修复directX函数，该函数在VB.NET中获取视频长度

Question

我找到了一个函数，它调用Microsoft.DirectX.AudioVideoPlayback来获取视频文件的长度。

这是代码：

`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`

我有一个计时器，它可以在2秒内调用这个函数来检查很多视频，而这个应用程序在前10个视频中运行得很好。在那之后，它

"Error in application" 

代之以留言。

Answer 1

通常，DirectShow/DirectX中的内容必须按照文档所要求的方式处理，否则这类事情就会发生。在这里，您正在创建videoToGetInfoOn对象，但从未发布它们。

在您的过程退出之前，您需要显式地释放您和它用videoToGetInfoOn = Nothing分配的所有资源。试试看。

我要补充的是，可以使用MediaInfo.DLL从媒体文件中获取everything，而不需要Dx的开销。有一个命令行版本，您可以从stdout中读取。

Answer 2

我让它起作用了。

代码需要一个dispose方法。

以下是最终代码：

`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`