Some API calls it uses are:
Declare Function mciGetErrorString Lib "winmm.dll" Alias _ "mciGetErrorStringA" _ (byval dwError as Long, byval lpstrBuffer as string, _ byval uLength as Long) as Long Declare Function mciSendString Lib "winmm.dll" Alias _ "mciSendStringA" _ (byval lpstrCommand as string, byval _ lpstrReturnString as string, _ byval uReturnLength as Long, byval hwndCallback as Long) _ as Long ' public hmem as Long ' public Const SND_ASYNC = &H1 public Const SND_NODEFAULT = &H2 public Const SND_PURGE = &H40 public Const SND_FILENAME = &H20000 ' public Const MMSYSERR_NOERROR = 0 public Const MAXPNAMELEN = 32 public Const MIXER_LONG_NAME_CHARS = 64 public Const MIXER_SHORT_NAME_CHARS = 16 public Const MIXER_GETLINEINFOF_COMPONENTTYPE = &H3& public Const MIXER_GETCONTROLDETAILSF_VALUE = &H0& public Const MIXER_SETCONTROLDETAILSF_VALUE = &H0& public Const MIXER_GETLINECONTROLSF_ONEBYTYPE = &H2& public Const MIXERLINE_COMPONENTTYPE_DST_FIRST = &H0& public Const MIXERLINE_COMPONENTTYPE_SRC_FIRST = &H1000& public Const MIXERLINE_COMPONENTTYPE_DST_SPEAKERS = _ (MIXERLINE_COMPONENTTYPE_DST_FIRST + 4) public Const MIXERLINE_COMPONENTTYPE_SRC_MICROPHONE = _ (MIXERLINE_COMPONENTTYPE_SRC_FIRST + 3) public Const MIXERLINE_COMPONENTTYPE_SRC_LINE = _ (MIXERLINE_COMPONENTTYPE_SRC_FIRST + 2) public Const MIXERCONTROL_CT_CLASS_FADER = &H50000000 public Const MIXERCONTROL_CT_UNITS_UNSIGNED = &H30000 public Const MIXERCONTROL_CONTROLTYPE_FADER = _ (MIXERCONTROL_CT_CLASS_FADER Or _ MIXERCONTROL_CT_UNITS_UNSIGNED) ' public Const MIXERCONTROL_CONTROLTYPE_VOLUME = _ (MIXERCONTROL_CONTROLTYPE_FADER + 1) ' public Type MIXERCONTROLDETAILS cbStruct as Long dwControlID as Long cChannels as Long item as Long cbDetails as Long paDetails as Long End Type ' public Type MIXERCONTROLDETAILS_UNSIGNED dwValue as Long End Type ' public Type MIXERCONTROL ' public Type MIXERLINE ' 'Allocates the specified number of bytes from the heap. ' Declare Function GlobalAlloc Lib "kernel32" (byval _ wFlags as Long, _ byval dwBytes as Long) as Long ' 'Locks a global memory object and returns a pointer to the ' first byte of the object's memory block. The memory block ' associated with a locked object cannot be moved or discarded. ' Declare Function GlobalLock Lib "kernel32" (byval _ hmem as Long) as Long ' 'Frees the specified global memory object and invalidates 'its handle. ' Declare Function GlobalFree Lib "kernel32" (byval hmem as Long) _ as Long ' Declare Sub CopyPtrFromStruct Lib "kernel32" Alias _ "RtlMoveMemory" _ (byval ptr as Long, struct as Any, byval cb as Long) ' Declare Sub CopyStructFromPtr Lib "kernel32" Alias "RtlMoveMemory" _ (struct as Any, byval ptr as Long, byval cb as Long) ' 'Opens a specified mixer device and ensures that the 'device will not be removed until the application 'closes the handle. ' Declare Function mixerOpen Lib "winmm.dll" _ (phmx as Long, byval uMxId as Long, byval dwCallback as Long, _ byval dwInstance as Long, byval fdwOpen as Long) as Long ' 'Sets properties of a single control associated with an 'audio line. ' Declare Function mixerSetControlDetails Lib "winmm.dll" _ (byval hmxobj as Long, pmxcd as MIXERCONTROLDETAILS, _ byval fdwDetails as Long) as Long ' 'Retrieves information about a specific line of a mixer device. ' Declare Function mixerGetLineInfo Lib "winmm.dll" _ Alias "mixerGetLineInfoA" (byval hmxobj as Long, _ pmxl as MIXERLINE, byval fdwInfo as Long) as Long ' 'Retrieves one or more controls associated with an audio line. ' Declare Function mixerGetLineControls Lib "winmm.dll" _ Alias "mixerGetLineControlsA" (byval hmxobj as Long, _ pmxlc as MIXERLINECONTROLS, byval fdwControls as Long) _ as Long ' public Function fGetVolumeControl(byval hmixer as Long, _ byval componentType as Long, byval ctrlType _ as Long, _ byref mxc as MIXERCONTROL) as Boolean '