user-0 提问: 如何用C语言调用API控制播放音频文件的声音大小

回复:
user: user-1
content: google mci接口

user: user-2
content: mixerSetControlDetails The mixerSetControlDetails function sets properties of a single control associated with an audio line.  MMRESULT mixerSetControlDetails(   HMIXEROBJ hmxobj,                LPMIXERCONTROLDETAILS pmxcd,     DWORD fdwDetails               );   Parameters hmxobj  Handle of the mixer device object for which properties are being set.  pmxcd  Address of a MIXERCONTROLDETAILS structure. This structure is used to reference control detail structures that contain the desired state for the control.  fdwDetails  Flags for setting properties for a control. The following values are defined:  MIXER_OBJECTF_AUX  The hmxobj parameter is an auxiliary device identifier in the range of zero to one less than the number of devices returned by the auxGetNumDevs function.  MIXER_OBJECTF_HMIDIIN  The hmxobj parameter is the handle of a MIDI input device. This handle must have been returned by the midiInOpen function.  MIXER_OBJECTF_HMIDIOUT  The hmxobj parameter is the handle of a MIDI output device. This handle must have been returned by the midiOutOpen function.  MIXER_OBJECTF_HMIXER  The hmxobj parameter is a mixer device handle returned by the mixerOpen function. This flag is optional.  MIXER_OBJECTF_HWAVEIN  The hmxobj parameter is a waveform-audio input handle returned by the waveInOpen function.  MIXER_OBJECTF_HWAVEOUT  The hmxobj parameter is a waveform-audio output handle returned by the waveOutOpen function.  MIXER_OBJECTF_MIDIIN  The hmxobj parameter is the identifier of a MIDI input device. This identifier must be in the range of zero to one less than the number of devices returned by the midiInGetNumDevs function.  MIXER_OBJECTF_MIDIOUT  The hmxobj parameter is the identifier of a MIDI output device. This identifier must be in the range of zero to one less than the number of devices returned by the midiOutGetNumDevs function.  MIXER_OBJECTF_MIXER  The hmxobj parameter is a mixer device identifier in the range of zero to one less than the number of devices returned by the mixerGetNumDevs function. This flag is optional.  MIXER_OBJECTF_WAVEIN  The hmxobj parameter is the identifier of a waveform-audio input device in the range of zero to one less than the number of devices returned by the waveInGetNumDevs function.  MIXER_OBJECTF_WAVEOUT  The hmxobj parameter is the identifier of a waveform-audio output device in the range of zero to one less than the number of devices returned by the waveOutGetNumDevs function.  MIXER_SETCONTROLDETAILSF_CUSTOM  A custom dialog box for the specified custom mixer control is displayed. The mixer device gathers the required information from the user and returns the data in the specified buffer. The handle for the owning window is specified in the hwndOwner member of the MIXERCONTROLDETAILS structure. (This handle can be set to NULL.) The application can then save the data from the dialog box and use it later to reset the control to the same state by using the MIXER_SETCONTROLDETAILSF_VALUE flag.  MIXER_SETCONTROLDETAILSF_VALUE  The current value(s) for a control are set. The paDetails member of the MIXERCONTROLDETAILS structure points to one or more mixer-control details structures of the appropriate class for the control.  Return Values Returns MMSYSERR_NOERROR if successful or an error otherwise. Possible error values include the following:   Value Description  MIXERR_INVALCONTROL The control reference is invalid.  MMSYSERR_BADDEVICEID The hmxobj parameter specifies an invalid device identifier.  MMSYSERR_INVALFLAG One or more flags are invalid.  MMSYSERR_INVALHANDLE The hmxobj parameter specifies an invalid handle.  MMSYSERR_INVALPARAM One or more parameters are invalid.  MMSYSERR_NODRIVER No mixer device is available for the object specified by hmxobj.    Remarks All members of the MIXERCONTROLDETAILS structure must be initialized before calling mixerSetControlDetails.   If an application needs to retrieve only the current state of a custom mixer control and not display a dialog box, then mixerGetControlDetails can be used with the MIXER_GETCONTROLDETAILSF_VALUE flag.  QuickInfo   Windows NT: Requires version 3.1 or later.   Windows: Requires Windows 95 or later.   Windows CE: Unsupported.   Header: Declared in mmsystem.h.   Import Library: Use winmm.lib.  See Also Audio Mixers Overview, Audio Mixer Functions, MIXERCONTROLDETAILS, auxGetNumDevs, midiInOpen, midiOutOpen, mixerOpen, waveInOpen, waveOutOpen, midiInGetNumDevs, midiOutGetNumDevs, mixerGetNumDevs, waveInGetNumDevs, waveOutGetNumDevs, mixerGetControlDetails