/// <summary>

        /// c#获取Amr文件的时长（毫秒）

        /// </summary>

        /// <param name="fileName">文件路径</param>

        /// <returns></returns>

        private long GetAMRFileDuration(string fileName)

        {

            long duration = ;

            FileStream fs = new FileStream(fileName, FileMode.Open, FileAccess.Read, FileShare.ReadWrite);

            {

                byte[] packed_size = { , , , , , , , , , , , , , , ,  };

                int pos = ;

                pos += ;

                long lenth = fs.Length;

                byte[] toc = new byte[];

                int framecount = ;

                byte ft;

                while (pos < lenth)

                {

                    fs.Seek(pos, SeekOrigin.Begin);

                    if ( != fs.Read(toc, , ))

                    {

                        fs.Close();

                        break;

                    }

                    ft = (byte)((toc[] / ) & 0x0F);

                    pos += packed_size[ft] + ;

                    framecount++;

                }

                duration = framecount * ;

            }

            fs.Close();

            return duration;

        }