c# 获取MP3和AMR文件格式的时长

//网上摘录整理
private long GetAMRFileDuration(string fileName)
        {
            long duration = 0;
            FileStream fs = new FileStream(fileName, FileMode.Open, FileAccess.Read, FileShare.ReadWrite);
            {
                byte[] packed_size = new byte[16] { 12, 13, 15, 17, 19, 20, 26, 31, 5, 0, 0, 0, 0, 0, 0, 0 };
                int pos = 0;
                pos += 6;
                long lenth = fs.Length;
                byte[] toc = new byte[1];
                int framecount = 0;
                byte ft;
                while (pos < lenth)
                {
                    fs.Seek(pos, SeekOrigin.Begin);
                    if (1 != fs.Read(toc, 0, 1))
                    {
                        duration = lenth > 0 ? ((lenth - 6) / 650) : 0;
                        fs.Close();
                        break;
                    }
                    ft = (byte)((toc[0] / 8) & 0x0F);
                    pos += packed_size[ft] + 1;
                    framecount++;
                }
                duration = framecount * 20 / 1000;
            }
            fs.Close();
            return duration;
        }


　　　　//添加引用：COM组件的Microsoft Shell Controls And Automation
　　　　//然后引用 using Shell32;
　　　　//如果出现“无法嵌入互操作类型 请改用适用的接口”报错————修改引用里面的shell32属性嵌入互操作类型改为false
        private long GetMP3FileDuration(string fileName)
        {
            ShellClass sh = new ShellClass();
            Folder dir = sh.NameSpace(Path.GetDirectoryName(fileName));
            FolderItem item = dir.ParseName(Path.GetFileName(fileName));
            string str = dir.GetDetailsOf(item, 27); // 获取歌曲时长。

            var matchs = Regex.Match(str, @"(d{2}):(d{2}):(d{2})");
            var hour = nt.PubTool.Comm.ConvertTo.ToInt32(matchs.Groups[1].Value);
            var minute = nt.PubTool.Comm.ConvertTo.ToInt32(matchs.Groups[2].Value);
            var second = nt.PubTool.Comm.ConvertTo.ToInt32(matchs.Groups[3].Value);

            var len = hour * 3600 + minute * 60 + second;
            return len;


        }