title: Convert 720p Mp4 to 480p with php ffmpeg
body: <p>I need to covert 720p or 1080p video to 480p mp4 video , i found below code </p>
  
  <pre><code>ffmpeg -i input -vf scale=-1:480 -vcodec mpeg4 -qscale 3 output.mp4
  </code></pre>
  
  <p>and please help me , i am unable to give it INPUT VIDEO ex.</p>
  
  <pre><code>$video='/path/to/mp4/video';
  exec('ffmpeg -i $video -vf scale=-1:480 -vcodec mpeg4 -qscale 3 output.mp4');
  </code></pre>
  
  <p>why above code is not working</p>