Dim p As New Diagnostics.Process, strInput As String, strOuput As String
        p.StartInfo.RedirectStandardError = True
        strInput = fichero0
        strOuput = Server.MapPath("../Anuncios_publico/") & "ejemplo.mp4"
        p.StartInfo.FileName = Server.MapPath("../Comun/Ffmpeg/ffmpeg.exe")
        p.StartInfo.UseShellExecute = False
        p.StartInfo.Arguments = String.Format("-i ""{0}"" -b 1500k -vcodec libx264  -s 640x360 ""{1}""", strInput, strOuput)
        p.Start()
PS: fichero0 is 'c:\inetpub\wwwroot\fich1.avi