Programmatically Increase, Decrease and Mute the Volume(VB.NET)

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TOPIC: Programmatically Increase, Decrease and Mute the Volume(VB.NET)

Programmatically Increase, Decrease and Mute the Volume(VB.NET) 03 May 2010 00:27 #368

Introduction
I was recently working on the Windows API and thought of creating a small application that can increase, decrease and mute the volume in .NET. Since we will be consuming unmanaged DLL functions, hence I will be using P/Invoke that enables managed code to call unmanaged functions implemented in DLL’s, like the ones in the Win32 API. For this purpose, we will be using the Imports System.Runtime.InteropServices namespace

In this article, I assume you are familiar with interoperating with Unmanaged Code. If you have never worked with unmanaged code, please read the MSDN article Interoperating with Unmanaged Code.
I have created a Windows Application and added three Button Controls to the form as shown below:

The Code
Let us see the code that will be invoked on every button click:

 Private Const APPCOMMAND_VOLUME_MUTE As Integer = &H80000
    Private Const APPCOMMAND_VOLUME_UP As Integer = &HA0000
    Private Const APPCOMMAND_VOLUME_DOWN As Integer = &H90000
    Private Const WM_APPCOMMAND As Integer = &H319
 
    <DllImport("user32.dll")> _
    Public Shared Function SendMessageW(ByVal hWnd As IntPtr, _
    ByVal Msg As Integer, ByVal wParam As IntPtr, _
    ByVal lParam As IntPtr) As IntPtr
    End Function

Mute / Unmute

 if (checkMute)
 SendMessageW(Me.Handle, WM_APPCOMMAND, _
 Me.Handle, New IntPtr(APPCOMMAND_VOLUME_MUTE))

Decrease

 SendMessageW(Me.Handle, WM_APPCOMMAND, _
 Me.Handle, New IntPtr(APPCOMMAND_VOLUME_DOWN))

Increase

SendMessageW(Me.Handle, WM_APPCOMMAND, _
  Me.Handle, New IntPtr(APPCOMMAND_VOLUME_UP))

As seen in the code above, we are first using the DllImportAttribute attribute that provides the information needed to call a function exported from an unmanaged DLL. On each button click, we are using the SendMessageW() function to send the specified message to a window to increase, decrease and mute the volume.
I hope you liked the article and I thank you for viewing it.

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Re: Programmatically Increase, Decrease and Mute the Volume(VB.NET) 03 May 2011 13:03 #425

Hi and thank you for his interesting post! I tried the code and it worked perfect! I am new to vb programming and i would like to give me some informations about the way tha the code works. (What is the .dll file, how the code affects the sound, etc). Is this possible? Thank you in advance. Tassos.	mpexos OFFLINE CE Newbie Posts: 1 Karma: 0
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