title: How can I add overlay text on a video, then re-encode it?
body: <p>I want to edit video from my iOS application. I want some text on the source video for language subtitles. I then want to save video with that text overlaid. text not just only display purpose. but when i open edited video it show updated  video.</p>
  
  <p>Is this possible in an iOS application? If so, how?</p>