				   This function does not attempt to configure
				   the samplerate.
* `PIPEWIRE_RATE=<num/denom>`      to configure a rate for the graph.
* `PIPEWIRE_QUANTUM=<num/denom>`   to configure latency as a fraction and a
				   samplerate. This function will attempt to change
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				   the graph samplerate to `denom` and use the
				   specified `num` as the buffer size.
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* `PIPEWIRE_NODE=<id>`             to request a link to the specified node. The
                    id can be a node.name or object.serial of the target node.
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### Using tools

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`pw-cat` can be used to play and record audio and midi. Use `pw-cat -h` to get
some more help. There are some aliases like `pw-play` and `pw-record` to make
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things easier:
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```
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$ pw-play /home/wim/data/01.\ Firepower.wav
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```

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### Running JACK applications
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Depending on how the system was configured, you can either run PipeWire and
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JACK side-by-side or have PipeWire take over the functionality of JACK
completely.

In dual mode, JACK apps will by default use the JACK server. To direct a JACK
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app to PipeWire, you can use the `pw-jack` script like this:
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```
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$ pw-jack <appname>
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```

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If you replaced JACK with PipeWire completely, `pw-jack` does not have any
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effect and can be omitted.
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JACK applications will automatically use the buffer-size chosen by the
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server. You can force a maximum buffer size (latency) by setting the
`PIPEWIRE_LATENCY` environment variable like so:

```
PIPEWIRE_LATENCY=128/48000 jack_simple_client
```
Requests the `jack_simple_client` to run with a buffer of 128 or
less samples.


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### Running PulseAudio applications
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PipeWire can run a PulseAudio compatible replacement server. You can't
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use both servers at the same time. Usually your package manager will
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make the server conflict so that you can only install one or the
other.

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PulseAudio applications still use the regular PulseAudio client
libraries and you don't need to do anything else than change the
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server implementation.
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A successful swap of the server can be verified by checking the
output of
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```
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pactl info
```
It should include the string:
```
...
Server Name: PulseAudio (on PipeWire 0.3.x)
...
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```

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You can use pavucontrol to change profiles and ports, change volumes
or redirect streams, just like with PulseAudio.


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### Running ALSA applications

If the PipeWire alsa module is installed, it can be seen with
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```
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$ aplay -L
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```
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ALSA applications can then use the `pipewire:` device to use PipeWire
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as the audio system.

### Running GStreamer applications

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PipeWire includes 2 GStreamer elements called `pipewiresrc` and
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`pipewiresink`. They can be used in pipelines such as this:
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```
$ gst-launch-1.0 pipewiresrc ! videoconvert ! autovideosink
```

Or to play a beeping sound:

```
$ gst-launch-1.0 audiotestsrc ! pipewiresink
```

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PipeWire provides a device monitor as well so that
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```
$ gst-device-monitor-1.0
```

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shows the PipeWire devices and applications like cheese will
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automatically use the PipeWire video source when possible.

### Inspecting the PipeWire state

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To inspect and manipulate the PipeWire graph via GUI, you can use [Helvum](https://gitlab.freedesktop.org/ryuukyu/helvum).

Alternatively, you can use use one of the excellent JACK tools, such as `Carla`,
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`catia`, `qjackctl`, ...
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However, you will not be able to see all features like the video
ports.
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`pw-mon` dumps and monitors the state of the PipeWire daemon.
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`pw-dot` can dump a graph of the pipeline, check out the help for
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how to do this.

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`pw-top` monitors the real-time status of the graph. This is handy to
find out what clients are running and how much DSP resources they
use.

`pw-dump` dumps the state of the PipeWire daemon in JSON format. This
can be used to find out the properties and parameters of the objects
in the PipeWire daemon.

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There is a more complicated tool to inspect the state of the server
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with `pw-cli`. This tool can be used interactively or it can execute
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single commands like this to get the server information:

```
$ pw-cli info 0
```

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## Documentation

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Find tutorials and design documentation [here](doc/index.dox).
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The (incomplete) autogenerated API docs are [here](https://docs.pipewire.org).
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The Wiki can be found [here](https://gitlab.freedesktop.org/pipewire/pipewire/-/wikis/home)

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## Contributing

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PipeWire is Free Software and is developed in the open. It is mostly
licensed under the [MIT license](COPYING). Check [LICENSE](LICENSE) for
more details about the exceptions.
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Contributors are encouraged to submit merge requests or file bugs on
[gitlab](https://gitlab.freedesktop.org/pipewire).
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Join us on IRC at #pipewire on [OFTC](https://www.oftc.net/).
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We adhere to the Contributor Covenant for our [code of conduct](CODE_OF_CONDUCT.md).
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[Donate using Liberapay](https://liberapay.com/PipeWire/donate).
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## Getting help

You can ask for help on the IRC channel (see above).  You can also ask
questions by [raising](https://gitlab.freedesktop.org/pipewire/pipewire/-/issues/new)
a gitlab issue.