寻找并获取 DirectShow.NET 的位置片段

引言

你是否想过在 DirectShow 电影中进行跳转？或者获取当前电影的位置并使用你的滑块显示它？

背景

请阅读以下相关文章

• CodeProject -> DirectShow 示例
• C# 与 VB.NET 之间的转换
• Informikon -> DirectShow
• MSDN 论坛 DirectShow
• MSDN 新闻组 DirectX Video
• Sourceforge Directshow.Net 论坛
• The March Hare -> DirectShow
• TheZBuffer -> DirectShow + Direct3D

使用代码

当你像这样创建你的图表时

f_MediaPositioning = CType(f_GraphManager, IMediaSeeking) '(f_graphmanager is the base) 
Public Event Movie_Playhead_Moved(ByVal frame as long, duration as long)
Public Sub Graph_Seek(ByVal frame As Long)
    If FilterGraphState = FilterGraphStateEnum.Ready Then
        Try
            Dim hr As Integer
            Dim duration As Long
            hr = f_MediaPositioning.GetDuration(duration) : DsError.ThrowExceptionForHR(hr)
            hr = f_MediaPositioning.SetPositions(frame, _
                    AMSeekingSeekingFlags.AbsolutePositioning, _
                    duration, AMSeekingSeekingFlags.AbsolutePositioning)
            RaiseEvent Movie_Playhead_Moved(frame , duration)
            DsError.ThrowExceptionForHR(hr)
        Catch ex As Exception
            ThrowError("error sub graph_seek : ", ex)
            'throwerror is my custom messagehandler
        End Try
    Else
        ThrowError("not ready to do seeking")
    End If
End Sub

Private Sub HeANewPlayheadEvent(byval frame as long, _
            byval duration as long) handles me.Movie_Playhead_Moved
    Invoke_trackbar_playhead_update(frame, duration)
End Sub

Public Sub Invoke_trackbar_playhead_update(ByVal frame as long, duration as long)
    If Me.TrackbarPlayhead.InvokeRequired Then
        Dim del As New Delegate_Trackbar_Playhead_Update(_
                       AddressOf Process_Trackbar_playhead_update)
        del.Invoke(frame,duration)
    Else
        Process_Trackbar_playhead_update(frame,duration)
    End If
End Sub

Private Sub Process_Trackbar_playhead_update(ByVal frame As long, ByVal duration As long)
    If TrackbarPlayhead.Value <> frame Then
        TrackbarPlayhead.Maximum = Cint(duration / 1000)
        TrackbarPlayhead.Value = CInt(frame / 1000)
        TrackbarPlayhead.TickFrequency = CInt(duration / 10)
        TrackbarPlayhead.Update()
        Application.DoEvents()
    End If
End Sub

你可以有一个单独的子程序，该子程序由定时器调用（每当你的图表加载并处于播放/暂停模式时）

Dim hr As Integer:Dim frame As Long
hr = f_MediaPositioning.GetCurrentPosition(frame) : DsError.ThrowExceptionForHR(hr)
hr = f_MediaPositioning.GetDuration(duration) : DsError.ThrowExceptionForHR(hr)
Invoke_trackbar_playhead_update(frame, duration)     

你可以使用 IMediaSeeking 接口来控制电影的速率。

历史

目前还没有历史记录。