.net application returns a connection reset when converting non-wav or non-mp3 files using FFmpeg

I am currently making a .NET application which allows the user to upload an audio file and convert it into an mp3. I am using FFmpeg. It works with .wav and .mp3, but the application returns a "connection was reset" (I use Firefox 4 for testing) when I try to upload formats like .wma or .m4a. Naturally, when I was testing for errors by uploading unsupported files like .jpg it also returned the same thing. The command line argument worked as intended when I did it using cmd.

Here is the code:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Web.UI.HtmlControls;
using S开发者_开发知识库ystem.Diagnostics;
using System.Media;
using System.ComponentModel;
using System.ComponentModel.Design;
using System.Text.RegularExpressions;

namespace AudioConvert
{
    public partial class _Default : System.Web.UI.Page
    {
        Process ffmpeg;
        protected void Page_Load(object sender, EventArgs e)
        {

        }

        protected void btnUpload_Click(object sender, EventArgs e)
        {
            string audio;
            string mp3;

            if (FileUpload1.HasFile)
            {
                FileUpload1.SaveAs(@"\Temp\"+FileUpload1.FileName);
            }

            //FileUpload1.SaveAs(Server.MapPath("") + System.IO.Path.GetFileName(FileUpload1.FileName));
            audio = @"\Temp\"+FileUpload1.FileName; //audio filepath
            mp3 = Page.MapPath("") + "\\Media\\"+FileUpload1.FileName+".mp3";
            ffmpeg = new Process();

            try
            {

                ffmpeg.StartInfo.Arguments = "-y -i \"" + audio + "\" -ab 128k \"" + mp3; //-command line argument, overwrites automatically
                ffmpeg.StartInfo.FileName = Page.MapPath("ffmpeg.exe"); //ffmpeg file location
                ffmpeg.Start();
                ffmpeg.WaitForExit();
                ffmpeg.Close();
            }
            catch
            {
            }
        }
    }
}