Windows API Guide - Reference - Volume 1: Version 3.0 For the MS-DOS and PC-DOS Operating Systems

2017-07-07 02:10:07

Declare Function auxGetVolume Lib "winmm.dll" (ByVal uDeviceID As Long, lpdwVolume As Long) As Long

Platforms

Windows 95: Supported.
Windows 98: Supported.
Windows NT: Requires Windows NT 3.1 or later.
Windows 2000: Supported.
Windows CE: Not Supported.

Description & Usage

auxGetVolume retrieves the current volume setting for an auxiliary audio device. This function will retreive the volume whether the device supports dual-channel volume control or not.

Return Value

If an error occured, the function returns a non-zero error code. If successful, the function returns 0.

Visual Basic-Specific Issues

None.

Parameters

uDeviceID: The device ID of the auxiliary audio device to retrieve the volume of. Valid values range from 0 to the number of auxiliary audio devices minus one.
lpdwVolume: Receives the volume settings of the device. If the device supports separate left and right channel volumes, the low-order word contains the left channel volume and the high-order word contains the right channel volume. If the device does not support separate volumes, the low-order word contains the overall volume. Valid volume settings range from &H0 or &HFFFF.

Example

' This code is licensed according to the terms and conditions listed here. ' Display the current volume setting of whatever device happens ' to be auxiliary audio device 0. This example identifies whether the ' device has dual-channel volumes or not. Dim auxinfo As AUXCAPS ' receives information about the device Dim numvols As Long ' identifies number of volumes on the device Dim lrvol As Long ' volumes of both channels (or just the overall volume) Dim lvol As Integer, rvol As Integer ' volumes of left and right channels Dim retval As Long ' return value ' Figure out whether the device has one or two volume settings. retval = auxGetDevCaps(0, auxinfo, Len(auxinfo)) If retval <> 0 Then ' error Debug.Print "Could not access auxiliary audio device 0 -- aborting." End ' give up End If If (auxinfo.dwSupport And AUXCAPS_LRVOLUME) = AUXCAPS_LRVOLUME Then numvols = 2 ' separate left and right volumes Else numvols = 1 ' only one overall volume End If ' Determine the device's current volume. retval = auxGetVolume(0, lrvol) ' Display the current volume setting for the device. If numvols = 2 Then ' Separate the left and right channel volumes. The next two lines look ' like an excessively complicated way of doing it, but because of a ' quirk in Visual Basic, the "obvious" way doesn't work properly. lvol = Val("&H" & Hex(lrvol And (Not &HFFFF0000))) rvol = (lrvol And &HFFFF0000) / &H10000 ' Display the results in hexadecimal. Debug.Print "Left Channel volume: "; Hex(lvol) Debug.Print "Right Channel volume: "; Hex(rvol) Else ' Extract the useful information as above, although we only want ' the low-order word (placed into lvol). lvol = Val("&H" & Hex(lrvol And (Not &HFFFF0000))) ' Display the results in hexadecimal. Debug.Print "Volume: "; hex(lvol) ' here, lvol is the overall volume End If