directshow不能播发MP4文件

directshow不能播放MP4文件
这个问题网上有些讨论，但是都不太清楚，哪位高手给个比较详细的答案啊？

THX

附录：一个简单的directshow视频播放程序，可以支持.wmv，.avi等，但是不能播放MP4格式的文件，应该怎么改啊？

#include "stdafx.h"

#include <dshow.h>
void main(void)
{
  IGraphBuilder *pGraph = NULL;
  IMediaControl *pControl = NULL;
  IMediaEvent *pEvent = NULL;

  // Initialize the COM library.
  HRESULT hr = CoInitialize(NULL);
  if (FAILED(hr))
  {
  printf("ERROR - Could not initialize COM library");
  return;
  }

  // Create the filter graph manager and query for interfaces.
  hr = CoCreateInstance(CLSID_FilterGraph, NULL, CLSCTX_INPROC_SERVER, 
  IID_IGraphBuilder, (void **)&pGraph);
  if (FAILED(hr))
  {
  printf("ERROR - Could not create the Filter Graph Manager.");
  return;
  }

  hr = pGraph->QueryInterface(IID_IMediaControl, (void **)&pControl);
  hr = pGraph->QueryInterface(IID_IMediaEvent, (void **)&pEvent);

  // Build the graph. IMPORTANT: Change this string to a file on your system.
  hr = pGraph->RenderFile(L"D:\\VideoProcess\\TestVideo\\C18.mp4", NULL);
  if (SUCCEEDED(hr))
  {
  // Run the graph.
  hr = pControl->Run();
  if (SUCCEEDED(hr))
  {
  // Wait for completion.
  long evCode;
  pEvent->WaitForCompletion(INFINITE, &evCode);

  // Note: Do not use INFINITE in a real application, because it
  // can block indefinitely.
  }
  }
  pControl->Release();
  pEvent->Release();
  pGraph->Release();
  CoUninitialize();
}





[解决办法]
你看看你的filter中有没有解码MP4的，在graph edit中先试试。没有的话在网上下一个filter注册上去再试！