Microsoft KB Archive/180032

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HOWTO: Select Soundcard in Visual Basic with Multimedia Control

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Q180032

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The information in this article applies to:


 * Microsoft Win32 Application Programming Interface (API), included with:
 * Microsoft Windows 95
 * the operating system: Microsoft Windows NT

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SUMMARY
This article describes how to set the WaveAudio device (soundcard) used by the Multimedia Control (MCI32.ocx) using Visual Basic.

MORE INFORMATION
To set the WaveAudio device (soundcard) used by the Multimedia Control, you must use the mciSendCommand API. The Multimedia Control does not directly provide a method to let you set the device used for playing or recording.

The following Visual Basic sample code shows how to use mciSendCommand to specify the device used for WaveAudio output.

Sample Code
Following are the required definitions and declarations. Place these in a module file:

  Public Const MMSYSERR_NOERROR = 0 Public Const MCI_SET = &H80D Public Const MCI_WAVE_OUTPUT = &H800000 Type MCI_WAVE_SET_PARMS dwCallback As Long dwTimeFormat As Long dwAudio As Long wInput As Long wOutput As Long wFormatTag As Integer wReserved2 As Integer nChannels As Integer wReserved3 As Integer nSamplesPerSec As Long nAvgBytesPerSec As Long nBlockAlign As Integer wReserved4 As Integer wBitsPerSample As Integer wReserved5 As Integer End Type

Declare Function mciGetErrorString Lib "winmm.dll" _ Alias "mciGetErrorStringA" (ByVal dwError As Long, _      ByVal lpstrBuffer As String, ByVal uLength As Long) As Long

Declare Function mciSendCommand Lib "winmm.dll" Alias _ "mciSendCommandA" (ByVal wDeviceID As Long, _      ByVal uMessage As Long, ByVal dwParam1 As Long, _       ByRef dwParam2 As Any) As Long

Sample Code
The following code sets the output device. This code assumes that you have a Multimedia Control called "MMControl1." This code should be called after the wave file to be played has been opened by MMControl1.

  Dim parms As MCI_WAVE_SET_PARMS Dim rc As Long

' Specify the soundcard. This specifies the soundcard with a deviceID ' of 0. If you have a single soundcard, then this will open it. If you ' have multiple soundcards, the deviceIDs will be 0, 1, 2, etc.   parms.wOutput = 0

' Send the MCI command to set the output device. rc = mciSendCommand(MMControl1.DeviceID, MCI_SET, _       MCI_WAVE_OUTPUT, parms)

if (rc <> MMSYSERR_NOERROR) then ' The command failed. End If