Question

该应用程序使用DirectShowLib和USB摄像头（Logitech C930e）在C＃中实现。该图使用RenderStream方法编译。由于没有提供预览引脚，因此会自动生成SmartTee过滤器。

RenderStream被调用一次以进行预览，然后进行捕获。但是，即使交换了（捕获然后预览），它也无法将第二个调用连接到SmartTee。抛出的错误处理程序是：-2147024809（0x80070057; E_INVALIDARG;参数不正确）

代码段如下

    DirectShowLib.ISampleGrabber sg = null;
    DirectShowLib.ICaptureGraphBuilder2 cg = null;
    DirectShowLib.IGraphBuilder fg = null;

    IBaseFilter capFilter;
    IBaseFilter videoCompressorFilter;
    IBaseFilter muxFilter;
    IBaseFilter grabFilter;
    IBaseFilter VideoRendererFilter;

    Guid captureCat = PinCategory.Capture;
    Guid previewCat = PinCategory.Preview;
    Guid med = MediaType.Video;              

    DsGuid DSCaptureCat = (DsGuid)captureCat;
    DsGuid DSPreviewCat = (DsGuid)previewCat;
    DsGuid DSmed = (DsGuid)med;

    /*GetInterfaces*/
    Type comType = null;
    object comObj = null;
    fg = (IGraphBuilder)new FilterGraph();
    comType = Type.GetTypeFromCLSID(CgGuid);
    comObj = Activator.CreateInstance(comType);
    cg = (ICaptureGraphBuilder2)comObj; comObj = null;
    sg = (ISampleGrabber)new SampleGrabber();
    grabFilter = (IBaseFilter)sg;
    VideoRendererFilter = (IBaseFilter)new VideoRenderer();

    /*CreateCaptureDevice*/
    object capObj = null;
    capFilter = (IBaseFilter)capObj;

    /*SetupGraph*/
    hr = cg.SetFiltergraph(fg);

    if (renderFromDevice && deviceSet)
    {
        hr = fg.AddFilter(capFilter, "CapFilter");
    }

    AMMediaType media = new AMMediaType();
    media.majorType = MediaType.Video;
    media.subType = MediaSubType.RGB24;
    media.formatType = FormatType.VideoInfo;
    hr = sg.SetMediaType(media);

    DsUtils.FreeAMMediaType(media);
    media = null;


[1]
    /*RenderToScreen*/ 
    hr = fg.AddFilter(grabFilter, "FrameGrabFilter");

    hr = cg.RenderStream(DSPreviewCat, DSmed, capFilter, grabFilter, null);

[2]
    /*DerenderGraph*/
    if (renderFromDevice)
        removeDownstream(capFilter, videoCompressorFilter == null);
    else if (grabFilter != null)
        removeDownstream(grabFilter, true);

[3] 
    /*RenderToMovie*/
    videoFilename = Path.Combine(dirname, "interview.avi");

    cg.SetOutputFileName(MediaSubType.Avi, videoFilename, out muxFilter, out fileWriterFilter); //this automatically adds muxFilter to graph!

    string s;
    AMMediaType media = new AMMediaType();
    hr = fileWriterFilter.GetCurFile(out s, media);
    hr = fileWriterFilter.SetFileName(videoFilename, media);
    DsUtils.FreeAMMediaType(media);
    media = null;

    hr = fg.AddFilter(muxFilter, "MuxFilter"); //this adds the second muxFilter! now removed

    hr = cg.RenderStream(DSCaptureCat, DSmed, capFilter, null, muxFilter);

[4]     
    /*RenderToScreen2*/
    hr = fg.AddFilter(grabFilter, "FrameGrabFilter");

    hr = fg.AddFilter(VideoRendererFilter, "VideoRendererFilter");

    IEnumFilters enumFilters = null; 
    FilterInfo pInfo;
    IBaseFilter pFilter1, pFilter2, pFilter3;
    IPin outPin1, inPin1, outPin2, inPin2, inPin3;

    hr = fg.EnumFilters(out enumFilters);

    IBaseFilter[] filters = new IBaseFilter[1];
    int fetched;

    while (enumFilters.Next(1, filters, out fetched) == 0)
    {
        hr = filters[0].QueryFilterInfo(out pInfo);

        hr = fg.FindFilterByName("Smart Tee", out pFilter1);

        inPin1 = DsFindPin.ByDirection(pFilter1, PinDirection.Input, 0);
        outPin1 = DsFindPin.ByName(pFilter1, "Preview");

        hr = fg.FindFilterByName("FrameGrabFilter", out pFilter2);

        inPin2 = DsFindPin.ByDirection(pFilter2, PinDirection.Input, 0);
        outPin2 = DsFindPin.ByDirection(pFilter2, PinDirection.Output, 0);

        hr = fg.FindFilterByName("VideoRendererFilter", out pFilter3);

        inPin3 = DsFindPin.ByDirection(pFilter3, PinDirection.Input, 0);

        hr = fg.Connect(outPin1, inPin2);

        hr = fg.Connect(outPin2, inPin3);
    }

下面的GraphEdit显示了与图形的远程连接。通过在GraphEdit中手动将SmartTee捕获链接到MuxFilter，图形可以正常运行。

非常感谢有关可能的错误原因的任何提示。

Answer 1

如果没有看到对ICaptureGRaphBuilder2.RenderStream的实际调用，我只能对E_INVALIDARG错误做一些假设。但是，从远程连接到图形，我可以看到图形存在严重错误。两个输出引脚不应连接到同一输入引脚。您应该始终首先为Capture路径调用RenderStream，因为它是协商媒体类型的Capture引脚。您的源过滤器上已经有Capture pin（其中有2个为什么？）。我认为您需要像这样调用Capture RenderStream：

RenderStream（PIN_CATEGORY_CAPTURE，MEDIATYPE_Video，pSource，pMux，pWriter）;

其中： pSource是Video Camera Terminal CapFilter的IBaseFilter接口， pMux是MuxFilter的IBaseFilter接口（图中只应添加一个MuxFilter！）， pWriter是Writer过滤器的IBaseFilter接口（interview.avi）。

您应该只添加一个Video Camera Terminal CapFilter实例，只添加一个MuxFilter实例（AVI Mux）和一个File Writer过滤器实例（interview.avi）。使用此设置，Capture路径的RenderStream调用应该会成功。之后，您可以尝试调用RenderStream作为预览路径，如果尚未添加第一个调用，则应添加智能tee。如果我能帮助你进一步解决这个问题，请告诉我。

使用DirectShow

1 个答案: