title: using libvlc_video_set_format_callbacks to transcode videos frame by frame
body: <p>I am trying to write a small program in C++ that transcodes a video frame by frame, and I am using the functions libvlc_video_set_callbacks and libvlc_video_set_format_callbacks to achieve this.</p>
  
  <p>The first function works fine, but I am not sure how to implement libvlc_video_set_format_callbacks.</p>
  
  <p>I tried it this way to start with but it gives me an argument error for 'setup':</p>
  
  <pre><code>int setup(void* pUserData, char *chroma, unsigned int *width, unsigned int *height, unsigned int *pitches, unsigned int *lines)
      {
          (void) pUserData;
          return 1;
      }
  
  libvlc_video_set_format_callbacks(mp, setup, cleanup);
  </code></pre>
  
  <p>Next thing is that I don't really know how to set the right video format properties.</p>
  
  <p>Can you please help me with this setup-function or at least point me to an example that shows how to implement it, as I didn't find one?
  As you can imagine, I am not a very experienced programmer so please be patient with me ;)
  Thanks in advance</p>