为什么IMediaControl播放声音文件没有声音？
m_FilgraphManager = new FilterGraph();
FileInfo fi = new FileInfo(m_FileName);
if (!fi.Exists) return;
m_MediaEventEx = m_FilgraphManager as IMediaEventEx;
m_MediaEventEx.SetNotifyWindow(m_Handle, WM_PlayGRAPHNOTIFY, IntPtr.Zero);
m_MediaControl = m_FilgraphManager as IMediaControl;
m_MediaControl.RenderFile(m_FileName);
int i = m_MediaControl.Run();
FilterState fs = FilterState.Running;
int msTimeout = 50000;
i = m_MediaControl.GetState(msTimeout, out fs);
通过fs 的值发现文件正在播放中（ FilterState.Running），但是就没有声音出来？请大家帮忙看看会是什么原因导致的 --------------------编程问答-------------------- 请各位帮忙看下问题，不胜感激
--------------------编程问答--------------------
音响没插线。补充：.NET技术 , C#
