volumeTest.py

import ctypes
import comtypes
from ctypes import wintypes

MMDeviceApiLib = comtypes.GUID(
    '{2FDAAFA3-7523-4F66-9957-9D5E7FE698F6}')
IID_IMMDevice = comtypes.GUID(
    '{D666063F-1587-4E43-81F1-B948E807363F}')
IID_IMMDeviceCollection = comtypes.GUID(
    '{0BD7A1BE-7A1A-44DB-8397-CC5392387B5E}')
IID_IMMDeviceEnumerator = comtypes.GUID(
    '{A95664D2-9614-4F35-A746-DE8DB63617E6}')
IID_IAudioEndpointVolume = comtypes.GUID(
    '{5CDF2C82-841E-4546-9722-0CF74078229A}')
CLSID_MMDeviceEnumerator = comtypes.GUID(
    '{BCDE0395-E52F-467C-8E3D-C4579291692E}')

# EDataFlow
eRender = 0 # audio rendering stream


# ERole
eMultimedia = 1 # music, movies, narration

LPCGUID = REFIID = ctypes.POINTER(comtypes.GUID)
LPFLOAT = ctypes.POINTER(ctypes.c_float)
LPDWORD = ctypes.POINTER(wintypes.DWORD)
LPUINT = ctypes.POINTER(wintypes.UINT)
LPBOOL = ctypes.POINTER(wintypes.BOOL)
PIUnknown = ctypes.POINTER(comtypes.IUnknown)

class IMMDevice(comtypes.IUnknown):
    _iid_ = IID_IMMDevice
    _methods_ = (
        comtypes.COMMETHOD([], ctypes.HRESULT, 'Activate',
            (['in'], REFIID, 'iid'),
            (['in'], wintypes.DWORD, 'dwClsCtx'),
            (['in'], LPDWORD, 'pActivationParams', None),
            (['out','retval'], ctypes.POINTER(PIUnknown), 'ppInterface')),
        comtypes.STDMETHOD(ctypes.HRESULT, 'OpenPropertyStore', []),
        comtypes.STDMETHOD(ctypes.HRESULT, 'GetId', []),
        comtypes.STDMETHOD(ctypes.HRESULT, 'GetState', []))

PIMMDevice = ctypes.POINTER(IMMDevice)

class IMMDeviceCollection(comtypes.IUnknown):
    _iid_ = IID_IMMDeviceCollection

PIMMDeviceCollection = ctypes.POINTER(IMMDeviceCollection)

class IMMDeviceEnumerator(comtypes.IUnknown):
    _iid_ = IID_IMMDeviceEnumerator
    _methods_ = (
        comtypes.COMMETHOD([], ctypes.HRESULT, 'EnumAudioEndpoints',
            (['in'], wintypes.DWORD, 'dataFlow'),
            (['in'], wintypes.DWORD, 'dwStateMask'),
            (['out','retval'], ctypes.POINTER(PIMMDeviceCollection),
             'ppDevices')),
        comtypes.COMMETHOD([], ctypes.HRESULT, 'GetDefaultAudioEndpoint',
            (['in'], wintypes.DWORD, 'dataFlow'),
            (['in'], wintypes.DWORD, 'role'),
            (['out','retval'], ctypes.POINTER(PIMMDevice), 'ppDevices')))
    @classmethod
    def get_default(cls, dataFlow, role):
        enumerator = comtypes.CoCreateInstance(
            CLSID_MMDeviceEnumerator, cls, comtypes.CLSCTX_INPROC_SERVER)
        return enumerator.GetDefaultAudioEndpoint(dataFlow, role)

class IAudioEndpointVolume(comtypes.IUnknown):
    _iid_ = IID_IAudioEndpointVolume
    _methods_ = (
        comtypes.COMMETHOD([], ctypes.HRESULT, 'SetMasterVolumeLevel',
            (['in'], ctypes.c_float, 'fLevelDB'),
            (['in'], LPCGUID, 'pguidEventContext', None)),
        comtypes.COMMETHOD([], ctypes.HRESULT, 'SetMasterVolumeLevelScalar',
            (['in'], ctypes.c_float, 'fLevel'),
            (['in'], LPCGUID, 'pguidEventContext', None)),
        comtypes.COMMETHOD([], ctypes.HRESULT, 'GetMasterVolumeLevel',
            (['out','retval'], LPFLOAT, 'pfLevelDB')),
        comtypes.COMMETHOD([], ctypes.HRESULT, 'GetMasterVolumeLevelScalar',
            (['out','retval'], LPFLOAT, 'pfLevel')),
        comtypes.COMMETHOD([], ctypes.HRESULT, 'SetChannelVolumeLevelScalar',
            (['in'], wintypes.UINT, 'nChannel'),
            (['in'], ctypes.c_float, 'fLevel'),
            (['in'], LPCGUID, 'pguidEventContext', None)),
        comtypes.COMMETHOD([], ctypes.HRESULT, 'SetMute',
            (['in'], wintypes.BOOL, 'bMute'),
            (['in'], LPCGUID, 'pguidEventContext', None)),
        comtypes.COMMETHOD([], ctypes.HRESULT, 'GetMute',
            (['out','retval'], LPBOOL, 'pbMute')),
        comtypes.COMMETHOD([], ctypes.HRESULT, 'GetVolumeStepInfo',
            (['out','retval'], LPUINT, 'pnStep'),
            (['out','retval'], LPUINT, 'pnStepCount')),
        comtypes.COMMETHOD([], ctypes.HRESULT, 'VolumeStepUp',
            (['in'], LPCGUID, 'pguidEventContext', None)),
        comtypes.COMMETHOD([], ctypes.HRESULT, 'VolumeStepDown',
            (['in'], LPCGUID, 'pguidEventContext', None)))
    @classmethod
    def get_default(cls):
        endpoint = IMMDeviceEnumerator.get_default(eRender, eMultimedia)
        interface = endpoint.Activate(cls._iid_, comtypes.CLSCTX_INPROC_SERVER)
        return ctypes.cast(interface, ctypes.POINTER(cls))


if __name__ == '__main__':

    def show_vol(ev):
        voldb = ev.GetMasterVolumeLevel()
        volsc = ev.GetMasterVolumeLevelScalar()
        volst, nstep = ev.GetVolumeStepInfo()
        print('Master Volume (dB): %0.4f' % voldb)
        print('Master Volume (scalar): %0.4f' % volsc)
        print('Master Volume (step): %d / %d' % (volst, nstep))





    def test():
        ev = IAudioEndpointVolume.get_default()
        vol = ev.GetMasterVolumeLevelScalar()
        vmin, vmax, vinc = ev.GetVolumeRange()
        print('Volume Range (min, max, step) (dB): '
              '%0.4f, %0.4f, %0.4f' % (vmin, vmax, vinc))
        show_vol(ev)
        try:
            print('\nIncrement the master volume')
            ev.VolumeStepUp()
            show_vol(ev)
            print('\nDecrement the master volume twice')
            ev.VolumeStepDown()
            ev.VolumeStepDown()
            show_vol(ev)
            print('\nSet the master volume to 0.75 scalar')
            ev.SetMasterVolumeLevelScalar(0.75)
            show_vol(ev)
            print('\nSet the master volume to 0.25 scalar')
            ev.SetMasterVolumeLevelScalar(0.25)
            show_vol(ev)
        finally:
            ev.SetMasterVolumeLevelScalar(vol)

    comtypes.CoInitialize()
    try:
        test()
    finally:
        comtypes.CoUninitialize()