title: Gstreamer AAC -> AAC but changing bitrate
body: <p>I am new with Gstreamer and I have not found on the web any solution to my problem (I only found how to convert from a certain format to another...). I would like to change the bitrate (from a high bitrate to a lower bitrate of course) of an AAC audio file. I am working on Ubuntu and have installed gstreamer-tools and gstreamer0.10-plugins-bad-multiverse to work with AAC format. Can someone give me the pipeline to do so? For example, from a src.aac (112 kbps) to a out.aac (56 kbps).</p>
  
  <p>Thanks a lot.</p>