Fixing a directX function which gets the video length in VB.NET - asp.net

Question

I have found a function which invokes Microsoft.DirectX.AudioVideoPlayback to get the length of a video file.
Here is that code:
`Private Function GetVideoInformation(ByVal videoFilePath As String) As VideoInfo
Try
If My.Computer.FileSystem.FileExists(videoFilePath) Then
Dim videoToGetInfoOn As Microsoft.DirectX.AudioVideoPlayback.Video
videoToGetInfoOn = New Microsoft.DirectX.AudioVideoPlayback.Video(videoFilePath)
Dim atpf As Double = videoToGetInfoOn.AverageTimePerFrame
Dim vidSize As New Size
vidSize = videoToGetInfoOn.Size
Dim thisVideoInfo As New VideoInfo
thisVideoInfo.videoWidth = vidSize.Width
thisVideoInfo.videoHeight = vidSize.Height
thisVideoInfo.videoDuration = videoToGetInfoOn.Duration
If videoToGetInfoOn.Duration > 0 Then
defaultLength = videoToGetInfoOn.Duration
End If
If atpf > 0 Then
thisVideoInfo.videoFps = 1 / atpf
Else
thisVideoInfo.videoFps = 0
End If
Return thisVideoInfo
Else
Throw New Exception("Video File Not Found" & vbCrLf & vbCrLf & videoFilePath)
Return Nothing
End If
Catch ex as Exception
msgbox(ex.message)
End Try
End Function`
I have a timer that calls this function once on 2 seconds to check many videos, and the app works fine for the first 10 videos or so. After that, it throws
"Error in application"
message instead.

Answer 1

In general, things from DirectShow/DirectX MUST be disposed of in the way the docs require or this sort of thing happens. Here, you are creating videoToGetInfoOn objects but never releasing them.
You need to explicitly release all the resources you and it allocated with videoToGetInfoOn = Nothing before your procedure exits. Try that.
I will add that MediaInfo.DLL can be used to get everything from a media file without the overhead of Dx. There is a commandline version that you might be able to read from reading stdout.

Answer 2

I got it working.
The code needs a dispose method.
Here is the final code:
`Private Function GetVideoInformation(ByVal videoFilePath As String) As VideoInfo
Try
If My.Computer.FileSystem.FileExists(videoFilePath) Then
Dim videoToGetInfoOn As Microsoft.DirectX.AudioVideoPlayback.Video
videoToGetInfoOn = New Microsoft.DirectX.AudioVideoPlayback.Video(videoFilePath)
Dim atpf As Double = videoToGetInfoOn.AverageTimePerFrame
Dim vidSize As New Size
vidSize = videoToGetInfoOn.Size
Dim thisVideoInfo As New VideoInfo
thisVideoInfo.videoWidth = vidSize.Width
thisVideoInfo.videoHeight = vidSize.Height
thisVideoInfo.videoDuration = videoToGetInfoOn.Duration
If videoToGetInfoOn.Duration > 0 Then
defaultLength = videoToGetInfoOn.Duration
End If
If atpf > 0 Then
thisVideoInfo.videoFps = 1 / atpf
Else
thisVideoInfo.videoFps = 0
End If
videoToGetInfoOn.Dispose() 'this line here needed to be added
Return thisVideoInfo
Else
Throw New Exception("Video File Not Found" & vbCrLf & vbCrLf & videoFilePath)
Return Nothing
End If
Catch ex as Exception
msgbox(ex.message)
End Try
End Function`