ffmpeg taking time to convert video

Question

hello all i am having a video hosting site like youtube where i allow almost all kinds of videos to be uploaded but i would like to convert all the uploaded videos to mp4 format

i can do this and my code is below

  require 'vendor/autoload.php';
        $getEXT_check=substr(@$_FILES['profileimage99']['name'],-3);
        if($getEXT_check !='mp4' || $getEXT_check !='MP4'){
        exec('ffmpeg -i '.$uploadfile.' -f mp4 -s 896x504 '.$new_flv.''); }
        //execute ffmpeg and create thumb
        exec('ffmpeg  -i '.$uploadfile.' -ss 00:00:28.435 -vframes 1  '.$new_image_path);
        $theduration=exec('ffprobe -v error -show_entries format=duration -of default=noprint_wrappers=1:nokey=1 '.$uploadfile.' 2>&1');
        $theduration_val=round($theduration/60, 2);

this code converts the non mp4 videos to mp4 and gets a thumbnail and gets duration correctly but the problem is that the process takes very much time like more than 2-3 hrs if i upload flv or mkv formats of about 100mbs.

please suggest me something better please if you need to see the full page code

Complete Code:

     <?php
    @session_start();
   include "conn.php";
    include "date.php";
   $sid = $_SESSION['id'];
   $ipIP=$_SERVER['REMOTE_ADDR'];
   $uploaddir = "members/$sid/video/";

     //Check the file is of correct format.  
      function checkfile($input){
      $ext = array('mpg', 'wma', 'mov', 'flv', 'mp4', 'avi', 'qt', 'wmv', 'rm', 'mkv', 'MP4','3gp');
      $extfile = substr($input['name'],-4);
      $extfile = explode('.',$extfile);
        $good = array();
      @$extfile = $extfile[1];
     if(in_array($extfile, $ext)){
     $good['safe'] = true;
     $good['ext'] = $extfile;
     }else{
      $good['safe'] = false;
       }
      return $good;
         }
       if($_FILES["profileimage99"]["size"] ==''){
     echo 'No file added';die;
        }
  // if the form was submitted process request if there is a file for uploading
   if(@$_FILES["profileimage99"]["size"] < 102400000000){
   //$live_dir is for videos after converted to mp4
    $live_dir = "mem/$sid/video/";
  //$live_img is for the first frame thumbs.
    $live_img = "mem/$sid/img/";        
    $seed = rand(11111111111193,9999999999999929) * rand(3,9);
    $getEXT=substr(@$_FILES['profileimage99']['name'],-5);
    $upload = $seed.$getEXT;
    $uploadfile = $uploaddir .$upload;        

    $safe_file = checkfile(@$_FILES['profileimage99']);
    if($safe_file['safe'] == 1){
                if (move_uploaded_file(@$_FILES['profileimage99']['tmp_name'], $uploadfile)) {

                $base = basename($uploadfile, $safe_file['ext']);
                $new_file = $base.'mp4';
                $new_image = $base.'jpg';
                $new_image_path = $live_img.$new_image;
                $new_flv = $live_dir.$new_file;

        require 'vendor/autoload.php';
        $getEXT_check=substr(@$_FILES['profileimage99']['name'],-3);
        if($getEXT_check !='mp4' || $getEXT_check !='MP4'){
        exec('ffmpeg -i '.$uploadfile.' -f mp4 -s 896x504 '.$new_flv.''); }
        //execute ffmpeg and create thumb
        exec('ffmpeg  -i '.$uploadfile.' -ss 00:00:28.435 -vframes 1  '.$new_image_path);
        $theduration=exec('ffprobe -v error -show_entries format=duration -of default=noprint_wrappers=1:nokey=1 '.$uploadfile.' 2>&1');
        $theduration_val=round($theduration/60, 2);
    //create query to store video
    if(isset($_POST['title'])){$titlename=$_POST['title'];}else{$titlename='';}
    if(isset($_POST['desc'])){$desc=$_POST['desc'];}else{$desc='';}
    if(isset($_POST['catag'])){$catag=$_POST['catag'];}else{$catag='';}
    if(isset($_POST['channel'])){$channel=$_POST['channel'];}else{$channel='';}
    $dbentry_o=mysqli_query($conn,"insert into vids (uid,chid,ctid,vname,vdisc,duration,time,ip,src,thumb) values ('$sid','$channel','$catag','$titlename','$desc','$theduration_val','$date','$ipIP','$new_file','$new_image')");
    echo "<img src='mem/$sid/img/$new_image' class='The_Append_L_snap'/>";die;
         } else {
                echo "Possible file upload attack!\n";
                print_r($_FILES);
         }

    }else{

         echo 'Invalid File Type Please Try Again. You file must be of type 
         .mpg, .wma, .mov, .flv, .mp4, .avi, .qt, .wmv, .rm'.$_FILES['profileimage99']['name'];

    }
  }else{
 echo 'Please choose a video';die;
  }
  ?>

The issue:
FFmpeg call above takes too much time to convert the video to MP4.

Note:
In the future I will be having a quality selector in my video.js player.

Answer 1

from this article

The general guideline is to use the slowest preset that you have patience for. Current presets in descending order of speed are: ultrafast,superfast, veryfast, faster, fast, medium, slow, slower, veryslow, placebo. The default preset is medium. Ignore placebo as it is not useful (see FAQ). You can see a list of current presets with -preset help (see example below), and what settings they apply with x264 --fullhelp.

you can use -preset ultrafast but be aware of qualality

additional links

https://superuser.com/questions/490683/cheat-sheets-and-presets-settings-that-actually-work-with-ffmpeg-1-0

https://askubuntu.com/questions/352920/fastest-way-to-convert-videos-batch-or-single