vb调用directshow提取avi音频？

Dim le As FilgraphManager
Sub SetAviDats(i$)
On Error GoTo e
Dim k As IFilterInfo, c As IFilterInfo, d As IFilterInfo, n As IFilterInfo, p(3) As IPinInfo
Set le = New FilgraphManager
SetFlter k, "WAV Dest"
SetFlter c, "AVI/WAV File Source"
SetFlter d, "AVI Mux"
SetFlter n, "File writer"
c.FileName = "E:\1.avi"
n.FileName = "E:\1.wav" '运行到这句错了,不知该怎么办？
c.FindPin "1", p(0)

e: MsgBox Err.Description
End Sub

Sub SetFlter(i As IFilterInfo, j$)
On Error GoTo e
Dim k As IRegFilterInfo, c$
For Each k In le.RegFilterCollection
If InStr(k.Name, j) Then
k.Filter i
GoTo e
End If
Next
e: Err.Clear
End Sub