title: How to do Chroma Keying in ios to process a video file using Swift
body: <p>I am working on a video editing application.</p>
  
  <p>I need a function to do chroma keying and replace green background in a video file (not live feed) with an image or another video.</p>
  
  <p>I have looked through the GPUImage framework but it is not suitable for my project as I cannot use third party frameworks for this project so I am wondering if there is another way to accomplish this.</p>
  
  <p>Here are my questions:</p>
  
  <ul>
  <li>Does it need to be done through Shaders in Opengl es? </li>
  <li>Is there another way to access the frames and replace the background  doing chroma keying using the AV Foundation framework?</li>
  </ul>
  
  <p>I am not too versed in Graphics processing so I really appreciate any help.</p>