Comment 29 for bug 807028

Try to install ladpsa plugins like it is aksed even Openshot doesn't need of those. MLT has perhaps need of those.
See here the corresponding thread : http://forum.ubuntu-fr.org/viewtopic.php?id=834251
Shortly, because it is in French , here the good command line :
sudo apt-get install ladspa-sdk
Another thought : What version of ffmpeg are you using ?
More explanations here :
http://openshotusers.com/forum/viewtopic.php?f=12&t=1261
http://openshotusers.com/forum/viewtopic.php?f=12&t=1053