title: No decoder available for type 'video/x-h264
body: <p>I am trying to run one of qt sample apps without any modification. It is called <code>player</code> and it is a multimedia widget demonstration. My system is Ubuntu 16.04 64bit. When I try to play a video, I see the following error in the console:</p>
  
  <p><code>No decoder available for type 'video/x-h264</code></p>
  
  <p>Here is the full error after trying two different videos:</p>
  
  <pre><code>Starting /home/aras/Qt5.7.0_Sept2016/Examples/Qt-5.7/multimediawidgets/build-player-Sept2016-Debug/player...
  Warning: "No decoder available for type 'video/x-h264, stream-format=(string)avc, alignment=(string)au, level=(string)3, profile=(string)constrained-baseline, codec_data=(buffer)0142e01eff0100192742e01ea9101405ff2e00d418041adb7a00f480f55ef7c04001000428de09c8, width=(int)640, height=(int)360, framerate=(fraction)2997/125, pixel-aspect-ratio=(fraction)1/1'."
  Warning: "No decoder available for type 'video/x-h264, stream-format=(string)avc, alignment=(string)au, level=(string)3, profile=(string)constrained-baseline, codec_data=(buffer)0142e01eff0100192742e01ea9101405ff2e00d418041adb7a00f480f55ef7c04001000428de09c8, width=(int)640, height=(int)360, framerate=(fraction)2997/125, pixel-aspect-ratio=(fraction)1/1'."
  Warning: "No decoder available for type 'video/x-h264, stream-format=(string)avc, pixel-aspect-ratio=(fraction)1/1, width=(int)1280, height=(int)720, framerate=(fraction)601600/10033'."
  </code></pre>
  
  <p>I have pretty much every package remotely related to gstreamer installed. When I run <code>gst-inspect-1.0</code> I get a lot of output and the last line is:</p>
  
  <p><code>Total count: 241 plugins (1 blacklist entry not shown), 1388 features
  </code></p>
  
  <pre><code>~$ gst-inspect-1.0 |grep x-h264
  typefindfunctions: video/x-h264: h264, x264, 264
  
  :~$ gst-inspect-1.0 avdec_h264
  Factory Details:
    Rank                     primary (256)
    Long-name                libav H.264 / AVC / MPEG-4 AVC / MPEG-4 part 10 decoder
    Klass                    Codec/Decoder/Video
    Description              libav h264 decoder
  </code></pre>
  
  <p>So it looks like to me that everything is installed properly. How come the Qt multimedia example does not work out of the box?</p>