DirectShow网络摄像头视频捕获

Question

我在XE2（see attached file [Demo2]）中使用以下示例来捕获网络摄像头视频。它在我的Win7桌面（USB网络摄像头）和Win10（集成网络摄像头）上工作得很好，但它在Win8（集成网络摄像头）平板电脑上失败，我不知道为什么。我设法跟踪VSimple.pas单元＆＃34;无法运行图表！＆＃34;。由于某种原因IMediaControl.Run方法失败（我尝试添加IMediaControl.GetState但没有运气）。我正在使用GetLastError，它给了我0（成功）。有没有人经历过这样的事情？我如何追踪错误？

编辑：已安装的K-Media编解码器包现在通过IMediaControl.Run，它显示未知压缩Datasize 86400 FourCC NV12 。插入USB网络摄像头会产生视频。我还能做什么？

FUNCTION TVideoSample.RestartVideoEx(Visible: boolean):HRESULT;
VAR
  pCut, pTyp : pGuiD;
  {
  pAMVidControl: IAMVideoControl;
  pPin         : IPin;
  }
BEGIN
  if (pIAMVideoProcAmp = nil) then
    if not(S_OK = pIBFVideoSource.QueryInterface(IID_IAMVideoProcAmp, pIAMVideoProcAmp)) then
      pIAMVideoProcAmp := nil;

   if (pIKsPropertySet = nil) then
    if not(S_OK = pIBFVideoSource.QueryInterface(IID_IKsPropertySet, pIKsPropertySet)) then
      pIKsPropertySet := nil;


    // Add Capture filter to our graph.
    Result := pIGraphBuilder.AddFilter(pIBFVideoSource, Widestring('Video Capture'));
    if (FAILED(Result)) then
      begin
        // Couldn''t add the capture filter to the graph!
        exit;
      end;

    Result := pIGraphBuilder.AddFilter(piBFSampleGrabber, Widestring('Sample Grabber'));
    if (FAILED(Result)) then
      EXIT;

    if not(Visible) then
      begin
        Result := pIGraphBuilder.AddFilter(pIBFNullRenderer, WideString('Null Renderer'));
        if (FAILED(Result)) then
          EXIT;
      end;

    // Render the preview pin on the video capture filter
    // Use this instead of pIGraphBuilder->RenderFile
    New(pCut);
    New(pTyp);
    //pCut^ := PIN_CATEGORY_PREVIEW;
    pCut^ := PIN_CATEGORY_CAPTURE;
    pTyp^ := MEDIATYPE_Video;
    try
      if Visible
        then Result := pICapGraphBuild2.RenderStream (pCut, pTyp,
                                    //Addr(PIN_CATEGORY_PREVIEW), Addr(MEDIATYPE_Video),
                                    pIBFVideoSource, piBFSampleGrabber, nil)

        else Result := pICapGraphBuild2.RenderStream (pCut, pTyp,
                                    //Addr(PIN_CATEGORY_PREVIEW), Addr(MEDIATYPE_Video),
                                    pIBFVideoSource, piBFSampleGrabber, pIBFNullRenderer);
    except
      Result := -1;
    end;
    if (FAILED(Result)) then
      begin
        // Couldn''t render the video capture stream.
        // The capture device may already be in use by another application.
        Dispose(pTyp);
        Dispose(pCut);
        exit;
      end;


    // Set video window style and position
    if Visible then
      begin
        Result := SetupVideoWindow();
        if (FAILED(Result)) then
          begin
            // Couldn't initialize video window!
            Dispose(pTyp);
            Dispose(pCut);
            exit;
          end;
      end;

{$ifdef REGISTER_FILTERGRAPH}
    // Add our graph to the running object table, which will allow
    // the GraphEdit application to "spy" on our graph
    try
      hr := AddGraphToRot(IUnknown(pIGraphBuilder), g_dwGraphRegister);
    except
      // Failed to register filter graph with ROT!
    end;
    if (FAILED(Result)) then
      begin
        // Failed to register filter graph with ROT!
        g_dwGraphRegister := 0;
      end;
{$endif}

  //  if Visible then
      begin
        SetLastError(0);
        // Start previewing video data
        Result := pIMediaControl.Run(); // Returns something like -27XXXX...
        if (FAILED(Result)) then
          begin
            // Couldn't run the graph! - GetLastError gives 0
          end;
      end;

    // Remember current state
    g_psCurrent := PS_Running;

    (*
    // !!!!!!!!!
    // Prepare getting images in higher resolution than video stream
    // See DirectX9 Help "Capturing an Image From a Still Image Pin"
    // Not working yet.....
    pAMVidControl := nil;
    Result := pIBFVideoSource.QueryInterface(IID_IAMVideoControl, pAMVidControl);
    IF succeeded(Result) then
      begin
        pTyp := 0;
        pPin := nil;
        Result := pICapGraphBuild2.FindPin(pIBFVideoSource, PINDIR_OUTPUT, PIN_CATEGORY_STILL, pTyp^, false, 0, pPin);
        if (SUCCEEDED(Result)) then
          Result := pAMVidControl.SetMode(pPin, VideoControlFlag_Trigger);
      end;
    *)
  Dispose(pTyp);
  Dispose(pCut);
end; {RestartVideoEx}