Question

我使用c＃创建了一个Directshow Filtergraph，但我不知道如何添加一个 WmAsfReader过滤器，可以将视频文件解码为过滤器图形。任何人都可以帮忙，谢谢！

以下代码就是我所做的。

/*MediaUriPlayer*/
protected virtual void OpenSource()
    {
        FrameCount = 0;
        /* Make sure we clean up any remaining mess */
        FreeResources();
        /* make sure source is not null */
        if (m_sourceUri == null)
            return;

        string fileSource = m_sourceUri.OriginalString;

        if (string.IsNullOrEmpty(fileSource))
            return;

        try
        {
            /* Creates the GraphBuilder COM object */
            m_graph = new FilterGraphNoThread() as IGraphBuilder;

            if (m_graph == null)
                throw new Exception("Could not create a graph");


            /* Add our prefered audio renderer */
            InsertAudioRenderer(AudioRenderer);

            var filterGraph = m_graph as IFilterGraph2;

            if (filterGraph == null)
                throw new Exception("Could not QueryInterface for the IFilterGraph2");

            IBaseFilter renderer = CreateVideoMixingRenderer9(m_graph, 1);                                

            IBaseFilter sourceFilter;

            /* Have DirectShow find the correct source filter for the Uri */
            var hr = filterGraph.AddSourceFilter(fileSource, fileSource, out sourceFilter);
            DsError.ThrowExceptionForHR(hr);

            /* We will want to enum all the pins on the source filter */
            IEnumPins pinEnum;

            hr = sourceFilter.EnumPins(out pinEnum);
            DsError.ThrowExceptionForHR(hr);

            IntPtr fetched = IntPtr.Zero;
            IPin[] pins = { null };

            /* Counter for how many pins successfully rendered */
            int pinsRendered = 0;                

            /* Loop over each pin of the source filter */
            while (pinEnum.Next(pins.Length, pins, fetched) == 0)
            {
                if (filterGraph.RenderEx(pins[0],
                                         AMRenderExFlags.RenderToExistingRenderers,
                                         IntPtr.Zero) >= 0)
                pinsRendered++;

                Marshal.ReleaseComObject(pins[0]);
            }

            Marshal.ReleaseComObject(pinEnum);
            Marshal.ReleaseComObject(sourceFilter);

            if (pinsRendered == 0)
                throw new Exception("Could not render any streams from the source Uri");

            /* Configure the graph in the base class */
            SetupFilterGraph(m_graph);

            HasVideo = true;
            /* Sets the NaturalVideoWidth/Height */
            //SetNativePixelSizes(renderer);
        }
        catch (Exception ex)
        {
            /* This exection will happen usually if the media does
             * not exist or could not open due to not having the
             * proper filters installed */
            FreeResources();

            /* Fire our failed event */
            InvokeMediaFailed(new MediaFailedEventArgs(ex.Message, ex));
        }

        InvokeMediaOpened();
    }

现在Directshow Filtergraph没有sourcefilter，我想添加一个WmAsfReader作为sourcefilter，但我不知道如何添加！

Answer 1

...现在Directshow Filtergraph没有sourcefilter，我想添加一个WmAsfReader作为sourcefilter，但我不知道如何添加！

如果没有提及代码整体状况良好，则code snippet会回答您的问题：

  hr = graphBuilder.AddSourceFilter(filename, "Source", out sourceFilter);
  if (hr < 0)
  {
    //if it doesn't work before failing try to load it with the WMV reader
    sourceFilter = (IBaseFilter)new WMAsfReader();
    hr = graphBuilder.AddFilter(sourceFilter, "WM/ASF Reader");
    DsError.ThrowExceptionForHR(hr);

如何使用c＃将一个WmAsfReader过滤器添加到directshow过滤器图中？使用qasf.dll吧？

1 个答案: