title: V4L2 help in camera settings
body: <p>I would like to change iris,exposure time and iso parameter using v4l2 lib in linux. 
  I have never used sth like that until now.<br>
  I found that i have to change this : V4L2_CID_EXPOSURE_AUTO; and i will do that with this part of code:</p>
  
  <pre><code>// open capture
  int descriptor = v4l2_open("/dev/video0", O_RDWR);
  
  // manual exposure control
  v4l2_control c;
  c.id = V4L2_CID_EXPOSURE_AUTO;
  c.value = V4L2_EXPOSURE_MANUAL;
  if(v4l2_ioctl(descriptor, VIDIOC_S_CTRL, &amp;c) == 0)
      cout &lt;&lt; "success";
  </code></pre>
  
  <p>After I would like to change these three camera parameters : iris, exposure time and  iso.</p>
  
  <p>But I cannot find how...</p>