change volume of single audio device
Jean-Michel Pichavant
jeanmichel at sequans.com
Wed Nov 13 10:43:50 EST 2013
----- Original Message -----
> hi,
>
> i'd like to change the volume of my av-receiver (HDMI) and speakers
> (analogue) simultaneously. in order to use both outputs i'm using
> virtual audio cable but if i set it as default device and change
> volume, hdmi and analogue remains unchanged.
> i intend to script a command line tool in python providing to change
> the volume of a single device (eg "setvolume {deviceID} {volume}")
>
> i've been looking for a similar tool, but none of them worked (eg
> nircmd); i'm using Win7.
>
> while looking for a solution i found that snippet of code
>
> [CODE]
> #!/usr/bin/env python
> #Boa:PyApp:main
> modules = {}
>
> import ctypes
>
> mixerSetControlDetails = (
> ctypes.windll.winmm.mixerSetControlDetails)
>
> mixerGetControlDetails = (
> ctypes.windll.winmm.mixerGetControlDetailsA)
>
> # Some constants
> MIXER_OBJECTF_MIXER = 0 # mmsystem.h
> VOLUME_CONTROL_ID = 0 # Same on all machines?
> SPEAKER_LINE_FADER_ID = 0 # "Identifier <identifier> in OID value
> does not resolve to a positive integer"
> MINIMUM_VOLUME = 0 # fader control (MSDN Library)
> MAXIMUM_VOLUME = 65535 # fader control (MSDN Library)
>
> class MIXERCONTROLDETAILS(ctypes.Structure):
> _pack_ = 1
> _fields_ = [('cbStruct', ctypes.c_ulong),
> ('dwControlID', ctypes.c_ulong),
> ('cChannels', ctypes.c_ulong),
> ('cMultipleItems', ctypes.c_ulong),
> ('cbDetails', ctypes.c_ulong),
> ('paDetails', ctypes.POINTER(ctypes.c_ulong))]
>
> def setVolume(volume):
> """Set the speaker volume on the 'Volume Control' mixer"""
> if not (MINIMUM_VOLUME <= volume <= MAXIMUM_VOLUME):
> raise ValueError, "Volume out of range"
> cd = MIXERCONTROLDETAILS(ctypes.sizeof(MIXERCONTROLDETAILS),
> SPEAKER_LINE_FADER_ID,
> 1, 0,
> ctypes.sizeof(ctypes.c_ulong),
> ctypes.pointer(ctypes.c_ulong(volume)))
>
> ret = mixerSetControlDetails(VOLUME_CONTROL_ID,
> ctypes.byref(cd),
> MIXER_OBJECTF_MIXER)
>
> if ret != 0:
> print WindowsError, "Error %d while setting volume" % ret
>
> ret = mixerGetControlDetails(VOLUME_CONTROL_ID,
> ctypes.byref(cd),
> MIXER_OBJECTF_MIXER)
> if ret != 0:
> print WindowsError, "Error %d while setting volume" % ret
> else:
> print 'cbStruct', cd.cbStruct
> print 'dwControlID', cd.dwControlID
> print 'cChannels', cd.cChannels
> print 'cMultipleItems', cd.cMultipleItems
> print 'cbDetails', cd.cbDetails
> print 'paDetails', cd.paDetails.contents
> return
>
> setVolume((2**16-1)/2)
>
> from ctypes import *
> from struct import *
>
> winmm= windll.winmm
> print
> print 'waveOutGetNumDevs=',winmm.waveOutGetNumDevs()
> print 'mixerGetNumDevs', winmm.mixerGetNumDevs()
>
> wvcps= ' '*52
> print 'res:', winmm.waveOutGetDevCapsA(0,wvcps,len(wvcps))
>
> res = unpack('IIL32cLI', wvcps)
> wMid=res[0]
> wPid=res[1]
> vDriverVersion=res[2]
> szPname=''.join(res[3:35])
> dwFormats=res[35]
> wChannels=res[36]
> print 'wMid=',wMid
> print 'wPid=',wPid
> print 'vDriverVersion=',vDriverVersion
> print 'szPname=',szPname
> print 'dwFormats=',dwFormats
> print 'wChannels=',wChannels
>
> vol=c_ulong()
> print 'res', winmm.waveOutGetVolume(0, byref(vol))
>
> print 'l:', vol.value & 0xffff, 'r:',vol.value >> 16 # left,
> right
> [/CODE]
>
>
> on executing i get
> [CODE]
> <<type 'exceptions.WindowsError'> Error 11 while setting volume
> <type 'exceptions.WindowsError'> Error 11 while setting volume
>
> waveOutGetNumDevs= 3
> mixerGetNumDevs 4
> res: 0
> wMid= 6553601
> wPid= 1537
> vDriverVersion= 2037083727
> szPname= o (AMD High Definition Audi
> dwFormats= 2
> wChannels= 36
> res 0
> l: 65535 r: 0
> [/CODE]
>
I'm afraid there's nothing related to python here.
It looks like the win function mixerSetControlDetails returned the error MMSYSERR_INVALPARAM.
You've set your devices IDs to 0. Are you sure this is correct ?
Cheers,
JM
-- IMPORTANT NOTICE:
The contents of this email and any attachments are confidential and may also be privileged. If you are not the intended recipient, please notify the sender immediately and do not disclose the contents to any other person, use it for any purpose, or store or copy the information in any medium. Thank you.
More information about the Python-list
mailing list