Modules

libpulse

List of the main objects defined by the libpulse module, excluding the LibPulse class and Ancillary classes:

• The constants that are defined by enums in the pulse headers and that are listed by pulse_enums.

• The following constants that are defined by the pulse headers as macros:

  • PA_INVALID_INDEX

  • PA_VOLUME_NORM

  • PA_VOLUME_MUTED

  • PA_VOLUME_MAX

  • PA_VOLUME_INVALID

  • PA_CHANNELS_MAX

• The ctypes foreign functions corresponding to (and having the same name as) the non-async pulse functions. That is, all the keys in the signatures dictionary of the pulse_functions module whose signature does not have a callback as one of its parameters.

• CTX_STATES, OPERATION_STATES, EVENT_FACILITIES and EVENT_TYPES dictionaries that map constant values to their symbolic names.

• struct_ctypes a dictionary mapping the name of each pulse structure defined by the pulse headers (see the pulse_structs module) to the corresponding subclass of the ctypes Structure class.

libpulse_ctypes

The libpulse_ctypes module is executed when its PulseCTypes class is instantiated by the mainloop module. This occurs when the libpulse module imports the mainloop module on startup.

The libpulse_ctypes module uses the pulse_types, pulse_structs and pulse_functions modules to build the following ctypes objects:

• The ctypes foreign functions corresponding to the pulse functions.

• The subclasses of the ctypes Structure class corresponding to the pulse structures.

The libpulse_ctypes module uses the pulse_enums module to set variables corresponding to the constants of the enums of the pulse library.

These four pulse_* modules are generated from the headers of the pulse library and may be re-generated using gcc and the pyclibrary package as explained in the Development section although this is not necessary, the ABI of the pulse library being pretty much stable. Using recent versions of Pulseaudio and Pipewire generates the same modules.

mainloop

The mainloop module implements the pulse Main Loop using the asyncio event loop.

The implementation supports multiple threads with one asyncio loop per thread using a dictionary to map the asyncio loop instance to the libpulse MainLoop instance.

pulse_enums

The pulse_enums dictionary holds all the pulse enum types whose values are themselves a dictionary of the enum constant names and their values. All constant names are different making it possible to have each defined as a constant in the libpulse module.

pulse_functions

The pulse_functions[‘signatures’] dictionary holds the signatures of all the pulse functions that are not callbacks. Async functions are those functions whose signature has a callback as one of its parameter, the callback signature being one of the values of the pulse_functions[‘callbacks’] dictionary.

The signatures are used to build ctypes Function prototypes that are instantiated to create the foreign functions to be used as the corresponding non-async functions, LibPulse coroutines or callbacks. Foreign functions are Python callables.

pulse_structs

The pulse_structs dictionary holds the definitions of the pulse structures used to build the ctypes Structure subclasses that are available in the struct_ctypes dictionary which is an attribute of the libpulse module.