如何在后台系统中上传视频后形成视频缩略图？（asp）

/// <summary>
/// 生成缩略图
/// </summary>
/// <param name="fileName">原文件</param>
/// <param name="width">宽度</param>
/// <param name="height">高度</param>
private void CreateThumbnailImage(string fileName, string smallPath, int width, int height)
{
//版权信息
string strAdd = "yzmbstudio.vicp.net 雨中漫步工作室 asp程序开发 电教平台";
//生成的缩略图的名字=年月日+文件大小(防止文件名相同)
string newFileName = smallPath;

System.Drawing.Image image, newImage;
//载入原图像
image = System.Drawing.Image.FromFile(Server.MapPath(fileName));
//回调
System.Drawing.Image.GetThumbnailImageAbort callb = new System.Drawing.Image.GetThumbnailImageAbort(callBack);
//生成缩略图
newImage = image.GetThumbnailImage(width, height, callb, new System.IntPtr());