The QtMultimedia library is not available in Ubuntu. If you’re trying to create in Qt a project that uses it, it will fail with following error:
error: cannot find -lQtMultimedia
To fix it, you have to install qtmobility and use multimedia items from this lib. Install qtmobility-dev and libdeclarative-multimedia. Then remove QT += multimedia from .pro file and add INCLUDEPATH to QtMobility and QtMultimediaKit directories.