Merge commit '5d273d3efac340ef8de445c955ff44c7abed4e8f'

* commit '5d273d3efac340ef8de445c955ff44c7abed4e8f':
  avconv: VAAPI hwcontext initialisation and hwaccel helper

Merged-by: Derek Buitenhuis <derek.buitenhuis@gmail.com>

ffmpeg.c

@@ -4213,6 +4213,8 @@ static int transcode(void)
         }
     }
 
+    av_buffer_unref(&hw_device_ctx);
+
     /* finished ! */
     ret = 0;