VLC should offer to open .QCP (audio/qcelp) files
Thanks to your great efforts, vlc can play .qcp speech files. But on Kubuntu 12.04 alpha 2, VLC media player 2.0.0 Twoflower (revision 2.0.0-0-g421a4fc) doesn't list them in its Media > Open File... dialog, whether you choose Filter "Media Files" or "Audio Files". The workaround is to use Filter "All Files".
This sounds like ticket #3485 (closed). I don't know if you can add support for a file extension on Linux without it being a known mimetype; (Patterns and Filepattern are deprecated in .desktop files). The XDG mime database doesn't know about qcp files, so I filed https://bugs.freedesktop.org/show_bug.cgi?id=46854