多个视频切换时，只改变SourceFilter,不改变Filter Graph中其他Filter的C#实现

时间：2011-02-14 来源：面壁居士

1 public void ChangeFileSource(string newfilename)
2         {
3             // 先加入新加入的文件名代表的SourceFilter
4             IPin nextOutPin = null;
5             int hr = 0;
6             IBaseFilter sourceFilter = null;
7             hr = m_FilterGraph.AddSourceFilter(newfilename, newfilename, out sourceFilter);
8             DsError.ThrowExceptionForHR(hr);
9
10             hr = sourceFilter.FindPin("Output", out nextOutPin);
11             DsError.ThrowExceptionForHR(hr);
12
13             //然后停止当前FilterGraph的播放，
14             hr = m_mediaCtrl.Stop();
15             DsError.ThrowExceptionForHR(hr);
16
17             //然后枚举所有Filter
18             IEnumFilters enumFilters = null;
19             hr = m_FilterGraph.EnumFilters(out enumFilters);
20
21             int iFiltCount = 0;
22
23             while (0 == enumFilters.Skip(1))
24             {
25                 iFiltCount++;
26             }
27             enumFilters.Reset();
28
29             int iPos = 0;
30             IBaseFilter[] filters = new IBaseFilter[iFiltCount];
31             while (iPos < iFiltCount)
32             {
33                 int numFiltersToGet = 1;
34                 IBaseFilter[] filter = new IBaseFilter[numFiltersToGet];
35                 IntPtr fetched = IntPtr.Zero;
36                 hr = enumFilters.Next(1, filter, fetched);
37                 DsError.ThrowExceptionForHR(hr);
38                 filters[iPos] = filter[0];
39                 iPos++;
40             }
41
42             //此循环将新加入的SourceFilter加入到FilterGraph中，并将原SourceFilter移除并释放掉
43             for (iPos = 0; iPos < iFiltCount; iPos++)
44             {
45                 m_FilterGraph.RemoveFilter(filters[iPos]);
46                 if (filters[iPos] != m_currentSource)
47                 {
48                     m_FilterGraph.AddFilter(filters[iPos], null);
49                 }
50                 else
51                 {
52                     Marshal.ReleaseComObject(filters[iPos]);
53                 }
54             }
55
56             hr = m_FilterGraph.Render(nextOutPin);
57             DsError.ThrowExceptionForHR(hr);
58             m_currentSource = sourceFilter;
59             sourceFilter = null;
60
61             m_mediaCtrl.Run();
62
63             if (enumFilters != null)
64             {
65                 Marshal.ReleaseComObject(enumFilters);
66                 enumFilters = null;
67             }
68         }