public static extern bool PlayM4_SetSourceBufCallBack(int nPort, uint nThreShold, SOURCEBUFCALLBACKI SourceBufCallBack, uint dwUser, IntPtr pReserved);
public static extern bool PlayM4_SetSourceBufCallBack(int nPort, uint nThreShold, SOURCEBUFCALLBACKI SourceBufCallBack, uint dwUser, IntPtr pReserved);