windows_get_volume.py

from ctypes import *
from struct import *
winmm = windll.winmm
vol = c_ulong()
print('res', winmm.waveOutGetVolume(0, byref(vol)))
print('left:', vol.value & 0xffff, 'right:',vol.value >> 16)

windows_get_volume2.py

import win32com
from comtypes import *
import comtypes.client
from ctypes import POINTER
from ctypes.wintypes import DWORD, BOOL

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

class IMMDeviceCollection(IUnknown):
    _iid_ = GUID('{0BD7A1BE-7A1A-44DB-8397-CC5392387B5E}')
    pass

class IAudioEndpointVolume(IUnknown):
    _iid_ = GUID('{5CDF2C82-841E-4546-9722-0CF74078229A}')
    _methods_ = [
        STDMETHOD(HRESULT, 'RegisterControlChangeNotify', []),
        STDMETHOD(HRESULT, 'UnregisterControlChangeNotify', []),
        STDMETHOD(HRESULT, 'GetChannelCount', []),
        COMMETHOD([], HRESULT, 'SetMasterVolumeLevel',
            (['in'], c_float, 'fLevelDB'),
            (['in'], POINTER(GUID), 'pguidEventContext')
        ),
        COMMETHOD([], HRESULT, 'SetMasterVolumeLevelScalar',
            (['in'], c_float, 'fLevelDB'),
            (['in'], POINTER(GUID), 'pguidEventContext')
        ),
        COMMETHOD([], HRESULT, 'GetMasterVolumeLevel',
            (['out','retval'], POINTER(c_float), 'pfLevelDB')
        ),
        COMMETHOD([], HRESULT, 'GetMasterVolumeLevelScalar',
            (['out','retval'], POINTER(c_float), 'pfLevelDB')
        ),
        COMMETHOD([], HRESULT, 'SetChannelVolumeLevel',
            (['in'], DWORD, 'nChannel'),
            (['in'], c_float, 'fLevelDB'),
            (['in'], POINTER(GUID), 'pguidEventContext')
        ),
        COMMETHOD([], HRESULT, 'SetChannelVolumeLevelScalar',
            (['in'], DWORD, 'nChannel'),
            (['in'], c_float, 'fLevelDB'),
            (['in'], POINTER(GUID), 'pguidEventContext')
        ),
        COMMETHOD([], HRESULT, 'GetChannelVolumeLevel',
            (['in'], DWORD, 'nChannel'),
            (['out','retval'], POINTER(c_float), 'pfLevelDB')
        ),
        COMMETHOD([], HRESULT, 'GetChannelVolumeLevelScalar',
            (['in'], DWORD, 'nChannel'),
            (['out','retval'], POINTER(c_float), 'pfLevelDB')
        ),
        COMMETHOD([], HRESULT, 'SetMute',
            (['in'], BOOL, 'bMute'),
            (['in'], POINTER(GUID), 'pguidEventContext')
        ),
        COMMETHOD([], HRESULT, 'GetMute',
            (['out','retval'], POINTER(BOOL), 'pbMute')
        ),
        COMMETHOD([], HRESULT, 'GetVolumeStepInfo',
            (['out','retval'], POINTER(c_float), 'pnStep'),
            (['out','retval'], POINTER(c_float), 'pnStepCount'),
        ),
        COMMETHOD([], HRESULT, 'VolumeStepUp',
            (['in'], POINTER(GUID), 'pguidEventContext')
        ),
        COMMETHOD([], HRESULT, 'VolumeStepDown',
            (['in'], POINTER(GUID), 'pguidEventContext')
        ),
        COMMETHOD([], HRESULT, 'QueryHardwareSupport',
            (['out','retval'], POINTER(DWORD), 'pdwHardwareSupportMask')
        ),
        COMMETHOD([], HRESULT, 'GetVolumeRange',
            (['out','retval'], POINTER(c_float), 'pfMin'),
            (['out','retval'], POINTER(c_float), 'pfMax'),
            (['out','retval'], POINTER(c_float), 'pfIncr')
        ),

    ]

class IMMDevice(IUnknown):
    _iid_ = GUID('{D666063F-1587-4E43-81F1-B948E807363F}')
    _methods_ = [
        COMMETHOD([], HRESULT, 'Activate',
            (['in'], POINTER(GUID), 'iid'),
            (['in'], DWORD, 'dwClsCtx'),
            (['in'], POINTER(DWORD), 'pActivationParans'),
            (['out','retval'], POINTER(POINTER(IAudioEndpointVolume)), 'ppInterface')
        ),
        STDMETHOD(HRESULT, 'OpenPropertyStore', []),
        STDMETHOD(HRESULT, 'GetId', []),
        STDMETHOD(HRESULT, 'GetState', [])
    ]
    pass

class IMMDeviceEnumerator(comtypes.IUnknown):
    _iid_ = GUID('{A95664D2-9614-4F35-A746-DE8DB63617E6}')

    _methods_ = [
        COMMETHOD([], HRESULT, 'EnumAudioEndpoints',
            (['in'], DWORD, 'dataFlow'),
            (['in'], DWORD, 'dwStateMask'),
            (['out','retval'], POINTER(POINTER(IMMDeviceCollection)), 'ppDevices')
        ),
        COMMETHOD([], HRESULT, 'GetDefaultAudioEndpoint',
            (['in'], DWORD, 'dataFlow'),
            (['in'], DWORD, 'role'),
            (['out','retval'], POINTER(POINTER(IMMDevice)), 'ppDevices')
        )
    ]

enumerator = comtypes.CoCreateInstance( 
    CLSID_MMDeviceEnumerator,
    IMMDeviceEnumerator,
    comtypes.CLSCTX_INPROC_SERVER
)

#print enumerator
endpoint = enumerator.GetDefaultAudioEndpoint( 0, 1 )
#print endpoint
volume = endpoint.Activate( IID_IAudioEndpointVolume, comtypes.CLSCTX_INPROC_SERVER, None )
print(volume)
print(volume.GetMasterVolumeLevelScalar())
print(volume.GetMasterVolumeLevel())
print(volume.GetVolumeRange())
#volume.SetMasterVolumeLevel(-20.0, None)