title: How to calculate the time duration between two unix time stamps in php?
body: <p>I have two time stamps from an API and i wanted to calculate the duration based on that times.</p>
  
  <p>I have streaming which has a start date and an end date as unix time stamp as follows:</p>
  
  <pre><code>"startTime": 1489041394000,
  "endTime": 1489041538000
  </code></pre>
  
  <p>From this times how can i calculate the duration of this video using php?</p>