DESCRIPTION¶
pw-cat is a simple tool for playing back or capturing raw
or encoded media files on a PipeWire server. It understands all audio file
formats supported by libsndfile for PCM capture and playback. When no
container is specified for capturing PCM, the filename extension is used to
guess the file format with the WAV file format as the default.
It understands standard MIDI files and MIDI 2.0 clip files for
playback and recording. This tool will not render MIDI files, it will simply
make the MIDI events available to the graph. You need a MIDI renderer such
as qsynth, timidity or a hardware MIDI renderer to hear the MIDI.
DSD playback is supported with the DSF file format. This tool will
only work with native DSD capable hardware and will produce an error when no
such hardware was found.
When the FILE is - input will be from STDIN. If no format
is specified, libsndfile will attempt to parse and stream the format from
STDIN. For some formats, this is not possible and libsndfile will give an
error. Raw, MIDI and DSD formats are all streamable from STDIN.
When the FILE is - output will be to STDOUT. If no format
is specified, libsndfile is instructed to output the .au format, which is
streamble and preserves the format, rate and channels. Raw and DSD formats
are all streamable to STDOUT.
OPTIONS¶
-h | --help
Show help.
--version
Show version information.
-v | --verbose
Verbose operation.
-R | --remote=NAME
The name the remote instance to connect to. If
left unspecified, a connection is made to the default PipeWire instance.
-p | --playback
Playback mode. Read data from the specified file, and
play it back. If the tool is called under the name pw-play,
pw-midiplay or pw-midi2play this is the default.
-r | --record
Recording mode. Capture data and write it to the
specified file. If the tool is called under the name pw-record,
pw-midirecord or pw-midi2record this is the default.
-m | --midi
MIDI mode. FILE is a MIDI file. If the tool is
called under the name pw-midiplay or pw-midirecord this is the
default. Note that this program will not render the MIDI events into
audible samples, it will simply provide the MIDI events in the graph. You need
a separate MIDI renderer such as qsynth, timidity or a hardware renderer to
hear the MIDI.
-c | --midi-clip
MIDI 2.0 clip mode. FILE is a MIDI 2.0 clip file.
If the tool is called under the name pw-midi2play or
pw-midi2record this is the default. Note that this program will
not render the MIDI events into audible samples, it will simply provide
the MIDI events in the graph. You need a separate MIDI renderer such as
qsynth, timidity or a hardware renderer to hear the MIDI.
-d | --dsd
DSD mode. FILE is a DSF file. If the tool is
called under the name pw-dsdplay this is the default. Note that this
program will not render the DSD audio. You need a DSD capable device to
play DSD content or this program will exit with an error.
-s | --sysex
SysEx mode. FILE is a File that contains a raw
SysEx MIDI message. If the tool is called under the name pw-sysex this
is the default. The File is read and sent as a MIDI control message into the
graph.
--media-type=VALUE
Set the media type property (default Audio/Midi depending
on mode). The media type is used by the session manager to select a suitable
target to link to.
--media-category=VALUE
Set the media category property (default Playback/Capture
depending on mode). The media type is used by the session manager to select a
suitable target to link to.
--media-role=VALUE
Set the media role property (default Music). The media
type is used by the session manager to select a suitable target to link
to.
--target=VALUE
Set a node target (default auto). The value can be:
- auto: Automatically select (Default)
- 0: Don't try to link this node
- <id>: The object.serial or the node.name of a target
node
--latency=VALUE[units]
Set the node latency (default 100ms)
The latency determines the minimum amount of time it takes for a
sample to travel from application to device (playback) and from device to
application (capture).
The latency determines the size of the buffers that the
application will be able to fill. Lower latency means smaller buffers but
higher overhead. Higher latency means larger buffers and lower overhead.
Units can be s for seconds, ms for milliseconds,
us for microseconds, ns for nanoseconds. If no units are
given, the latency value is samples with the samplerate of the file.
-P | --properties=VALUE
Set extra stream properties as a JSON object.
-q | --quality=VALUE
Resampler quality. When the samplerate of the source or
destination file does not match the samplerate of the server, the data will be
resampled. Higher quality uses more CPU. Values between 0 and 15 are allowed,
the default quality is 4.
-a | --raw
Raw samples will be read or written. The --rate,
--format, --channels and --channelmap can be used to specify the raw
format.
-M | --force-midi
Force midi format, one of "midi" or
"ump", (default ump). When reading or writing midi, for one of midi
or UMP.
-n | --sample-count=COUNT
Stop after COUNT samples.
--rate=VALUE
The sample rate, default 48000.
--channels=VALUE
The number of channels, default 2.
--channel-map=VALUE
The channelmap. Possible values include are either a
channel layout such as mono, stereo, surround-21,
quad, surround-22, surround-40, or comma separated array
of channel names such as FL,FR. See --list-layouts and
--list-channel-names to get a complete list of possible values.
--list-layouts
List all known channel layouts. One of these can be used
as the --channel-map value.
--list-channel-names
List all known channel names. An array of these can be
used as the --channel-map value.
--format=VALUE
The sample format to use. Some possible values include:
u8, s8, s16 (default), s24, s32,
f32, f64. See --list-formats to get a complete list of
values.
--list-formats
List all known format values.
--container=VALUE
Specify the container to use when saving. This is usually
guessed from the filename extension but can be specified explicitly. When
using STDOUT and no container is specified, the AU container will be used.
Then using a filename and the container was not specified and it could not be
derived from the filename, the WAV container is used.
--list-containers
List all known container values.
--volume=VALUE
The stream volume, default 1.000. Depending on the locale
you have configured, "," or "." may be used as a decimal
separator. Check with locale command.
