[python-win32] Control Volume on Windows [SEC=UNCLASSIFIED]

[Tim Roberts]

Andrew MacIntyre wrote:
>> Trevor Haba wrote:
>>> I'm looking for a way to use python to change the volume on windows.
>>> After some googling the best I could come up with was this script I 
>>> got from a relatively ancient entry on this mailing list (I think it 
>>> was from 2005 or something). I'm using windows 7, and I would like it 
>>> to work on windows 8 if possible, though its not necessary. I don't 
>>> need to support any previous versions of windows.
> To which Tim Roberts replied:
>> Alas, the news is not good.
> I think that comtypes (https://pypi.python.org/pypi/comtypes) can deal with early binding interfaces?

You are quite right, and the attached script does it.  NOTE! that I have
not correctly defined all of the IMM interfaces for the general case;
I've only created enough of them to make this particular example work. 
On my Win 7 machine, this is able to fetch the default endpoint, display
the volume range (from -65.25 to 0 in steps of 0.75) and change the setting.

I'm glad you brought this up.  I've never played with comtypes before,
and this was a revealing exercise.

-- 
Tim Roberts, timr at probo.com
Providenza & Boekelheide, Inc.

-------------- next part --------------
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.GetMasterVolumeLevel()
print volume.GetVolumeRange()
volume.SetMasterVolumeLevel(-20.0, None)