title: unrar archive while downloading it
body: <p>I've got a program that downloads part01, then part02 etc of a rar file split across the internet.
  My program downloads part01 first, then part02 and so on.
  After some tests, I found out that using, on example, UnRAR2 for python I can extract the first part of the file (an .avi file) contained in the archive and I'm able to play it for the first minutes. When I add another file it extracts a bit more and so on. What I wonder is: is it possible to make it extract single files WHILE downloading them?
  I'd need it to start extracting part01 without having to wait for it to finish downloading... is that possible?</p>
  
  <p>Thank you very much!</p>
  
  <p>Matteo</p>