title: decode a mp4 video with gstreamer
body: <p>I want to play a mp4 video in Gstreamer, but i got an error with the x264dec which is not found. I wrote this pipeline  </p>
  
  <pre><code>  gst-launch filesrc \
       location=/media/thesis/Gstreamer/pub_Irma.mp4 \
     ! qtdemux name=demux demux. ! queue ! faad \
     ! audioconvert ! audioresample ! autoaudiosink demuxer. \
     ! queue ! x264dec ! ffmpegcolorspace ! autovideosink 
  </code></pre>
  
  <p>After this step, my aim is to generate execution traces of a mp4 video decoding. 
  I don't know where is the problem with x264dec.</p>