title: resize buffer pixel libjpeg c++
body: <p>I have a buffer of pixel (BGRA) of an image in full HD for example (1920x1080). And I would like to scale it in 1280x720.</p>
  
  <p>My buffer is contained in an <code>unsigned char *</code>.
  How to do it with libjpeg in C++ ?</p>