Package: pulsectl
Python (3.x and 2.x) blocking high-level interface and ctypes-based bindings
forPulseAudio(libpulse), to use in a simple synchronous code.Wrappers are mostly for mixer-like controls and introspection-related operations,
as opposed to e.g. submitting sound samples to play and player-like client.For async version to use withasyncio, seepulsectl-asyncioproject instead.Originally forked frompulsemixerproject, which had this code bundled.ContentsUsageNotesThings not yet wrapped/exposed in pythonVolumeString valuesEnumerated/named values (enums)Event-handling code, threadsTestsChangelog and versioning schemeInstallationLinksRepository URLs:https://github.com/mk-fg/python-pulse-controlhttps://codeberg.org/mk-fg/python-pulse-controlhttps://fraggod.net/code/git/python-pulse-controlUsageSimple example:import pulsectl

with pulsectl.Pulse('volume-increaser') as pulse:
  for sink in pulse.sink_list():
    # Volume is usually in 0-1.0 range, with >1.0 being soft-boosted
    pulse.volume_change_all_chans(sink, 0.1)Listening for server state change events:import pulsectl

with pulsectl.Pulse('event-printer') as pulse:
  # print('Event types:', pulsectl.PulseEventTypeEnum)
  # print('Event facilities:', pulsectl.PulseEventFacilityEnum)
  # print('Event masks:', pulsectl.PulseEventMaskEnum)

  def print_events(ev):
    print('Pulse event:', ev)
    ### Raise PulseLoopStop for event_listen() to return before timeout (if any)
    # raise pulsectl.PulseLoopStop

  pulse.event_mask_set('all')
  pulse.event_callback_set(print_events)
  pulse.event_listen(timeout=10)Misc other tinkering:>>> import pulsectl
>>> pulse = pulsectl.Pulse('my-client-name')

>>> pulse.sink_list()
[<PulseSinkInfo at 7f85cfd053d0 - desc='Built-in Audio', index=0L, mute=0, name='alsa-speakers', channels=2, volumes='44.0%, 44.0%'>]

>>> pulse.sink_input_list()
[<PulseSinkInputInfo at 7fa06562d3d0 - index=181L, mute=0, name='mpv Media Player', channels=2, volumes='25.0%, 25.0%'>]

>>> pulse.sink_input_list()[0].proplist
{'application.icon_name': 'mpv',
 'application.language': 'C',
 'application.name': 'mpv Media Player',
 ...
 'native-protocol.version': '30',
 'window.x11.display': ':1.0'}

>>> pulse.source_list()
[<PulseSourceInfo at 7fcb0615d8d0 - desc='Monitor of Built-in Audio', index=0L, mute=0, name='alsa-speakers.monitor', channels=2, volumes='100.0%, 100.0%'>,
 <PulseSourceInfo at 7fcb0615da10 - desc='Built-in Audio', index=1L, mute=0, name='alsa-mic', channels=2, volumes='100.0%, 100.0%'>]

>>> sink = pulse.sink_list()[0]
>>> pulse.volume_change_all_chans(sink, -0.1)
>>> pulse.volume_set_all_chans(sink, 0.5)

>>> pulse.server_info().default_sink_name
'alsa_output.pci-0000_00_14.2.analog-stereo'
>>> pulse.default_set(sink)

>>> card = pulse.card_list()[0]
>>> card.profile_list
[<PulseCardProfileInfo at 7f02e7e88ac8 - description='Analog Stereo Input', n_sinks=0, n_sources=1, name='input:analog-stereo', priority=60>,
 <PulseCardProfileInfo at 7f02e7e88b70 - description='Analog Stereo Output', n_sinks=1, n_sources=0, name='output:analog-stereo', priority=6000>,
 ...
 <PulseCardProfileInfo at 7f02e7e9a4e0 - description='Off', n_sinks=0, n_sources=0, name='off', priority=0>]
>>> pulse.card_profile_set(card, 'output:hdmi-stereo')

>>> help(pulse)
...

>>> pulse.close()Current code logic is that all methods are invoked through the Pulse instance,
and everything returned from these are “Pulse-Something-Info” objects - thin
wrappers around C structs that describe the thing, without any methods attached.Aside from a few added convenience methods, most of them should have similar
signature and do same thing as their C libpulse API counterparts, so seepulseaudio doxygen documentationfor more information on them.Pulse client can be integrated into existing eventloop (e.g. asyncio, twisted,
etc) usingPulse.set_poll_func()orPulse.event_listen()in a separate
thread.Somewhat extended usage example can be found inpulseaudio-mixer-cliproject
code, as well as tests here.NotesSome less obvious things are described in this section.Things not yet wrapped/exposed in pythonThere are plenty of information, methods and other things in libpulse not yet
wrapped/exposed by this module, as they weren’t needed (yet) for author/devs
use-case(s).Making them accessible from python code can be as simple as adding an attribute
name to the “c_struct_fields” value in PulseSomethingInfo objects.Seegithub #3for a more concrete example of finding/adding such stuff.For info and commands that are not available through libpulse introspection API,
it is possible to usepulsectl.connect_to_cli()fallback function, which
will open unix socket to server’s “module-cli” (signaling to load it, if
necessary), which can be used in exactly same way as “pacmd” tool (not to be
confused with “pactl”, which uses native protocol instead of module-cli) or
pulseaudio startup files (e.g. “default.pa”).Probably a bad idea to parse string output from commands there though, as these
are not only subject to change, but can also vary depending on system locale.VolumeIn PulseAudio, “volume” for anything is not a flat number, but essentially a
list of numbers, one per channel (as in “left”, “right”, “front”, “rear”, etc),
which should correspond to channel map of the object it relates/is-applied to.In this module, such lists are represented by PulseVolumeInfo objects.I.e.sink.volumeis a PulseVolumeInfo instance, and all thin/simple wrappers
that accept index of the object, expect such instance to be passed, e.g.pulse.sink_input_volume_set(sink.index, sink.volume).There are conveniencevolume_get_all_chans,volume_set_all_chansandvolume_change_all_chansmethods to get/set/adjust volume as/by a single
numeric value, which is also accessible on PulseVolumeInfo objects as avalue_flatproperty.PulseVolumeInfo can be constructed from a numeric volume value plus number of
channels, or a python list of per-channel numbers.All per-channel volume values in PulseVolumeInfo (and flat values in the wrapper
funcs above), are float objects in 0-65536 range, with following meanings:0.0 volume is “no sound” (corresponds to PA_VOLUME_MUTED).1.0 value is “current sink volume level”, 100% or PA_VOLUME_NORM.>1.0 and up to 65536.0 (PA_VOLUME_MAX / PA_VOLUME_NORM) - software-boosted
sound volume (higher values will negatively affect sound quality).Probably a good idea to set volume only in 0-1.0 range and boost volume in
hardware without quality loss, e.g. by tweaking sink volume (which corresponds
to ALSA/hardware volume), if that option is available.Note thatflat-volumes=yesoption (“yes” by default on some distros, “no” in
e.g. Arch Linux) in pulseaudio daemon.conf already scales device-volume with the
volume of the “loudest” application, so already does what’s suggested above.Fractional volume values used in the module get translated (in a linear fashion)
to/from pa_volume_t integers for libpulse. Seesrc/pulse/volume.hin
pulseaudio sources for all the gory details on the latter (e.g. how it relates
to sound level in dB).Code example:from pulsectl import Pulse, PulseVolumeInfo

with Pulse('volume-example') as pulse:
  sink_input = pulse.sink_input_list()[0] # first random sink-input stream

  volume = sink_input.volume
  print(volume.values) # list of per-channel values (floats)
  print(volume.value_flat) # average level across channels (float)

  time.sleep(1)

  volume.value_flat = 0.3 # sets all volume.values to 0.3
  pulse.volume_set(sink_input, volume) # applies the change

  time.sleep(1)

  n_channels = len(volume.values)
  new_volume = PulseVolumeInfo(0.5, n_channels) # 0.5 across all n_channels
  # new_volume = PulseVolumeInfo([0.15, 0.25]) # from a list of channel levels (stereo)
  pulse.volume_set(sink_input, new_volume)
  # pulse.sink_input_volume_set(sink_input.index, new_volume) # same as aboveIn most common cases, doing something likepulse.volume_set_all_chans(sink_input, 0.2)should do the trick though -
no need to bother with specific channels in PulseVolumeInfo there.String valueslibpulse explicitly returns utf-8-encoded string values, which are always
decoded to “abstract string” type in both python-2 (where it’s called “unicode”)
and python-3 (“str”), for consistency.It might be wise to avoid mixing these with encoded strings (“bytes”) in the code,
especially in python-2, where “bytes” is often used as a default string type.Enumerated/named values (enums)In place of C integers that correspond to some enum or constant (e.g. -1 for
PA_SINK_INVALID_STATE), module returns EnumValue objects, which are comparable
to strings (“str” type in py2/py3).For example:>>> pulsectl.PulseEventTypeEnum.change == 'change'
True
>>> pulsectl.PulseEventTypeEnum.change
<EnumValue event-type=change>
>>> pulsectl.PulseEventTypeEnum
<Enum event-type [change new remove]>It might be preferrable to use enums instead of strings in the code so that
interpreter can signal error on any typos or unknown values specified, as
opposed to always silently failing checks with bogus strings.Event-handling code, threadslibpulse clients always work as an event loop, though this module kinda hides
it, presenting a more old-style blocking interface.So what happens on any call (e.g.pulse.mute(...)) is:Make a call to libpulse, specifying callback for when operation will be completed.Run libpulse event loop until that callback gets called.Return result passed to that callback call, if any (for various “get” methods).event_callback_set()andevent_listen()calls essentally do raw first
and second step here.Which means that any pulse calls from callback function can’t be used whenevent_listen()(or any other pulse call through this module, for that matter)
waits for return value and runs libpulse loop already.One can raise PulseLoopStop exception there to makeevent_listen()return,
run whatever pulse calls after that, then re-start theevent_listen()thing.This will not miss any events, as all blocking calls do same thing asevent_listen()does (second step above), and can cause callable passed toevent_callback_set()to be called (when loop is running).Also, same instance of libpulse eventloop can’t be run from different threads,
naturally, so if threads are used, client can be initialized withthreading_lock=Trueoption (can also accept lock instance instead of True)
to create a mutex around step-2 (run event loop) from the list above, so
multiple threads won’t do it at the same time.For proper python eventloop integration (think twisted or asyncio),
usepulsectl-asynciomodule instead.There are also some tricks mentioned ingithub #11to shoehorn this
module into async apps, but even with non-asyncio eventloop, starting from
pulsectl-asyncio would probably be much easier.TestsTest code is packaged/installed with the module and can be useful to run when
changing module code, or to check if current python, module and pulseudio
versions all work fine together.Commands to run tests from either checkout directory or installed module:% python2 -m unittest discover
% python3 -m unittest discoverNote that if “pulsectl” module is available both in current directory
(e.g. checkout dir) and user/system python module path, former should always
take priority for commands above.Add e.g.-ktest_stream_movefor commands above to match and run specific
test(s), and when isolating specific failure, it might also be useful to run
with PA_DEBUG=1 env-var to get full verbose pulseaudio log, for example:% PA_DEBUG=1 python -m unittest discover -k test_module_funcsTest suite runs ad-hoc isolated pulseaudio instance with null-sinks (not
touching hardware), custom (non-default) startup script and environment,
and interacts only with that instance, terminating it afterwards.
Still uses system/user daemon.conf files though, so these can affect the tests.Any test failures can indicate incompatibilities, bugs in the module code,
issues with pulseaudio (or its daemon.conf) and underlying dependencies.
There are no “expected” test case failures.All tests can run for up to 10 seconds currently (v19.9.6), due to some
involving playback (using paplay from /dev/urandom) being time-sensitive.Changelog and versioning schemeThis package uses one-version-per-commit scheme (updated by pre-commit hook)
and pretty much one release per git commit, unless more immediate follow-up
commits are planned or too lazy to runpy setup.py sdist bdist_wheel uploadfor some trivial README typo fix.Version scheme:{year}.{month}.{git-commit-count-this-month}I.e. “16.9.10” is “11th commit on Sep 2016”.There is aCHANGES.rstfile with the list of any intentional
breaking changes (should be exceptionally rare, if any) and new/added
non-trivial functionality.It can be a bit out of date though, as one has to remember to update it manually.“Last synced/updated:” line there might give a hint as to by how much.InstallationIt’s a regular package for Python (3.x or 2.x).If a package is available for your distribution,
using your package manager is the recommended way to install it.Otherwise, usingpipis the best way:% pip install pulsectl(add –user option to install into $HOME for current user only)Be sure to use python3/python2, pip3/pip2, easy_install-… commands
based on which python version you want to install the module for,
if you are still using python2 (and likely have python3 on the system as well).If you don’t have “pip” command:% python -m ensurepip
% python -m pip install --upgrade pip
% python -m pip install pulsectl(same suggestion wrt “install –user” as above)On a very old systems, one of these might work:% curl https://bootstrap.pypa.io/get-pip.py | python
% pip install pulsectl

% easy_install pulsectl

% git clone --depth=1 https://github.com/mk-fg/python-pulse-control
% cd python-pulse-control
% python setup.py install(all of install-commands here also have –user option)Current-git version can be installed like this:% pip install 'git+https://github.com/mk-fg/python-pulse-control#egg=pulsectl'Note that to install stuff to system-wide PATH and site-packages
(without –user), elevated privileges (i.e. root and su/sudo) are often required.Use “…install –user”,~/.pydistutils.cfgorvirtualenvto do unprivileged installs into custom paths.More info on python packaging can be found atpackaging.python.org.Linkspulsemixer- initial source for this project (embedded in the tool).pulsectl-asyncio- similar libpulse wrapper to this one, but for async python code.libpulseaudio-
different libpulse bindings module, more low-level, auto-generated from
pulseaudio header files.Branches there have bindings for different (newer) pulseaudio versions.pypulseaudio-
high-level bindings module, rather similar to this one.pulseaudio-mixer-cli- alsamixer-like script built on top of this module.