title: Difference between video capture read and grab
body: <p>I'm not doing nothing in particular, but i'm reading the opencv documentation and I can't understand the difference between the method <code>read</code> and <code>grab</code> from the <code>VideoCapture</code>, here this what they do:</p>
  
  <blockquote>
    <p>grab: The methods/functions grab the next frame from video file or
    camera and return true (non-zero) in the case of success.</p>
    
    <p>read: decodes and returns the next video frame.</p>
  </blockquote>
  
  <p>In the two method extract the next frame. what is the difference? <a href="https://docs.opencv.org/2.4/modules/highgui/doc/reading_and_writing_images_and_video.html" rel="noreferrer">Link to the documentation</a></p>