I have downloaded qt-everywhere-opensource-src-5.4.1 and build and installed static. Next i built QMultimedia and installed.
I get "Unknown module(s) in QT: multimedia" from the .pro when including QT += multimedia.
I have QtMultimedia,QtMultimediaQuick_p and QtMultimediaWidgets in /usr/local/Qt-5.4.1/include. Also have mediaservice,playlistformats in /usr/local/Qt-5.4.1/plugins Also have QtMobility,QtMultimediaKit in /usr/include
I am running Ubuntu 15.0
All related issues i've found did not help.
Please run:
afterwards you can install other multimedia packages as needed, but this enables the multimedia in general.