title: Split pdf a4 to a5 with a command line tool
body: <p>I'm looking for a free command line tool able to Split a A4 pdf document info a A5 pdf file.</p>
  
  <p>I have already looked at <a href="http://www.pdflabs.com/tools/pdftk-the-pdf-toolkit/" rel="nofollow noreferrer">http://www.pdflabs.com/tools/pdftk-the-pdf-toolkit/</a> But it lacks documentation, so I haven't been able to use it.</p>
  
  <p>My A4 document consist of multiple pages where one side is always empty.
  <img src="https://i.stack.imgur.com/2PAOe.png" alt="Original A4 PDF"> 
  I want to end up with a result like this.
  <img src="https://i.stack.imgur.com/yl29D.png" alt="enter image description here"></p>
  
  <p>A commandline tool would be preferred, but a solution in C# would also be accepted.</p>