How to Control the Volume of Sound Files from Visual Basic
ID: Q118377
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The information in this article applies to:
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Microsoft Visual Basic Professional Edition for Windows, version 3.0
SUMMARY
The Visual Basic MCI Control doesn't allow volume control of a Windows
sound file. The volume can be controlled through the Multimedia API by
using the waveOutSetVolume function. You can also use the function
waveOutGetVolume() to read the current volume settings.
MORE INFORMATION
The waveOutSetVolume() function sets the volume of a waveform output
device. With this function, you can control the right- and left-channel
volume settings independently.
Declaration Syntax
Use one the following Declare statements to declare the waveOutGetVolume()
Windows API function in your Visual Basic program:
Enter each Declare statement as one, single line:
Declare Function waveOutSetVolume Lib "MMSYSTEM.DLL"
(ByVal wDeviceID as Integer, ByVal dwVolume as Long) as Integer
Declare Function waveOutGetVolume Lib "MMSYSTEM.DLL"
(ByVal wDeviceID as Integer, dwVolume as Long) as Integer
As an alternative, you can declare the waveOutSetVolume function by passing
the dwVolume parameter as two separate integers, one for the left-channel
setting and one for the right-channel setting. Pass the high-order word
first and then the low-order word.
Enter the following Declare statement as one, single line:
Declare Function waveOutSetVolume Lib "MMSYSTEM.DLL"
(ByVal wDeviceID as Integer, ByVal dwVolumeRight as Integer
ByVal dwVolumeLeft as Integer) as Integer
Parameters Explained
wDeviceID This parameter identifies the waveform-output device. If
you were to play one wave file, you would set this
parameter to 0. If you were to play multiple wave files, you
would set this parameter to 1 for the second, 2 for the third,
and so on.
dwVolume For the waveOutSetVloume function, this parameter specifies
the new volume setting. For the waveOutGetVolume
function, it specifies a far pointer to a location that will be
filled with the current volume setting.
The low-order word contains the left-channel volume setting,
and the high-order word contains the right-channel volume
setting.
A value of &HFFFF represents full volume, and a value of
&H0000 represents no volume.
If a device does not support both left and right volume
control, the low-order word of dwVolume specifies the volume
level, and the high-order word is ignored.
Return Value
?? returns zero if the function is successful. Otherwise, it returns an
error number. Possible return values are:
- MMSYSERR_INVALIHANDLE = 5 Specific device handle is invalid
- MMSYSERR_NOTSUPPORTED = 8 Function isn't supported
- MMSYSERR_NODRIVER = 6 The driver was not installed
NOTE: Not all devices support volume changes or volume control on both the
left and right channels. Most devices do not support the full 16 bits of
volume-level control and will not use the high-order bits.
Step-by-Step Example
This example demonstrates how to use the waveOutSetVolume(),
waveOutGetVolume(), and sndPlaySound Multimedia API functions to
increase or decrease the sound in either the left or right channels:
- Start a new project in Visual Basic; Form1 is created by default.
- Add the following controls to Form1 and set their properties as
indicated:
Control Property Setting
----------------------------------------
Command Button Name PlaySound
Caption Play Sound
Command Button Name LeftUp
Caption Left Up
Command Button Name LeftDown
Caption Left Down
Command Button Name RightUp
Caption Right Up
Command Button Name RightDown
Caption Right Down
Label Name LeftVol
Label Name RightVol
- Add the following code to the General Declarations section of Form1:
' Enter each of the following Declare statements as one, single line:
Declare Function sndPlaySound Lib "MMSYSTEM.DLL"
(ByVal lpszSoundName As String, ByVal wFlags As Integer) As Integer
Declare Function waveoutSetVolume Lib "mmsystem.dll"
(ByVal wDeviceID As Integer, ByVal dwVolumeRight As Integer,
ByVal dwVolumeLeft As Integer) As Integer
Declare Function waveOutGetVolume Lib "MMSYSTEM.DLL"
(ByVal wDeviceID As Integer, lpdwvolume As Long) As Integer
Const SND_ASYNC = &H1
Const SND_NODEFAULT = &H2
Dim CurrentVolLeft As Long
Dim CurrentVolRight As Long
- Add the sample code shown below to the appropriate Form or Control event
procedure.
- Save your work, and run the program.
- You will see the current channel setting in the labels. Choose
the Play Sound button to hear the tada wave file play.
- Click one of the other command buttons to change either the left- or
right-channel setting, and then click the Play Sound command button
again. The volume level has changed.
Sample Code
Sub Form_Load ()
Dim x As Integer
Dim BothVolumes As Long
' Note that the waveid is 0 indicating the first wave output device.
' If you were to play multiple wavefiles on multiple wave output devices
' you would use 1 for the second wave output device, 2 for the third and
' so on.
' This code will retrieve the current volume setting
x = waveOutGetVolume(0, BothVolumes)
' This code isolates the low-order word.
' Note that the value &HFFFF& is a Long Integer, which is the same
' as 0000FFFF, but because Visual Basic would automatically
' truncate this to FFFF, you must force the logical operation to use
' a four-byte Long Integer (0000FFFF) rather than a two-byte Integer
' (FFFF). This is accomplished by using the type casting
' character (&).
CurrentVolLeft = BothVolumes And &HFFFF&
' This code isolates the high-order word.
' Enter the following two lines as one, single line:
CurrentVolRight = ((BothVolumes And &HFFFF0000) / &H10000)
And &HFFFF&
LeftVol.Caption = Hex$(CurrentVolLeft) ' Update the label with the
RightVol.Caption = Hex$(CurrentVolRight) ' current volume settings.
End Sub
Sub PlaySound_Click ()
Dim x As Integer
Dim wFlags As Integer
Dim SoundName As String
SoundName = "C:\WINDOWS\MSREMIND.WAV" ' Pick any wave file.
wFlags = SND_ASYNC Or SND_NODEFAULT
x = sndPlaySound(SoundName$, wFlags%) ' Play the wave file.
End Sub
Sub LeftUp_Click ()
' Increase the left sound channel setting:
Dim x As Integer
CurrentVolLeft = CurrentVolLeft + &H1000&
' Prevent the channel setting from exceeding the maximum limit:
If CurrentVolLeft > &HFFFF& Then CurrentVolLeft = &HFFFF&
LeftVol.Caption = Format$(Hex$(CurrentVolLeft))
' Enter the following two lines as one, single line:
x = waveoutSetVolume(0, CInt("&H" + Hex$(CurrentVolRight)),
CInt("&H" + Hex$(CurrentVolLeft)))
End Sub
Sub LeftDown_Click ()
' Decrease the left sound channel setting:
Dim x As Integer
CurrentVolLeft = CurrentVolLeft - &H1000&
' Prevent the channel setting from dropping below the minimum limit:
If CurrentVolLeft < &H0& Then CurrentVolLeft = &H0&
LeftVol.Caption = Hex$(CurrentVolLeft)
' Enter the following two lines as one, single line:
x = waveoutSetVolume(0, CInt("&H" + Hex$(CurrentVolRight)),
CInt("&H" + Hex$(CurrentVolLeft)))
End Sub
Sub RightUp_Click ()
' Increase the right sound channel setting:
Dim x As Integer
CurrentVolRight = CurrentVolRight + &H1000&
' Prevent the channel setting from exceeding the maximum limit.
If CurrentVolRight > &HFFFF& Then CurrentVolRight = &HFFFF&
RightVol.Caption = Hex$(CurrentVolRight)
' Enter the following two lines as one, single line:
x = waveoutSetVolume(0, CInt("&H" + Hex$(CurrentVolRight)),
CInt("&H" + Hex$(CurrentVolLeft)))
End Sub
Sub RightDown_Click ()
' Decrease the right sound channel setting:
Dim x As Integer
CurrentVolRight = CurrentVolRight - &H1000&
' Prevent the channel setting from dropping below the minimum limit:
If CurrentVolRight < 0 Then CurrentVolRight = 0
RightVol.Caption = Hex$(CurrentVolRight)
' Enter the following two lines as one, single line:
x = waveoutSetVolume(0, CInt("&H" + Hex$(CurrentVolRight)),
CInt("&H" + Hex$(CurrentVolLeft)))
End Sub
REFERENCES
For more detailed information on these and other Multimedia-related
functions, please see the "Multimedia Programmer's Reference Guide"
included with the Microsoft Windows version 3.1 Software Development Kit.
For information on other Visual Basic declarations and constant values for
Multimedia-related functions, see the WINMMSYS.TXT text file. This file
comes as part of the Professional edition of Visual Basic. Assuming default
installation, you can find this file in the C:\VB\WINAPI\ directory.
Additional query words:
3.00
Keywords : kbcode
Version : 3.00
Platform : WINDOWS
Issue type :