如何指定用于mciSendString API的声卡

Question

我正在更新一个旧的VB6应用程序。当时，我在mciSendString命令周围编写了一个包装器，以便能够录制和回放音频。当时，计算机通常只有一块声卡。

现在，许多客户都有多个声卡(通常是内置声卡和USB耳机)。

我似乎找不到指定mciSendString使用哪块声卡的接口。谁能给我指个方向？

Answer 1

微软提供了answer。

要设置多媒体控件使用的WaveAudio设备(声卡)，必须使用mciSendCommand API。多媒体控件不直接提供让您设置播放或录制所使用的设备的方法。

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)

Answer 2

请在这里查看源码(Ergebnisse des Wettbewerbs /德语)的几个解决方案：http://www.activevb.de/rubriken/wettbewerbe/2009_september/comp_2009_september_mp3_player.html

下面是我的项目的一些源代码

''' <summary>
''' Return all audio devices by names
''' </summary>
Private Function ListSoundDevices(ByRef LDev As List(Of String)) As Boolean

    Dim intItem As New Integer
    Dim intNext As New Integer
    Dim intCount As New Integer
    Dim tWIC As New WaveInCaps
    Dim Enc As System.Text.ASCIIEncoding = New System.Text.ASCIIEncoding()
    Dim res As Boolean = False

    Try
        'Throw New Exception("test")
        intCount = waveInGetNumDevs()
    Catch ex As Exception
        'no devices found
        Return False
    End Try

    If intCount <> 0 Then
        For intItem = 0 To intCount - 1
            If waveInGetDevCaps(intItem, tWIC, Marshal.SizeOf(tWIC)) = MMSYSERR_NOERROR Then
                If (tWIC.Formats And WAVE_FORMAT_4S16) = WAVE_FORMAT_4S16 Then
                    If LDev Is Nothing Then LDev = New List(Of String)
                    Dim B() As Byte = System.Text.Encoding.Default.GetBytes(tWIC.ProductName.ToString.ToCharArray)
                    LDev.Add(Enc.GetString(B, 0, B.Length))
                    intNext += 1
                End If
            End If
        Next

        If intNext > 0 Then res = True
    End If

    Return res
End Function

使用设备ID开始录制和使用。希望这能有所帮助