title: Apply GPUImage filter to part of video
body: <p>I want to add two filters to one video, so half of the screen shows one filter and the other half another filter. But they should be applied to the same video, just on different parts of the screen.</p>
  
  <p>Is it possible to do with GPUImage? If not, what are the alternatives?</p>
  
  <p><a href="https://i.stack.imgur.com/ERbET.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/ERbET.png" alt="enter image description here"></a></p>